Missing optional lib

1 files changed, 2639 insertions, 0 deletions

diff --git a/lib/Python/Lib/OpenSSL/crypto.py b/lib/Python/Lib/OpenSSL/crypto.py
new file mode 100644
index 000000000..50ff74fad
--- /dev/null
+++ b/lib/Python/Lib/OpenSSL/crypto.py
@@ -0,0 +1,2639 @@
+from time import time
+from base64 import b16encode
+from functools import partial
+from operator import __eq__, __ne__, __lt__, __le__, __gt__, __ge__
+from warnings import warn as _warn
+
+from six import (
+    integer_types as _integer_types,
+    text_type as _text_type,
+    PY3 as _PY3)
+
+from OpenSSL._util import (
+    ffi as _ffi,
+    lib as _lib,
+    exception_from_error_queue as _exception_from_error_queue,
+    byte_string as _byte_string,
+    native as _native,
+    UNSPECIFIED as _UNSPECIFIED,
+    text_to_bytes_and_warn as _text_to_bytes_and_warn,
+)
+
+FILETYPE_PEM = _lib.SSL_FILETYPE_PEM
+FILETYPE_ASN1 = _lib.SSL_FILETYPE_ASN1
+
+# TODO This was an API mistake.  OpenSSL has no such constant.
+FILETYPE_TEXT = 2 ** 16 - 1
+
+TYPE_RSA = _lib.EVP_PKEY_RSA
+TYPE_DSA = _lib.EVP_PKEY_DSA
+
+
+
+class Error(Exception):
+    """
+    An error occurred in an `OpenSSL.crypto` API.
+    """
+
+
+_raise_current_error = partial(_exception_from_error_queue, Error)
+
+
+
+def _untested_error(where):
+    """
+    An OpenSSL API failed somehow.  Additionally, the failure which was
+    encountered isn't one that's exercised by the test suite so future behavior
+    of pyOpenSSL is now somewhat less predictable.
+    """
+    raise RuntimeError("Unknown %s failure" % (where,))
+
+
+
+def _new_mem_buf(buffer=None):
+    """
+    Allocate a new OpenSSL memory BIO.
+
+    Arrange for the garbage collector to clean it up automatically.
+
+    :param buffer: None or some bytes to use to put into the BIO so that they
+        can be read out.
+    """
+    if buffer is None:
+        bio = _lib.BIO_new(_lib.BIO_s_mem())
+        free = _lib.BIO_free
+    else:
+        data = _ffi.new("char[]", buffer)
+        bio = _lib.BIO_new_mem_buf(data, len(buffer))
+        # Keep the memory alive as long as the bio is alive!
+        def free(bio, ref=data):
+            return _lib.BIO_free(bio)
+
+    if bio == _ffi.NULL:
+        # TODO: This is untested.
+        _raise_current_error()
+
+    bio = _ffi.gc(bio, free)
+    return bio
+
+
+
+def _bio_to_string(bio):
+    """
+    Copy the contents of an OpenSSL BIO object into a Python byte string.
+    """
+    result_buffer = _ffi.new('char**')
+    buffer_length = _lib.BIO_get_mem_data(bio, result_buffer)
+    return _ffi.buffer(result_buffer[0], buffer_length)[:]
+
+
+
+def _set_asn1_time(boundary, when):
+    """
+    The the time value of an ASN1 time object.
+
+    @param boundary: An ASN1_GENERALIZEDTIME pointer (or an object safely
+        castable to that type) which will have its value set.
+    @param when: A string representation of the desired time value.
+
+    @raise TypeError: If C{when} is not a L{bytes} string.
+    @raise ValueError: If C{when} does not represent a time in the required
+        format.
+    @raise RuntimeError: If the time value cannot be set for some other
+        (unspecified) reason.
+    """
+    if not isinstance(when, bytes):
+        raise TypeError("when must be a byte string")
+
+    set_result = _lib.ASN1_GENERALIZEDTIME_set_string(
+        _ffi.cast('ASN1_GENERALIZEDTIME*', boundary), when)
+    if set_result == 0:
+        dummy = _ffi.gc(_lib.ASN1_STRING_new(), _lib.ASN1_STRING_free)
+        _lib.ASN1_STRING_set(dummy, when, len(when))
+        check_result = _lib.ASN1_GENERALIZEDTIME_check(
+            _ffi.cast('ASN1_GENERALIZEDTIME*', dummy))
+        if not check_result:
+            raise ValueError("Invalid string")
+        else:
+            _untested_error()
+
+
+
+def _get_asn1_time(timestamp):
+    """
+    Retrieve the time value of an ASN1 time object.
+
+    @param timestamp: An ASN1_GENERALIZEDTIME* (or an object safely castable to
+        that type) from which the time value will be retrieved.
+
+    @return: The time value from C{timestamp} as a L{bytes} string in a certain
+        format.  Or C{None} if the object contains no time value.
+    """
+    string_timestamp = _ffi.cast('ASN1_STRING*', timestamp)
+    if _lib.ASN1_STRING_length(string_timestamp) == 0:
+        return None
+    elif _lib.ASN1_STRING_type(string_timestamp) == _lib.V_ASN1_GENERALIZEDTIME:
+        return _ffi.string(_lib.ASN1_STRING_data(string_timestamp))
+    else:
+        generalized_timestamp = _ffi.new("ASN1_GENERALIZEDTIME**")
+        _lib.ASN1_TIME_to_generalizedtime(timestamp, generalized_timestamp)
+        if generalized_timestamp[0] == _ffi.NULL:
+            # This may happen:
+            #   - if timestamp was not an ASN1_TIME
+            #   - if allocating memory for the ASN1_GENERALIZEDTIME failed
+            #   - if a copy of the time data from timestamp cannot be made for
+            #     the newly allocated ASN1_GENERALIZEDTIME
+            #
+            # These are difficult to test.  cffi enforces the ASN1_TIME type.
+            # Memory allocation failures are a pain to trigger
+            # deterministically.
+            _untested_error("ASN1_TIME_to_generalizedtime")
+        else:
+            string_timestamp = _ffi.cast(
+                "ASN1_STRING*", generalized_timestamp[0])
+            string_data = _lib.ASN1_STRING_data(string_timestamp)
+            string_result = _ffi.string(string_data)
+            _lib.ASN1_GENERALIZEDTIME_free(generalized_timestamp[0])
+            return string_result
+
+
+
+class PKey(object):
+    _only_public = False
+    _initialized = True
+
+    def __init__(self):
+        pkey = _lib.EVP_PKEY_new()
+        self._pkey = _ffi.gc(pkey, _lib.EVP_PKEY_free)
+        self._initialized = False
+
+
+    def generate_key(self, type, bits):
+        """
+        Generate a key of a given type, with a given number of a bits
+
+        :param type: The key type (TYPE_RSA or TYPE_DSA)
+        :param bits: The number of bits
+
+        :return: None
+        """
+        if not isinstance(type, int):
+            raise TypeError("type must be an integer")
+
+        if not isinstance(bits, int):
+            raise TypeError("bits must be an integer")
+
+        # TODO Check error return
+        exponent = _lib.BN_new()
+        exponent = _ffi.gc(exponent, _lib.BN_free)
+        _lib.BN_set_word(exponent, _lib.RSA_F4)
+
+        if type == TYPE_RSA:
+            if bits <= 0:
+                raise ValueError("Invalid number of bits")
+
+            rsa = _lib.RSA_new()
+
+            result = _lib.RSA_generate_key_ex(rsa, bits, exponent, _ffi.NULL)
+            if result == 0:
+                # TODO: The test for this case is commented out.  Different
+                # builds of OpenSSL appear to have different failure modes that
+                # make it hard to test.  Visual inspection of the OpenSSL
+                # source reveals that a return value of 0 signals an error.
+                # Manual testing on a particular build of OpenSSL suggests that
+                # this is probably the appropriate way to handle those errors.
+                _raise_current_error()
+
+            result = _lib.EVP_PKEY_assign_RSA(self._pkey, rsa)
+            if not result:
+                # TODO: It appears as though this can fail if an engine is in
+                # use which does not support RSA.
+                _raise_current_error()
+
+        elif type == TYPE_DSA:
+            dsa = _lib.DSA_generate_parameters(
+                bits, _ffi.NULL, 0, _ffi.NULL, _ffi.NULL, _ffi.NULL, _ffi.NULL)
+            if dsa == _ffi.NULL:
+                # TODO: This is untested.
+                _raise_current_error()
+            if not _lib.DSA_generate_key(dsa):
+                # TODO: This is untested.
+                _raise_current_error()
+            if not _lib.EVP_PKEY_assign_DSA(self._pkey, dsa):
+                # TODO: This is untested.
+                _raise_current_error()
+        else:
+            raise Error("No such key type")
+
+        self._initialized = True
+
+
+    def check(self):
+        """
+        Check the consistency of an RSA private key.
+
+        :return: True if key is consistent.
+        :raise Error: if the key is inconsistent.
+        :raise TypeError: if the key is of a type which cannot be checked.
+            Only RSA keys can currently be checked.
+        """
+        if self._only_public:
+            raise TypeError("public key only")
+
+        if _lib.EVP_PKEY_type(self._pkey.type) != _lib.EVP_PKEY_RSA:
+            raise TypeError("key type unsupported")
+
+        rsa = _lib.EVP_PKEY_get1_RSA(self._pkey)
+        rsa = _ffi.gc(rsa, _lib.RSA_free)
+        result = _lib.RSA_check_key(rsa)
+        if result:
+            return True
+        _raise_current_error()
+
+
+    def type(self):
+        """
+        Returns the type of the key
+
+        :return: The type of the key.
+        """
+        return self._pkey.type
+
+
+    def bits(self):
+        """
+        Returns the number of bits of the key
+
+        :return: The number of bits of the key.
+        """
+        return _lib.EVP_PKEY_bits(self._pkey)
+PKeyType = PKey
+
+
+
+class _EllipticCurve(object):
+    """
+    A representation of a supported elliptic curve.
+
+    @cvar _curves: :py:obj:`None` until an attempt is made to load the curves.
+        Thereafter, a :py:type:`set` containing :py:type:`_EllipticCurve`
+        instances each of which represents one curve supported by the system.
+    @type _curves: :py:type:`NoneType` or :py:type:`set`
+    """
+    _curves = None
+
+    if _PY3:
+        # This only necessary on Python 3.  Morever, it is broken on Python 2.
+        def __ne__(self, other):
+            """
+            Implement cooperation with the right-hand side argument of ``!=``.
+
+            Python 3 seems to have dropped this cooperation in this very narrow
+            circumstance.
+            """
+            if isinstance(other, _EllipticCurve):
+                return super(_EllipticCurve, self).__ne__(other)
+            return NotImplemented
+
+
+    @classmethod
+    def _load_elliptic_curves(cls, lib):
+        """
+        Get the curves supported by OpenSSL.
