Drop OpenSSL 0.9.8 (#2978)

* Drop OpenSSL 0.9.8

* Drop this test, it's not relevant any longer

* unused import

* Remove CRYPTOGRAPHY_ALLOW_OPENSSL_098=1 from our tox

* removed unused code for Cryptography_HAS_PKEY_CTX

* return unused code for _AESCTRCipherContext

* syntax :-(

* remove some unused tests and skips

* remove unused code for Cryptography_HAS_PBKDF2_HMAC

* Revert "return unused code for _AESCTRCipherContext"

This reverts commit 7d149729205aa4c9735eb322414b167a75b302df.

* Remove unused RSA code

* Remove unused test code for conditional bindings

* Remove unused dsa code

* unused import

* Remove unused x509 extension code

* Remove unused EC code

* Attempt to remove unused DER key loading code

* document this

* grammar

* Added back this paragraph

* Update docs

13 files changed, 44 insertions, 394 deletions

diff --git a/.travis.yml b/.travis.yml
index 2945075e..418633cc 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -30,18 +30,6 @@ matrix:
           env: TOXENV=py27 OPENSSL=1.0.0
         - python: 3.5
           env: TOXENV=py35 OPENSSL=1.0.0
-        - python: 2.6
-          env: TOXENV=py26 OPENSSL=0.9.8
-        - python: 2.7
-          env: TOXENV=py27 OPENSSL=0.9.8
-        - python: 3.3
-          env: TOXENV=py33 OPENSSL=0.9.8
-        - python: 3.4
-          env: TOXENV=py34 OPENSSL=0.9.8
-        - python: 3.5
-          env: TOXENV=py35 OPENSSL=0.9.8
-        - python: pypy
-          env: TOXENV=pypy OPENSSL=0.9.8 PYPY_VERSION=5.1
         - python: 2.7
           env: TOXENV=docs
           addons:
diff --git a/docs/faq.rst b/docs/faq.rst
index 76dc4f3d..2ddc5db8 100644
--- a/docs/faq.rst
+++ b/docs/faq.rst
@@ -40,8 +40,8 @@ If you have no other libraries using OpenSSL in your process, or they do not
 appear to be at fault, it's possible that this is a bug in ``cryptography``.
 Please file an `issue`_ with instructions on how to reproduce it.
 
-Importing cryptography causes a ``RuntimeError`` about OpenSSL 0.9.8
---------------------------------------------------------------------
+Installing cryptography with OpenSSL 0.9.8 fails
+------------------------------------------------
 
 The OpenSSL project has dropped support for the 0.9.8 release series. Since it
 is no longer receiving security patches from upstream, ``cryptography`` is also
@@ -49,9 +49,9 @@ dropping support for it. To fix this issue you should upgrade to a newer
 version of OpenSSL (1.0.1 or later). This may require you to upgrade to a newer
 operating system.
 
-For the 1.4 release, you can set the ``CRYPTOGRAPHY_ALLOW_OPENSSL_098``
-environment variable. Please note that this is *temporary* and will be removed
-in ``cryptography`` 1.5.
+In ``cryptography`` 1.4, you can set the ``CRYPTOGRAPHY_ALLOW_OPENSSL_098``
+environment variable. Please note that this is *temporary* and is removed in
+``cryptography`` 1.5.
 
 .. _`NaCl`: https://nacl.cr.yp.to/
 .. _`PyNaCl`: https://pynacl.readthedocs.io
diff --git a/docs/hazmat/backends/openssl.rst b/docs/hazmat/backends/openssl.rst
index f488a8bc..8bc7dac5 100644
--- a/docs/hazmat/backends/openssl.rst
+++ b/docs/hazmat/backends/openssl.rst
@@ -3,9 +3,8 @@
 OpenSSL backend
 ===============
 
-The `OpenSSL`_ C library. Cryptography supports version ``0.9.8e`` (present in
-Red Hat Enterprise Linux 5) and greater. Earlier versions may work but are
-**not tested or supported**.
+The `OpenSSL`_ C library. Cryptography supports OpenSSL version ``1.0.0`` and
+greater.
 
 .. data:: cryptography.hazmat.backends.openssl.backend
 
diff --git a/docs/hazmat/bindings/openssl.rst b/docs/hazmat/bindings/openssl.rst
index 8935093f..8aef4883 100644
--- a/docs/hazmat/bindings/openssl.rst
+++ b/docs/hazmat/bindings/openssl.rst
@@ -6,8 +6,7 @@ OpenSSL binding
 .. currentmodule:: cryptography.hazmat.bindings.openssl.binding
 
 These are `CFFI`_ bindings to the `OpenSSL`_ C library. Cryptography supports
-version ``0.9.8e`` (present in Red Hat Enterprise Linux 5) and greater. Earlier
-versions may work but are **not tested or supported**.
+OpenSSL version ``1.0.0`` and greater.
 
