pwman3/pwman/util/crypto/rijndael.py

"""
Copyright (c) 2014  Philippe Teuwen <phil@teuwen.org>


Permission is hereby granted, free of charge, to any person obtaining a copy of 
this software and associated documentation files (the "Software"), to deal in 
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING 
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS 
IN THE SOFTWARE.

This code is taken from https://github.com/doegox/python-cryptoplus/

A pure python (slow) implementation of rijndael with a decent interface

To include -

from rijndael import rijndael

To do a key setup -

r = rijndael(key, block_size = 16)

key must be a string of length 16, 24, or 32
blocksize must be 16, 24, or 32. Default is 16

To use -

ciphertext = r.encrypt(plaintext)
plaintext = r.decrypt(ciphertext)

If any strings are of the wrong length a ValueError is thrown



"""

# ported from the Java reference code by Bram Cohen, bram@gawth.com, April 2001
# this code is public domain, unless someone makes
# an intellectual property claim against the reference
# code, in which case it can be made public domain by
# deleting all the comments and renaming all the variables

import copy


#-----------------------
#TREV - ADDED BECAUSE THERE'S WARNINGS ABOUT INT OVERFLOW BEHAVIOR CHANGING IN
#2.4.....
#import os
#if os.name != "java":
#    import exceptions
#    if hasattr(exceptions, "FutureWarning"):
#        import warnings
#        warnings.filterwarnings("ignore", category=FutureWarning, append=1)
#-----------------------



shifts = [[[0, 0], [1, 3], [2, 2], [3, 1]],
          [[0, 0], [1, 5], [2, 4], [3, 3]],
          [[0, 0], [1, 7], [3, 5], [4, 4]]]

# [keysize][block_size]
num_rounds = {16: {16: 10, 24: 12, 32: 14}, 24: {16: 12, 24: 12, 32: 14}, 32: {16: 14, 24: 14, 32: 14}}

A = [[1, 1, 1, 1, 1, 0, 0, 0],
     [0, 1, 1, 1, 1, 1, 0, 0],
     [0, 0, 1, 1, 1, 1, 1, 0],
     [0, 0, 0, 1, 1, 1, 1, 1],
     [1, 0, 0, 0, 1, 1, 1, 1],
     [1, 1, 0, 0, 0, 1, 1, 1],
     [1, 1, 1, 0, 0, 0, 1, 1],
     [1, 1, 1, 1, 0, 0, 0, 1]]

# produce log and alog tables, needed for multiplying in the
# field GF(2^m) (generator = 3)
alog = [1]
for i in range(255):
    j = (alog[-1] << 1) ^ alog[-1]
    if j & 0x100 != 0:
        j ^= 0x11B
    alog.append(j)

log = [0] * 256
for i in range(1, 255):
    log[alog[i]] = i

# multiply two elements of GF(2^m)
def mul(a, b):
    if a == 0 or b == 0:
        return 0
    return alog[(log[a & 0xFF] + log[b & 0xFF]) % 255]

# substitution box based on F^{-1}(x)
box = [[0] * 8 for i in range(256)]
box[1][7] = 1
for i in range(2, 256):
    j = alog[255 - log[i]]
    for t in range(8):
        box[i][t] = (j >> (7 - t)) & 0x01

B = [0, 1, 1, 0, 0, 0, 1, 1]

# affine transform:  box[i] <- B + A*box[i]
cox = [[0] * 8 for i in range(256)]
for i in range(256):
    for t in range(8):
        cox[i][t] = B[t]
        for j in range(8):
            cox[i][t] ^= A[t][j] * box[i][j]

# S-boxes and inverse S-boxes
S =  [0] * 256
Si = [0] * 256
for i in range(256):
    S[i] = cox[i][0] << 7
    for t in range(1, 8):
        S[i] ^= cox[i][t] << (7-t)
    Si[S[i] & 0xFF] = i

# T-boxes
G = [[2, 1, 1, 3],
    [3, 2, 1, 1],
    [1, 3, 2, 1],
    [1, 1, 3, 2]]

AA = [[0] * 8 for i in range(4)]

for i in range(4):
    for j in range(4):
        AA[i][j] = G[i][j]
        AA[i][i+4] = 1

for i in range(4):
    pivot = AA[i][i]
    if pivot == 0:
        t = i + 1
        while AA[t][i] == 0 and t < 4:
            t += 1
            assert t != 4, 'G matrix must be invertible'
            for j in range(8):
                AA[i][j], AA[t][j] = AA[t][j], AA[i][j]
            pivot = AA[i][i]
    for j in range(8):
        if AA[i][j] != 0:
            AA[i][j] = alog[(255 + log[AA[i][j] & 0xFF] - log[pivot & 0xFF]) % 255]
    for t in range(4):
        if i != t:
            for j in range(i+1, 8):
                AA[t][j] ^= mul(AA[i][j], AA[t][i])
            AA[t][i] = 0

iG = [[0] * 4 for i in range(4)]

for i in range(4):
    for j in range(4):
        iG[i][j] = AA[i][j + 4]

def mul4(a, bs):
    if a == 0:
        return 0
    r = 0
    for b in bs:
        r <<= 8
        if b != 0:
            r = r | mul(a, b)
    return r