+
+        :param lib: The OpenSSL library binding object.
+
+        :return: A :py:type:`set` of ``cls`` instances giving the names of the
+            elliptic curves the underlying library supports.
+        """
+        if lib.Cryptography_HAS_EC:
+            num_curves = lib.EC_get_builtin_curves(_ffi.NULL, 0)
+            builtin_curves = _ffi.new('EC_builtin_curve[]', num_curves)
+            # The return value on this call should be num_curves again.  We could
+            # check it to make sure but if it *isn't* then.. what could we do?
+            # Abort the whole process, I suppose...?  -exarkun
+            lib.EC_get_builtin_curves(builtin_curves, num_curves)
+            return set(
+                cls.from_nid(lib, c.nid)
+                for c in builtin_curves)
+        return set()
+
+
+    @classmethod
+    def _get_elliptic_curves(cls, lib):
+        """
+        Get, cache, and return the curves supported by OpenSSL.
+
+        :param lib: The OpenSSL library binding object.
+
+        :return: A :py:type:`set` of ``cls`` instances giving the names of the
+            elliptic curves the underlying library supports.
+        """
+        if cls._curves is None:
+            cls._curves = cls._load_elliptic_curves(lib)
+        return cls._curves
+
+
+    @classmethod
+    def from_nid(cls, lib, nid):
+        """
+        Instantiate a new :py:class:`_EllipticCurve` associated with the given
+        OpenSSL NID.
+
+        :param lib: The OpenSSL library binding object.
+
+        :param nid: The OpenSSL NID the resulting curve object will represent.
+            This must be a curve NID (and not, for example, a hash NID) or
+            subsequent operations will fail in unpredictable ways.
+        :type nid: :py:class:`int`
+
+        :return: The curve object.
+        """
+        return cls(lib, nid, _ffi.string(lib.OBJ_nid2sn(nid)).decode("ascii"))
+
+
+    def __init__(self, lib, nid, name):
+        """
+        :param _lib: The :py:mod:`cryptography` binding instance used to
+            interface with OpenSSL.
+
+        :param _nid: The OpenSSL NID identifying the curve this object
+            represents.
+        :type _nid: :py:class:`int`
+
+        :param name: The OpenSSL short name identifying the curve this object
+            represents.
+        :type name: :py:class:`unicode`
+        """
+        self._lib = lib
+        self._nid = nid
+        self.name = name
+
+
+    def __repr__(self):
+        return "<Curve %r>" % (self.name,)
+
+
+    def _to_EC_KEY(self):
+        """
+        Create a new OpenSSL EC_KEY structure initialized to use this curve.
+
+        The structure is automatically garbage collected when the Python object
+        is garbage collected.
+        """
+        key = self._lib.EC_KEY_new_by_curve_name(self._nid)
+        return _ffi.gc(key, _lib.EC_KEY_free)
+
+
+
+def get_elliptic_curves():
+    """
+    Return a set of objects representing the elliptic curves supported in the
+    OpenSSL build in use.
+
+    The curve objects have a :py:class:`unicode` ``name`` attribute by which
+    they identify themselves.
+
+    The curve objects are useful as values for the argument accepted by
+    :py:meth:`Context.set_tmp_ecdh` to specify which elliptical curve should be
+    used for ECDHE key exchange.
+    """
+    return _EllipticCurve._get_elliptic_curves(_lib)
+
+
+
+def get_elliptic_curve(name):
+    """
+    Return a single curve object selected by name.
+
+    See :py:func:`get_elliptic_curves` for information about curve objects.
+
+    :param name: The OpenSSL short name identifying the curve object to
+        retrieve.
+    :type name: :py:class:`unicode`
+
+    If the named curve is not supported then :py:class:`ValueError` is raised.
+    """
+    for curve in get_elliptic_curves():
+        if curve.name == name:
+            return curve
+    raise ValueError("unknown curve name", name)
+
+
+
+class X509Name(object):
+    def __init__(self, name):
+        """
+        Create a new X509Name, copying the given X509Name instance.
+
+        :param name: An X509Name object to copy
+        """
+        name = _lib.X509_NAME_dup(name._name)
+        self._name = _ffi.gc(name, _lib.X509_NAME_free)
+
+
+    def __setattr__(self, name, value):
+        if name.startswith('_'):
+            return super(X509Name, self).__setattr__(name, value)
+
+        # Note: we really do not want str subclasses here, so we do not use
+        # isinstance.
+        if type(name) is not str:
+            raise TypeError("attribute name must be string, not '%.200s'" % (
+                    type(value).__name__,))
+
+        nid = _lib.OBJ_txt2nid(_byte_string(name))
+        if nid == _lib.NID_undef:
+            try:
+                _raise_current_error()
+            except Error:
+                pass
+            raise AttributeError("No such attribute")
+
+        # If there's an old entry for this NID, remove it
+        for i in range(_lib.X509_NAME_entry_count(self._name)):
+            ent = _lib.X509_NAME_get_entry(self._name, i)
+            ent_obj = _lib.X509_NAME_ENTRY_get_object(ent)
+            ent_nid = _lib.OBJ_obj2nid(ent_obj)
+            if nid == ent_nid:
+                ent = _lib.X509_NAME_delete_entry(self._name, i)
+                _lib.X509_NAME_ENTRY_free(ent)
+                break
+
+        if isinstance(value, _text_type):
+            value = value.encode('utf-8')
+
+        add_result = _lib.X509_NAME_add_entry_by_NID(
+            self._name, nid, _lib.MBSTRING_UTF8, value, -1, -1, 0)
+        if not add_result:
+            _raise_current_error()
+
+
+    def __getattr__(self, name):
+        """
+        Find attribute. An X509Name object has the following attributes:
+        countryName (alias C), stateOrProvince (alias ST), locality (alias L),
+        organization (alias O), organizationalUnit (alias OU), commonName (alias
+        CN) and more...
+        """
+        nid = _lib.OBJ_txt2nid(_byte_string(name))
+        if nid == _lib.NID_undef:
+            # This is a bit weird.  OBJ_txt2nid indicated failure, but it seems
+            # a lower level function, a2d_ASN1_OBJECT, also feels the need to
+            # push something onto the error queue.  If we don't clean that up
+            # now, someone else will bump into it later and be quite confused.
+            # See lp#314814.
+            try:
+                _raise_current_error()
+            except Error:
+                pass
+            return super(X509Name, self).__getattr__(name)
+
+        entry_index = _lib.X509_NAME_get_index_by_NID(self._name, nid, -1)
+        if entry_index == -1:
+            return None
+
+        entry = _lib.X509_NAME_get_entry(self._name, entry_index)
+        data = _lib.X509_NAME_ENTRY_get_data(entry)
+
+        result_buffer = _ffi.new("unsigned char**")
+        data_length = _lib.ASN1_STRING_to_UTF8(result_buffer, data)
+        if data_length < 0:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        try:
+            result = _ffi.buffer(result_buffer[0], data_length)[:].decode('utf-8')
+        finally:
+            # XXX untested
+            _lib.OPENSSL_free(result_buffer[0])
+        return result
+
+
+    def _cmp(op):
+        def f(self, other):
+            if not isinstance(other, X509Name):
+                return NotImplemented
+            result = _lib.X509_NAME_cmp(self._name, other._name)
+            return op(result, 0)
+        return f
+
+    __eq__ = _cmp(__eq__)
+    __ne__ = _cmp(__ne__)
+
+    __lt__ = _cmp(__lt__)
+    __le__ = _cmp(__le__)
+
+    __gt__ = _cmp(__gt__)
+    __ge__ = _cmp(__ge__)
+
+    def __repr__(self):
+        """
+        String representation of an X509Name
+        """
+        result_buffer = _ffi.new("char[]", 512);
+        format_result = _lib.X509_NAME_oneline(
+            self._name, result_buffer, len(result_buffer))
+
+        if format_result == _ffi.NULL:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        return "<X509Name object '%s'>" % (
+            _native(_ffi.string(result_buffer)),)
+
+
+    def hash(self):
+        """
+        Return the hash value of this name
+
+        :return: None
+        """
+        return _lib.X509_NAME_hash(self._name)
+
+
+    def der(self):
+        """
+        Return the DER encoding of this name
+
+        :return: A :py:class:`bytes` instance giving the DER encoded form of
+            this name.
+        """
+        result_buffer = _ffi.new('unsigned char**')
+        encode_result = _lib.i2d_X509_NAME(self._name, result_buffer)
+        if encode_result < 0:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        string_result = _ffi.buffer(result_buffer[0], encode_result)[:]
+        _lib.OPENSSL_free(result_buffer[0])
+        return string_result
+
+
+    def get_components(self):
+        """
+        Returns the split-up components of this name.
+
+        :return: List of tuples (name, value).
+        """
+        result = []
+        for i in range(_lib.X509_NAME_entry_count(self._name)):
+            ent = _lib.X509_NAME_get_entry(self._name, i)
+
+            fname = _lib.X509_NAME_ENTRY_get_object(ent)
+            fval = _lib.X509_NAME_ENTRY_get_data(ent)
+
+            nid = _lib.OBJ_obj2nid(fname)
+            name = _lib.OBJ_nid2sn(nid)
+
+            result.append((
+                    _ffi.string(name),
+                    _ffi.string(
+                        _lib.ASN1_STRING_data(fval),
+                        _lib.ASN1_STRING_length(fval))))
+
+        return result
+X509NameType = X509Name
+
+
+class X509Extension(object):
+    def __init__(self, type_name, critical, value, subject=None, issuer=None):
+        """
+        :param typename: The name of the extension to create.
+        :type typename: :py:data:`str`
+
+        :param critical: A flag indicating whether this is a critical extension.
+
+        :param value: The value of the extension.
+        :type value: :py:data:`str`
+
+        :param subject: Optional X509 cert to use as subject.
+        :type subject: :py:class:`X509`
+
+        :param issuer: Optional X509 cert to use as issuer.
+        :type issuer: :py:class:`X509`
+
+        :return: The X509Extension object
+        """
+        ctx = _ffi.new("X509V3_CTX*")
+
+        # A context is necessary for any extension which uses the r2i conversion
+        # method.  That is, X509V3_EXT_nconf may segfault if passed a NULL ctx.
+        # Start off by initializing most of the fields to NULL.
+        _lib.X509V3_set_ctx(ctx, _ffi.NULL, _ffi.NULL, _ffi.NULL, _ffi.NULL, 0)
+
+        # We have no configuration database - but perhaps we should (some
+        # extensions may require it).
+        _lib.X509V3_set_ctx_nodb(ctx)
+
+        # Initialize the subject and issuer, if appropriate.  ctx is a local,
+        # and as far as I can tell none of the X509V3_* APIs invoked here steal
+        # any references, so no need to mess with reference counts or duplicates.