 .. class:: cryptography.hazmat.bindings.openssl.binding.Binding()
 
diff --git a/docs/installation.rst b/docs/installation.rst
index cb876b8f..a2455c24 100644
--- a/docs/installation.rst
+++ b/docs/installation.rst
@@ -13,7 +13,7 @@ Supported platforms
 Currently we test ``cryptography`` on Python 2.6, 2.7, 3.3, 3.4, 3.5, and PyPy
 2.6+ on these operating systems.
 
-* x86-64 CentOS 7.x, 6.4 and CentOS 5.x
+* x86-64 CentOS 7.x, 6.4
 * x86-64 FreeBSD 10
 * OS X 10.11 El Capitan, 10.10 Yosemite, 10.9 Mavericks, 10.8 Mountain Lion,
   and 10.7 Lion
@@ -28,8 +28,6 @@ Currently we test ``cryptography`` on Python 2.6, 2.7, 3.3, 3.4, 3.5, and PyPy
 We test compiling with ``clang`` as well as ``gcc`` and use the following
 OpenSSL releases:
 
-* ``OpenSSL 0.9.8e-fips-rhel5`` (``RHEL/CentOS 5``)
-* ``OpenSSL 0.9.8k``
 * ``OpenSSL 1.0.0-fips`` (``RHEL/CentOS 6.4``)
 * ``OpenSSL 1.0.1``
 * ``OpenSSL 1.0.1e-fips`` (``RHEL/CentOS 7``)
@@ -38,9 +36,8 @@ OpenSSL releases:
 * ``OpenSSL 1.0.2-latest``
 
 .. warning::
-    OpenSSL versions 0.9.8 and 1.0.0 are no longer supported by the OpenSSL
-    project. Cryptography 1.4 has dropped support for OpenSSL 0.9.8, see the
-    :doc:`FAQ </faq>` for more details.
+    OpenSSL 1.0.0 is no longer supported by the OpenSSL project. Cryptography
+    will drop support for it in a future release.
 
 On Windows
 ----------
diff --git a/src/_cffi_src/openssl/evp.py b/src/_cffi_src/openssl/evp.py
index 308e2b3c..62847265 100644
--- a/src/_cffi_src/openssl/evp.py
+++ b/src/_cffi_src/openssl/evp.py
@@ -180,7 +180,7 @@ const long EVP_CTRL_GCM_GET_TAG = -1;
 const long EVP_CTRL_GCM_SET_TAG = -1;
 const long EVP_CTRL_GCM_SET_IVLEN = -1;
 #endif
-#if OPENSSL_VERSION_NUMBER >= 0x10000000L
+
 const long Cryptography_HAS_PBKDF2_HMAC = 1;
 const long Cryptography_HAS_PKEY_CTX = 1;
 
