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from __future__ import print_function

import math

def rearrange(bitString32):

"""[summary]

Regroups the given binary string.

Arguments:

bitString32 {[string]} -- [32 bit binary]

Raises:

ValueError -- [if the given string not are 32 bit binary string]

Returns:

[string] -- [32 bit binary string]

"""

if len(bitString32) != 32:

raise ValueError("Need length 32")

newString = ""

for i in [3,2,1,0]:

newString += bitString32[8*i:8*i+8]

return newString

def reformatHex(i):

"""[summary]

Converts the given integer into 8-digit hex number.

Arguments:

i {[int]} -- [integer]

"""

hexrep = format(i,'08x')

thing = ""

for i in [3,2,1,0]:

thing += hexrep[2*i:2*i+2]

return thing

def pad(bitString):

"""[summary]

Fills up the binary string to a 512 bit binary string

Arguments:

bitString {[string]} -- [binary string]

Returns:

[string] -- [binary string]

"""

startLength = len(bitString)

bitString += '1'

while len(bitString) % 512 != 448:

bitString += '0'

lastPart = format(startLength,'064b')

bitString += rearrange(lastPart[32:]) + rearrange(lastPart[:32])

return bitString

def getBlock(bitString):

"""[summary]

Iterator:

Returns by each call a list of length 16 with the 32 bit

integer blocks.

Arguments:

bitString {[string]} -- [binary string >= 512]

"""

currPos = 0

while currPos < len(bitString):

currPart = bitString[currPos:currPos+512]

mySplits = []

for i in range(16):

mySplits.append(int(rearrange(currPart[32*i:32*i+32]),2))

yield mySplits

currPos += 512

def not32(i):

i_str = format(i,'032b')

new_str = ''

for c in i_str:

new_str += '1' if c=='0' else '0'

return int(new_str,2)

def sum32(a,b):

return (a + b) % 2**32

def leftrot32(i,s):

return (i << s) ^ (i >> (32-s))

def md5me(testString):

"""[summary]

Returns a 32-bit hash code of the string 'testString'

Arguments:

testString {[string]} -- [message]

"""

bs =''

for i in testString:

bs += format(ord(i),'08b')

bs = pad(bs)

tvals = [int(2**32 * abs(math.sin(i+1))) for i in range(64)]

a0 = 0x67452301

b0 = 0xefcdab89

c0 = 0x98badcfe

d0 = 0x10325476

s = [7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, 7, 12, 17, 22, \

5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, 5, 9, 14, 20, \

4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, 4, 11, 16, 23, \

6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21, 6, 10, 15, 21 ]

for m in getBlock(bs):

A = a0

B = b0

C = c0

D = d0

for i in range(64):

if i <= 15:

#f = (B & C) | (not32(B) & D)

f = D ^ (B & (C ^ D))

g = i

elif i<= 31:

#f = (D & B) | (not32(D) & C)

f = C ^ (D & (B ^ C))

g = (5*i+1) % 16

elif i <= 47:

f = B ^ C ^ D

g = (3*i+5) % 16

else:

f = C ^ (B | not32(D))

g = (7*i) % 16

dtemp = D

D = C

C = B

B = sum32(B,leftrot32((A + f + tvals[i] + m[g]) % 2**32, s[i]))

A = dtemp

a0 = sum32(a0, A)

b0 = sum32(b0, B)

c0 = sum32(c0, C)

d0 = sum32(d0, D)

digest = reformatHex(a0) + reformatHex(b0) + reformatHex(c0) + reformatHex(d0)

return digest

def test():

assert md5me("") == "d41d8cd98f00b204e9800998ecf8427e"

assert md5me("The quick brown fox jumps over the lazy dog") == "9e107d9d372bb6826bd81d3542a419d6"

print("Success.")

if __name__ == "__main__":

test()

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