+        if issuer is not None:
+            if not isinstance(issuer, X509):
+                raise TypeError("issuer must be an X509 instance")
+            ctx.issuer_cert = issuer._x509
+        if subject is not None:
+            if not isinstance(subject, X509):
+                raise TypeError("subject must be an X509 instance")
+            ctx.subject_cert = subject._x509
+
+        if critical:
+            # There are other OpenSSL APIs which would let us pass in critical
+            # separately, but they're harder to use, and since value is already
+            # a pile of crappy junk smuggling a ton of utterly important
+            # structured data, what's the point of trying to avoid nasty stuff
+            # with strings? (However, X509V3_EXT_i2d in particular seems like it
+            # would be a better API to invoke.  I do not know where to get the
+            # ext_struc it desires for its last parameter, though.)
+            value = b"critical," + value
+
+        extension = _lib.X509V3_EXT_nconf(_ffi.NULL, ctx, type_name, value)
+        if extension == _ffi.NULL:
+            _raise_current_error()
+        self._extension = _ffi.gc(extension, _lib.X509_EXTENSION_free)
+
+
+    @property
+    def _nid(self):
+        return _lib.OBJ_obj2nid(self._extension.object)
+
+    _prefixes = {
+        _lib.GEN_EMAIL: "email",
+        _lib.GEN_DNS: "DNS",
+        _lib.GEN_URI: "URI",
+        }
+
+    def _subjectAltNameString(self):
+        method = _lib.X509V3_EXT_get(self._extension)
+        if method == _ffi.NULL:
+            # TODO: This is untested.
+            _raise_current_error()
+        payload = self._extension.value.data
+        length = self._extension.value.length
+
+        payloadptr = _ffi.new("unsigned char**")
+        payloadptr[0] = payload
+
+        if method.it != _ffi.NULL:
+            ptr = _lib.ASN1_ITEM_ptr(method.it)
+            data = _lib.ASN1_item_d2i(_ffi.NULL, payloadptr, length, ptr)
+            names = _ffi.cast("GENERAL_NAMES*", data)
+        else:
+            names = _ffi.cast(
+                "GENERAL_NAMES*",
+                method.d2i(_ffi.NULL, payloadptr, length))
+
+        parts = []
+        for i in range(_lib.sk_GENERAL_NAME_num(names)):
+            name = _lib.sk_GENERAL_NAME_value(names, i)
+            try:
+                label = self._prefixes[name.type]
+            except KeyError:
+                bio = _new_mem_buf()
+                _lib.GENERAL_NAME_print(bio, name)
+                parts.append(_native(_bio_to_string(bio)))
+            else:
+                value = _native(
+                    _ffi.buffer(name.d.ia5.data, name.d.ia5.length)[:])
+                parts.append(label + ":" + value)
+        return ", ".join(parts)
+
+
+    def __str__(self):
+        """
+        :return: a nice text representation of the extension
+        """
+        if _lib.NID_subject_alt_name == self._nid:
+            return self._subjectAltNameString()
+
+        bio = _new_mem_buf()
+        print_result = _lib.X509V3_EXT_print(bio, self._extension, 0, 0)
+        if not print_result:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        return _native(_bio_to_string(bio))
+
+
+    def get_critical(self):
+        """
+        Returns the critical field of the X509Extension
+
+        :return: The critical field.
+        """
+        return _lib.X509_EXTENSION_get_critical(self._extension)
+
+
+    def get_short_name(self):
+        """
+        Returns the short version of the type name of the X509Extension
+
+        :return: The short type name.
+        """
+        obj = _lib.X509_EXTENSION_get_object(self._extension)
+        nid = _lib.OBJ_obj2nid(obj)
+        return _ffi.string(_lib.OBJ_nid2sn(nid))
+
+
+    def get_data(self):
+        """
+        Returns the data of the X509Extension
+
+        :return: A :py:data:`str` giving the X509Extension's ASN.1 encoded data.
+        """
+        octet_result = _lib.X509_EXTENSION_get_data(self._extension)
+        string_result = _ffi.cast('ASN1_STRING*', octet_result)
+        char_result = _lib.ASN1_STRING_data(string_result)
+        result_length = _lib.ASN1_STRING_length(string_result)
+        return _ffi.buffer(char_result, result_length)[:]
+
+X509ExtensionType = X509Extension
+
+
+class X509Req(object):
+    def __init__(self):
+        req = _lib.X509_REQ_new()
+        self._req = _ffi.gc(req, _lib.X509_REQ_free)
+
+
+    def set_pubkey(self, pkey):
+        """
+        Set the public key of the certificate request
+
+        :param pkey: The public key to use
+        :return: None
+        """
+        set_result = _lib.X509_REQ_set_pubkey(self._req, pkey._pkey)
+        if not set_result:
+            # TODO: This is untested.
+            _raise_current_error()
+
+
+    def get_pubkey(self):
+        """
+        Get the public key from the certificate request
+
+        :return: The public key
+        """
+        pkey = PKey.__new__(PKey)
+        pkey._pkey = _lib.X509_REQ_get_pubkey(self._req)
+        if pkey._pkey == _ffi.NULL:
+            # TODO: This is untested.
+            _raise_current_error()
+        pkey._pkey = _ffi.gc(pkey._pkey, _lib.EVP_PKEY_free)
+        pkey._only_public = True
+        return pkey
+
+
+    def set_version(self, version):
+        """
+        Set the version subfield (RFC 2459, section 4.1.2.1) of the certificate
+        request.
+
+        :param version: The version number
+        :return: None
+        """
+        set_result = _lib.X509_REQ_set_version(self._req, version)
+        if not set_result:
+            _raise_current_error()
+
+
+    def get_version(self):
+        """
+        Get the version subfield (RFC 2459, section 4.1.2.1) of the certificate
+        request.
+
+        :return: an integer giving the value of the version subfield
+        """
+        return _lib.X509_REQ_get_version(self._req)
+
+
+    def get_subject(self):
+        """
+        Create an X509Name object for the subject of the certificate request
+
+        :return: An X509Name object
+        """
+        name = X509Name.__new__(X509Name)
+        name._name = _lib.X509_REQ_get_subject_name(self._req)
+        if name._name == _ffi.NULL:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        # The name is owned by the X509Req structure.  As long as the X509Name
+        # Python object is alive, keep the X509Req Python object alive.
+        name._owner = self
+
+        return name
+
+
+    def add_extensions(self, extensions):
+        """
+        Add extensions to the request.
+
+        :param extensions: a sequence of X509Extension objects
+        :return: None
+        """
+        stack = _lib.sk_X509_EXTENSION_new_null()
+        if stack == _ffi.NULL:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        stack = _ffi.gc(stack, _lib.sk_X509_EXTENSION_free)
+
+        for ext in extensions:
+            if not isinstance(ext, X509Extension):
+                raise ValueError("One of the elements is not an X509Extension")
+
+            # TODO push can fail (here and elsewhere)
+            _lib.sk_X509_EXTENSION_push(stack, ext._extension)
+
+        add_result = _lib.X509_REQ_add_extensions(self._req, stack)
+        if not add_result:
+            # TODO: This is untested.
+            _raise_current_error()
+
+
+    def get_extensions(self):
+        """
+        Get extensions to the request.
+
+        :return: A :py:class:`list` of :py:class:`X509Extension` objects.
+        """
+        exts = []
+        native_exts_obj = _lib.X509_REQ_get_extensions(self._req)
+        for i in range(_lib.sk_X509_EXTENSION_num(native_exts_obj)):
+            ext = X509Extension.__new__(X509Extension)
+            ext._extension = _lib.sk_X509_EXTENSION_value(native_exts_obj, i)
+            exts.append(ext)
+        return exts
+
+
+    def sign(self, pkey, digest):
+        """
+        Sign the certificate request using the supplied key and digest
+
+        :param pkey: The key to sign with
+        :param digest: The message digest to use
+        :return: None
+        """
+        if pkey._only_public:
+            raise ValueError("Key has only public part")
+
+        if not pkey._initialized:
+            raise ValueError("Key is uninitialized")
+
+        digest_obj = _lib.EVP_get_digestbyname(_byte_string(digest))
+        if digest_obj == _ffi.NULL:
+            raise ValueError("No such digest method")
+
+        sign_result = _lib.X509_REQ_sign(self._req, pkey._pkey, digest_obj)
+        if not sign_result:
+            # TODO: This is untested.
+            _raise_current_error()
+
+
+    def verify(self, pkey):
+        """
+        Verifies a certificate request using the supplied public key
+
+        :param key: a public key
+        :return: True if the signature is correct.
+
+        :raise OpenSSL.crypto.Error: If the signature is invalid or there is a
+            problem verifying the signature.
+        """
+        if not isinstance(pkey, PKey):
+            raise TypeError("pkey must be a PKey instance")
+
+        result = _lib.X509_REQ_verify(self._req, pkey._pkey)
+        if result <= 0:
+            _raise_current_error()
+
+        return result
+
+
+X509ReqType = X509Req
+
+
+
+class X509(object):
+    def __init__(self):
+        # TODO Allocation failure?  And why not __new__ instead of __init__?
+        x509 = _lib.X509_new()
+        self._x509 = _ffi.gc(x509, _lib.X509_free)
+
+
+    def set_version(self, version):
+        """
+        Set version number of the certificate
+
+        :param version: The version number
+        :type version: :py:class:`int`
+
+        :return: None
+        """
+        if not isinstance(version, int):
+            raise TypeError("version must be an integer")
+
+        _lib.X509_set_version(self._x509, version)
+
+
+    def get_version(self):
+        """
+        Return version number of the certificate
+
+        :return: Version number as a Python integer
+        """
+        return _lib.X509_get_version(self._x509)
+
+
+    def get_pubkey(self):
+        """
+        Get the public key of the certificate
+
+        :return: The public key
+        """
+        pkey = PKey.__new__(PKey)
+        pkey._pkey = _lib.X509_get_pubkey(self._x509)
+        if pkey._pkey == _ffi.NULL:
+            _raise_current_error()
+        pkey._pkey = _ffi.gc(pkey._pkey, _lib.EVP_PKEY_free)
+        pkey._only_public = True
+        return pkey
+
+
+    def set_pubkey(self, pkey):
+        """
+        Set the public key of the certificate
+
+        :param pkey: The public key
+
+        :return: None
+        """
+        if not isinstance(pkey, PKey):
+            raise TypeError("pkey must be a PKey instance")
+
+        set_result = _lib.X509_set_pubkey(self._x509, pkey._pkey)
+        if not set_result:
+            _raise_current_error()
+
+
+    def sign(self, pkey, digest):
+        """
+        Sign the certificate using the supplied key and digest
+
+        :param pkey: The key to sign with
+        :param digest: The message digest to use
+        :return: None
+        """
+        if not isinstance(pkey, PKey):
+            raise TypeError("pkey must be a PKey instance")
+
+        if pkey._only_public:
+            raise ValueError("Key only has public part")
+
+        if not pkey._initialized:
+            raise ValueError("Key is uninitialized")
+
+        evp_md = _lib.EVP_get_digestbyname(_byte_string(digest))
+        if evp_md == _ffi.NULL:
+            raise ValueError("No such digest method")
+
+        sign_result = _lib.X509_sign(self._x509, pkey._pkey, evp_md)
+        if not sign_result:
+            _raise_current_error()
+
+
+    def get_signature_algorithm(self):
+        """
+        Retrieve the signature algorithm used in the certificate
+
+        :return: A byte string giving the name of the signature algorithm used in
+                 the certificate.
