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DES-CBC.py
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DES-CBC.py
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#DES-CBC
print("Data Encryption Standard - DES")
pc1_table = [57, 49, 41, 33, 25, 17, 9, 1, 58, 50, 42, 34, 26, 18, 10, 2, 59, 51, 43, 35, 27, 19, 11, 3, 60, 52, 44, 36, 63, 55, 47, 39, 31, 23, 15, 7, 62, 54, 46, 38, 30, 22, 14, 6, 61, 53, 45, 37, 29, 21, 13, 5, 28, 20, 12, 4]
ls_scheme = [1, 1, 2, 2, 2, 2, 2, 2, 1, 2, 2, 2, 2, 2, 2, 1]
pc2_table = [14, 17, 11, 24, 1, 5, 3, 28, 15, 6, 21, 10, 23, 19, 12, 4, 26, 8, 16, 7, 27, 20, 13, 2, 41, 52, 31, 37, 47, 55, 30, 40, 51, 45, 33, 48, 44, 49, 39, 56, 34, 53, 46, 42, 50, 36, 29, 32]
ip_table = [58, 50, 42, 34, 26, 18, 10, 2, 60, 52, 44, 36, 28, 20, 12, 4, 62, 54, 46, 38, 30, 22, 14, 6, 64, 56, 48, 40, 32, 24, 16, 8, 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]
e_table = [32, 1, 2, 3, 4, 5, 4, 5, 6, 7, 8, 9, 8, 9, 10, 11, 12, 13, 12, 13, 14, 15, 16, 17, 16, 17, 18, 19, 20, 21, 20, 21, 22, 23, 24, 25, 24, 25, 26, 27, 28, 29, 28, 29, 30, 31, 32, 1]
p_table = [16, 7, 20, 21, 29, 12, 28, 17, 1, 15, 23, 26, 5, 18, 31, 10, 2, 8, 24, 14, 32, 27, 3, 9, 19, 13, 30, 6, 22, 11, 4, 25]
ip_inv_table = [40, 8, 48, 16, 56, 24, 64, 32, 39, 7, 47, 15, 55, 23, 63, 31, 38, 6, 46, 14, 54, 22, 62, 30, 37, 5, 45, 13, 53, 21, 61, 29, 36, 4, 44, 12, 52, 20, 60, 28, 35, 3, 43, 11, 51, 19, 59, 27, 34, 2, 42, 10, 50, 18, 58, 26, 33, 1, 41, 9, 49, 17, 57, 25]
s_boxes = [[[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]],
[[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]],
[[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]],
[[ 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]],
[[ 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]],
[[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]],
[[ 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]],
[[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]]]
def ascii2bin(string):
binary = ''
for char in string:
bin_char = bin(ord(char))[2:]
while len(bin_char) < 8:
bin_char = "0" + bin_char
binary += bin_char
out = []
for bit in binary:
out.append(bit)
return out
def bin2ascii(binary):
out = ""
for i in range(int(len(binary) / 8)):
byte = binary[i * 8:i * 8 + 8]
out += chr(int(bin2dec(byte)))
return out
def list2string(input_list):
out = ""
for i in input_list:
out += i
return out
def string2list(string):
out = []
for char in string:
out.append(char)
return out
def hex2bin(hexa):
out = ""
for digit in hexa:
out += bin(int(digit, 16))[2:].zfill(4)
return string2list(out)
def bin2hex(binary):
out = ""
for nibble in range(int(len(binary) / 4)):
out += hex(int(binary[nibble * 4: nibble * 4 + 4], 2))[2:]
return out
def bin2dec(binary):
return str(int(binary, 2))
def dec2bin(dec):
return bin(dec)[2:].zfill(4)
def XOR(arg1, arg2):
out = []
for pos in range(len(arg1)):
if arg1[pos] == arg2[pos]:
out.append('0')
else:
out.append('1')
return out
def permute(inp, table):
output = []
for pos in table:
output.append(inp[pos - 1])
return output
def substitute(inp, s_box):
out = []
for i in range(8):
row = bin2dec(inp[i][0] + inp[i][5])