T1 = []
T2 = []
T3 = []
T4 = []
T5 = []
T6 = []
T7 = []
T8 = []
U1 = []
U2 = []
U3 = []
U4 = []

for t in range(256):
    s = S[t]
    T1.append(mul4(s, G[0]))
    T2.append(mul4(s, G[1]))
    T3.append(mul4(s, G[2]))
    T4.append(mul4(s, G[3]))

    s = Si[t]
    T5.append(mul4(s, iG[0]))
    T6.append(mul4(s, iG[1]))
    T7.append(mul4(s, iG[2]))
    T8.append(mul4(s, iG[3]))

    U1.append(mul4(t, iG[0]))
    U2.append(mul4(t, iG[1]))
    U3.append(mul4(t, iG[2]))
    U4.append(mul4(t, iG[3]))

# round constants
rcon = [1]
r = 1
for t in range(1, 30):
    r = mul(2, r)
    rcon.append(r)

del A
del AA
del pivot
del B
del G
del box
del log
del alog
del i
del j
del r
del s
del t
del mul
del mul4
del cox
del iG

class rijndael:
    def __init__(self, key, block_size = 16):
        if block_size != 16 and block_size != 24 and block_size != 32:
            raise ValueError('Invalid block size: ' + str(block_size))
        if len(key) != 16 and len(key) != 24 and len(key) != 32:
            raise ValueError('Invalid key size: ' + str(len(key)))
        self.block_size = block_size
        ROUNDS = num_rounds[len(key)][block_size]
        BC = block_size // 4
        # encryption round keys
        Ke = [[0] * BC for i in range(ROUNDS + 1)]
        # decryption round keys
        Kd = [[0] * BC for i in range(ROUNDS + 1)]
        ROUND_KEY_COUNT = (ROUNDS + 1) * BC
        KC = len(key) // 4

        # copy user material bytes into temporary ints
        tk = []
        for i in range(0, KC):
            tk.append((ord(key[i * 4]) << 24) | (ord(key[i * 4 + 1]) << 16) |
                (ord(key[i * 4 + 2]) << 8) | ord(key[i * 4 + 3]))

        # copy values into round key arrays
        t = 0
        j = 0
        while j < KC and t < ROUND_KEY_COUNT:
            Ke[t // BC][t % BC] = tk[j]
            Kd[ROUNDS - (t // BC)][t % BC] = tk[j]
            j += 1
            t += 1
        tt = 0
        rconpointer = 0
        while t < ROUND_KEY_COUNT:
            # extrapolate using phi (the round key evolution function)
            tt = tk[KC - 1]
            tk[0] ^= (S[(tt >> 16) & 0xFF] & 0xFF) << 24 ^  \
                     (S[(tt >>  8) & 0xFF] & 0xFF) << 16 ^  \
                     (S[ tt        & 0xFF] & 0xFF) <<  8 ^  \
                     (S[(tt >> 24) & 0xFF] & 0xFF)       ^  \
                     (rcon[rconpointer]    & 0xFF) << 24
            rconpointer += 1
            if KC != 8:
                for i in range(1, KC):
                    tk[i] ^= tk[i-1]
            else:
                for i in range(1, KC // 2):
                    tk[i] ^= tk[i-1]
                tt = tk[KC // 2 - 1]
                tk[KC // 2] ^= (S[ tt        & 0xFF] & 0xFF)       ^ \
                               (S[(tt >>  8) & 0xFF] & 0xFF) <<  8 ^ \
                               (S[(tt >> 16) & 0xFF] & 0xFF) << 16 ^ \
                               (S[(tt >> 24) & 0xFF] & 0xFF) << 24
                for i in range(KC // 2 + 1, KC):
                    tk[i] ^= tk[i-1]
            # copy values into round key arrays
            j = 0
            while j < KC and t < ROUND_KEY_COUNT:
                Ke[t // BC][t % BC] = tk[j]
                Kd[ROUNDS - (t // BC)][t % BC] = tk[j]
                j += 1
                t += 1
        # inverse MixColumn where needed
        for r in range(1, ROUNDS):
            for j in range(BC):
                tt = Kd[r][j]
                Kd[r][j] = U1[(tt >> 24) & 0xFF] ^ \
                           U2[(tt >> 16) & 0xFF] ^ \
                           U3[(tt >>  8) & 0xFF] ^ \
                           U4[ tt        & 0xFF]
        self.Ke = Ke
        self.Kd = Kd

    def encrypt(self, plaintext):
        if len(plaintext) != self.block_size:
            raise ValueError('wrong block length, expected ' + str(self.block_size) + ' got ' + str(len(plaintext)))
        Ke = self.Ke