+        :raise ValueError: If the signature algorithm is undefined.
+        """
+        alg = self._x509.cert_info.signature.algorithm
+        nid = _lib.OBJ_obj2nid(alg)
+        if nid == _lib.NID_undef:
+            raise ValueError("Undefined signature algorithm")
+        return _ffi.string(_lib.OBJ_nid2ln(nid))
+
+
+    def digest(self, digest_name):
+        """
+        Return the digest of the X509 object.
+
+        :param digest_name: The name of the digest algorithm to use.
+        :type digest_name: :py:class:`bytes`
+
+        :return: The digest of the object
+        """
+        digest = _lib.EVP_get_digestbyname(_byte_string(digest_name))
+        if digest == _ffi.NULL:
+            raise ValueError("No such digest method")
+
+        result_buffer = _ffi.new("char[]", _lib.EVP_MAX_MD_SIZE)
+        result_length = _ffi.new("unsigned int[]", 1)
+        result_length[0] = len(result_buffer)
+
+        digest_result = _lib.X509_digest(
+            self._x509, digest, result_buffer, result_length)
+
+        if not digest_result:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        return b":".join([
+                b16encode(ch).upper() for ch
+                in _ffi.buffer(result_buffer, result_length[0])])
+
+
+    def subject_name_hash(self):
+        """
+        Return the hash of the X509 subject.
+
+        :return: The hash of the subject.
+        """
+        return _lib.X509_subject_name_hash(self._x509)
+
+
+    def set_serial_number(self, serial):
+        """
+        Set serial number of the certificate
+
+        :param serial: The serial number
+        :type serial: :py:class:`int`
+
+        :return: None
+        """
+        if not isinstance(serial, _integer_types):
+            raise TypeError("serial must be an integer")
+
+        hex_serial = hex(serial)[2:]
+        if not isinstance(hex_serial, bytes):
+            hex_serial = hex_serial.encode('ascii')
+
+        bignum_serial = _ffi.new("BIGNUM**")
+
+        # BN_hex2bn stores the result in &bignum.  Unless it doesn't feel like
+        # it.  If bignum is still NULL after this call, then the return value is
+        # actually the result.  I hope.  -exarkun
+        small_serial = _lib.BN_hex2bn(bignum_serial, hex_serial)
+
+        if bignum_serial[0] == _ffi.NULL:
+            set_result = _lib.ASN1_INTEGER_set(
+                _lib.X509_get_serialNumber(self._x509), small_serial)
+            if set_result:
+                # TODO Not tested
+                _raise_current_error()
+        else:
+            asn1_serial = _lib.BN_to_ASN1_INTEGER(bignum_serial[0], _ffi.NULL)
+            _lib.BN_free(bignum_serial[0])
+            if asn1_serial == _ffi.NULL:
+                # TODO Not tested
+                _raise_current_error()
+            asn1_serial = _ffi.gc(asn1_serial, _lib.ASN1_INTEGER_free)
+            set_result = _lib.X509_set_serialNumber(self._x509, asn1_serial)
+            if not set_result:
+                # TODO Not tested
+                _raise_current_error()
+
+
+    def get_serial_number(self):
+        """
+        Return serial number of the certificate
+
+        :return: Serial number as a Python integer
+        """
+        asn1_serial = _lib.X509_get_serialNumber(self._x509)
+        bignum_serial = _lib.ASN1_INTEGER_to_BN(asn1_serial, _ffi.NULL)
+        try:
+            hex_serial = _lib.BN_bn2hex(bignum_serial)
+            try:
+                hexstring_serial = _ffi.string(hex_serial)
+                serial = int(hexstring_serial, 16)
+                return serial
+            finally:
+                _lib.OPENSSL_free(hex_serial)
+        finally:
+            _lib.BN_free(bignum_serial)
+
+
+    def gmtime_adj_notAfter(self, amount):
+        """
+        Adjust the time stamp for when the certificate stops being valid
+
+        :param amount: The number of seconds by which to adjust the ending
+                       validity time.
+        :type amount: :py:class:`int`
+
+        :return: None
+        """
+        if not isinstance(amount, int):
+            raise TypeError("amount must be an integer")
+
+        notAfter = _lib.X509_get_notAfter(self._x509)
+        _lib.X509_gmtime_adj(notAfter, amount)
+
+
+    def gmtime_adj_notBefore(self, amount):
+        """
+        Change the timestamp for when the certificate starts being valid to the current
+        time plus an offset.
+
+        :param amount: The number of seconds by which to adjust the starting validity
+                       time.
+        :return: None
+        """
+        if not isinstance(amount, int):
+            raise TypeError("amount must be an integer")
+
+        notBefore = _lib.X509_get_notBefore(self._x509)
+        _lib.X509_gmtime_adj(notBefore, amount)
+
+
+    def has_expired(self):
+        """
+        Check whether the certificate has expired.
+
+        :return: True if the certificate has expired, false otherwise
+        """
+        now = int(time())
+        notAfter = _lib.X509_get_notAfter(self._x509)
+        return _lib.ASN1_UTCTIME_cmp_time_t(
+            _ffi.cast('ASN1_UTCTIME*', notAfter), now) < 0
+
+
+    def _get_boundary_time(self, which):
+        return _get_asn1_time(which(self._x509))
+
+
+    def get_notBefore(self):
+        """
+        Retrieve the time stamp for when the certificate starts being valid
+
+        :return: A string giving the timestamp, in the format::
+
+                         YYYYMMDDhhmmssZ
+                         YYYYMMDDhhmmss+hhmm
+                         YYYYMMDDhhmmss-hhmm
+
+                 or None if there is no value set.
+        """
+        return self._get_boundary_time(_lib.X509_get_notBefore)
+
+
+    def _set_boundary_time(self, which, when):
+        return _set_asn1_time(which(self._x509), when)
+
+
+    def set_notBefore(self, when):
+        """
+        Set the time stamp for when the certificate starts being valid
+
+        :param when: A string giving the timestamp, in the format:
+
+                         YYYYMMDDhhmmssZ
+                         YYYYMMDDhhmmss+hhmm
+                         YYYYMMDDhhmmss-hhmm
+        :type when: :py:class:`bytes`
+
+        :return: None
+        """
+        return self._set_boundary_time(_lib.X509_get_notBefore, when)
+
+
+    def get_notAfter(self):
+        """
+        Retrieve the time stamp for when the certificate stops being valid
+
+        :return: A string giving the timestamp, in the format::
+
+                         YYYYMMDDhhmmssZ
+                         YYYYMMDDhhmmss+hhmm
+                         YYYYMMDDhhmmss-hhmm
+
+                 or None if there is no value set.
+        """
+        return self._get_boundary_time(_lib.X509_get_notAfter)
+
+
+    def set_notAfter(self, when):
+        """
+        Set the time stamp for when the certificate stops being valid
+
+        :param when: A string giving the timestamp, in the format:
+
+                         YYYYMMDDhhmmssZ
+                         YYYYMMDDhhmmss+hhmm
+                         YYYYMMDDhhmmss-hhmm
+        :type when: :py:class:`bytes`
+
+        :return: None
+        """
+        return self._set_boundary_time(_lib.X509_get_notAfter, when)
+
+
+    def _get_name(self, which):
+        name = X509Name.__new__(X509Name)
+        name._name = which(self._x509)
+        if name._name == _ffi.NULL:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        # The name is owned by the X509 structure.  As long as the X509Name
+        # Python object is alive, keep the X509 Python object alive.
+        name._owner = self
+
+        return name
+
+
+    def _set_name(self, which, name):
+        if not isinstance(name, X509Name):
+            raise TypeError("name must be an X509Name")
+        set_result = which(self._x509, name._name)
+        if not set_result:
+            # TODO: This is untested.
+            _raise_current_error()
+
+
+    def get_issuer(self):
+        """
+        Create an X509Name object for the issuer of the certificate
+
+        :return: An X509Name object
+        """
+        return self._get_name(_lib.X509_get_issuer_name)
+
+
+    def set_issuer(self, issuer):
+        """
+        Set the issuer of the certificate
+
+        :param issuer: The issuer name
+        :type issuer: :py:class:`X509Name`
+
+        :return: None
+        """
+        return self._set_name(_lib.X509_set_issuer_name, issuer)
+
+
+    def get_subject(self):
+        """
+        Create an X509Name object for the subject of the certificate
+
+        :return: An X509Name object
+        """
+        return self._get_name(_lib.X509_get_subject_name)
+
+
+    def set_subject(self, subject):
+        """
+        Set the subject of the certificate
+
+        :param subject: The subject name
+        :type subject: :py:class:`X509Name`
+        :return: None
+        """
+        return self._set_name(_lib.X509_set_subject_name, subject)
+
+
+    def get_extension_count(self):
+        """
+        Get the number of extensions on the certificate.
+
+        :return: The number of extensions as an integer.
+        """
+        return _lib.X509_get_ext_count(self._x509)
+
+
+    def add_extensions(self, extensions):
+        """
+        Add extensions to the certificate.
+
+        :param extensions: a sequence of X509Extension objects
+        :return: None
+        """
+        for ext in extensions:
+            if not isinstance(ext, X509Extension):
+                raise ValueError("One of the elements is not an X509Extension")
+
+            add_result = _lib.X509_add_ext(self._x509, ext._extension, -1)
+            if not add_result:
+                _raise_current_error()
+
+
+    def get_extension(self, index):
+        """
+        Get a specific extension of the certificate by index.
+
+        :param index: The index of the extension to retrieve.
+        :return: The X509Extension object at the specified index.
