RFC 2104 HMAC class. Also complies with RFC 4231. This supports the API for Cryptographic Hash Functions (PEP 247).
| 25 | |
| 26 | |
| 27 | class HMAC: |
| 28 | """RFC 2104 HMAC class. Also complies with RFC 4231. |
| 29 | |
| 30 | This supports the API for Cryptographic Hash Functions (PEP 247). |
| 31 | """ |
| 32 | blocksize = 64 # 512-bit HMAC; can be changed in subclasses. |
| 33 | |
| 34 | __slots__ = ( |
| 35 | "_hmac", "_inner", "_outer", "block_size", "digest_size" |
| 36 | ) |
| 37 | |
| 38 | def __init__(self, key, msg=None, digestmod=''): |
| 39 | """Create a new HMAC object. |
| 40 | |
| 41 | key: bytes or buffer, key for the keyed hash object. |
| 42 | msg: bytes or buffer, Initial input for the hash or None. |
| 43 | digestmod: A hash name suitable for hashlib.new(). *OR* |
| 44 | A hashlib constructor returning a new hash object. *OR* |
| 45 | A module supporting PEP 247. |
| 46 | |
| 47 | Required as of 3.8, despite its position after the optional |
| 48 | msg argument. Passing it as a keyword argument is |
| 49 | recommended, though not required for legacy API reasons. |
| 50 | """ |
| 51 | |
| 52 | if not isinstance(key, (bytes, bytearray)): |
| 53 | raise TypeError("key: expected bytes or bytearray, but got %r" % type(key).__name__) |
| 54 | |
| 55 | if not digestmod: |
| 56 | raise TypeError("Missing required argument 'digestmod'.") |
| 57 | |
| 58 | if _hashopenssl and isinstance(digestmod, (str, _functype)): |
| 59 | try: |
| 60 | self._init_hmac(key, msg, digestmod) |
| 61 | except _hashopenssl.UnsupportedDigestmodError: |
| 62 | self._init_old(key, msg, digestmod) |
| 63 | else: |
| 64 | self._init_old(key, msg, digestmod) |
| 65 | |
| 66 | def _init_hmac(self, key, msg, digestmod): |
| 67 | self._hmac = _hashopenssl.hmac_new(key, msg, digestmod=digestmod) |
| 68 | self.digest_size = self._hmac.digest_size |
| 69 | self.block_size = self._hmac.block_size |
| 70 | |
| 71 | def _init_old(self, key, msg, digestmod): |
| 72 | if callable(digestmod): |
| 73 | digest_cons = digestmod |
| 74 | elif isinstance(digestmod, str): |
| 75 | digest_cons = lambda d=b'': _hashlib.new(digestmod, d) |
| 76 | else: |
| 77 | digest_cons = lambda d=b'': digestmod.new(d) |
| 78 | |
| 79 | self._hmac = None |
| 80 | self._outer = digest_cons() |
| 81 | self._inner = digest_cons() |
| 82 | self.digest_size = self._inner.digest_size |
| 83 | |
| 84 | if hasattr(self._inner, 'block_size'): |