Pure-Python implementation of Rijndael (AES) cipher.

rijndael.py

#############################################################################
# Original code ported from the Java reference code by Bram Cohen, April 2001,
# with the following statement:
#
#         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
#
class Rijndael(object):
    """
    A pure python (slow) implementation of rijndael with a decent interface.

    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
    """

    @classmethod
    def create(cls):

        if hasattr(cls, "RIJNDAEL_CREATED"):
            return

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

        cls.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]]]

        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 xrange(255):
            j = (alog[-1] << 1) ^ alog[-1]
            if j & 0x100 != 0:
                j ^= 0x11B
            alog.append(j)

        log = [0] * 256
        for i in xrange(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 xrange(256)]
        box[1][7] = 1
        for i in xrange(2, 256):
            j = alog[255 - log[i]]
            for t in xrange(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 xrange(256)]
        for i in xrange(256):
            for t in xrange(8):
                cox[i][t] = B[t]
                for j in xrange(8):
                    cox[i][t] ^= A[t][j] * box[i][j]

        # cls.S-boxes and inverse cls.S-boxes
        cls.S =  [0] * 256
        cls.Si = [0] * 256
        for i in xrange(256):
            cls.S[i] = cox[i][0] << 7
            for t in xrange(1, 8):
                cls.S[i] ^= cox[i][t] << (7-t)
            cls.Si[cls.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 xrange(4)]

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

        for i in xrange(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 xrange(8):
                        AA[i][j], AA[t][j] = AA[t][j], AA[i][j]
                    pivot = AA[i][i]
            for j in xrange(8):
                if AA[i][j] != 0:
                    AA[i][j] = alog[(255 + log[AA[i][j] & 0xFF] - log[pivot & 0xFF]) % 255]
            for t in xrange(4):
                if i != t:
                    for j in xrange(i+1, 8):
                        AA[t][j] ^= mul(AA[i][j], AA[t][i])
                    AA[t][i] = 0

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

        for i in xrange(4):
            for j in xrange(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

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

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

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

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

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

        cls.RIJNDAEL_CREATED = True

    def __init__(self, key, block_size = 16):

        # create common meta-instance infrastructure
        self.create()

        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 = Rijndael.num_rounds[len(key)][block_size]
        BC = block_size / 4
        # encryption round keys
        Ke = [[0] * BC for i in xrange(ROUNDS + 1)]
        # decryption round keys
        Kd = [[0] * BC for i in xrange(ROUNDS + 1)]
        ROUND_KEY_COUNT = (ROUNDS + 1) * BC
        KC = len(key) / 4

        # copy user material bytes into temporary ints
        tk = []
        for i in xrange(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] ^= (Rijndael.S[(tt >> 16) & 0xFF] & 0xFF) << 24 ^  \
                     (Rijndael.S[(tt >>  8) & 0xFF] & 0xFF) << 16 ^  \
                     (Rijndael.S[ tt        & 0xFF] & 0xFF) <<  8 ^  \
                     (Rijndael.S[(tt >> 24) & 0xFF] & 0xFF)       ^  \
                     (Rijndael.rcon[rconpointer]    & 0xFF) << 24
            rconpointer += 1
            if KC != 8:
                for i in xrange(1, KC):
                    tk[i] ^= tk[i-1]
            else:
                for i in xrange(1, KC / 2):
                    tk[i] ^= tk[i-1]
                tt = tk[KC / 2 - 1]
                tk[KC / 2] ^= (Rijndael.S[ tt        & 0xFF] & 0xFF)       ^ \
                              (Rijndael.S[(tt >>  8) & 0xFF] & 0xFF) <<  8 ^ \
                              (Rijndael.S[(tt >> 16) & 0xFF] & 0xFF) << 16 ^ \
                              (Rijndael.S[(tt >> 24) & 0xFF] & 0xFF) << 24
                for i in xrange(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 xrange(1, ROUNDS):
            for j in xrange(BC):
                tt = Kd[r][j]
                Kd[r][j] = Rijndael.U1[(tt >> 24) & 0xFF] ^ \
                           Rijndael.U2[(tt >> 16) & 0xFF] ^ \
                           Rijndael.U3[(tt >>  8) & 0xFF] ^ \
                           Rijndael.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:
            Rijndael.SC = 0
        elif BC == 6:
            Rijndael.SC = 1
        else:
            Rijndael.SC = 2
        s1 = Rijndael.shifts[Rijndael.SC][1][0]
        s2 = Rijndael.shifts[Rijndael.SC][2][0]
        s3 = Rijndael.shifts[Rijndael.SC][3][0]
        a = [0] * BC
        # temporary work array
        t = []
        # plaintext to ints + key
        for i in xrange(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 xrange(1, ROUNDS):
            for i in xrange(BC):
                a[i] = (Rijndael.T1[(t[ i           ] >> 24) & 0xFF] ^
                        Rijndael.T2[(t[(i + s1) % BC] >> 16) & 0xFF] ^
                        Rijndael.T3[(t[(i + s2) % BC] >>  8) & 0xFF] ^
                        Rijndael.T4[ t[(i + s3) % BC]        & 0xFF]  ) ^ Ke[r][i]
            t = copy.copy(a)
        # last round is special
        result = []
        for i in xrange(BC):
            tt = Ke[ROUNDS][i]
            result.append((Rijndael.S[(t[ i           ] >> 24) & 0xFF] ^ (tt >> 24)) & 0xFF)
            result.append((Rijndael.S[(t[(i + s1) % BC] >> 16) & 0xFF] ^ (tt >> 16)) & 0xFF)
            result.append((Rijndael.S[(t[(i + s2) % BC] >>  8) & 0xFF] ^ (tt >>  8)) & 0xFF)
            result.append((Rijndael.S[ t[(i + s3) % BC]        & 0xFF] ^  tt       ) & 0xFF)
        return string.join(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(ciphertext)))
        Kd = self.Kd