@@ -198,31 +198,7 @@ int Cryptography_EVP_PKEY_decrypt(EVP_PKEY_CTX *ctx, unsigned char *out,
                                   size_t inlen) {
     return EVP_PKEY_decrypt(ctx, out, outlen, in, inlen);
 }
-#else
-const long Cryptography_HAS_PBKDF2_HMAC = 0;
-int (*PKCS5_PBKDF2_HMAC)(const char *, int, const unsigned char *, int, int,
-                         const EVP_MD *, int, unsigned char *) = NULL;
-const long Cryptography_HAS_PKEY_CTX = 0;
-typedef void EVP_PKEY_CTX;
-int (*EVP_PKEY_CTX_set_signature_md)(EVP_PKEY_CTX *, const EVP_MD *) = NULL;
-int (*EVP_PKEY_sign_init)(EVP_PKEY_CTX *) = NULL;
-int (*EVP_PKEY_sign)(EVP_PKEY_CTX *, unsigned char *, size_t *,
-                     const unsigned char *, size_t) = NULL;
-int (*EVP_PKEY_verify_init)(EVP_PKEY_CTX *) = NULL;
-int (*EVP_PKEY_verify)(EVP_PKEY_CTX *, const unsigned char *, size_t,
-                       const unsigned char *, size_t) = NULL;
-EVP_PKEY_CTX *(*EVP_PKEY_CTX_new)(EVP_PKEY *, ENGINE *) = NULL;
-EVP_PKEY_CTX *(*EVP_PKEY_CTX_new_id)(int, ENGINE *) = NULL;
-EVP_PKEY_CTX *(*EVP_PKEY_CTX_dup)(EVP_PKEY_CTX *) = NULL;
-void (*EVP_PKEY_CTX_free)(EVP_PKEY_CTX *) = NULL;
-int (*EVP_PKEY_encrypt_init)(EVP_PKEY_CTX *) = NULL;
-int (*EVP_PKEY_decrypt_init)(EVP_PKEY_CTX *) = NULL;
-int (*Cryptography_EVP_PKEY_encrypt)(EVP_PKEY_CTX *, unsigned char *, size_t *,
-                                     const unsigned char *, size_t) = NULL;
-int (*Cryptography_EVP_PKEY_decrypt)(EVP_PKEY_CTX *, unsigned char *, size_t *,
-                                     const unsigned char *, size_t) = NULL;
-int (*EVP_PKEY_id)(const EVP_PKEY *) = NULL;
-#endif
+
 #ifdef OPENSSL_NO_EC
 int (*EVP_PKEY_assign_EC_KEY)(EVP_PKEY *, EC_KEY *) = NULL;
 EC_KEY *(*EVP_PKEY_get1_EC_KEY)(EVP_PKEY *) = NULL;
diff --git a/src/cryptography/hazmat/backends/openssl/backend.py b/src/cryptography/hazmat/backends/openssl/backend.py
index 9a89ae83..37621b14 100644
--- a/src/cryptography/hazmat/backends/openssl/backend.py
+++ b/src/cryptography/hazmat/backends/openssl/backend.py
@@ -290,50 +290,25 @@ class Backend(object):
             return _CipherContext(self, cipher, mode, _CipherContext._DECRYPT)
 
     def pbkdf2_hmac_supported(self, algorithm):
-        if self._lib.Cryptography_HAS_PBKDF2_HMAC:
-            return self.hmac_supported(algorithm)
-        else:
-            # OpenSSL < 1.0.0 has an explicit PBKDF2-HMAC-SHA1 function,
-            # so if the PBKDF2_HMAC function is missing we only support
-            # SHA1 via PBKDF2_HMAC_SHA1.
-            return isinstance(algorithm, hashes.SHA1)
+        return self.hmac_supported(algorithm)
 
     def derive_pbkdf2_hmac(self, algorithm, length, salt, iterations,
                            key_material):
         buf = self._ffi.new("char[]", length)
-        if self._lib.Cryptography_HAS_PBKDF2_HMAC:
-            evp_md = self._lib.EVP_get_digestbyname(
-                algorithm.name.encode("ascii"))
-            self.openssl_assert(evp_md != self._ffi.NULL)
-            res = self._lib.PKCS5_PBKDF2_HMAC(
-                key_material,
-                len(key_material),
-                salt,
-                len(salt),
-                iterations,
-                evp_md,
-                length,
-                buf
-            )
-            self.openssl_assert(res == 1)
-        else:
-            if not isinstance(algorithm, hashes.SHA1):
-                raise UnsupportedAlgorithm(
-                    "This version of OpenSSL only supports PBKDF2HMAC with "
-                    "SHA1.",
-                    _Reasons.UNSUPPORTED_HASH
-                )
-            res = self._lib.PKCS5_PBKDF2_HMAC_SHA1(
-                key_material,
-                len(key_material),
-                salt,
-                len(salt),
-                iterations,
-                length,
-                buf
-            )
-            self.openssl_assert(res == 1)
-
+        evp_md = self._lib.EVP_get_digestbyname(
+            algorithm.name.encode("ascii"))
+        self.openssl_assert(evp_md != self._ffi.NULL)
+        res = self._lib.PKCS5_PBKDF2_HMAC(
+            key_material,
+            len(key_material),
+            salt,
+            len(salt),
+            iterations,
+            evp_md,
+            length,
+            buf
+        )
+        self.openssl_assert(res == 1)
         return self._ffi.buffer(buf)[:]
 
     def _consume_errors(self):
@@ -617,12 +592,6 @@ class Backend(object):
         if key_size not in (1024, 2048, 3072):
             raise ValueError("Key size must be 1024 or 2048 or 3072 bits.")
 
