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80 lines
3.0 KiB
80 lines
3.0 KiB
# This file is dual licensed under the terms of the Apache License, Version
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# 2.0, and the BSD License. See the LICENSE file in the root of this repository
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# for complete details.
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from __future__ import absolute_import, division, print_function
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from cryptography import utils
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from cryptography.hazmat.primitives.asymmetric.x25519 import (
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X25519PrivateKey, X25519PublicKey
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)
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@utils.register_interface(X25519PublicKey)
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class _X25519PublicKey(object):
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def __init__(self, backend, evp_pkey):
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self._backend = backend
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self._evp_pkey = evp_pkey
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def public_bytes(self):
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ucharpp = self._backend._ffi.new("unsigned char **")
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res = self._backend._lib.EVP_PKEY_get1_tls_encodedpoint(
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self._evp_pkey, ucharpp
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)
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self._backend.openssl_assert(res == 32)
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self._backend.openssl_assert(ucharpp[0] != self._backend._ffi.NULL)
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data = self._backend._ffi.gc(
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ucharpp[0], self._backend._lib.OPENSSL_free
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)
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return self._backend._ffi.buffer(data, res)[:]
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@utils.register_interface(X25519PrivateKey)
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class _X25519PrivateKey(object):
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def __init__(self, backend, evp_pkey):
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self._backend = backend
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self._evp_pkey = evp_pkey
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def public_key(self):
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bio = self._backend._create_mem_bio_gc()
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res = self._backend._lib.i2d_PUBKEY_bio(bio, self._evp_pkey)
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self._backend.openssl_assert(res == 1)
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evp_pkey = self._backend._lib.d2i_PUBKEY_bio(
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bio, self._backend._ffi.NULL
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)
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self._backend.openssl_assert(evp_pkey != self._backend._ffi.NULL)
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evp_pkey = self._backend._ffi.gc(
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evp_pkey, self._backend._lib.EVP_PKEY_free
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)
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return _X25519PublicKey(self._backend, evp_pkey)
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def exchange(self, peer_public_key):
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if not isinstance(peer_public_key, X25519PublicKey):
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raise TypeError("peer_public_key must be X25519PublicKey.")
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ctx = self._backend._lib.EVP_PKEY_CTX_new(
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self._evp_pkey, self._backend._ffi.NULL
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)
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self._backend.openssl_assert(ctx != self._backend._ffi.NULL)
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ctx = self._backend._ffi.gc(ctx, self._backend._lib.EVP_PKEY_CTX_free)
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res = self._backend._lib.EVP_PKEY_derive_init(ctx)
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self._backend.openssl_assert(res == 1)
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res = self._backend._lib.EVP_PKEY_derive_set_peer(
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ctx, peer_public_key._evp_pkey
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)
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self._backend.openssl_assert(res == 1)
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keylen = self._backend._ffi.new("size_t *")
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res = self._backend._lib.EVP_PKEY_derive(
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ctx, self._backend._ffi.NULL, keylen
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)
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self._backend.openssl_assert(res == 1)
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self._backend.openssl_assert(keylen[0] > 0)
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buf = self._backend._ffi.new("unsigned char[]", keylen[0])
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res = self._backend._lib.EVP_PKEY_derive(ctx, buf, keylen)
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if res != 1:
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raise ValueError(
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"Null shared key derived from public/private pair."
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)
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return self._backend._ffi.buffer(buf, keylen[0])[:]
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