Added internal python-only HMAC implementation
This commit is contained in:
Mark Qvist
parent
d24f3a490a
commit
f1dcda82ac
183
RNS/Cryptography/HMAC.py
Normal file
183
RNS/Cryptography/HMAC.py
Normal file
@ -0,0 +1,183 @@
|
||||
# This HMAC implementation comes directly from the HMAC implementation
|
||||
# included in Python 3.10.4, and is almost completely identical. It has
|
||||
# been modified to be a pure Python implementation, that is not dependent
|
||||
# on the system having OpenSSL binaries installed.
|
||||
|
||||
import warnings as _warnings
|
||||
import hashlib as _hashlib
|
||||
|
||||
trans_5C = bytes((x ^ 0x5C) for x in range(256))
|
||||
trans_36 = bytes((x ^ 0x36) for x in range(256))
|
||||
|
||||
# The size of the digests returned by HMAC depends on the underlying
|
||||
# hashing module used. Use digest_size from the instance of HMAC instead.
|
||||
digest_size = None
|
||||
|
||||
|
||||
class HMAC:
|
||||
"""RFC 2104 HMAC class. Also complies with RFC 4231.
|
||||
This supports the API for Cryptographic Hash Functions (PEP 247).
|
||||
"""
|
||||
blocksize = 64 # 512-bit HMAC; can be changed in subclasses.
|
||||
|
||||
__slots__ = (
|
||||
"_hmac", "_inner", "_outer", "block_size", "digest_size"
|
||||
)
|
||||
|
||||
def __init__(self, key, msg=None, digestmod=''):
|
||||
"""Create a new HMAC object.
|
||||
key: bytes or buffer, key for the keyed hash object.
|
||||
msg: bytes or buffer, Initial input for the hash or None.
|
||||
digestmod: A hash name suitable for hashlib.new(). *OR*
|
||||
A hashlib constructor returning a new hash object. *OR*
|
||||
A module supporting PEP 247.
|
||||
Required as of 3.8, despite its position after the optional
|
||||
msg argument. Passing it as a keyword argument is
|
||||
recommended, though not required for legacy API reasons.
|
||||
"""
|
||||
|
||||
if not isinstance(key, (bytes, bytearray)):
|
||||
raise TypeError("key: expected bytes or bytearray, but got %r" % type(key).__name__)
|
||||
|
||||
if not digestmod:
|
||||
raise TypeError("Missing required parameter 'digestmod'.")
|
||||
|
||||
self._hmac_init(key, msg, digestmod)
|
||||
|
||||
def _hmac_init(self, key, msg, digestmod):
|
||||
if callable(digestmod):
|
||||
digest_cons = digestmod
|
||||
elif isinstance(digestmod, str):
|
||||
digest_cons = lambda d=b'': _hashlib.new(digestmod, d)
|
||||
else:
|
||||
digest_cons = lambda d=b'': digestmod.new(d)
|
||||
|
||||
self._hmac = None
|
||||
self._outer = digest_cons()
|
||||
self._inner = digest_cons()
|
||||
self.digest_size = self._inner.digest_size
|
||||
|
||||
if hasattr(self._inner, 'block_size'):
|
||||
blocksize = self._inner.block_size
|
||||
if blocksize < 16:
|
||||
_warnings.warn('block_size of %d seems too small; using our '
|
||||
'default of %d.' % (blocksize, self.blocksize),
|
||||
RuntimeWarning, 2)
|
||||
blocksize = self.blocksize
|
||||
else:
|
||||
_warnings.warn('No block_size attribute on given digest object; '
|
||||
'Assuming %d.' % (self.blocksize),
|
||||
RuntimeWarning, 2)
|
||||
blocksize = self.blocksize
|
||||
|
||||
if len(key) > blocksize:
|
||||
key = digest_cons(key).digest()
|
||||
|
||||
# self.blocksize is the default blocksize. self.block_size is
|
||||
# effective block size as well as the public API attribute.
|
||||
self.block_size = blocksize
|
||||
|
||||
key = key.ljust(blocksize, b'\0')
|
||||
self._outer.update(key.translate(trans_5C))
|
||||
self._inner.update(key.translate(trans_36))
|
||||
if msg is not None:
|
||||
self.update(msg)
|
||||
|
||||
@property
|
||||
def name(self):
|
||||
if self._hmac:
|
||||
return self._hmac.name
|
||||
else:
|
||||
return f"hmac-{self._inner.name}"
|
||||
|
||||
def update(self, msg):
|
||||
"""Feed data from msg into this hashing object."""
