PietuCipher 1.0

# PietuCipher1
# version 1.0

def _keyval(key):
    total = 1
    for pos1 in range(len(key)):
        for pos2 in range(len(key)):
            total = ((total + key[pos1]) ** key[pos2]) % 0xffffffff
    return total

def _tables(cols, rows):
    table = []
    revtable = []
    for row in rows:
        items = [(pos, (row + col) % 256) for pos, col in enumerate(cols)]
        poss = [0] * len(cols)
        vals = [0] * len(cols)
        for pos, val in items:
            poss[val] = pos
            vals[pos] = val
        table += [vals]
        revtable += [poss]
    return table, revtable

def _gentables(key):
    import random
    val = _keyval(key)
    rand = random.Random(val)
    cols, rows = list(range(256)), list(range(256))
    rand.shuffle(cols)
    rand.shuffle(rows)
    result = _tables(cols, rows)
    return result

def encrypt(data, key):
    table, revtable = _gentables(key)
    prev = 0
    out = []
    for x in data:
        y = table[prev][x]
        out += [y]
        prev = y
    return bytes(out)

def decrypt(data, key):
    table, revtable = _gentables(key)
    prev = 0
    out = []
    for x in data:
        out += [revtable[prev][x]]
        prev = x
    return bytes(out)

if __name__ == "__main__":
    mode = ""
    while mode not in ["E", "D"]: mode = input("[E]ncrypt or [D]ecrypt? ").upper()
    key = bytes(input("Key: "), "utf-8")
    data = input("Input file: ")
    out = input("Output file: ")
    infile = open(data, "rb")
    indata = infile.read()
    infile.close()
    outdata = [encrypt, decrypt][mode == "D"](indata, key)
    outfile = open(out, "wb")
    outfile.write(outdata)
    outfile.close()