+        """
+        ext = X509Extension.__new__(X509Extension)
+        ext._extension = _lib.X509_get_ext(self._x509, index)
+        if ext._extension == _ffi.NULL:
+            raise IndexError("extension index out of bounds")
+
+        extension = _lib.X509_EXTENSION_dup(ext._extension)
+        ext._extension = _ffi.gc(extension, _lib.X509_EXTENSION_free)
+        return ext
+
+X509Type = X509
+
+
+
+class X509Store(object):
+    def __init__(self):
+        store = _lib.X509_STORE_new()
+        self._store = _ffi.gc(store, _lib.X509_STORE_free)
+
+
+    def add_cert(self, cert):
+        if not isinstance(cert, X509):
+            raise TypeError()
+
+        result = _lib.X509_STORE_add_cert(self._store, cert._x509)
+        if not result:
+            _raise_current_error()
+
+
+X509StoreType = X509Store
+
+
+class X509StoreContextError(Exception):
+    """
+    An error occurred while verifying a certificate using
+    `OpenSSL.X509StoreContext.verify_certificate`.
+
+    :ivar certificate: The certificate which caused verificate failure.
+    :type cert: :class:`X509`
+
+    """
+    def __init__(self, message, certificate):
+        super(X509StoreContextError, self).__init__(message)
+        self.certificate = certificate
+
+
+class X509StoreContext(object):
+    """
+    An X.509 store context.
+
+    An :py:class:`X509StoreContext` is used to define some of the criteria for
+    certificate verification.  The information encapsulated in this object
+    includes, but is not limited to, a set of trusted certificates,
+    verification parameters, and revoked certificates.
+
+    Of these, only the set of trusted certificates is currently exposed.
+
+    :ivar _store_ctx: The underlying X509_STORE_CTX structure used by this
+        instance.  It is dynamically allocated and automatically garbage
+        collected.
+
+    :ivar _store: See the ``store`` ``__init__`` parameter.
+
+    :ivar _cert: See the ``certificate`` ``__init__`` parameter.
+    """
+
+    def __init__(self, store, certificate):
+        """
+        :param X509Store store: The certificates which will be trusted for the
+            purposes of any verifications.
+
+        :param X509 certificate: The certificate to be verified.
+        """
+        store_ctx = _lib.X509_STORE_CTX_new()
+        self._store_ctx = _ffi.gc(store_ctx, _lib.X509_STORE_CTX_free)
+        self._store = store
+        self._cert = certificate
+        # Make the store context available for use after instantiating this
+        # class by initializing it now. Per testing, subsequent calls to
+        # :py:meth:`_init` have no adverse affect.
+        self._init()
+
+
+    def _init(self):
+        """
+        Set up the store context for a subsequent verification operation.
+        """
+        ret = _lib.X509_STORE_CTX_init(self._store_ctx, self._store._store, self._cert._x509, _ffi.NULL)
+        if ret <= 0:
+            _raise_current_error()
+
+
+    def _cleanup(self):
+        """
+        Internally cleans up the store context.
+
+        The store context can then be reused with a new call to
+        :py:meth:`_init`.
+        """
+        _lib.X509_STORE_CTX_cleanup(self._store_ctx)
+
+
+    def _exception_from_context(self):
+        """
+        Convert an OpenSSL native context error failure into a Python
+        exception.
+
+        When a call to native OpenSSL X509_verify_cert fails, additonal information
+        about the failure can be obtained from the store context.
+        """
+        errors = [
+            _lib.X509_STORE_CTX_get_error(self._store_ctx),
+            _lib.X509_STORE_CTX_get_error_depth(self._store_ctx),
+            _native(_ffi.string(_lib.X509_verify_cert_error_string(
+                        _lib.X509_STORE_CTX_get_error(self._store_ctx)))),
+        ]
+        # A context error should always be associated with a certificate, so we
+        # expect this call to never return :class:`None`.
+        _x509 = _lib.X509_STORE_CTX_get_current_cert(self._store_ctx)
+        _cert = _lib.X509_dup(_x509)
+        pycert = X509.__new__(X509)
+        pycert._x509 = _ffi.gc(_cert, _lib.X509_free)
+        return X509StoreContextError(errors, pycert)
+
+
+    def set_store(self, store):
+        """
+        Set the context's trust store.
+
+        :param X509Store store: The certificates which will be trusted for the
+            purposes of any *future* verifications.
+        """
+        self._store = store
+
+
+    def verify_certificate(self):
+        """
+        Verify a certificate in a context.
+
+        :param store_ctx: The :py:class:`X509StoreContext` to verify.
+        :raises: Error
+        """
+        # Always re-initialize the store context in case
+        # :py:meth:`verify_certificate` is called multiple times.
+        self._init()
+        ret = _lib.X509_verify_cert(self._store_ctx)
+        self._cleanup()
+        if ret <= 0:
+            raise self._exception_from_context()
+
+
+
+def load_certificate(type, buffer):
+    """
+    Load a certificate from a buffer
+
+    :param type: The file type (one of FILETYPE_PEM, FILETYPE_ASN1)
+
+    :param buffer: The buffer the certificate is stored in
+    :type buffer: :py:class:`bytes`
+
+    :return: The X509 object
+    """
+    if isinstance(buffer, _text_type):
+        buffer = buffer.encode("ascii")
+
+    bio = _new_mem_buf(buffer)
+
+    if type == FILETYPE_PEM:
+        x509 = _lib.PEM_read_bio_X509(bio, _ffi.NULL, _ffi.NULL, _ffi.NULL)
+    elif type == FILETYPE_ASN1:
+        x509 = _lib.d2i_X509_bio(bio, _ffi.NULL);
+    else:
+        raise ValueError(
+            "type argument must be FILETYPE_PEM or FILETYPE_ASN1")
+
+    if x509 == _ffi.NULL:
+        _raise_current_error()
+
+    cert = X509.__new__(X509)
+    cert._x509 = _ffi.gc(x509, _lib.X509_free)
+    return cert
+
+
+def dump_certificate(type, cert):
+    """
+    Dump a certificate to a buffer
+
+    :param type: The file type (one of FILETYPE_PEM, FILETYPE_ASN1, or
+        FILETYPE_TEXT)
+    :param cert: The certificate to dump
+    :return: The buffer with the dumped certificate in
+    """
+    bio = _new_mem_buf()
+
+    if type == FILETYPE_PEM:
+        result_code = _lib.PEM_write_bio_X509(bio, cert._x509)
+    elif type == FILETYPE_ASN1:
+        result_code = _lib.i2d_X509_bio(bio, cert._x509)
+    elif type == FILETYPE_TEXT:
+        result_code = _lib.X509_print_ex(bio, cert._x509, 0, 0)
+    else:
+        raise ValueError(
+            "type argument must be FILETYPE_PEM, FILETYPE_ASN1, or "
+            "FILETYPE_TEXT")
+
+    return _bio_to_string(bio)
+
+
+
+def dump_privatekey(type, pkey, cipher=None, passphrase=None):
+    """
+    Dump a private key to a buffer
+
+    :param type: The file type (one of FILETYPE_PEM, FILETYPE_ASN1, or
+        FILETYPE_TEXT)
+    :param pkey: The PKey to dump
+    :param cipher: (optional) if encrypted PEM format, the cipher to
+                   use
+    :param passphrase: (optional) if encrypted PEM format, this can be either
+                       the passphrase to use, or a callback for providing the
+                       passphrase.
+    :return: The buffer with the dumped key in
+    :rtype: :py:data:`str`
+    """
+    bio = _new_mem_buf()
+
+    if cipher is not None:
+        if passphrase is None:
+            raise TypeError(
+                "if a value is given for cipher "
+                "one must also be given for passphrase")
+        cipher_obj = _lib.EVP_get_cipherbyname(_byte_string(cipher))
+        if cipher_obj == _ffi.NULL:
+            raise ValueError("Invalid cipher name")
+    else:
+        cipher_obj = _ffi.NULL
+
+    helper = _PassphraseHelper(type, passphrase)
+    if type == FILETYPE_PEM:
+        result_code = _lib.PEM_write_bio_PrivateKey(
+            bio, pkey._pkey, cipher_obj, _ffi.NULL, 0,
+            helper.callback, helper.callback_args)
+        helper.raise_if_problem()
+    elif type == FILETYPE_ASN1:
+        result_code = _lib.i2d_PrivateKey_bio(bio, pkey._pkey)
+    elif type == FILETYPE_TEXT:
+        rsa = _lib.EVP_PKEY_get1_RSA(pkey._pkey)
+        result_code = _lib.RSA_print(bio, rsa, 0)
+        # TODO RSA_free(rsa)?
+    else:
+        raise ValueError(
+            "type argument must be FILETYPE_PEM, FILETYPE_ASN1, or "
+            "FILETYPE_TEXT")
+
+    if result_code == 0:
+        _raise_current_error()
+
+    return _bio_to_string(bio)
+
+
+
+def _X509_REVOKED_dup(original):
+    copy = _lib.X509_REVOKED_new()
+    if copy == _ffi.NULL:
+        # TODO: This is untested.
+        _raise_current_error()
+
+    if original.serialNumber != _ffi.NULL:
+        _lib.ASN1_INTEGER_free(copy.serialNumber)
+        copy.serialNumber = _lib.ASN1_INTEGER_dup(original.serialNumber)
+
+    if original.revocationDate != _ffi.NULL:
+        _lib.ASN1_TIME_free(copy.revocationDate)
+        copy.revocationDate = _lib.M_ASN1_TIME_dup(original.revocationDate)
+
+    if original.extensions != _ffi.NULL:
+        extension_stack = _lib.sk_X509_EXTENSION_new_null()
+        for i in range(_lib.sk_X509_EXTENSION_num(original.extensions)):
+            original_ext = _lib.sk_X509_EXTENSION_value(original.extensions, i)
+            copy_ext = _lib.X509_EXTENSION_dup(original_ext)
+            _lib.sk_X509_EXTENSION_push(extension_stack, copy_ext)
+        copy.extensions = extension_stack
+
+    copy.sequence = original.sequence
+    return copy
+
+
+
+class Revoked(object):
+    # http://www.openssl.org/docs/apps/x509v3_config.html#CRL_distribution_points_
+    # which differs from crl_reasons of crypto/x509v3/v3_enum.c that matches
+    # OCSP_crl_reason_str.  We use the latter, just like the command line
+    # program.
+    _crl_reasons = [
+        b"unspecified",
+        b"keyCompromise",
+        b"CACompromise",
+        b"affiliationChanged",
+        b"superseded",
+        b"cessationOfOperation",
+        b"certificateHold",
+        # b"removeFromCRL",
+        ]
+
+    def __init__(self):
+        revoked = _lib.X509_REVOKED_new()
+        self._revoked = _ffi.gc(revoked, _lib.X509_REVOKED_free)
+
+
+    def set_serial(self, hex_str):
+        """
+        Set the serial number of a revoked Revoked structure
+
+        :param hex_str: The new serial number.
