Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/cryptography/hazmat/backends/openssl/utils.py: 19%

1# This file is dual licensed under the terms of the Apache License, Version 

2# 2.0, and the BSD License. See the LICENSE file in the root of this repository 

3# for complete details. 

4 

5import typing 

6 

7from cryptography.hazmat.primitives import hashes 

8from cryptography.hazmat.primitives.asymmetric.utils import Prehashed 

9 

10if typing.TYPE_CHECKING: 

11 from cryptography.hazmat.backends.openssl.backend import Backend 

12 

13 

14def _evp_pkey_derive(backend: "Backend", evp_pkey, peer_public_key) -> bytes: 

15 ctx = backend._lib.EVP_PKEY_CTX_new(evp_pkey, backend._ffi.NULL) 

16 backend.openssl_assert(ctx != backend._ffi.NULL) 

17 ctx = backend._ffi.gc(ctx, backend._lib.EVP_PKEY_CTX_free) 

18 res = backend._lib.EVP_PKEY_derive_init(ctx) 

19 backend.openssl_assert(res == 1) 

20 res = backend._lib.EVP_PKEY_derive_set_peer(ctx, peer_public_key._evp_pkey) 

21 backend.openssl_assert(res == 1) 

22 keylen = backend._ffi.new("size_t *") 

23 res = backend._lib.EVP_PKEY_derive(ctx, backend._ffi.NULL, keylen) 

24 backend.openssl_assert(res == 1) 

25 backend.openssl_assert(keylen[0] > 0) 

26 buf = backend._ffi.new("unsigned char[]", keylen[0]) 

27 res = backend._lib.EVP_PKEY_derive(ctx, buf, keylen) 

28 if res != 1: 

29 errors_with_text = backend._consume_errors_with_text() 

30 raise ValueError("Error computing shared key.", errors_with_text) 

31 

32 return backend._ffi.buffer(buf, keylen[0])[:] 

33 

34 

35def _calculate_digest_and_algorithm( 

36 data: bytes, 

37 algorithm: typing.Union[Prehashed, hashes.HashAlgorithm], 

38) -> typing.Tuple[bytes, hashes.HashAlgorithm]: 

39 if not isinstance(algorithm, Prehashed): 

40 hash_ctx = hashes.Hash(algorithm) 

41 hash_ctx.update(data) 

42 data = hash_ctx.finalize() 

43 else: 

44 algorithm = algorithm._algorithm 

45 

46 if len(data) != algorithm.digest_size: 

47 raise ValueError( 

48 "The provided data must be the same length as the hash " 

49 "algorithm's digest size." 

50 ) 

51 

52 return (data, algorithm)