JezK
Edit File: x25519.py
# 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. import typing from cryptography.hazmat.backends.openssl.utils import _evp_pkey_derive from cryptography.hazmat.primitives import serialization from cryptography.hazmat.primitives.asymmetric.x25519 import ( X25519PrivateKey, X25519PublicKey, ) if typing.TYPE_CHECKING: from cryptography.hazmat.backends.openssl.backend import Backend _X25519_KEY_SIZE = 32 class _X25519PublicKey(X25519PublicKey): def __init__(self, backend: "Backend", evp_pkey): self._backend = backend self._evp_pkey = evp_pkey def public_bytes( self, encoding: serialization.Encoding, format: serialization.PublicFormat, ) -> bytes: if ( encoding is serialization.Encoding.Raw or format is serialization.PublicFormat.Raw ): if ( encoding is not serialization.Encoding.Raw or format is not serialization.PublicFormat.Raw ): raise ValueError( "When using Raw both encoding and format must be Raw" ) return self._raw_public_bytes() return self._backend._public_key_bytes( encoding, format, self, self._evp_pkey, None ) def _raw_public_bytes(self) -> bytes: 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)[:] class _X25519PrivateKey(X25519PrivateKey): def __init__(self, backend: "Backend", evp_pkey): self._backend = backend self._evp_pkey = evp_pkey def public_key(self) -> X25519PublicKey: 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 ) self._backend.openssl_assert(evp_pkey != self._backend._ffi.NULL) evp_pkey = self._backend._ffi.gc( evp_pkey, self._backend._lib.EVP_PKEY_free ) return _X25519PublicKey(self._backend, evp_pkey) def exchange(self, peer_public_key: X25519PublicKey) -> bytes: if not isinstance(peer_public_key, X25519PublicKey): raise TypeError("peer_public_key must be X25519PublicKey.") return _evp_pkey_derive(self._backend, self._evp_pkey, peer_public_key) def private_bytes( self, encoding: serialization.Encoding, format: serialization.PrivateFormat, encryption_algorithm: serialization.KeySerializationEncryption, ) -> bytes: if ( encoding is serialization.Encoding.Raw or format is serialization.PublicFormat.Raw ): if ( format is not serialization.PrivateFormat.Raw or encoding is not serialization.Encoding.Raw or not isinstance( encryption_algorithm, serialization.NoEncryption ) ): raise ValueError( "When using Raw both encoding and format must be Raw " "and encryption_algorithm must be NoEncryption()" ) return self._raw_private_bytes() return self._backend._private_key_bytes( encoding, format, encryption_algorithm, self, self._evp_pkey, None ) def _raw_private_bytes(self) -> bytes: # When we drop support for CRYPTOGRAPHY_OPENSSL_LESS_THAN_111 we can # switch this to EVP_PKEY_new_raw_private_key # The trick we use here is serializing to a PKCS8 key and just # using the last 32 bytes, which is the key itself. bio = self._backend._create_mem_bio_gc() res = self._backend._lib.i2d_PKCS8PrivateKey_bio( bio, self._evp_pkey, self._backend._ffi.NULL, self._backend._ffi.NULL, 0, self._backend._ffi.NULL, self._backend._ffi.NULL, ) self._backend.openssl_assert(res == 1) pkcs8 = self._backend._read_mem_bio(bio) self._backend.openssl_assert(len(pkcs8) == 48) return pkcs8[-_X25519_KEY_SIZE:]