-        if (self._lib.OPENSSL_VERSION_NUMBER < 0x1000000f and
-                key_size > 1024):
-            raise ValueError(
-                "Key size must be 1024 because OpenSSL < 1.0.0 doesn't "
-                "support larger key sizes.")
-
         ctx = self._lib.DSA_new()
         self.openssl_assert(ctx != self._ffi.NULL)
         ctx = self._ffi.gc(ctx, self._lib.DSA_free)
@@ -731,16 +700,10 @@ class Backend(object):
         return evp_pkey
 
     def dsa_hash_supported(self, algorithm):
-        if self._lib.OPENSSL_VERSION_NUMBER < 0x1000000f:
-            return isinstance(algorithm, hashes.SHA1)
-        else:
-            return self.hash_supported(algorithm)
+        return self.hash_supported(algorithm)
 
     def dsa_parameters_supported(self, p, q, g):
-        if self._lib.OPENSSL_VERSION_NUMBER < 0x1000000f:
-            return utils.bit_length(p) <= 1024 and utils.bit_length(q) <= 160
-        else:
-            return True
+        return True
 
     def cmac_algorithm_supported(self, algorithm):
         return (
@@ -1049,32 +1012,9 @@ class Backend(object):
                 extension.oid.dotted_string.encode("ascii")
             )
             backend.openssl_assert(nid != self._lib.NID_undef)
-            x509_extension = self._lib.X509V3_EXT_i2d(
+            return self._lib.X509V3_EXT_i2d(
                 nid, 1 if extension.critical else 0, ext_struct
             )
-            if (
-                x509_extension == self._ffi.NULL and
-                extension.oid == x509.OID_CERTIFICATE_ISSUER
-            ):
-                # This path exists to support OpenSSL 0.9.8, which does not
-                # know how to encode a CERTIFICATE_ISSUER for CRLs. Once we
-                # drop 0.9.8 support we can remove this.
-                self._consume_errors()
-                pp = backend._ffi.new("unsigned char **")
-                r = self._lib.i2d_GENERAL_NAMES(ext_struct, pp)
-                backend.openssl_assert(r > 0)
-                pp = backend._ffi.gc(
-                    pp,
-                    lambda pointer: backend._lib.OPENSSL_free(pointer[0])
-                )
-                obj = _txt2obj_gc(self, extension.oid.dotted_string)
-                return self._lib.X509_EXTENSION_create_by_OBJ(
-                    self._ffi.NULL,
-                    obj,
-                    1 if extension.critical else 0,
-                    _encode_asn1_str_gc(self, pp[0], r)
-                )
-            return x509_extension
 
     def create_x509_revoked_certificate(self, builder):
         if not isinstance(builder, x509.RevokedCertificateBuilder):
@@ -1142,19 +1082,10 @@ class Backend(object):
     def load_der_private_key(self, data, password):
         # OpenSSL has a function called d2i_AutoPrivateKey that can simplify
         # this. Unfortunately it doesn't properly support PKCS8 on OpenSSL
-        # 0.9.8 so we can't use it. Instead we sequentially try to load it 3
+        # 0.9.8 so we can't use it. Instead we sequentially try to load it 2
         # different ways. First we'll try to load it as a traditional key
         bio_data = self._bytes_to_bio(data)
         key = self._evp_pkey_from_der_traditional_key(bio_data, password)
-        if not key:
-            # Okay so it's not a traditional key. Let's try
-            # PKCS8 unencrypted. OpenSSL 0.9.8 can't load unencrypted
-            # PKCS8 keys using d2i_PKCS8PrivateKey_bio so we do this instead.
-            # Reset the memory BIO so we can read the data again.
-            res = self._lib.BIO_reset(bio_data.bio)
-            self.openssl_assert(res == 1)
-            key = self._evp_pkey_from_der_unencrypted_pkcs8(bio_data, password)
-
         if key:
             return self._evp_pkey_to_private_key(key)
         else:
@@ -1181,24 +1112,6 @@ class Backend(object):
             self._consume_errors()
             return None
 
-    def _evp_pkey_from_der_unencrypted_pkcs8(self, bio_data, password):
-        info = self._lib.d2i_PKCS8_PRIV_KEY_INFO_bio(
-            bio_data.bio, self._ffi.NULL
-        )
-        info = self._ffi.gc(info, self._lib.PKCS8_PRIV_KEY_INFO_free)
-        if info != self._ffi.NULL:
-            key = self._lib.EVP_PKCS82PKEY(info)
-            self.openssl_assert(key != self._ffi.NULL)
-            key = self._ffi.gc(key, self._lib.EVP_PKEY_free)
-            if password is not None:
-                raise TypeError(
-                    "Password was given but private key is not encrypted."
-                )
-            return key
-        else:
-            self._consume_errors()
-            return None
-
     def load_der_public_key(self, data):
         mem_bio = self._bytes_to_bio(data)
         evp_pkey = self._lib.d2i_PUBKEY_bio(mem_bio.bio, self._ffi.NULL)
@@ -1418,13 +1331,6 @@ class Backend(object):
         if not isinstance(signature_algorithm, ec.ECDSA):
             return False
 
