conversion of list to bitarray in python

Question

I am trying to build a DES code using my humble python knowledge: I get the following error: " xor_lf = l1 ^ Bn TypeError: bitarray object expected for bitwise operation" Do I need to convert Bn or l1 to bitarray? And how?

from bitarray import bitarray
iptable=[57, 49, 41, 33, 25, 17, 9,  1,
        59, 51, 43, 35, 27, 19, 11, 3,
        61, 53, 45, 37, 29, 21, 13, 5,
        63, 55, 47, 39, 31, 23, 15, 7,
        56, 48, 40, 32, 24, 16, 8,  0,
        58, 50, 42, 34, 26, 18, 10, 2,
        60, 52, 44, 36, 28, 20, 12, 4,
        62, 54, 46, 38, 30, 22, 14, 6
    ]
pc1=[56, 48, 40, 32, 24, 16,  8,
          0, 57, 49, 41, 33, 25, 17,
          9,  1, 58, 50, 42, 34, 26,
         18, 10,  2, 59, 51, 43, 35,
         62, 54, 46, 38, 30, 22, 14,
          6, 61, 53, 45, 37, 29, 21,
         13,  5, 60, 52, 44, 36, 28,
         20, 12,  4, 27, 19, 11,  3
    ]
expTable=[31,  0,  1,  2,  3,  4,
         3,  4,  5,  6,  7,  8,
         7,  8,  9, 10, 11, 12,
        11, 12, 13, 14, 15, 16,
        15, 16, 17, 18, 19, 20,
        19, 20, 21, 22, 23, 24,
        23, 24, 25, 26, 27, 28,
        27, 28, 29, 30, 31,  0]
pc2 = [13, 16, 10, 23,  0,  4,
         2, 27, 14,  5, 20,  9,
        22, 18, 11,  3, 25,  7,
        15,  6, 26, 19, 12,  1,
        40, 51, 30, 36, 46, 54,
        29, 39, 50, 44, 32, 47,
        43, 48, 38, 55, 33, 52,
        45, 41, 49, 35, 28, 31] 
# The (in)famous S-boxes
__sbox = [
        # S1
        [14, 4, 13, 1, 2, 15, 11, 8, 3, 10, 6, 12, 5, 9, 0, 7,
         0, 15, 7, 4, 14, 2, 13, 1, 10, 6, 12, 11, 9, 5, 3, 8,
         4, 1, 14, 8, 13, 6, 2, 11, 15, 12, 9, 7, 3, 10, 5, 0,
         15, 12, 8, 2, 4, 9, 1, 7, 5, 11, 3, 14, 10, 0, 6, 13],

        # S2
        [15, 1, 8, 14, 6, 11, 3, 4, 9, 7, 2, 13, 12, 0, 5, 10,
         3, 13, 4, 7, 15, 2, 8, 14, 12, 0, 1, 10, 6, 9, 11, 5,
         0, 14, 7, 11, 10, 4, 13, 1, 5, 8, 12, 6, 9, 3, 2, 15,
         13, 8, 10, 1, 3, 15, 4, 2, 11, 6, 7, 12, 0, 5, 14, 9],

        # S3
        [10, 0, 9, 14, 6, 3, 15, 5, 1, 13, 12, 7, 11, 4, 2, 8,
         13, 7, 0, 9, 3, 4, 6, 10, 2, 8, 5, 14, 12, 11, 15, 1,
         13, 6, 4, 9, 8, 15, 3, 0, 11, 1, 2, 12, 5, 10, 14, 7,
         1, 10, 13, 0, 6, 9, 8, 7, 4, 15, 14, 3, 11, 5, 2, 12],

        # S4
        [7, 13, 14, 3, 0, 6, 9, 10, 1, 2, 8, 5, 11, 12, 4, 15,
         13, 8, 11, 5, 6, 15, 0, 3, 4, 7, 2, 12, 1, 10, 14, 9,
         10, 6, 9, 0, 12, 11, 7, 13, 15, 1, 3, 14, 5, 2, 8, 4,
         3, 15, 0, 6, 10, 1, 13, 8, 9, 4, 5, 11, 12, 7, 2, 14],

