Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/cryptography/hazmat/backends/openssl/utils.py: 18%

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 

21 if backend._lib.Cryptography_HAS_EVP_PKEY_SET_PEER_EX: 

22 res = backend._lib.EVP_PKEY_derive_set_peer_ex( 

23 ctx, peer_public_key._evp_pkey, 0 

24 ) 

25 else: 

26 res = backend._lib.EVP_PKEY_derive_set_peer( 

27 ctx, peer_public_key._evp_pkey 

28 ) 

29 backend.openssl_assert(res == 1) 

30 

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

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

33 backend.openssl_assert(res == 1) 

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

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

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

37 if res != 1: 

38 errors = backend._consume_errors() 

39 raise ValueError("Error computing shared key.", errors) 

40 

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

42 

43 

44def _calculate_digest_and_algorithm( 

45 data: bytes, 

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

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

48 if not isinstance(algorithm, Prehashed): 

49 hash_ctx = hashes.Hash(algorithm) 

50 hash_ctx.update(data) 

51 data = hash_ctx.finalize() 

52 else: 

53 algorithm = algorithm._algorithm 

54 

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

56 raise ValueError( 

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

58 "algorithm's digest size." 

59 ) 

60 

61 return (data, algorithm)