-        # Before 0.9.8m OpenSSL can't cope with digests longer than the curve.
-        if (
-            self._lib.OPENSSL_VERSION_NUMBER < 0x009080df and
-            curve.key_size < signature_algorithm.algorithm.digest_size * 8
-        ):
-            return False
-
         return self.elliptic_curve_supported(curve)
 
     def generate_elliptic_curve_private_key(self, curve):
diff --git a/src/cryptography/hazmat/backends/openssl/rsa.py b/src/cryptography/hazmat/backends/openssl/rsa.py
index 10c51fee..e0f2a853 100644
--- a/src/cryptography/hazmat/backends/openssl/rsa.py
+++ b/src/cryptography/hazmat/backends/openssl/rsa.py
@@ -8,7 +8,7 @@ import math
 
 from cryptography import utils
 from cryptography.exceptions import (
-    AlreadyFinalized, InvalidSignature, UnsupportedAlgorithm, _Reasons
+    InvalidSignature, UnsupportedAlgorithm, _Reasons
 )
 from cryptography.hazmat.primitives import hashes
 from cryptography.hazmat.primitives.asymmetric import (
@@ -68,10 +68,7 @@ def _enc_dec_rsa(backend, key, data, padding):
             _Reasons.UNSUPPORTED_PADDING
         )
 
-    if backend._lib.Cryptography_HAS_PKEY_CTX:
-        return _enc_dec_rsa_pkey_ctx(backend, key, data, padding_enum, padding)
-    else:
-        return _enc_dec_rsa_098(backend, key, data, padding_enum)
+    return _enc_dec_rsa_pkey_ctx(backend, key, data, padding_enum, padding)
 
 
 def _enc_dec_rsa_pkey_ctx(backend, key, data, padding_enum, padding):
@@ -118,22 +115,6 @@ def _enc_dec_rsa_pkey_ctx(backend, key, data, padding_enum, padding):
     return backend._ffi.buffer(buf)[:outlen[0]]
 
 
-def _enc_dec_rsa_098(backend, key, data, padding_enum):
-    if isinstance(key, _RSAPublicKey):
-        crypt = backend._lib.RSA_public_encrypt
-    else:
-        crypt = backend._lib.RSA_private_decrypt
-
-    key_size = backend._lib.RSA_size(key._rsa_cdata)
-    backend.openssl_assert(key_size > 0)
-    buf = backend._ffi.new("unsigned char[]", key_size)
-    res = crypt(len(data), data, buf, key._rsa_cdata, padding_enum)
-    if res < 0:
-        _handle_rsa_enc_dec_error(backend, key)
-
-    return backend._ffi.buffer(buf)[:res]
-
-
 def _handle_rsa_enc_dec_error(backend, key):
     errors = backend._consume_errors()
     assert errors
@@ -177,11 +158,8 @@ class _RSASignatureContext(object):
         self._backend.openssl_assert(self._pkey_size > 0)
 
         if isinstance(padding, PKCS1v15):
-            if self._backend._lib.Cryptography_HAS_PKEY_CTX:
-                self._finalize_method = self._finalize_pkey_ctx
-                self._padding_enum = self._backend._lib.RSA_PKCS1_PADDING
-            else:
-                self._finalize_method = self._finalize_pkcs1
+            self._finalize_method = self._finalize_pkey_ctx
+            self._padding_enum = self._backend._lib.RSA_PKCS1_PADDING
         elif isinstance(padding, PSS):
             if not isinstance(padding._mgf, MGF1):
                 raise UnsupportedAlgorithm(
@@ -204,11 +182,8 @@ class _RSASignatureContext(object):
                     _Reasons.UNSUPPORTED_HASH
                 )
 
-            if self._backend._lib.Cryptography_HAS_PKEY_CTX:
-                self._finalize_method = self._finalize_pkey_ctx
-                self._padding_enum = self._backend._lib.RSA_PKCS1_PSS_PADDING
-            else:
-                self._finalize_method = self._finalize_pss
+            self._finalize_method = self._finalize_pkey_ctx
+            self._padding_enum = self._backend._lib.RSA_PKCS1_PSS_PADDING
         else:
             raise UnsupportedAlgorithm(
                 "{0} is not supported by this backend.".format(padding.name),
@@ -297,62 +272,6 @@ class _RSASignatureContext(object):
 
         return self._backend._ffi.buffer(buf)[:]
 