|
||||
inst = self._hmac or self._inner
|
||||
inst.update(msg)
|
||||
|
||||
def copy(self):
|
||||
"""Return a separate copy of this hashing object.
|
||||
An update to this copy won't affect the original object.
|
||||
"""
|
||||
# Call __new__ directly to avoid the expensive __init__.
|
||||
other = self.__class__.__new__(self.__class__)
|
||||
other.digest_size = self.digest_size
|
||||
if self._hmac:
|
||||
other._hmac = self._hmac.copy()
|
||||
other._inner = other._outer = None
|
||||
else:
|
||||
other._hmac = None
|
||||
other._inner = self._inner.copy()
|
||||
other._outer = self._outer.copy()
|
||||
return other
|
||||
|
||||
def _current(self):
|
||||
"""Return a hash object for the current state.
|
||||
To be used only internally with digest() and hexdigest().
|
||||
"""
|
||||
if self._hmac:
|
||||
return self._hmac
|
||||
else:
|
||||
h = self._outer.copy()
|
||||
h.update(self._inner.digest())
|
||||
return h
|
||||
|
||||
def digest(self):
|
||||
"""Return the hash value of this hashing object.
|
||||
This returns the hmac value as bytes. The object is
|
||||
not altered in any way by this function; you can continue
|
||||
updating the object after calling this function.
|
||||
"""
|
||||
h = self._current()
|
||||
return h.digest()
|
||||
|
||||
def hexdigest(self):
|
||||
"""Like digest(), but returns a string of hexadecimal digits instead.
|
||||
"""
|
||||
h = self._current()
|
||||
return h.hexdigest()
|
||||
|
||||
def new(key, msg=None, digestmod=''):
|
||||
"""Create a new hashing object and return it.
|
||||
key: bytes or buffer, The starting key for the hash.
|
||||
msg: bytes or buffer, Initial input for the hash, or None.
|
||||
digestmod: A hash name suitable for hashlib.new(). *OR*
|
||||
A hashlib constructor returning a new hash object. *OR*
|
||||
A module supporting PEP 247.
|
||||
Required as of 3.8, despite its position after the optional
|
||||
msg argument. Passing it as a keyword argument is
|
||||
recommended, though not required for legacy API reasons.
|
||||
You can now feed arbitrary bytes into the object using its update()
|
||||
method, and can ask for the hash value at any time by calling its digest()
|
||||
or hexdigest() methods.
|
||||
"""
|
||||
return HMAC(key, msg, digestmod)
|
||||
|
||||
|
||||
def digest(key, msg, digest):
|
||||
"""Fast inline implementation of HMAC.
|
||||
key: bytes or buffer, The key for the keyed hash object.
|
||||
msg: bytes or buffer, Input message.
|
||||
digest: A hash name suitable for hashlib.new() for best performance. *OR*
|
||||
A hashlib constructor returning a new hash object. *OR*
|
||||
A module supporting PEP 247.
|
||||
"""
|
||||
if callable(digest):
|
||||
digest_cons = digest
|
||||
elif isinstance(digest, str):
|
||||
digest_cons = lambda d=b'': _hashlib.new(digest, d)
|
||||
else:
|
||||
digest_cons = lambda d=b'': digest.new(d)
|
||||
|
||||
inner = digest_cons()
|
||||
outer = digest_cons()
|
||||
blocksize = getattr(inner, 'block_size', 64)
|
||||
if len(key) > blocksize:
|
||||
key = digest_cons(key).digest()
|
||||
|
||||
key = key + b'\x00' * (blocksize - len(key))
|
||||
inner.update(key.translate(trans_36))
|
||||
outer.update(key.translate(trans_5C))
|
||||
inner.update(msg)
|
||||
outer.update(inner.digest())
|
||||
return outer.digest()
|
||||
Loading…
Reference in New Issue
Block a user