CNS Practical-11

import hashlib

def md5_hash(message):
    md5 = hashlib.md5()
    md5.update(message.encode())
    return md5.hexdigest()

message = "Hello, this is a test message for MD5 hashing!"
hashed_message = md5_hash(message)

print(f"Original Message: {message}")
print(f"MD5 Hash: {hashed_message}")

import struct
import math

# Left rotation function
def left_rotate(x, amount):
    x &= 0xFFFFFFFF
    return ((x << amount) | (x >> (32 - amount))) & 0xFFFFFFFF

# Main MD5 function
def md5(message):
    # s specifies the per-round shift amounts
    s = [7, 12, 17, 22] * 4 + \
        [5, 9, 14, 20] * 4 + \
        [4, 11, 16, 23] * 4 + \
        [6, 10, 15, 21] * 4

    # Use binary integer part of the sines of integers (in radians) as constants
    K = [int(abs(math.sin(i + 1)) * 2**32) & 0xFFFFFFFF for i in range(64)]

    # Initialize variables
    a0 = 0x67452301  # A
    b0 = 0xEFCDAB89  # B
    c0 = 0x98BADCFE  # C
    d0 = 0x10325476  # D

    # Pre-processing
    original_len_in_bits = (8 * len(message)) & 0xffffffffffffffff
    message += b'\x80'
    while len(message) % 64 != 56:
        message += b'\x00'
    message += struct.pack('<Q', original_len_in_bits)

    # Process the message in 512-bit (64-byte) chunks
    for chunk_offset in range(0, len(message), 64):
        chunk = message[chunk_offset:chunk_offset+64]
        M = list(struct.unpack('<16I', chunk))

        A, B, C, D = a0, b0, c0, d0

        for i in range(64):
            if 0 <= i <= 15:
                F = (B & C) | (~B & D)
                g = i
            elif 16 <= i <= 31:
                F = (D & B) | (~D & C)
                g = (5*i + 1) % 16
            elif 32 <= i <= 47:
                F = B ^ C ^ D
                g = (3*i + 5) % 16
            elif 48 <= i <= 63:
                F = C ^ (B | ~D)
                g = (7*i) % 16

            F = (F + A + K[i] + M[g]) & 0xFFFFFFFF
            A, D, C, B = D, C, B, (B + left_rotate(F, s[i])) & 0xFFFFFFFF

        # Add this chunk's hash to result so far:
        a0 = (a0 + A) & 0xFFFFFFFF
        b0 = (b0 + B) & 0xFFFFFFFF
        c0 = (c0 + C) & 0xFFFFFFFF
        d0 = (d0 + D) & 0xFFFFFFFF

    # Return the final MD5 digest as a 32-digit hexadecimal string
    return ''.join(f'{x:02x}' for x in struct.pack('<4I', a0, b0, c0, d0))


# Example usage
if __name__ == '__main__':
    test1 = b"hello world"
    test2 = b"GeeksForGeeks"
    
    print("MD5 of 'hello world':", md5(test1))
    print("MD5 of 'GeeksForGeeks':", md5(test2))