-    def _finalize_pkcs1(self, evp_md):
-        if self._hash_ctx._ctx is None:
-            raise AlreadyFinalized("Context has already been finalized.")
-
-        sig_buf = self._backend._ffi.new("char[]", self._pkey_size)
-        sig_len = self._backend._ffi.new("unsigned int *")
-        res = self._backend._lib.EVP_SignFinal(
-            self._hash_ctx._ctx._ctx,
-            sig_buf,
-            sig_len,
-            self._private_key._evp_pkey
-        )
-        self._hash_ctx.finalize()
-        if res == 0:
-            errors = self._backend._consume_errors()
-            assert errors[0].lib == self._backend._lib.ERR_LIB_RSA
-            assert (errors[0].reason ==
-                    self._backend._lib.RSA_R_DIGEST_TOO_BIG_FOR_RSA_KEY)
-            raise ValueError("Digest too large for key size. Use a larger "
-                             "key.")
-
-        return self._backend._ffi.buffer(sig_buf)[:sig_len[0]]
-
-    def _finalize_pss(self, evp_md):
-        data_to_sign = self._hash_ctx.finalize()
-        padded = self._backend._ffi.new("unsigned char[]", self._pkey_size)
-        res = self._backend._lib.RSA_padding_add_PKCS1_PSS(
-            self._private_key._rsa_cdata,
-            padded,
-            data_to_sign,
-            evp_md,
-            _get_rsa_pss_salt_length(
-                self._padding,
-                self._private_key.key_size,
-                len(data_to_sign)
-            )
-        )
-        if res != 1:
-            errors = self._backend._consume_errors()
-            assert errors[0].lib == self._backend._lib.ERR_LIB_RSA
-            assert (errors[0].reason ==
-                    self._backend._lib.RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE)
-            raise ValueError("Salt length too long for key size. Try using "
-                             "MAX_LENGTH instead.")
-
-        sig_buf = self._backend._ffi.new("char[]", self._pkey_size)
-        sig_len = self._backend._lib.RSA_private_encrypt(
-            self._pkey_size,
-            padded,
-            sig_buf,
-            self._private_key._rsa_cdata,
-            self._backend._lib.RSA_NO_PADDING
-        )
-        self._backend.openssl_assert(sig_len != -1)
-        return self._backend._ffi.buffer(sig_buf)[:sig_len]
-
 
 @utils.register_interface(AsymmetricVerificationContext)
 class _RSAVerificationContext(object):
@@ -370,11 +289,8 @@ class _RSAVerificationContext(object):
         self._backend.openssl_assert(self._pkey_size > 0)
 
         if isinstance(padding, PKCS1v15):
-            if self._backend._lib.Cryptography_HAS_PKEY_CTX:
-                self._verify_method = self._verify_pkey_ctx
-                self._padding_enum = self._backend._lib.RSA_PKCS1_PADDING
-            else:
-                self._verify_method = self._verify_pkcs1
+            self._verify_method = self._verify_pkey_ctx
+            self._padding_enum = self._backend._lib.RSA_PKCS1_PADDING
         elif isinstance(padding, PSS):
             if not isinstance(padding._mgf, MGF1):
                 raise UnsupportedAlgorithm(
@@ -399,11 +315,8 @@ class _RSAVerificationContext(object):
                     _Reasons.UNSUPPORTED_HASH
                 )
 
-            if self._backend._lib.Cryptography_HAS_PKEY_CTX:
-                self._verify_method = self._verify_pkey_ctx
-                self._padding_enum = self._backend._lib.RSA_PKCS1_PSS_PADDING
-            else:
-                self._verify_method = self._verify_pss
+            self._verify_method = self._verify_pkey_ctx
+            self._padding_enum = self._backend._lib.RSA_PKCS1_PSS_PADDING
         else:
             raise UnsupportedAlgorithm(
                 "{0} is not supported by this backend.".format(padding.name),
@@ -479,57 +392,6 @@ class _RSAVerificationContext(object):
             assert errors
             raise InvalidSignature
 
