Coverage for /pythoncovmergedfiles/medio/medio/usr/local/lib/python3.8/site-packages/cryptography/hazmat/backends/openssl/utils.py: 37%

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 

5from __future__ import annotations 

6 

7import typing 

8 

9from cryptography.hazmat.primitives import hashes 

10from cryptography.hazmat.primitives.asymmetric.utils import Prehashed 

11 

12if typing.TYPE_CHECKING: 

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

14 

15 

16def _evp_pkey_derive(backend: Backend, evp_pkey, peer_public_key) -> bytes: 

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

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

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

20 res = backend._lib.EVP_PKEY_derive_init(ctx) 

21 backend.openssl_assert(res == 1) 

22 

23 if backend._lib.Cryptography_HAS_EVP_PKEY_SET_PEER_EX: 

24 res = backend._lib.EVP_PKEY_derive_set_peer_ex( 

25 ctx, peer_public_key._evp_pkey, 0 

26 ) 

27 else: 

28 res = backend._lib.EVP_PKEY_derive_set_peer( 

29 ctx, peer_public_key._evp_pkey 

30 ) 

31 backend.openssl_assert(res == 1) 

32 

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

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

35 backend.openssl_assert(res == 1) 

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

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

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

39 if res != 1: 

40 errors = backend._consume_errors() 

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

42 

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

44 

45 

46def _calculate_digest_and_algorithm( 

47 data: bytes, 

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

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

50 if not isinstance(algorithm, Prehashed): 

51 hash_ctx = hashes.Hash(algorithm) 

52 hash_ctx.update(data) 

53 data = hash_ctx.finalize() 

54 else: 

55 algorithm = algorithm._algorithm 

56 

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

58 raise ValueError( 

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

60 "algorithm's digest size." 

61 ) 

62 

63 return (data, algorithm)