Current File : //lib/calibre/calibre/ebooks/lit/mssha1.py
"""
Modified version of SHA-1 used in Microsoft LIT files.
Adapted from the PyPy pure-Python SHA-1 implementation.
"""
__license__ = 'GPL v3'
__copyright__ = '2008, Marshall T. Vandegrift <llasram@gmail.com>'
import struct, copy
from polyglot.builtins import long_type
# ======================================================================
# Bit-Manipulation helpers
#
# _long2bytes() was contributed by Barry Warsaw
# and is reused here with tiny modifications.
# ======================================================================
def _long2bytesBigEndian(n, blocksize=0):
"""Convert a long integer to a byte string.
If optional blocksize is given and greater than zero, pad the front
of the byte string with binary zeros so that the length is a multiple
of blocksize.
"""
# After much testing, this algorithm was deemed to be the fastest.
s = b''
pack = struct.pack
while n > 0:
s = pack('>I', n & 0xffffffff) + s
n = n >> 32
# Strip off leading zeros.
s = s.lstrip(b'\0')
# Add back some pad bytes. This could be done more efficiently
# w.r.t. the de-padding being done above, but sigh...
if blocksize > 0 and len(s) % blocksize:
s = (blocksize - len(s) % blocksize) * b'\000' + s
return s
def _bytelist2longBigEndian(blist):
"Transform a list of characters into a list of longs."
imax = len(blist)//4
hl = [0] * imax
j = 0
i = 0
while i < imax:
b0 = long_type(blist[j]) << 24
b1 = long_type(blist[j+1]) << 16
b2 = long_type(blist[j+2]) << 8
b3 = long_type(blist[j+3])
hl[i] = b0 | b1 | b2 | b3
i = i+1
j = j+4
return hl
def _rotateLeft(x, n):
"Rotate x (32 bit) left n bits circular."
return (x << n) | (x >> (32-n))
# ======================================================================
# The SHA transformation functions
#
# ======================================================================
def f0_19(B, C, D):
return (B & (C ^ D)) ^ D
def f20_39(B, C, D):
return B ^ C ^ D
def f40_59(B, C, D):
return ((B | C) & D) | (B & C)
def f60_79(B, C, D):
return B ^ C ^ D
# Microsoft's lovely addition...
def f6_42(B, C, D):
return (B + C) ^ C
f = [f0_19]*20 + [f20_39]*20 + [f40_59]*20 + [f60_79]*20
# ...and delightful changes
f[3] = f20_39
f[6] = f6_42
f[10] = f20_39
f[15] = f20_39
f[26] = f0_19
f[31] = f40_59
f[42] = f6_42
f[51] = f20_39
f[68] = f0_19
# Constants to be used
K = [
0x5A827999, # ( 0 <= t <= 19)
0x6ED9EBA1, # (20 <= t <= 39)
0x8F1BBCDC, # (40 <= t <= 59)
0xCA62C1D6 # (60 <= t <= 79)
]
class mssha1:
"An implementation of the MD5 hash function in pure Python."
def __init__(self):
"Initialisation."
# Initial message length in bits(!).
self.length = 0
self.count = [0, 0]
# Initial empty message as a sequence of bytes (8 bit characters).
self.input = bytearray()
# Call a separate init function, that can be used repeatedly
# to start from scratch on the same object.
self.init()
def init(self):
"Initialize the message-digest and set all fields to zero."
self.length = 0
self.input = []
# Initial 160 bit message digest (5 times 32 bit).
# Also changed by Microsoft from standard.
self.H0 = 0x32107654
self.H1 = 0x23016745
self.H2 = 0xC4E680A2
self.H3 = 0xDC679823
self.H4 = 0xD0857A34
def _transform(self, W):
for t in range(16, 80):
W.append(_rotateLeft(
W[t-3] ^ W[t-8] ^ W[t-14] ^ W[t-16], 1) & 0xffffffff)
A = self.H0
B = self.H1
C = self.H2
D = self.H3
E = self.H4
for t in range(0, 80):
TEMP = _rotateLeft(A, 5) + f[t](B, C, D) + E + W[t] + K[t//20]
E = D
D = C
C = _rotateLeft(B, 30) & 0xffffffff
B = A
A = TEMP & 0xffffffff
self.H0 = (self.H0 + A) & 0xffffffff
self.H1 = (self.H1 + B) & 0xffffffff
self.H2 = (self.H2 + C) & 0xffffffff
self.H3 = (self.H3 + D) & 0xffffffff
self.H4 = (self.H4 + E) & 0xffffffff
# Down from here all methods follow the Python Standard Library
# API of the sha module.
def update(self, inBuf):
"""Add to the current message.