col = bin2dec(list2string(inp[i][1:5]))
cell = s_box[i][int(row)][int(col)]
out += string2list(dec2bin(cell))
return out
def left_shift(inp, num):
for i in range(num):
inp.append(inp.pop(0))
return inp
def pkcs5_pad(inp):
last_block = inp[len(inp) // 64 * 64:]
pad_length = int((64 - len(last_block)) / 8)
pad_bits = ""
for i in range(pad_length):
pad_bits += "0000" + dec2bin(pad_length)
last_block += string2list(pad_bits)
out = inp[0:len(inp) // 64 * 64] + last_block
return out
def pkcs5_unpad(inp):
last_byte = int(bin2dec(list2string(inp[len(inp) - 7:])))
if 1 <= last_byte <= 7:
out = inp[:-8 * last_byte]
return out
elif last_byte == 8:
return ""
else:
return inp
def blockify(inp, block_length):
out = []
for i in range(len(inp) // block_length + 1):
if len(inp) % block_length == 0 and i == len(inp) // block_length:
break
out.append(inp[i * block_length: i * block_length + block_length])
return out
def subkey_gen(c0, d0):
global subkeys
c = []
d = []
prev_c = c0
prev_d = d0
#1. Left shift c0 and d0 according to the LS Scheme to obtain c1 to c16 and d1 to d16
for i in range(16):
shifted = left_shift(prev_c, ls_scheme[i])
c.append(shifted[:])
for i in range(16):
shifted = left_shift(prev_d, ls_scheme[i])
d.append(shifted[:])
#2. Permute cNdN using PC-2 Table to obtain 16 subkeys:
#14 17 11 24 1 5
# 3 28 15 6 21 10
#23 19 12 4 26 8
#16 7 27 20 13 2
#41 52 31 37 47 55
#30 40 51 45 33 48
#44 49 39 56 34 53
#46 42 50 36 29 32
subkeys = []
for i in range(1, 17):
cd = c[i-1] + d[i-1]
subkeys.append(permute(cd, pc2_table))
def keygen(key):
#1. Permute using PC-1 Table:
#57 49 41 33 25 17 9
#1 58 50 42 34 26 18
#10 2 59 51 43 35 27
#19 11 3 60 52 44 36
#63 55 47 39 31 23 15
#7 62 54 46 38 30 22
#14 6 61 53 45 37 29
#21 13 5 28 20 12 4
pc1_key = permute(key, pc1_table)
#2. Split key in half
c0 = pc1_key[0:28]
d0 = pc1_key[28:56]
#3. Generate 16 subkeys
subkey_gen(c0, d0)
def DES_Round(l, r, n):
#1. Expansion using E Table:
#32 1 2 3 4 5
# 4 5 6 7 8 9
# 8 9 10 11 12 13
#12 13 14 15 16 17
#16 17 18 19 20 21
#20 21 22 23 24 25
#24 25 26 27 28 29
#28 29 30 31 32 1
expanded_r = permute(r, e_table)
#2. XOR round key with expanded right half-block
xor_r = XOR(subkeys[n], expanded_r)
#3. Substitute XORed right half-block with S-boxes S1 to S8
pre_sub = []
for i in range(8):
pre_sub.append(xor_r[i * 6: i * 6 + 6])
sub_r = substitute(pre_sub, s_boxes)
#4. Permute substituted right half-block using P Table:
#16 7 20 21
#29 12 28 17
# 1 15 23 26
# 5 18 31 10
# 2 8 24 14
#32 27 3 9
#19 13 30 6
#22 11 4 25
permuted_r = permute(sub_r, p_table)
#5. XOR L(n-1) with permuted right half-block
ln = r
rn = XOR(l, permuted_r)
prev_lr["prev_l"] = ln
prev_lr["prev_r"] = rn
round_out = ln + rn
return round_out
def DES_Block(text):
#1. Initial permutation using IP Table:
#58 50 42 34 26 18 10 2
#60 52 44 36 28 20 12 4
#62 54 46 38 30 22 14 6
#64 56 48 40 32 24 16 8
#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
permuted_text = permute(text, ip_table)
#2. Split text in half
l0 = permuted_text[0:32]
r0 = permuted_text[32:64]
#3. Perform 16 rounds
global prev_lr
prev_lr = {"prev_l" : l0, "prev_r" : r0}
if method == "e":
