Viewing file:  x25519.py (2.73 KB) -rw-r--r--
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# 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])[:]
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