-    def _verify_pkcs1(self, evp_md):
-        if self._hash_ctx._ctx is None:
-            raise AlreadyFinalized("Context has already been finalized.")
-
-        res = self._backend._lib.EVP_VerifyFinal(
-            self._hash_ctx._ctx._ctx,
-            self._signature,
-            len(self._signature),
-            self._public_key._evp_pkey
-        )
-        self._hash_ctx.finalize()
-        # The previous call can return negative numbers in the event of an
-        # error. This is not a signature failure but we need to fail if it
-        # occurs.
-        self._backend.openssl_assert(res >= 0)
-        if res == 0:
-            errors = self._backend._consume_errors()
-            assert errors
-            raise InvalidSignature
-
-    def _verify_pss(self, evp_md):
-        buf = self._backend._ffi.new("unsigned char[]", self._pkey_size)
-        res = self._backend._lib.RSA_public_decrypt(
-            len(self._signature),
-            self._signature,
-            buf,
-            self._public_key._rsa_cdata,
-            self._backend._lib.RSA_NO_PADDING
-        )
-        if res != self._pkey_size:
-            errors = self._backend._consume_errors()
-            assert errors
-            raise InvalidSignature
-
-        data_to_verify = self._hash_ctx.finalize()
-        res = self._backend._lib.RSA_verify_PKCS1_PSS(
-            self._public_key._rsa_cdata,
-            data_to_verify,
-            evp_md,
-            buf,
-            _get_rsa_pss_salt_length(
-                self._padding,
-                self._public_key.key_size,
-                len(data_to_verify)
-            )
-        )
-        if res != 1:
-            errors = self._backend._consume_errors()
-            assert errors
-            raise InvalidSignature
-
 
 @utils.register_interface(RSAPrivateKeyWithSerialization)
 class _RSAPrivateKey(object):
diff --git a/src/cryptography/hazmat/bindings/openssl/_conditional.py b/src/cryptography/hazmat/bindings/openssl/_conditional.py
index 18bb54b6..bdfeca91 100644
--- a/src/cryptography/hazmat/bindings/openssl/_conditional.py
+++ b/src/cryptography/hazmat/bindings/openssl/_conditional.py
@@ -215,27 +215,6 @@ CONDITIONAL_NAMES = {
         "EVP_CTRL_GCM_SET_TAG",
         "EVP_CTRL_GCM_SET_IVLEN",
     ],
-    "Cryptography_HAS_PBKDF2_HMAC": [
-        "PKCS5_PBKDF2_HMAC"
-    ],
-    "Cryptography_HAS_PKEY_CTX": [
-        "EVP_PKEY_CTX_new",
-        "EVP_PKEY_CTX_new_id",
-        "EVP_PKEY_CTX_dup",
-        "EVP_PKEY_CTX_free",
-        "EVP_PKEY_sign",
-        "EVP_PKEY_sign_init",
-        "EVP_PKEY_verify",
-        "EVP_PKEY_verify_init",
-        "Cryptography_EVP_PKEY_encrypt",
-        "EVP_PKEY_encrypt_init",
-        "Cryptography_EVP_PKEY_decrypt",
-        "EVP_PKEY_decrypt_init",
-        "EVP_PKEY_CTX_set_signature_md",
-        "EVP_PKEY_id",
-        "EVP_PKEY_CTX_set_rsa_padding",
-        "EVP_PKEY_CTX_set_rsa_pss_saltlen",
-    ],
     "Cryptography_HAS_ECDSA_SHA2_NIDS": [
         "NID_ecdsa_with_SHA224",
         "NID_ecdsa_with_SHA256",
diff --git a/src/cryptography/hazmat/bindings/openssl/binding.py b/src/cryptography/hazmat/bindings/openssl/binding.py
index 7727ad8d..2b9dca5c 100644
--- a/src/cryptography/hazmat/bindings/openssl/binding.py
+++ b/src/cryptography/hazmat/bindings/openssl/binding.py
@@ -217,21 +217,7 @@ class Binding(object):
 
 
 def _verify_openssl_version(version):
-    if version < 0x10000000:
-        if os.environ.get("CRYPTOGRAPHY_ALLOW_OPENSSL_098"):
-            warnings.warn(
-                "OpenSSL version 0.9.8 is no longer supported by the OpenSSL "
-                "project, please upgrade. The next version of cryptography "
-                "will completely remove support for it.",
-                DeprecationWarning
-            )
-        else:
-            raise RuntimeError(
-                "You are linking against OpenSSL 0.9.8, which is no longer "
-                "support by the OpenSSL project. You need to upgrade to a "
-                "newer version of OpenSSL."
-            )
-    elif version < 0x10001000:
+    if version < 0x10001000:
         warnings.warn(
             "OpenSSL versions less than 1.0.1 are no longer supported by the "
             "OpenSSL project, please upgrade. A future version of "
diff --git a/tests/hazmat/backends/test_openssl.py b/tests/hazmat/backends/test_openssl.py
index 2a49dcbb..a85262dc 100644
--- a/tests/hazmat/backends/test_openssl.py
+++ b/tests/hazmat/backends/test_openssl.py
@@ -142,27 +142,6 @@ class TestOpenSSL(object):
         with pytest.raises(InternalError):
             enc.finalize()
 