        BC = self.block_size / 4
        ROUNDS = len(Kd) - 1
        if BC == 4:
            Rijndael.SC = 0
        elif BC == 6:
            Rijndael.SC = 1
        else:
            Rijndael.SC = 2
        s1 = Rijndael.shifts[Rijndael.SC][1][1]
        s2 = Rijndael.shifts[Rijndael.SC][2][1]
        s3 = Rijndael.shifts[Rijndael.SC][3][1]
        a = [0] * BC
        # temporary work array
        t = [0] * BC
        # ciphertext to ints + key
        for i in xrange(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 xrange(1, ROUNDS):
            for i in xrange(BC):
                a[i] = (Rijndael.T5[(t[ i           ] >> 24) & 0xFF] ^
                        Rijndael.T6[(t[(i + s1) % BC] >> 16) & 0xFF] ^
                        Rijndael.T7[(t[(i + s2) % BC] >>  8) & 0xFF] ^
                        Rijndael.T8[ t[(i + s3) % BC]        & 0xFF]  ) ^ Kd[r][i]
            t = copy.copy(a)
        # last round is special
        result = []
        for i in xrange(BC):
            tt = Kd[ROUNDS][i]
            result.append((Rijndael.Si[(t[ i           ] >> 24) & 0xFF] ^ (tt >> 24)) & 0xFF)
            result.append((Rijndael.Si[(t[(i + s1) % BC] >> 16) & 0xFF] ^ (tt >> 16)) & 0xFF)
            result.append((Rijndael.Si[(t[(i + s2) % BC] >>  8) & 0xFF] ^ (tt >>  8)) & 0xFF)
            result.append((Rijndael.Si[ t[(i + s3) % BC]        & 0xFF] ^  tt       ) & 0xFF)
        return string.join(map(chr, result), '')

    # @staticmethod
    # def encrypt_block(key, block):
    #     return Rijndael(key, len(block)).encrypt(block)

    # @staticmethod
    # def decrypt_block(key, block):
    #     return Rijndael(key, len(block)).decrypt(block)

    @staticmethod
    def test():
        def t(kl, bl):
            b = 'b' * bl
            r = Rijndael('a' * kl, bl)
            x = r.encrypt(b)
            assert x != b
            assert r.decrypt(x) == 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)
# Rijndael
#############################################################################

@jeetsukumaran : I like your script, it's fast enough for me to generated box, invsbox and rcon :)

Everywhere on the web, I see the box, invsbox and rcon lists are hardcoded and containing each 256 items.

You actually generated them, which is really great and I thank you for that.

The fist drawback is that your cls.rcon list only has 30 items instead of 255 (not counting cls.rcon[0]): (line 179 in your script: for t in xrange(1, 30):)

Can you please change the number of items of your cls.rcon list from 30 upto 255 so ?

The second is that your script does not work in python3.

To make it both Python2 and Python3 compatible, you need to search and replace xrange by range and / by //.

Can you please modify it, that would be great ?

this is a python 3 implementation of it. I just edited a few things to make the original posters code work in Python 3,however, there is a bug in python that makes it so you can no longer print something in the code after printing the cipher text. not sure if it only affects pyscripter though.

import copy
class Rijndael(object):
    @classmethod
    def create(cls):

        if hasattr(cls, "RIJNDAEL_CREATED"):
            return

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

        cls.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]]]

        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]

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

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

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

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

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

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

        cls.RIJNDAEL_CREATED = True

    def __init__(self, key, block_size = 16):

