An implementation of CictroHash

cictro-hash.py

def pad(txt):
    while (len(txt) % 4 != 0):
        txt += '\0'
    return txt

def create_w(s):
    w = [[s[0], s[1], s[2], s[3]],
         [s[4], s[5], s[6], s[7]]]
    return w

def f(S):
    w = create_w(S)
    for _ in range(50):
        triangle(w)
    return [w[0][0], w[0][1], w[0][2], w[0][3], w[1][0], w[1][1], w[1][2], w[1][3]]

def triangle(w):
    a(w)
    b(w)
    c(w)
    d(w)

def a(w):
    w[0], w[1] = w[1], w[0]

def b(w):
    w[0][0] ^= w[1][3]
    w[0][1] ^= w[1][2]
    w[0][2] ^= w[1][1]
    w[0][3] ^= w[1][0]

def c(w):
    t = [[w[1][3], w[1][0], w[1][2], w[0][0]],
            [w[1][1], w[0][3], w[0][1], w[0][2]]]
    w[0][0] = t[0][0]
    w[0][1] = t[0][1]
    w[0][2] = t[0][2]
    w[0][3] = t[0][3]
    w[1][0] = t[1][0]
    w[1][1] = t[1][1]
    w[1][2] = t[1][2]
    w[1][3] = t[1][3]


def d(w):
    def rotate_right(n):
        return ((n >> 1) | (n << 7)) & 0b11111111
    def rotate_left(n):
        return ((n << 1) | (n >> 7)) & 0b11111111

    w[0][0] = rotate_left(w[0][0])
    w[1][0] = rotate_left(w[1][0])
    w[0][2] = rotate_left(w[0][2])
    w[1][2] = rotate_left(w[1][2])
    
    w[0][1] = rotate_right(w[0][1])
    w[1][1] = rotate_right(w[1][1])
    w[0][3] = rotate_right(w[0][3])
    w[1][3] = rotate_right(w[1][3])

def hash(pre_image):
    S = [31, 56, 156, 167, 38, 240, 174, 248]
    pre = pre_image
    pre = pad(pre)
    for i in range(0, len(pre), 4):
        pre_block = pre[i:i+4]
        for j in range(4):
            S[j] ^= ord(pre_block[j])
        S = f(S)

    answer = ""
    for i in range(4):
        answer += "{0:x}".format(S[i])
    return answer