186 lines
6.7 KiB
Python
186 lines
6.7 KiB
Python
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# -*- coding: utf-8 -*-
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#
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# ===================================================================
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# The contents of this file are dedicated to the public domain. To
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# the extent that dedication to the public domain is not available,
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# everyone is granted a worldwide, perpetual, royalty-free,
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# non-exclusive license to exercise all rights associated with the
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# contents of this file for any purpose whatsoever.
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# No rights are reserved.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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# BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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# ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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# SOFTWARE.
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# ===================================================================
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from Cryptodome.Util.py3compat import bord
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from Cryptodome.Util._raw_api import (load_pycryptodome_raw_lib,
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VoidPointer, SmartPointer,
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create_string_buffer,
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get_raw_buffer, c_size_t,
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c_uint8_ptr)
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_raw_sha256_lib = load_pycryptodome_raw_lib("Cryptodome.Hash._SHA256",
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"""
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int SHA256_init(void **shaState);
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int SHA256_destroy(void *shaState);
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int SHA256_update(void *hs,
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const uint8_t *buf,
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size_t len);
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int SHA256_digest(const void *shaState,
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uint8_t *digest,
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size_t digest_size);
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int SHA256_copy(const void *src, void *dst);
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int SHA256_pbkdf2_hmac_assist(const void *inner,
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const void *outer,
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const uint8_t *first_digest,
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uint8_t *final_digest,
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size_t iterations,
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size_t digest_size);
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""")
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class SHA256Hash(object):
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"""A SHA-256 hash object.
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Do not instantiate directly. Use the :func:`new` function.
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:ivar oid: ASN.1 Object ID
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:vartype oid: string
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:ivar block_size: the size in bytes of the internal message block,
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input to the compression function
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:vartype block_size: integer
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:ivar digest_size: the size in bytes of the resulting hash
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:vartype digest_size: integer
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"""
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# The size of the resulting hash in bytes.
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digest_size = 32
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# The internal block size of the hash algorithm in bytes.
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block_size = 64
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# ASN.1 Object ID
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oid = "2.16.840.1.101.3.4.2.1"
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def __init__(self, data=None):
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state = VoidPointer()
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result = _raw_sha256_lib.SHA256_init(state.address_of())
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if result:
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raise ValueError("Error %d while instantiating SHA256"
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% result)
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self._state = SmartPointer(state.get(),
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_raw_sha256_lib.SHA256_destroy)
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if data:
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self.update(data)
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def update(self, data):
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"""Continue hashing of a message by consuming the next chunk of data.
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Args:
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data (byte string/byte array/memoryview): The next chunk of the message being hashed.
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"""
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result = _raw_sha256_lib.SHA256_update(self._state.get(),
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c_uint8_ptr(data),
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c_size_t(len(data)))
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if result:
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raise ValueError("Error %d while hashing data with SHA256"
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% result)
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def digest(self):
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"""Return the **binary** (non-printable) digest of the message that has been hashed so far.
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:return: The hash digest, computed over the data processed so far.
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Binary form.
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:rtype: byte string
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"""
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bfr = create_string_buffer(self.digest_size)
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result = _raw_sha256_lib.SHA256_digest(self._state.get(),
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bfr,
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c_size_t(self.digest_size))
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if result:
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raise ValueError("Error %d while making SHA256 digest"
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% result)
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return get_raw_buffer(bfr)
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def hexdigest(self):
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"""Return the **printable** digest of the message that has been hashed so far.
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:return: The hash digest, computed over the data processed so far.
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Hexadecimal encoded.
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:rtype: string
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"""
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return "".join(["%02x" % bord(x) for x in self.digest()])
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def copy(self):
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"""Return a copy ("clone") of the hash object.
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The copy will have the same internal state as the original hash
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object.
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This can be used to efficiently compute the digests of strings that
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share a common initial substring.
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:return: A hash object of the same type
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"""
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clone = SHA256Hash()
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result = _raw_sha256_lib.SHA256_copy(self._state.get(),
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clone._state.get())
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if result:
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raise ValueError("Error %d while copying SHA256" % result)
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return clone
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def new(self, data=None):
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"""Create a fresh SHA-256 hash object."""
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return SHA256Hash(data)
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def new(data=None):
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"""Create a new hash object.
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:parameter data:
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Optional. The very first chunk of the message to hash.
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It is equivalent to an early call to :meth:`SHA256Hash.update`.
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:type data: byte string/byte array/memoryview
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:Return: A :class:`SHA256Hash` hash object
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"""
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return SHA256Hash().new(data)
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# The size of the resulting hash in bytes.
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digest_size = SHA256Hash.digest_size
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# The internal block size of the hash algorithm in bytes.
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block_size = SHA256Hash.block_size
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def _pbkdf2_hmac_assist(inner, outer, first_digest, iterations):
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"""Compute the expensive inner loop in PBKDF-HMAC."""
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assert iterations > 0
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bfr = create_string_buffer(len(first_digest));
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result = _raw_sha256_lib.SHA256_pbkdf2_hmac_assist(
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inner._state.get(),
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outer._state.get(),
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first_digest,
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bfr,
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c_size_t(iterations),
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c_size_t(len(first_digest)))
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if result:
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raise ValueError("Error %d with PBKDF2-HMAC assist for SHA256" % result)
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return get_raw_buffer(bfr)
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