        # create common meta-instance infrastructure
        self.create()

        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 = Rijndael.num_rounds[len(key)][block_size]
        BC = int(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 = int(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[int(t / BC)][t % BC] = tk[j]
            Kd[ROUNDS - (int(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] ^= (Rijndael.S[(tt >> 16) & 0xFF] & 0xFF) << 24 ^  \
                     (Rijndael.S[(tt >>  8) & 0xFF] & 0xFF) << 16 ^  \
                     (Rijndael.S[ tt        & 0xFF] & 0xFF) <<  8 ^  \
                     (Rijndael.S[(tt >> 24) & 0xFF] & 0xFF)       ^  \
                     (Rijndael.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, int(KC / 2)):
                    tk[i] ^= tk[i-1]
                tt = tk[int(KC / 2 - 1)]
                tk[int(KC / 2)] ^= (Rijndael.S[ tt        & 0xFF] & 0xFF)       ^ \
                              (Rijndael.S[(tt >>  8) & 0xFF] & 0xFF) <<  8 ^ \
                              (Rijndael.S[(tt >> 16) & 0xFF] & 0xFF) << 16 ^ \
                              (Rijndael.S[(tt >> 24) & 0xFF] & 0xFF) << 24
                for i in range(int(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[int(t / BC)][t % BC] = tk[j]
                Kd[ROUNDS - (int(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] = Rijndael.U1[(tt >> 24) & 0xFF] ^ \
                           Rijndael.U2[(tt >> 16) & 0xFF] ^ \
                           Rijndael.U3[(tt >>  8) & 0xFF] ^ \
                           Rijndael.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 = int(self.block_size / 4)
        ROUNDS = len(Ke) - 1
        if BC == 4:
            Rijndael.SC = 0
        elif BC == 6:
            Rijndael.SC = 1
        else:
            Rijndael.SC = 2
        s1 = Rijndael.shifts[Rijndael.SC][1][0]
        s2 = Rijndael.shifts[Rijndael.SC][2][0]
        s3 = Rijndael.shifts[Rijndael.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] = (Rijndael.T1[(t[ i           ] >> 24) & 0xFF] ^
                        Rijndael.T2[(t[(i + s1) % BC] >> 16) & 0xFF] ^
                        Rijndael.T3[(t[(i + s2) % BC] >>  8) & 0xFF] ^
                        Rijndael.T4[ t[(i + s3) % BC]        & 0xFF]  ) ^ Ke[r][i]
            t = copy.deepcopy(a)
        # last round is special
        result = []
        for i in range(BC):
            tt = Ke[ROUNDS][i]
            result.append((Rijndael.S[(t[ i           ] >> 24) & 0xFF] ^ (tt >> 24)) & 0xFF)
            result.append((Rijndael.S[(t[(i + s1) % BC] >> 16) & 0xFF] ^ (tt >> 16)) & 0xFF)
            result.append((Rijndael.S[(t[(i + s2) % BC] >>  8) & 0xFF] ^ (tt >>  8)) & 0xFF)
            result.append((Rijndael.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(ciphertext)))
        Kd = self.Kd

        BC = int(self.block_size / 4)
        ROUNDS = len(Kd) - 1
        if BC == 4:
            Rijndael.SC = 0
        elif BC == 6:
            Rijndael.SC = 1
        else:
            Rijndael.SC = 2
        s1 = Rijndael.shifts[Rijndael.SC][1][1]
        s2 = Rijndael.shifts[Rijndael.SC][2][1]
        s3 = Rijndael.shifts[Rijndael.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] = (Rijndael.T5[(t[ i           ] >> 24) & 0xFF] ^
                        Rijndael.T6[(t[(i + s1) % BC] >> 16) & 0xFF] ^
                        Rijndael.T7[(t[(i + s2) % BC] >>  8) & 0xFF] ^
                        Rijndael.T8[ t[(i + s3) % BC]        & 0xFF]  ) ^ Kd[r][i]
            t = copy.deepcopy(a)
        # last round is special
        result = []
        for i in range(BC):
            tt = Kd[ROUNDS][i]
            result.append((Rijndael.Si[(t[ i           ] >> 24) & 0xFF] ^ (tt >> 24)) & 0xFF)
            result.append((Rijndael.Si[(t[(i + s1) % BC] >> 16) & 0xFF] ^ (tt >> 16)) & 0xFF)
            result.append((Rijndael.Si[(t[(i + s2) % BC] >>  8) & 0xFF] ^ (tt >>  8)) & 0xFF)
            result.append((Rijndael.Si[ t[(i + s3) % BC]        & 0xFF] ^  tt       ) & 0xFF)
        return ''.join(list(map(chr, result)))

    # @staticmethod
    # def encrypt_block(key, block):
    #     return Rijndael(key, len(block)).encrypt(block)

    # @staticmethod
    # def decrypt_block(key, block):
    #     return Rijndael(key, len(block)).decrypt(block)

    @staticmethod
    def test():
        def t(kl, bl):
            b = 'b' * bl
            r = Rijndael('a' * kl, bl)
            x = r.encrypt(b)
            assert x != b
            assert r.decrypt(x) == 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)
r = Rijndael("abcdefg1234567890123456789012345", block_size = 32)
ciphertext = r.encrypt("abcdefg1234567890123456789012345")
plaintext = r.decrypt(ciphertext)
print (plaintext,ciphertext)`

Unbelievable！

Added CBC option: https://github.com/sysopfb/pyrijndael

Your implementation as a package: https://github.com/meyt/py3rijndael

How can I use the code to encrypt a Windows or Linux partition? e.g. F:/ or sda4 ?

How can I use the code to encrypt a Windows or Linux partition? e.g. F:/ or sda4 ?

@MichaelK866 Please don't. This was probably written as an exercise to understand the algorithm. To encrypt/decrypt your stuff, use more standardized, battle tested tools(like LUKS for linux).