Update the mssha1 object with the string arg. Repeated calls
are equivalent to a single call with the concatenation of all
the arguments, i.e. s.update(a); s.update(b) is equivalent
to s.update(a+b).
The hash is immediately calculated for all full blocks. The final
calculation is made in digest(). It will calculate 1-2 blocks,
depending on how much padding we have to add. This allows us to
keep an intermediate value for the hash, so that we only need to
make minimal recalculation if we call update() to add more data
to the hashed string.
"""
inBuf = bytearray(inBuf)
leninBuf = long_type(len(inBuf))
# Compute number of bytes mod 64.
index = (self.count[1] >> 3) & 0x3F
# Update number of bits.
self.count[1] = self.count[1] + (leninBuf << 3)
if self.count[1] < (leninBuf << 3):
self.count[0] = self.count[0] + 1
self.count[0] = self.count[0] + (leninBuf >> 29)
partLen = 64 - index
if leninBuf >= partLen:
self.input[index:] = inBuf[:partLen]
self._transform(_bytelist2longBigEndian(self.input))
i = partLen
while i + 63 < leninBuf:
self._transform(_bytelist2longBigEndian(inBuf[i:i+64]))
i = i + 64
else:
self.input = inBuf[i:leninBuf]
else:
i = 0
self.input = self.input + inBuf
def digest(self):
"""Terminate the message-digest computation and return digest.
Return the digest of the strings passed to the update()
method so far. This is a 16-byte string which may contain
non-ASCII characters, including null bytes.
"""
H0 = self.H0
H1 = self.H1
H2 = self.H2
H3 = self.H3
H4 = self.H4
inp = bytearray(self.input)
count = [] + self.count
index = (self.count[1] >> 3) & 0x3f
if index < 56:
padLen = 56 - index
else:
padLen = 120 - index
padding = b'\200' + (b'\000' * 63)
self.update(padding[:padLen])
# Append length (before padding).
bits = _bytelist2longBigEndian(self.input[:56]) + count
self._transform(bits)
# Store state in digest.
digest = _long2bytesBigEndian(self.H0, 4) + \
_long2bytesBigEndian(self.H1, 4) + \
_long2bytesBigEndian(self.H2, 4) + \
_long2bytesBigEndian(self.H3, 4) + \
_long2bytesBigEndian(self.H4, 4)
self.H0 = H0
self.H1 = H1
self.H2 = H2
self.H3 = H3
self.H4 = H4
self.input = inp
self.count = count
return digest
def hexdigest(self):
"""Terminate and return digest in HEX form.
Like digest() except the digest is returned as a string of
length 32, containing only hexadecimal digits. This may be
used to exchange the value safely in email or other non-
binary environments.
"""
return ''.join(['%02x' % c for c in bytearray(self.digest())])
def copy(self):
"""Return a clone object.
Return a copy ('clone') of the md5 object. This can be used
to efficiently compute the digests of strings that share
a common initial substring.
"""
return copy.deepcopy(self)
# ======================================================================
# Mimic Python top-level functions from standard library API
# for consistency with the md5 module of the standard library.
# ======================================================================
# These are mandatory variables in the module. They have constant values
# in the SHA standard.
digest_size = digestsize = 20
blocksize = 1
def new(arg=None):
"""Return a new mssha1 crypto object.
If arg is present, the method call update(arg) is made.
"""
crypto = mssha1()
if arg:
crypto.update(arg)
return crypto
if __name__ == '__main__':
def main():
import sys
file = None
if len(sys.argv) > 2:
print("usage: %s [FILE]" % sys.argv[0])
return
elif len(sys.argv) < 2:
file = sys.stdin
else:
file = open(sys.argv[1], 'rb')
context = new()
data = file.read(16384)
while data:
context.update(data)
data = file.read(16384)
file.close()
digest = context.hexdigest().upper()
for i in range(0, 40, 8):
print(digest[i:i+8], end=' ')
print()
main()
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