From 3e357f704008f38261aee011a9fe674dc43cc0ae Mon Sep 17 00:00:00 2001 From: Paul Kehrer Date: Fri, 9 Jun 2017 02:31:30 -1000 Subject: X25519 Support (#3686) * early days * sort of working * more things * remove private_bytes * public bytes, interface fix * load public keys * x25519 support basically done now * private_bytes is gone * some reminders * doctest this too * remove a thing that doesn't matter * x25519 supported checks * libressl has the NID, but a different API, so check for OpenSSL * pep8 * add missing coverage * update to use reasons * expand test a little * add changelog entry * review feedback --- .../hazmat/backends/openssl/backend.py | 54 ++++++++++++++++ src/cryptography/hazmat/backends/openssl/x25519.py | 71 ++++++++++++++++++++++ .../hazmat/primitives/asymmetric/x25519.py | 54 ++++++++++++++++ 3 files changed, 179 insertions(+) create mode 100644 src/cryptography/hazmat/backends/openssl/x25519.py create mode 100644 src/cryptography/hazmat/primitives/asymmetric/x25519.py (limited to 'src') diff --git a/src/cryptography/hazmat/backends/openssl/backend.py b/src/cryptography/hazmat/backends/openssl/backend.py index c003b6d3..d17b38ca 100644 --- a/src/cryptography/hazmat/backends/openssl/backend.py +++ b/src/cryptography/hazmat/backends/openssl/backend.py @@ -43,6 +43,9 @@ from cryptography.hazmat.backends.openssl.hmac import _HMACContext from cryptography.hazmat.backends.openssl.rsa import ( _RSAPrivateKey, _RSAPublicKey ) +from cryptography.hazmat.backends.openssl.x25519 import ( + _X25519PrivateKey, _X25519PublicKey +) from cryptography.hazmat.backends.openssl.x509 import ( _Certificate, _CertificateRevocationList, _CertificateSigningRequest, _RevokedCertificate @@ -1772,6 +1775,57 @@ class Backend(object): self.openssl_assert(res > 0) return self._ffi.buffer(pp[0], res)[:] + def x25519_load_public_bytes(self, data): + evp_pkey = self._create_evp_pkey_gc() + res = self._lib.EVP_PKEY_set_type(evp_pkey, self._lib.NID_X25519) + backend.openssl_assert(res == 1) + res = self._lib.EVP_PKEY_set1_tls_encodedpoint( + evp_pkey, data, len(data) + ) + backend.openssl_assert(res == 1) + return _X25519PublicKey(self, evp_pkey) + + def x25519_load_private_bytes(self, data): + # OpenSSL only has facilities for loading PKCS8 formatted private + # keys using the algorithm identifiers specified in + # https://tools.ietf.org/html/draft-ietf-curdle-pkix-03. + # This is the standard PKCS8 prefix for a 32 byte X25519 key. + # The form is: + # 0:d=0 hl=2 l= 46 cons: SEQUENCE + # 2:d=1 hl=2 l= 1 prim: INTEGER :00 + # 5:d=1 hl=2 l= 5 cons: SEQUENCE + # 7:d=2 hl=2 l= 3 prim: OBJECT :1.3.101.110 + # 12:d=1 hl=2 l= 34 prim: OCTET STRING (the key) + # Of course there's a bit more complexity. In reality OCTET STRING + # contains an OCTET STRING of length 32! So the last two bytes here + # are \x04\x20, which is an OCTET STRING of length 32. + pkcs8_prefix = b'0.\x02\x01\x000\x05\x06\x03+en\x04"\x04 ' + bio = self._bytes_to_bio(pkcs8_prefix + data) + evp_pkey = backend._lib.d2i_PrivateKey_bio(bio.bio, self._ffi.NULL) + self.openssl_assert(evp_pkey != self._ffi.NULL) + evp_pkey = self._ffi.gc(evp_pkey, self._lib.EVP_PKEY_free) + return _X25519PrivateKey(self, evp_pkey) + + def x25519_generate_key(self): + evp_pkey_ctx = self._lib.EVP_PKEY_CTX_new_id( + self._lib.NID_X25519, self._ffi.NULL + ) + self.openssl_assert(evp_pkey_ctx != self._ffi.NULL) + evp_pkey_ctx = self._ffi.gc( + evp_pkey_ctx, self._lib.EVP_PKEY_CTX_free + ) + res = self._lib.EVP_PKEY_keygen_init(evp_pkey_ctx) + self.openssl_assert(res == 1) + evp_ppkey = self._ffi.new("EVP_PKEY **") + res = self._lib.EVP_PKEY_keygen(evp_pkey_ctx, evp_ppkey) + self.openssl_assert(res == 1) + self.openssl_assert(evp_ppkey[0] != self._ffi.NULL) + evp_pkey = self._ffi.gc(evp_ppkey[0], self._lib.EVP_PKEY_free) + return _X25519PrivateKey(self, evp_pkey) + + def x25519_supported(self): + return self._lib.CRYPTOGRAPHY_OPENSSL_110_OR_GREATER + def derive_scrypt(self, key_material, salt, length, n, r, p): buf = self._ffi.new("unsigned char[]", length) res = self._lib.EVP_PBE_scrypt( diff --git a/src/cryptography/hazmat/backends/openssl/x25519.py b/src/cryptography/hazmat/backends/openssl/x25519.py new file mode 100644 index 00000000..f92b184b --- /dev/null +++ b/src/cryptography/hazmat/backends/openssl/x25519.py @@ -0,0 +1,71 @@ +# This file is dual licensed under the terms of the Apache License, Version +# 2.0, and the BSD License. See the LICENSE file in the root of this repository +# for complete details. + +from __future__ import absolute_import, division, print_function + +from cryptography import utils +from cryptography.hazmat.primitives.asymmetric.x25519 import ( + X25519PrivateKey, X25519PublicKey +) + + +@utils.register_interface(X25519PublicKey) +class _X25519PublicKey(object): + def __init__(self, backend, evp_pkey): + self._backend = backend + self._evp_pkey = evp_pkey + + def public_bytes(self): + ucharpp = self._backend._ffi.new("unsigned char **") + res = self._backend._lib.EVP_PKEY_get1_tls_encodedpoint( + self._evp_pkey, ucharpp + ) + self._backend.openssl_assert(res == 32) + self._backend.openssl_assert(ucharpp[0] != self._backend._ffi.NULL) + data = self._backend._ffi.gc( + ucharpp[0], self._backend._lib.OPENSSL_free + ) + return self._backend._ffi.buffer(data, res)[:] + + +@utils.register_interface(X25519PrivateKey) +class _X25519PrivateKey(object): + def __init__(self, backend, evp_pkey): + self._backend = backend + self._evp_pkey = evp_pkey + + def public_key(self): + bio = self._backend._create_mem_bio_gc() + res = self._backend._lib.i2d_PUBKEY_bio(bio, self._evp_pkey) + self._backend.openssl_assert(res == 1) + evp_pkey = self._backend._lib.d2i_PUBKEY_bio( + bio, self._backend._ffi.NULL + ) + return _X25519PublicKey(self._backend, evp_pkey) + + def exchange(self, peer_public_key): + if not isinstance(peer_public_key, X25519PublicKey): + raise TypeError("peer_public_key must be X25519PublicKey.") + + ctx = self._backend._lib.EVP_PKEY_CTX_new( + self._evp_pkey, self._backend._ffi.NULL + ) + self._backend.openssl_assert(ctx != self._backend._ffi.NULL) + ctx = self._backend._ffi.gc(ctx, self._backend._lib.EVP_PKEY_CTX_free) + res = self._backend._lib.EVP_PKEY_derive_init(ctx) + self._backend.openssl_assert(res == 1) + res = self._backend._lib.EVP_PKEY_derive_set_peer( + ctx, peer_public_key._evp_pkey + ) + self._backend.openssl_assert(res == 1) + keylen = self._backend._ffi.new("size_t *") + res = self._backend._lib.EVP_PKEY_derive( + ctx, self._backend._ffi.NULL, keylen + ) + self._backend.openssl_assert(res == 1) + self._backend.openssl_assert(keylen[0] > 0) + buf = self._backend._ffi.new("unsigned char[]", keylen[0]) + res = self._backend._lib.EVP_PKEY_derive(ctx, buf, keylen) + self._backend.openssl_assert(res == 1) + return self._backend._ffi.buffer(buf, keylen[0])[:] diff --git a/src/cryptography/hazmat/primitives/asymmetric/x25519.py b/src/cryptography/hazmat/primitives/asymmetric/x25519.py new file mode 100644 index 00000000..5c4652ae --- /dev/null +++ b/src/cryptography/hazmat/primitives/asymmetric/x25519.py @@ -0,0 +1,54 @@ +# This file is dual licensed under the terms of the Apache License, Version +# 2.0, and the BSD License. See the LICENSE file in the root of this repository +# for complete details. + +from __future__ import absolute_import, division, print_function + +import abc + +import six + +from cryptography.exceptions import UnsupportedAlgorithm, _Reasons + + +@six.add_metaclass(abc.ABCMeta) +class X25519PublicKey(object): + @classmethod + def from_public_bytes(cls, data): + from cryptography.hazmat.backends.openssl.backend import backend + if not backend.x25519_supported(): + raise UnsupportedAlgorithm( + "X25519 is not supported by this version of OpenSSL.", + _Reasons.UNSUPPORTED_EXCHANGE_ALGORITHM + ) + return backend.x25519_load_public_bytes(data) + + @abc.abstractmethod + def public_bytes(self): + pass + + +@six.add_metaclass(abc.ABCMeta) +class X25519PrivateKey(object): + @classmethod + def generate(cls): + from cryptography.hazmat.backends.openssl.backend import backend + if not backend.x25519_supported(): + raise UnsupportedAlgorithm( + "X25519 is not supported by this version of OpenSSL.", + _Reasons.UNSUPPORTED_EXCHANGE_ALGORITHM + ) + return backend.x25519_generate_key() + + @classmethod + def _from_private_bytes(cls, data): + from cryptography.hazmat.backends.openssl.backend import backend + return backend.x25519_load_private_bytes(data) + + @abc.abstractmethod + def public_key(self): + pass + + @abc.abstractmethod + def exchange(self, peer_public_key): + pass -- cgit v1.2.3