        BC = self.block_size // 4
        ROUNDS = len(Ke) - 1
        if BC == 4:
            SC = 0
        elif BC == 6:
            SC = 1
        else:
            SC = 2
        s1 = shifts[SC][1][0]
        s2 = shifts[SC][2][0]
        s3 = shifts[SC][3][0]
        a = [0] * BC
        # temporary work array
        t = []
        # plaintext to ints + key
        for i in range(BC):
            t.append((ord(plaintext[i * 4    ]) << 24 |
                      ord(plaintext[i * 4 + 1]) << 16 |
                      ord(plaintext[i * 4 + 2]) <<  8 |
                      ord(plaintext[i * 4 + 3])        ) ^ Ke[0][i])
        # apply round transforms
        for r in range(1, ROUNDS):
            for i in range(BC):
                a[i] = (T1[(t[ i           ] >> 24) & 0xFF] ^
                        T2[(t[(i + s1) % BC] >> 16) & 0xFF] ^
                        T3[(t[(i + s2) % BC] >>  8) & 0xFF] ^
                        T4[ t[(i + s3) % BC]        & 0xFF]  ) ^ Ke[r][i]
            t = copy.copy(a)
        # last round is special
        result = []
        for i in range(BC):
            tt = Ke[ROUNDS][i]
            result.append((S[(t[ i           ] >> 24) & 0xFF] ^ (tt >> 24)) & 0xFF)
            result.append((S[(t[(i + s1) % BC] >> 16) & 0xFF] ^ (tt >> 16)) & 0xFF)
            result.append((S[(t[(i + s2) % BC] >>  8) & 0xFF] ^ (tt >>  8)) & 0xFF)
            result.append((S[ t[(i + s3) % BC]        & 0xFF] ^  tt       ) & 0xFF)
        return "".join(list(map(chr, result)))

    def decrypt(self, ciphertext):
        if len(ciphertext) != self.block_size:
            raise ValueError('wrong block length, expected ' + str(self.block_size) + ' got ' + str(len(plaintext)))
        Kd = self.Kd

        BC = self.block_size // 4
        ROUNDS = len(Kd) - 1
        if BC == 4:
            SC = 0
        elif BC == 6:
            SC = 1
        else:
            SC = 2
        s1 = shifts[SC][1][1]
        s2 = shifts[SC][2][1]
        s3 = shifts[SC][3][1]
        a = [0] * BC
        # temporary work array
        t = [0] * BC
        # ciphertext to ints + key
        for i in range(BC):
            t[i] = (ord(ciphertext[i * 4    ]) << 24 |
                    ord(ciphertext[i * 4 + 1]) << 16 |
                    ord(ciphertext[i * 4 + 2]) <<  8 |
                    ord(ciphertext[i * 4 + 3])        ) ^ Kd[0][i]
        # apply round transforms
        for r in range(1, ROUNDS):
            for i in range(BC):
                a[i] = (T5[(t[ i           ] >> 24) & 0xFF] ^
                        T6[(t[(i + s1) % BC] >> 16) & 0xFF] ^
                        T7[(t[(i + s2) % BC] >>  8) & 0xFF] ^
                        T8[ t[(i + s3) % BC]        & 0xFF]  ) ^ Kd[r][i]
            t = copy.copy(a)
        # last round is special
        result = []
        for i in range(BC):
            tt = Kd[ROUNDS][i]
            result.append((Si[(t[ i           ] >> 24) & 0xFF] ^ (tt >> 24)) & 0xFF)
            result.append((Si[(t[(i + s1) % BC] >> 16) & 0xFF] ^ (tt >> 16)) & 0xFF)
            result.append((Si[(t[(i + s2) % BC] >>  8) & 0xFF] ^ (tt >>  8)) & 0xFF)
            result.append((Si[ t[(i + s3) % BC]        & 0xFF] ^  tt       ) & 0xFF)
        return "".join(list(map(chr, result)))


def encrypt(key, block):
    return rijndael(key, len(block)).encrypt(block)


def decrypt(key, block):
    return rijndael(key, len(block)).decrypt(block)


if __name__ == '__main__':
    # test
    def t(kl, bl):
        b = 'b' * bl
        r = rijndael('a' * kl, bl)
        assert r.decrypt(r.encrypt(b)) == b

    t(16, 16)
    t(16, 24)
    t(16, 32)
    t(24, 16)
    t(24, 24)
    t(24, 32)
    t(32, 16)
    t(32, 24)
    t(32, 32)