-    def test_derive_pbkdf2_raises_unsupported_on_old_openssl(self):
-        if backend.pbkdf2_hmac_supported(hashes.SHA256()):
-            pytest.skip("Requires an older OpenSSL")
-        with raises_unsupported_algorithm(_Reasons.UNSUPPORTED_HASH):
-            backend.derive_pbkdf2_hmac(hashes.SHA256(), 10, b"", 1000, b"")
-
-    @pytest.mark.skipif(
-        backend._lib.OPENSSL_VERSION_NUMBER >= 0x1000000f,
-        reason="Requires an older OpenSSL. Must be < 1.0.0"
-    )
-    def test_large_key_size_on_old_openssl(self):
-        with pytest.raises(ValueError):
-            dsa.generate_parameters(2048, backend=backend)
-
-        with pytest.raises(ValueError):
-            dsa.generate_parameters(3072, backend=backend)
-
-    @pytest.mark.skipif(
-        backend._lib.OPENSSL_VERSION_NUMBER < 0x1000000f,
-        reason="Requires a newer OpenSSL. Must be >= 1.0.0"
-    )
     def test_large_key_size_on_new_openssl(self):
         parameters = dsa.generate_parameters(2048, backend)
         param_num = parameters.parameter_numbers()
@@ -743,10 +722,6 @@ class TestRSAPEMSerialization(object):
 
 
 class TestGOSTCertificate(object):
-    @pytest.mark.skipif(
-        backend._lib.OPENSSL_VERSION_NUMBER < 0x1000000f,
-        reason="Requires a newer OpenSSL. Must be >= 1.0.0"
-    )
     def test_numeric_string_x509_name_entry(self):
         cert = _load_cert(
             os.path.join("x509", "e-trust.ru.der"),
diff --git a/tests/hazmat/bindings/test_openssl.py b/tests/hazmat/bindings/test_openssl.py
index 34c23ab2..41c653b9 100644
--- a/tests/hazmat/bindings/test_openssl.py
+++ b/tests/hazmat/bindings/test_openssl.py
@@ -8,7 +8,7 @@ import pytest
 
 from cryptography.exceptions import InternalError
 from cryptography.hazmat.bindings.openssl.binding import (
-    Binding, _OpenSSLErrorWithText, _openssl_assert, _verify_openssl_version
+    Binding, _OpenSSLErrorWithText, _openssl_assert
 )
 
 
@@ -137,15 +137,6 @@ class TestOpenSSL(object):
 
     def test_conditional_removal(self):
         b = Binding()
-        if b.lib.OPENSSL_VERSION_NUMBER >= 0x10000000:
-            assert b.lib.X509_V_ERR_DIFFERENT_CRL_SCOPE
-            assert b.lib.X509_V_ERR_CRL_PATH_VALIDATION_ERROR
-        else:
-            with pytest.raises(AttributeError):
-                b.lib.X509_V_ERR_DIFFERENT_CRL_SCOPE
-
-            with pytest.raises(AttributeError):
-                b.lib.X509_V_ERR_CRL_PATH_VALIDATION_ERROR
 
         if b.lib.OPENSSL_VERSION_NUMBER >= 0x10001000:
             assert b.lib.CMAC_Init
@@ -175,9 +166,3 @@ class TestOpenSSL(object):
                 b'ex:data not multiple of block length'
             )
         )]
-
-    def test_verify_openssl_version(self, monkeypatch):
-        monkeypatch.delenv("CRYPTOGRAPHY_ALLOW_OPENSSL_098", raising=False)
-        with pytest.raises(RuntimeError):
-            # OpenSSL 0.9.8zg
-            _verify_openssl_version(0x9081DF)
diff --git a/tox.ini b/tox.ini
index c8b3e76a..6650e95e 100644
--- a/tox.ini
+++ b/tox.ini
@@ -7,8 +7,6 @@ deps =
     .[test]
     ./vectors
 passenv = ARCHFLAGS LDFLAGS CFLAGS INCLUDE LIB LD_LIBRARY_PATH USERNAME
-setenv =
-    CRYPTOGRAPHY_ALLOW_OPENSSL_098=1
 commands =
     pip list
     # We use parallel mode and then combine here so that coverage.py will take