+        :type hex_str: :py:data:`str`
+        :return: None
+        """
+        bignum_serial = _ffi.gc(_lib.BN_new(), _lib.BN_free)
+        bignum_ptr = _ffi.new("BIGNUM**")
+        bignum_ptr[0] = bignum_serial
+        bn_result = _lib.BN_hex2bn(bignum_ptr, hex_str)
+        if not bn_result:
+            raise ValueError("bad hex string")
+
+        asn1_serial = _ffi.gc(
+            _lib.BN_to_ASN1_INTEGER(bignum_serial, _ffi.NULL),
+            _lib.ASN1_INTEGER_free)
+        _lib.X509_REVOKED_set_serialNumber(self._revoked, asn1_serial)
+
+
+    def get_serial(self):
+        """
+        Return the serial number of a Revoked structure
+
+        :return: The serial number as a string
+        """
+        bio = _new_mem_buf()
+
+        result = _lib.i2a_ASN1_INTEGER(bio, self._revoked.serialNumber)
+        if result < 0:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        return _bio_to_string(bio)
+
+
+    def _delete_reason(self):
+        stack = self._revoked.extensions
+        for i in range(_lib.sk_X509_EXTENSION_num(stack)):
+            ext = _lib.sk_X509_EXTENSION_value(stack, i)
+            if _lib.OBJ_obj2nid(ext.object) == _lib.NID_crl_reason:
+                _lib.X509_EXTENSION_free(ext)
+                _lib.sk_X509_EXTENSION_delete(stack, i)
+                break
+
+
+    def set_reason(self, reason):
+        """
+        Set the reason of a Revoked object.
+
+        If :py:data:`reason` is :py:data:`None`, delete the reason instead.
+
+        :param reason: The reason string.
+        :type reason: :py:class:`str` or :py:class:`NoneType`
+        :return: None
+        """
+        if reason is None:
+            self._delete_reason()
+        elif not isinstance(reason, bytes):
+            raise TypeError("reason must be None or a byte string")
+        else:
+            reason = reason.lower().replace(b' ', b'')
+            reason_code = [r.lower() for r in self._crl_reasons].index(reason)
+
+            new_reason_ext = _lib.ASN1_ENUMERATED_new()
+            if new_reason_ext == _ffi.NULL:
+                # TODO: This is untested.
+                _raise_current_error()
+            new_reason_ext = _ffi.gc(new_reason_ext, _lib.ASN1_ENUMERATED_free)
+
+            set_result = _lib.ASN1_ENUMERATED_set(new_reason_ext, reason_code)
+            if set_result == _ffi.NULL:
+                # TODO: This is untested.
+                _raise_current_error()
+
+            self._delete_reason()
+            add_result = _lib.X509_REVOKED_add1_ext_i2d(
+                self._revoked, _lib.NID_crl_reason, new_reason_ext, 0, 0)
+
+            if not add_result:
+                # TODO: This is untested.
+                _raise_current_error()
+
+
+    def get_reason(self):
+        """
+        Return the reason of a Revoked object.
+
+        :return: The reason as a string
+        """
+        extensions = self._revoked.extensions
+        for i in range(_lib.sk_X509_EXTENSION_num(extensions)):
+            ext = _lib.sk_X509_EXTENSION_value(extensions, i)
+            if _lib.OBJ_obj2nid(ext.object) == _lib.NID_crl_reason:
+                bio = _new_mem_buf()
+
+                print_result = _lib.X509V3_EXT_print(bio, ext, 0, 0)
+                if not print_result:
+                    print_result = _lib.M_ASN1_OCTET_STRING_print(bio, ext.value)
+                    if print_result == 0:
+                        # TODO: This is untested.
+                        _raise_current_error()
+
+                return _bio_to_string(bio)
+
+
+    def all_reasons(self):
+        """
+        Return a list of all the supported reason strings.
+
+        :return: A list of reason strings.
+        """
+        return self._crl_reasons[:]
+
+
+    def set_rev_date(self, when):
+        """
+        Set the revocation timestamp
+
+        :param when: A string giving the timestamp, in the format:
+
+                         YYYYMMDDhhmmssZ
+                         YYYYMMDDhhmmss+hhmm
+                         YYYYMMDDhhmmss-hhmm
+
+        :return: None
+        """
+        return _set_asn1_time(self._revoked.revocationDate, when)
+
+
+    def get_rev_date(self):
+        """
+        Retrieve the revocation date
+
+        :return: A string giving the timestamp, in the format:
+
+                         YYYYMMDDhhmmssZ
+                         YYYYMMDDhhmmss+hhmm
+                         YYYYMMDDhhmmss-hhmm
+        """
+        return _get_asn1_time(self._revoked.revocationDate)
+
+
+
+class CRL(object):
+    def __init__(self):
+        """
+        Create a new empty CRL object.
+        """
+        crl = _lib.X509_CRL_new()
+        self._crl = _ffi.gc(crl, _lib.X509_CRL_free)
+
+
+    def get_revoked(self):
+        """
+        Return revoked portion of the CRL structure (by value not reference).
+
+        :return: A tuple of Revoked objects.
+        """
+        results = []
+        revoked_stack = self._crl.crl.revoked
+        for i in range(_lib.sk_X509_REVOKED_num(revoked_stack)):
+            revoked = _lib.sk_X509_REVOKED_value(revoked_stack, i)
+            revoked_copy = _X509_REVOKED_dup(revoked)
+            pyrev = Revoked.__new__(Revoked)
+            pyrev._revoked = _ffi.gc(revoked_copy, _lib.X509_REVOKED_free)
+            results.append(pyrev)
+        if results:
+            return tuple(results)
+
+
+    def add_revoked(self, revoked):
+        """
+        Add a revoked (by value not reference) to the CRL structure
+
+        :param revoked: The new revoked.
+        :type revoked: :class:`X509`
+
+        :return: None
+        """
+        copy = _X509_REVOKED_dup(revoked._revoked)
+        if copy == _ffi.NULL:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        add_result = _lib.X509_CRL_add0_revoked(self._crl, copy)
+        if add_result == 0:
+            # TODO: This is untested.
+            _raise_current_error()
+
+
+    def export(self, cert, key, type=FILETYPE_PEM, days=100,
+               digest=_UNSPECIFIED):
+        """
+        export a CRL as a string
+
+        :param cert: Used to sign CRL.
+        :type cert: :class:`X509`
+
+        :param key: Used to sign CRL.
+        :type key: :class:`PKey`
+
+        :param type: The export format, either :py:data:`FILETYPE_PEM`,
+            :py:data:`FILETYPE_ASN1`, or :py:data:`FILETYPE_TEXT`.
+
+        :param int days: The number of days until the next update of this CRL.
+
+        :param bytes digest: The name of the message digest to use (eg
+            ``b"sha1"``).
+
+        :return: :py:data:`bytes`
+        """
+        if not isinstance(cert, X509):
+            raise TypeError("cert must be an X509 instance")
+        if not isinstance(key, PKey):
+            raise TypeError("key must be a PKey instance")
+        if not isinstance(type, int):
+            raise TypeError("type must be an integer")
+
+        if digest is _UNSPECIFIED:
+            _warn(
+                "The default message digest (md5) is deprecated.  "
+                "Pass the name of a message digest explicitly.",
+                category=DeprecationWarning,
+                stacklevel=2,
+            )
+            digest = b"md5"
+
+        digest_obj = _lib.EVP_get_digestbyname(digest)
+        if digest_obj == _ffi.NULL:
+            raise ValueError("No such digest method")
+
+        bio = _lib.BIO_new(_lib.BIO_s_mem())
+        if bio == _ffi.NULL:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        # A scratch time object to give different values to different CRL fields
+        sometime = _lib.ASN1_TIME_new()
+        if sometime == _ffi.NULL:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        _lib.X509_gmtime_adj(sometime, 0)
+        _lib.X509_CRL_set_lastUpdate(self._crl, sometime)
+
+        _lib.X509_gmtime_adj(sometime, days * 24 * 60 * 60)
+        _lib.X509_CRL_set_nextUpdate(self._crl, sometime)
+
+        _lib.X509_CRL_set_issuer_name(self._crl, _lib.X509_get_subject_name(cert._x509))
+
+        sign_result = _lib.X509_CRL_sign(self._crl, key._pkey, digest_obj)
+        if not sign_result:
+            _raise_current_error()
+
+        if type == FILETYPE_PEM:
+            ret = _lib.PEM_write_bio_X509_CRL(bio, self._crl)
+        elif type == FILETYPE_ASN1:
+            ret = _lib.i2d_X509_CRL_bio(bio, self._crl)
+        elif type == FILETYPE_TEXT:
+            ret = _lib.X509_CRL_print(bio, self._crl)
+        else:
+            raise ValueError(
+                "type argument must be FILETYPE_PEM, FILETYPE_ASN1, or FILETYPE_TEXT")
+
+        if not ret:
+            # TODO: This is untested.
+            _raise_current_error()
+
+        return _bio_to_string(bio)
+CRLType = CRL
+
+
+
+class PKCS7(object):
+    def type_is_signed(self):
+        """
+        Check if this NID_pkcs7_signed object
+
+        :return: True if the PKCS7 is of type signed
+        """
+        if _lib.PKCS7_type_is_signed(self._pkcs7):
+            return True
+        return False
+
+
+    def type_is_enveloped(self):
+        """
+        Check if this NID_pkcs7_enveloped object
+
+        :returns: True if the PKCS7 is of type enveloped
+        """
+        if _lib.PKCS7_type_is_enveloped(self._pkcs7):
+            return True
+        return False
+
+
+    def type_is_signedAndEnveloped(self):
+        """
+        Check if this NID_pkcs7_signedAndEnveloped object
+
+        :returns: True if the PKCS7 is of type signedAndEnveloped
+        """
+        if _lib.PKCS7_type_is_signedAndEnveloped(self._pkcs7):
+            return True
+        return False
+
+
+    def type_is_data(self):
+        """
+        Check if this NID_pkcs7_data object
+
+        :return: True if the PKCS7 is of type data
+        """
+        if _lib.PKCS7_type_is_data(self._pkcs7):
+            return True
+        return False
+
+
+    def get_type_name(self):
+        """
+        Returns the type name of the PKCS7 structure
+
+        :return: A string with the typename
+        """
+        nid = _lib.OBJ_obj2nid(self._pkcs7.type)
+        string_type = _lib.OBJ_nid2sn(nid)
+        return _ffi.string(string_type)
+
+PKCS7Type = PKCS7
+
+
+
+class PKCS12(object):
+    def __init__(self):
+        self._pkey = None
+        self._cert = None
+        self._cacerts = None
+        self._friendlyname = None
+
+
+    def get_certificate(self):
+        """
+        Return certificate portion of the PKCS12 structure
+
+        :return: X509 object containing the certificate
+        """
+        return self._cert
+
+
+    def set_certificate(self, cert):
+        """
+        Replace the certificate portion of the PKCS12 structure
+
+        :param cert: The new certificate.
