MD5.py

import math

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, ]


def rearrange(bitString32):
    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):
    hexrep = format(i, "08x")
    thing = ""
    for i in [3, 2, 1, 0]:
        thing += hexrep[2 * i: 2 * i + 2]
    return thing


def pad(bitString):
    startLength = len(bitString)
    bitString += "1"
    while len(bitString) % 512 != 448:
        bitString += "0"
    lastPart = format(startLength, "064b")
    #lastPart = "{0:064b}".format(startLength)
    bitString += rearrange(lastPart[32:]) + rearrange(lastPart[:32])
    return bitString


def getBlock(bitString):

    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):
    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

    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():
    print(md5me("hellowwwwwwwwww"))
    assert (
        md5me("The quick brown fox jumps over the lazy dog")
        == "9e107d9d372bb6826bd81d3542a419d6"
    )
    print("Success.")


if __name__ == "__main__":
    test()