        # S5
        [2, 12, 4, 1, 7, 10, 11, 6, 8, 5, 3, 15, 13, 0, 14, 9,
         14, 11, 2, 12, 4, 7, 13, 1, 5, 0, 15, 10, 3, 9, 8, 6,
         4, 2, 1, 11, 10, 13, 7, 8, 15, 9, 12, 5, 6, 3, 0, 14,
         11, 8, 12, 7, 1, 14, 2, 13, 6, 15, 0, 9, 10, 4, 5, 3],

        # S6
        [12, 1, 10, 15, 9, 2, 6, 8, 0, 13, 3, 4, 14, 7, 5, 11,
         10, 15, 4, 2, 7, 12, 9, 5, 6, 1, 13, 14, 0, 11, 3, 8,
         9, 14, 15, 5, 2, 8, 12, 3, 7, 0, 4, 10, 1, 13, 11, 6,
         4, 3, 2, 12, 9, 5, 15, 10, 11, 14, 1, 7, 6, 0, 8, 13],

        # S7
        [4, 11, 2, 14, 15, 0, 8, 13, 3, 12, 9, 7, 5, 10, 6, 1,
         13, 0, 11, 7, 4, 9, 1, 10, 14, 3, 5, 12, 2, 15, 8, 6,
         1, 4, 11, 13, 12, 3, 7, 14, 10, 15, 6, 8, 0, 5, 9, 2,
         6, 11, 13, 8, 1, 4, 10, 7, 9, 5, 0, 15, 14, 2, 3, 12],

        # S8
        [13, 2, 8, 4, 6, 15, 11, 1, 10, 9, 3, 14, 5, 0, 12, 7,
         1, 15, 13, 8, 10, 3, 7, 4, 12, 5, 6, 11, 0, 14, 9, 2,
         7, 11, 4, 1, 9, 12, 14, 2, 0, 6, 10, 13, 15, 3, 5, 8,
         2, 1, 14, 7, 4, 10, 8, 13, 15, 12, 9, 0, 3, 5, 6, 11],
    ]
msg= bitarray(endian='little')
msg.frombytes(b'ABCDEFGH')
perm = bitarray(endian='little')
key= bitarray(endian='little')
key.frombytes(b'FFQQSSMM')
keyPc1 = bitarray(endian='little')
keyPc2 = bitarray(endian='little')
exp = bitarray(endian='little')
for z in pc1:
    keyPc1.append(key[z])
c0 = keyPc1[0:28]
d0 = keyPc1[28:]
key0 = c0 + d0
#permutation of key
for k in pc2:
    keyPc2.append(key0[k])
#permutation of message
for x in iptable:
    perm.append(msg[x])
l1 = perm[0:32]
r1 = perm[32:]
#Expansion of R
for y in expTable:
    exp.append(r1[y])
#XORing R & key
xor_rk = keyPc2 ^ exp
#Working with S-boxes!
B = [xor_rk[0:6], xor_rk[6:12], xor_rk[12:18], xor_rk[18:24], xor_rk[24:30], xor_rk[30:36], xor_rk[36:42], xor_rk[36:]]
j = 0
Bn = [0] * 32
pos = 0
while j < 8:
    # Work out the offsets
    m = (B[j][0] << 1) + B[j][5]
    n = (B[j][1] << 3) + (B[j][2] << 2) + (B[j][3] << 1) + B[j][4]
    # Find the permutation value
    v = __sbox[j][(m << 4) + n]
    # Turn value into bits, add it to result: Bn
    Bn[pos] = (v & 8) >> 3
    Bn[pos + 1] = (v & 4) >> 2
    Bn[pos + 2] = (v & 2) >> 1
    Bn[pos + 3] = v & 1
    pos += 4
    j += 1
print (Bn)
print (l1)
xor_lf = l1 ^ Bn

Could you provide a smaller working sample?

David Zwicker
– David Zwicker

2013-12-17 08:34:39 +00:00
Commented Dec 17, 2013 at 8:34 — David Zwicker
– David Zwicker, Commented Dec 17, 2013 at 8:34

Buddhima Gamlath · Accepted Answer · 2013-12-17 08:55:12Z

1

The problem here is that Bn is of type list and l1 is of type bitarray. An easy fix is to convert Bn to a bitarray just after creating it. After,

Bn = [0] * 32

add,

Bn = bitarray(Bn)

answered Dec 17, 2013 at 8:55

Buddhima Gamlath

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