+        :type cert: :py:class:`X509` or :py:data:`None`
+        :return: None
+        """
+        if not isinstance(cert, X509):
+            raise TypeError("cert must be an X509 instance")
+        self._cert = cert
+
+
+    def get_privatekey(self):
+        """
+        Return private key portion of the PKCS12 structure
+
+        :returns: PKey object containing the private key
+        """
+        return self._pkey
+
+
+    def set_privatekey(self, pkey):
+        """
+        Replace or set the certificate portion of the PKCS12 structure
+
+        :param pkey: The new private key.
+        :type pkey: :py:class:`PKey`
+        :return: None
+        """
+        if not isinstance(pkey, PKey):
+            raise TypeError("pkey must be a PKey instance")
+        self._pkey = pkey
+
+
+    def get_ca_certificates(self):
+        """
+        Return CA certificates within of the PKCS12 object
+
+        :return: A newly created tuple containing the CA certificates in the chain,
+                 if any are present, or None if no CA certificates are present.
+        """
+        if self._cacerts is not None:
+            return tuple(self._cacerts)
+
+
+    def set_ca_certificates(self, cacerts):
+        """
+        Replace or set the CA certificates within the PKCS12 object.
+
+        :param cacerts: The new CA certificates.
+        :type cacerts: :py:data:`None` or an iterable of :py:class:`X509`
+        :return: None
+        """
+        if cacerts is None:
+            self._cacerts = None
+        else:
+            cacerts = list(cacerts)
+            for cert in cacerts:
+                if not isinstance(cert, X509):
+                    raise TypeError("iterable must only contain X509 instances")
+            self._cacerts = cacerts
+
+
+    def set_friendlyname(self, name):
+        """
+        Replace or set the certificate portion of the PKCS12 structure
+
+        :param name: The new friendly name.
+        :type name: :py:class:`bytes`
+        :return: None
+        """
+        if name is None:
+            self._friendlyname = None
+        elif not isinstance(name, bytes):
+            raise TypeError("name must be a byte string or None (not %r)" % (name,))
+        self._friendlyname = name
+
+
+    def get_friendlyname(self):
+        """
+        Return friendly name portion of the PKCS12 structure
+
+        :returns: String containing the friendlyname
+        """
+        return self._friendlyname
+
+
+    def export(self, passphrase=None, iter=2048, maciter=1):
+        """
+        Dump a PKCS12 object as a string.  See also "man PKCS12_create".
+
+        :param passphrase: used to encrypt the PKCS12
+        :type passphrase: :py:data:`bytes`
+
+        :param iter: How many times to repeat the encryption
+        :type iter: :py:data:`int`
+
+        :param maciter: How many times to repeat the MAC
+        :type maciter: :py:data:`int`
+
+        :return: The string containing the PKCS12
+        """
+        passphrase = _text_to_bytes_and_warn("passphrase", passphrase)
+
+        if self._cacerts is None:
+            cacerts = _ffi.NULL
+        else:
+            cacerts = _lib.sk_X509_new_null()
+            cacerts = _ffi.gc(cacerts, _lib.sk_X509_free)
+            for cert in self._cacerts:
+                _lib.sk_X509_push(cacerts, cert._x509)
+
+        if passphrase is None:
+            passphrase = _ffi.NULL
+
+        friendlyname = self._friendlyname
+        if friendlyname is None:
+            friendlyname = _ffi.NULL
+
+        if self._pkey is None:
+            pkey = _ffi.NULL
+        else:
+            pkey = self._pkey._pkey
+
+        if self._cert is None:
+            cert = _ffi.NULL
+        else:
+            cert = self._cert._x509
+
+        pkcs12 = _lib.PKCS12_create(
+            passphrase, friendlyname, pkey, cert, cacerts,
+            _lib.NID_pbe_WithSHA1And3_Key_TripleDES_CBC,
+            _lib.NID_pbe_WithSHA1And3_Key_TripleDES_CBC,
+            iter, maciter, 0)
+        if pkcs12 == _ffi.NULL:
+            _raise_current_error()
+        pkcs12 = _ffi.gc(pkcs12, _lib.PKCS12_free)
+
+        bio = _new_mem_buf()
+        _lib.i2d_PKCS12_bio(bio, pkcs12)
+        return _bio_to_string(bio)
+
+PKCS12Type = PKCS12
+
+
+
+class NetscapeSPKI(object):
+    def __init__(self):
+        spki = _lib.NETSCAPE_SPKI_new()
+        self._spki = _ffi.gc(spki, _lib.NETSCAPE_SPKI_free)
+
+
+    def sign(self, pkey, digest):
+        """
+        Sign the certificate request using the supplied key and digest
+
+        :param pkey: The key to sign with
+        :param digest: The message digest to use
+        :return: None
+        """
+        if pkey._only_public:
+            raise ValueError("Key has only public part")
+
+        if not pkey._initialized:
+            raise ValueError("Key is uninitialized")
+
+        digest_obj = _lib.EVP_get_digestbyname(_byte_string(digest))
+        if digest_obj == _ffi.NULL:
+            raise ValueError("No such digest method")
+
+        sign_result = _lib.NETSCAPE_SPKI_sign(self._spki, pkey._pkey, digest_obj)
+        if not sign_result:
+            # TODO: This is untested.
+            _raise_current_error()
+
+
+    def verify(self, key):
+        """
+        Verifies a certificate request using the supplied public key
+
+        :param key: a public key
+        :return: True if the signature is correct.
+        :raise OpenSSL.crypto.Error: If the signature is invalid or there is a
+            problem verifying the signature.
+        """
+        answer = _lib.NETSCAPE_SPKI_verify(self._spki, key._pkey)
+        if answer <= 0:
+            _raise_current_error()
+        return True
+
+
+    def b64_encode(self):
+        """
+        Generate a base64 encoded string from an SPKI
+
+        :return: The base64 encoded string
+        """
+        encoded = _lib.NETSCAPE_SPKI_b64_encode(self._spki)
+        result = _ffi.string(encoded)
+        _lib.CRYPTO_free(encoded)
+        return result
+
+
+    def get_pubkey(self):
+        """
+        Get the public key of the certificate
+
+        :return: The public key
+        """
+        pkey = PKey.__new__(PKey)
+        pkey._pkey = _lib.NETSCAPE_SPKI_get_pubkey(self._spki)
+        if pkey._pkey == _ffi.NULL:
+            # TODO: This is untested.
+            _raise_current_error()
+        pkey._pkey = _ffi.gc(pkey._pkey, _lib.EVP_PKEY_free)
+        pkey._only_public = True
+        return pkey
+
+
+    def set_pubkey(self, pkey):
+        """
+        Set the public key of the certificate
+
+        :param pkey: The public key
+        :return: None
+        """
+        set_result = _lib.NETSCAPE_SPKI_set_pubkey(self._spki, pkey._pkey)
+        if not set_result:
+            # TODO: This is untested.
+            _raise_current_error()
+NetscapeSPKIType = NetscapeSPKI
+
+
+class _PassphraseHelper(object):
+    def __init__(self, type, passphrase, more_args=False, truncate=False):
+        if type != FILETYPE_PEM and passphrase is not None:
+            raise ValueError("only FILETYPE_PEM key format supports encryption")
+        self._passphrase = passphrase
+        self._more_args = more_args
+        self._truncate = truncate
+        self._problems = []
+
+
+    @property
+    def callback(self):
+        if self._passphrase is None:
+            return _ffi.NULL
+        elif isinstance(self._passphrase, bytes):
+            return _ffi.NULL
+        elif callable(self._passphrase):
+            return _ffi.callback("pem_password_cb", self._read_passphrase)
+        else:
+            raise TypeError("Last argument must be string or callable")
+
+
+    @property
+    def callback_args(self):
+        if self._passphrase is None:
+            return _ffi.NULL
+        elif isinstance(self._passphrase, bytes):
+            return self._passphrase
+        elif callable(self._passphrase):
+            return _ffi.NULL
+        else:
+            raise TypeError("Last argument must be string or callable")
+
+
+    def raise_if_problem(self, exceptionType=Error):
+        try:
+            _exception_from_error_queue(exceptionType)
+        except exceptionType as e:
+            from_queue = e
+        if self._problems:
+            raise self._problems[0]
+        return from_queue
+
+
+    def _read_passphrase(self, buf, size, rwflag, userdata):
+        try:
+            if self._more_args:
+                result = self._passphrase(size, rwflag, userdata)
+            else:
+                result = self._passphrase(rwflag)
+            if not isinstance(result, bytes):
+                raise ValueError("String expected")
+            if len(result) > size:
+                if self._truncate:
+                    result = result[:size]
+                else:
+                    raise ValueError("passphrase returned by callback is too long")
+            for i in range(len(result)):
+                buf[i] = result[i:i + 1]
+            return len(result)
+        except Exception as e:
+            self._problems.append(e)
+            return 0
+
+
+
+def load_privatekey(type, buffer, passphrase=None):
+    """
+    Load a private key from a buffer
+
+    :param type: The file type (one of FILETYPE_PEM, FILETYPE_ASN1)
+    :param buffer: The buffer the key is stored in
+    :param passphrase: (optional) if encrypted PEM format, this can be
+                       either the passphrase to use, or a callback for
+                       providing the passphrase.
+
+    :return: The PKey object
+    """
+    if isinstance(buffer, _text_type):
+        buffer = buffer.encode("ascii")
+
+    bio = _new_mem_buf(buffer)
+
+    helper = _PassphraseHelper(type, passphrase)
+    if type == FILETYPE_PEM:
+        evp_pkey = _lib.PEM_read_bio_PrivateKey(
+            bio, _ffi.NULL, helper.callback, helper.callback_args)
+        helper.raise_if_problem()
+    elif type == FILETYPE_ASN1:
+        evp_pkey = _lib.d2i_PrivateKey_bio(bio, _ffi.NULL)
+    else:
+        raise ValueError("type argument must be FILETYPE_PEM or FILETYPE_ASN1")
+
+    if evp_pkey == _ffi.NULL:
+        _raise_current_error()
+
+    pkey = PKey.__new__(PKey)
+    pkey._pkey = _ffi.gc(evp_pkey, _lib.EVP_PKEY_free)
+    return pkey
+
+
+
+def dump_certificate_request(type, req):
+    """
+    Dump a certificate request to a buffer
+
+    :param type: The file type (one of FILETYPE_PEM, FILETYPE_ASN1)
+    :param req: The certificate request to dump
+    :return: The buffer with the dumped certificate request in
+    """
+    bio = _new_mem_buf()
+
+    if type == FILETYPE_PEM:
+        result_code = _lib.PEM_write_bio_X509_REQ(bio, req._req)
+    elif type == FILETYPE_ASN1:
+        result_code = _lib.i2d_X509_REQ_bio(bio, req._req)
+    elif type == FILETYPE_TEXT:
+        result_code = _lib.X509_REQ_print_ex(bio, req._req, 0, 0)
+    else:
+        raise ValueError("type argument must be FILETYPE_PEM, FILETYPE_ASN1, or FILETYPE_TEXT")
+
+    if result_code == 0:
+        # TODO: This is untested.