for n in range(16):
final_block = DES_Round(prev_lr["prev_l"], prev_lr["prev_r"], n)
elif method == "d":
for n in range(15, -1, -1):
final_block = DES_Round(prev_lr["prev_l"], prev_lr["prev_r"], n)
#4. Switch the left and right half-blocks
final_block = final_block[32:64] + final_block[0:32]
#5. Inverse permute using IP-1 Table:
#40 8 48 16 56 24 64 32
#39 7 47 15 55 23 63 31
#38 6 46 14 54 22 62 30
#37 5 45 13 53 21 61 29
#36 4 44 12 52 20 60 28
#35 3 43 11 51 19 59 27
#34 2 42 10 50 18 58 26
#33 1 41 9 49 17 57 25
block_out = permute(final_block, ip_inv_table)
return block_out
def DES_ECB_encrypt(plaintext):
bin_encrypted = ""
for block in plaintext:
if block == plaintext[-1]:
bin_encrypted += list2string(DES_Block(pkcs5_pad(ascii2bin(block))))
else:
bin_encrypted += list2string(DES_Block(ascii2bin(block)))
hex_encrypted = bin2hex(bin_encrypted)
print("\n\nBinary: " + bin_encrypted)
print("Hex: " + hex_encrypted)
def DES_ECB_decrypt(ciphertext):
decrypted = ""
for block in ciphertext:
if block == ciphertext[-1]:
decrypted += list2string(pkcs5_unpad(DES_Block(hex2bin(block))))
else:
decrypted += list2string(DES_Block(hex2bin(block)))
print("Plaintext: " + bin2ascii(decrypted))
def DES_CBC_encrypt(plaintext, iv):
bin_encrypted = ""
next_iv = iv
for block in plaintext:
if block == plaintext[-1]:
padded_xor_block = XOR(pkcs5_pad(ascii2bin(block)), next_iv)
bin_encrypted += list2string(DES_Block(padded_xor_block))
else:
xor_block = XOR(ascii2bin(block), next_iv)
block_out = DES_Block(xor_block)
bin_encrypted += list2string(block_out)
next_iv = block_out
hex_encrypted = bin2hex(bin_encrypted)
print("\n\nBinary: " + bin_encrypted)
print("Hex: " + hex_encrypted)
def DES_CBC_decrypt(ciphertext, iv):
decrypted = ""
for block in range(len(ciphertext) - 1, -1, -1):
block_out = DES_Block(hex2bin(ciphertext[block]))
if block == 0:
xor_block = XOR(block_out, iv)
decrypted = list2string(pkcs5_unpad(xor_block)) + decrypted
else:
next_iv = hex2bin(ciphertext[block - 1])
xor_block = XOR(block_out, next_iv)
decrypted = list2string(xor_block) + decrypted
print("Plaintext: " + bin2ascii(decrypted))
def DES_ECB():
if method == "e":
plaintext = blockify(input("Plaintext (PKCS#5/#7 padding will be applied): "), 8)
DES_ECB_encrypt(plaintext)
elif method == "d":
ciphertext = blockify(input("Ciphertext (in hex): "), 16)
DES_ECB_decrypt(ciphertext)
def DES_CBC():
if method == "e":
iv = string2list(input("64-bit IV (in binary; optionally leave blank for randomisation): "))
if iv == []:
from random import randint
for i in range(64):
iv.append(str(randint(0, 1)))
print("IV: " + list2string(iv))
elif method == "d":
iv = input("64-bit IV (in binary): ")
if method == "e":
plaintext = blockify(input("Plaintext (PKCS#5/#7 padding will be applied): "), 8)
DES_CBC_encrypt(plaintext, iv)
elif method == "d":
ciphertext = blockify(input("Ciphertext (in hex): "), 16)
DES_CBC_decrypt(ciphertext, iv)
def main():
global method
mode = input("(e) ECB or (c) CBC: ")
method = input("(e)ncrypt or (d)ecrypt: ")
key = input("64-bit Key: ")
keygen(ascii2bin(key))
if mode == "e":
DES_ECB()
elif mode == "c":
DES_CBC()
if __name__ == "__main__":
main()