sha-256.py

def sha256(message):
    
    K = [
        0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
        0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
        0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
        0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
        0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
        0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
        0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
        0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2
    ]
    
    h0 = 0x6a09e667
    h1 = 0xbb67ae85
    h2 = 0x3c6ef372
    h3 = 0xa54ff53a
    h4 = 0x510e527f
    h5 = 0x9b05688c
    h6 = 0x1f83d9ab
    h7 = 0x5be0cd19

    def right_rotate(n, d):
        return (n >> d) | (n << (32 - d)) & 0xFFFFFFFF

    def preprocess(message):
        
        if isinstance(message, str):
            message = message.encode()
        
        
        length = len(message) * 8
        
        message = bytearray(message)
        message.append(0x80)
        while (len(message) * 8 + 64) % 512 != 0:
            message.append(0x00)
            
        
        message += length.to_bytes(8, 'big')
        return message

    def process_chunk(chunk):
        w = [0] * 64
        
        for i in range(16):
            w[i] = int.from_bytes(chunk[i*4:(i+1)*4], 'big')
           
        for i in range(16, 64):
            s0 = right_rotate(w[i-15], 7) ^ right_rotate(w[i-15], 18) ^ (w[i-15] >> 3)
            s1 = right_rotate(w[i-2], 17) ^ right_rotate(w[i-2], 19) ^ (w[i-2] >> 10)
            w[i] = (w[i-16] + s0 + w[i-7] + s1) & 0xFFFFFFFF
            
        a, b, c, d, e, f, g, h = h0, h1, h2, h3, h4, h5, h6, h7
        
        for i in range(64):
            S1 = right_rotate(e, 6) ^ right_rotate(e, 11) ^ right_rotate(e, 25)
            ch = (e & f) ^ (~e & g)
            temp1 = (h + S1 + ch + K[i] + w[i]) & 0xFFFFFFFF
            S0 = right_rotate(a, 2) ^ right_rotate(a, 13) ^ right_rotate(a, 22)
            maj = (a & b) ^ (a & c) ^ (b & c)
            temp2 = (S0 + maj) & 0xFFFFFFFF
            
            h = g
            g = f
            f = e
            e = (d + temp1) & 0xFFFFFFFF
            d = c
            c = b
            b = a
            a = (temp1 + temp2) & 0xFFFFFFFF
            
        
        nonlocal h0, h1, h2, h3, h4, h5, h6, h7
        h0 = (h0 + a) & 0xFFFFFFFF
        h1 = (h1 + b) & 0xFFFFFFFF
        h2 = (h2 + c) & 0xFFFFFFFF
        h3 = (h3 + d) & 0xFFFFFFFF
        h4 = (h4 + e) & 0xFFFFFFFF
        h5 = (h5 + f) & 0xFFFFFFFF
        h6 = (h6 + g) & 0xFFFFFFFF
        h7 = (h7 + h) & 0xFFFFFFFF

    message = preprocess(message)

    for i in range(0, len(message), 64):
        process_chunk(message[i:i+64])
    
    digest = (h0 << 224) | (h1 << 192) | (h2 << 160) | (h3 << 128) | \
             (h4 << 96) | (h5 << 64) | (h6 << 32) | h7
    
    return hex(digest)[2:].zfill(64)