+        _raise_current_error()
+
+    return _bio_to_string(bio)
+
+
+
+def load_certificate_request(type, buffer):
+    """
+    Load a certificate request from a buffer
+
+    :param type: The file type (one of FILETYPE_PEM, FILETYPE_ASN1)
+    :param buffer: The buffer the certificate request is stored in
+    :return: The X509Req object
+    """
+    if isinstance(buffer, _text_type):
+        buffer = buffer.encode("ascii")
+
+    bio = _new_mem_buf(buffer)
+
+    if type == FILETYPE_PEM:
+        req = _lib.PEM_read_bio_X509_REQ(bio, _ffi.NULL, _ffi.NULL, _ffi.NULL)
+    elif type == FILETYPE_ASN1:
+        req = _lib.d2i_X509_REQ_bio(bio, _ffi.NULL)
+    else:
+        raise ValueError("type argument must be FILETYPE_PEM or FILETYPE_ASN1")
+
+    if req == _ffi.NULL:
+        # TODO: This is untested.
+        _raise_current_error()
+
+    x509req = X509Req.__new__(X509Req)
+    x509req._req = _ffi.gc(req, _lib.X509_REQ_free)
+    return x509req
+
+
+
+def sign(pkey, data, digest):
+    """
+    Sign data with a digest
+
+    :param pkey: Pkey to sign with
+    :param data: data to be signed
+    :param digest: message digest to use
+    :return: signature
+    """
+    data = _text_to_bytes_and_warn("data", data)
+
+    digest_obj = _lib.EVP_get_digestbyname(_byte_string(digest))
+    if digest_obj == _ffi.NULL:
+        raise ValueError("No such digest method")
+
+    md_ctx = _ffi.new("EVP_MD_CTX*")
+    md_ctx = _ffi.gc(md_ctx, _lib.EVP_MD_CTX_cleanup)
+
+    _lib.EVP_SignInit(md_ctx, digest_obj)
+    _lib.EVP_SignUpdate(md_ctx, data, len(data))
+
+    signature_buffer = _ffi.new("unsigned char[]", 512)
+    signature_length = _ffi.new("unsigned int*")
+    signature_length[0] = len(signature_buffer)
+    final_result = _lib.EVP_SignFinal(
+        md_ctx, signature_buffer, signature_length, pkey._pkey)
+
+    if final_result != 1:
+        # TODO: This is untested.
+        _raise_current_error()
+
+    return _ffi.buffer(signature_buffer, signature_length[0])[:]
+
+
+
+def verify(cert, signature, data, digest):
+    """
+    Verify a signature
+
+    :param cert: signing certificate (X509 object)
+    :param signature: signature returned by sign function
+    :param data: data to be verified
+    :param digest: message digest to use
+    :return: None if the signature is correct, raise exception otherwise
+    """
+    data = _text_to_bytes_and_warn("data", data)
+
+    digest_obj = _lib.EVP_get_digestbyname(_byte_string(digest))
+    if digest_obj == _ffi.NULL:
+        raise ValueError("No such digest method")
+
+    pkey = _lib.X509_get_pubkey(cert._x509)
+    if pkey == _ffi.NULL:
+        # TODO: This is untested.
+        _raise_current_error()
+    pkey = _ffi.gc(pkey, _lib.EVP_PKEY_free)
+
+    md_ctx = _ffi.new("EVP_MD_CTX*")
+    md_ctx = _ffi.gc(md_ctx, _lib.EVP_MD_CTX_cleanup)
+
+    _lib.EVP_VerifyInit(md_ctx, digest_obj)
+    _lib.EVP_VerifyUpdate(md_ctx, data, len(data))
+    verify_result = _lib.EVP_VerifyFinal(md_ctx, signature, len(signature), pkey)
+
+    if verify_result != 1:
+        _raise_current_error()
+
+
+def load_crl(type, buffer):
+    """
+    Load a certificate revocation list from a buffer
+
+    :param type: The file type (one of FILETYPE_PEM, FILETYPE_ASN1)
+    :param buffer: The buffer the CRL is stored in
+
+    :return: The PKey object
+    """
+    if isinstance(buffer, _text_type):
+        buffer = buffer.encode("ascii")
+
+    bio = _new_mem_buf(buffer)
+
+    if type == FILETYPE_PEM:
+        crl = _lib.PEM_read_bio_X509_CRL(bio, _ffi.NULL, _ffi.NULL, _ffi.NULL)
+    elif type == FILETYPE_ASN1:
+        crl = _lib.d2i_X509_CRL_bio(bio, _ffi.NULL)
+    else:
+        raise ValueError("type argument must be FILETYPE_PEM or FILETYPE_ASN1")
+
+    if crl == _ffi.NULL:
+        _raise_current_error()
+
+    result = CRL.__new__(CRL)
+    result._crl = crl
+    return result
+
+
+
+def load_pkcs7_data(type, buffer):
+    """
+    Load pkcs7 data from a buffer
+
+    :param type: The file type (one of FILETYPE_PEM or FILETYPE_ASN1)
+    :param buffer: The buffer with the pkcs7 data.
+    :return: The PKCS7 object
+    """
+    if isinstance(buffer, _text_type):
+        buffer = buffer.encode("ascii")
+
+    bio = _new_mem_buf(buffer)
+
+    if type == FILETYPE_PEM:
+        pkcs7 = _lib.PEM_read_bio_PKCS7(bio, _ffi.NULL, _ffi.NULL, _ffi.NULL)
+    elif type == FILETYPE_ASN1:
+        pkcs7 = _lib.d2i_PKCS7_bio(bio, _ffi.NULL)
+    else:
+        # TODO: This is untested.
+        _raise_current_error()
+        raise ValueError("type argument must be FILETYPE_PEM or FILETYPE_ASN1")
+
+    if pkcs7 == _ffi.NULL:
+        _raise_current_error()
+
+    pypkcs7 = PKCS7.__new__(PKCS7)
+    pypkcs7._pkcs7 = _ffi.gc(pkcs7, _lib.PKCS7_free)
+    return pypkcs7
+
+
+
+def load_pkcs12(buffer, passphrase=None):
+    """
+    Load a PKCS12 object from a buffer
+
+    :param buffer: The buffer the certificate is stored in
+    :param passphrase: (Optional) The password to decrypt the PKCS12 lump
+    :returns: The PKCS12 object
+    """
+    passphrase = _text_to_bytes_and_warn("passphrase", passphrase)
+
+    if isinstance(buffer, _text_type):
+        buffer = buffer.encode("ascii")
+
+    bio = _new_mem_buf(buffer)
+
+    # Use null passphrase if passphrase is None or empty string. With PKCS#12
+    # password based encryption no password and a zero length password are two
+    # different things, but OpenSSL implementation will try both to figure out
+    # which one works.
+    if not passphrase:
+        passphrase = _ffi.NULL
+
+    p12 = _lib.d2i_PKCS12_bio(bio, _ffi.NULL)
+    if p12 == _ffi.NULL:
+        _raise_current_error()
+    p12 = _ffi.gc(p12, _lib.PKCS12_free)
+
+    pkey = _ffi.new("EVP_PKEY**")
+    cert = _ffi.new("X509**")
+    cacerts = _ffi.new("Cryptography_STACK_OF_X509**")
+
+    parse_result = _lib.PKCS12_parse(p12, passphrase, pkey, cert, cacerts)
+    if not parse_result:
+        _raise_current_error()
+
+    cacerts = _ffi.gc(cacerts[0], _lib.sk_X509_free)
+
+    # openssl 1.0.0 sometimes leaves an X509_check_private_key error in the
+    # queue for no particular reason.  This error isn't interesting to anyone
+    # outside this function.  It's not even interesting to us.  Get rid of it.
+    try:
+        _raise_current_error()
+    except Error:
+        pass
+
+    if pkey[0] == _ffi.NULL:
+        pykey = None
+    else:
+        pykey = PKey.__new__(PKey)
+        pykey._pkey = _ffi.gc(pkey[0], _lib.EVP_PKEY_free)
+
+    if cert[0] == _ffi.NULL:
+        pycert = None
+        friendlyname = None
+    else:
+        pycert = X509.__new__(X509)
+        pycert._x509 = _ffi.gc(cert[0], _lib.X509_free)
+
+        friendlyname_length = _ffi.new("int*")
+        friendlyname_buffer = _lib.X509_alias_get0(cert[0], friendlyname_length)
+        friendlyname = _ffi.buffer(friendlyname_buffer, friendlyname_length[0])[:]
+        if friendlyname_buffer == _ffi.NULL:
+            friendlyname = None
+
+    pycacerts = []
+    for i in range(_lib.sk_X509_num(cacerts)):
+        pycacert = X509.__new__(X509)
+        pycacert._x509 = _lib.sk_X509_value(cacerts, i)
+        pycacerts.append(pycacert)
+    if not pycacerts:
+        pycacerts = None
+
+    pkcs12 = PKCS12.__new__(PKCS12)
+    pkcs12._pkey = pykey
+    pkcs12._cert = pycert
+    pkcs12._cacerts = pycacerts
+    pkcs12._friendlyname = friendlyname
+    return pkcs12
+
+
+def _initialize_openssl_threads(get_ident, Lock):
+    import _ssl
+    return
+
+    locks = list(Lock() for n in range(_lib.CRYPTO_num_locks()))
+
+    def locking_function(mode, index, filename, line):
+        if mode & _lib.CRYPTO_LOCK:
+            locks[index].acquire()
+        else:
+            locks[index].release()
+
+    _lib.CRYPTO_set_id_callback(
+        _ffi.callback("unsigned long (*)(void)", get_ident))
+
+    _lib.CRYPTO_set_locking_callback(
+        _ffi.callback(
+            "void (*)(int, int, const char*, int)", locking_function))
+
+
+try:
+    from thread import get_ident
+    from threading import Lock
+except ImportError:
+    pass
+else:
+    _initialize_openssl_threads(get_ident, Lock)
+    del get_ident, Lock
+
+# There are no direct unit tests for this initialization.  It is tested
+# indirectly since it is necessary for functions like dump_privatekey when
+# using encryption.
+#
+# Thus OpenSSL.test.test_crypto.FunctionTests.test_dump_privatekey_passphrase
+# and some other similar tests may fail without this (though they may not if
+# the Python runtime has already done some initialization of the underlying
+# OpenSSL library (and is linked against the same one that cryptography is
+# using)).
+_lib.OpenSSL_add_all_algorithms()
+
+# This is similar but exercised mainly by exception_from_error_queue.  It calls
+# both ERR_load_crypto_strings() and ERR_load_SSL_strings().
+_lib.SSL_load_error_strings()