Have you tried this (also included below)? It implements a Rijndael block block for 16, 24, or 32 bytes. You are using a 256-bit (32-byte) version of block encryption.
""" 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, 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 import string 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(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: 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(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)
Note that the rijndael.py file implements only a block cipher. The encrypt / decrypt functions only process text files that are exactly block size. This means that the caller of these functions will have to provide the mode of operation of block encryption and zero filling itself.
Python sample code (from a Java programmer, beware):
class zeropad: def __init__(self, block_size): assert block_size > 0 and block_size < 256 self.block_size = block_size def pad(self, pt): ptlen = len(pt) padsize = self.block_size - ((ptlen + self.block_size - 1) % self.block_size + 1) return pt + "\0" * padsize def unpad(self, ppt): assert len(ppt) % self.block_size == 0 offset = len(ppt) if (offset == 0): return '' end = offset - self.block_size + 1 while (offset > end): offset -= 1; if (ppt[offset] != "\0"): return ppt[:offset + 1] assert false class cbc: def __init__(self, padding, cipher, iv): assert padding.block_size == cipher.block_size; assert len(iv) == cipher.block_size; self.padding = padding self.cipher = cipher self.iv = iv def encrypt(self, pt): ppt = self.padding.pad(pt) offset = 0 ct = '' v = self.iv while (offset < len(ppt)): block = ppt[offset:offset + self.cipher.block_size] block = self.xorblock(block, v) block = self.cipher.encrypt(block) ct += block offset += self.cipher.block_size v = block return ct; def decrypt(self, ct): assert len(ct) % self.cipher.block_size == 0 ppt = '' offset = 0 v = self.iv while (offset < len(ct)): block = ct[offset:offset + self.cipher.block_size] decrypted = self.cipher.decrypt(block) ppt += self.xorblock(decrypted, v) offset += self.cipher.block_size v = block pt = self.padding.unpad(ppt) return pt; def xorblock(self, b1, b2):