create des.py (#346)

This is a code is for solving data encryption standard (des) using python3

Author: sugashsm

Python/des.py

@@ -0,0 +1,315 @@
+#This is a code is for solving data encryption standard (des) using python3
+
+# Hexadecimal to binary conversion
+
+def hex2bin(s):
+	mp = {'0': "0000",
+		'1': "0001",
+		'2': "0010",
+		'3': "0011",
+		'4': "0100",
+		'5': "0101",
+		'6': "0110",
+		'7': "0111",
+		'8': "1000",
+		'9': "1001",
+		'A': "1010",
+		'B': "1011",
+		'C': "1100",
+		'D': "1101",
+		'E': "1110",
+		'F': "1111"}
+	bin = ""
+	for i in range(len(s)):
+		bin = bin + mp[s[i]]
+	return bin
+
+# Binary to hexadecimal conversion
+
+
+def bin2hex(s):
+	mp = {"0000": '0',
+		"0001": '1',
+		"0010": '2',
+		"0011": '3',
+		"0100": '4',
+		"0101": '5',
+		"0110": '6',
+		"0111": '7',
+		"1000": '8',
+		"1001": '9',
+		"1010": 'A',
+		"1011": 'B',
+		"1100": 'C',
+		"1101": 'D',
+		"1110": 'E',
+		"1111": 'F'}
+	hex = ""
+	for i in range(0, len(s), 4):
+		ch = ""
+		ch = ch + s[i]
+		ch = ch + s[i + 1]
+		ch = ch + s[i + 2]
+		ch = ch + s[i + 3]
+		hex = hex + mp[ch]
+
+	return hex
+
+# Binary to decimal conversion
+
+
+def bin2dec(binary):
+
+	binary1 = binary
+	decimal, i, n = 0, 0, 0
+	while(binary != 0):
+		dec = binary % 10
+		decimal = decimal + dec * pow(2, i)
+		binary = binary//10
+		i += 1
+	return decimal
+
+# Decimal to binary conversion
+
+
+def dec2bin(num):
+	res = bin(num).replace("0b", "")
+	if(len(res) % 4 != 0):
+		div = len(res) / 4
+		div = int(div)
+		counter = (4 * (div + 1)) - len(res)
+		for i in range(0, counter):
+			res = '0' + res
+	return res
+
+# Permute function to rearrange the bits
+
+
+def permute(k, arr, n):
+	permutation = ""
+	for i in range(0, n):
+		permutation = permutation + k[arr[i] - 1]
+	return permutation
+
+# shifting the bits towards left by nth shifts
+
+
+def shift_left(k, nth_shifts):
+	s = ""
+	for i in range(nth_shifts):
+		for j in range(1, len(k)):
+			s = s + k[j]
+		s = s + k[0]
+		k = s
+		s = ""
+	return k
+
+# calculating xow of two strings of binary number a and b
+
+
+def xor(a, b):
+	ans = ""
+	for i in range(len(a)):
+		if a[i] == b[i]:
+			ans = ans + "0"
+		else:
+			ans = ans + "1"
+	return ans
+
+
+# Table of Position of 64 bits at initial level: Initial Permutation Table
+initial_perm = [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]
+
+# Expansion D-box Table
+exp_d = [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]
+
+# Straight Permutation Table
+per = [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]
+
+# S-box Table
+sbox = [[[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]]]
+
+# Final Permutation Table
+final_perm = [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]
+
+
+def encrypt(pt, rkb, rk):
+	pt = hex2bin(pt)
+
+	# Initial Permutation
+	pt = permute(pt, initial_perm, 64)
+	print("After initial permutation", bin2hex(pt))
+
+	# Splitting
+	left = pt[0:32]
+	right = pt[32:64]
+	for i in range(0, 16):
+		# Expansion D-box: Expanding the 32 bits data into 48 bits
+		right_expanded = permute(right, exp_d, 48)
+
+		# XOR RoundKey[i] and right_expanded
+		xor_x = xor(right_expanded, rkb[i])
+
+		# S-boxex: substituting the value from s-box table by calculating row and column
+		sbox_str = ""
+		for j in range(0, 8):
+			row = bin2dec(int(xor_x[j * 6] + xor_x[j * 6 + 5]))
+			col = bin2dec(
+				int(xor_x[j * 6 + 1] + xor_x[j * 6 + 2] + xor_x[j * 6 + 3] + xor_x[j * 6 + 4]))
+			val = sbox[j][row][col]
+			sbox_str = sbox_str + dec2bin(val)
+
+		# Straight D-box: After substituting rearranging the bits
+		sbox_str = permute(sbox_str, per, 32)
+
+		# XOR left and sbox_str
+		result = xor(left, sbox_str)
+		left = result
+
+		# Swapper
+		if(i != 15):
+			left, right = right, left
+		print("Round ", i + 1, " ", bin2hex(left),
+			" ", bin2hex(right), " ", rk[i])
+
+	# Combination
+	combine = left + right
+
+	# Final permutation: final rearranging of bits to get cipher text
+	cipher_text = permute(combine, final_perm, 64)
+	return cipher_text
+
+
+pt = "123456ABCD132536"
+key = "AABB09182736CCDD"
+
+
+
+# Key generation
+# --hex to binary
+key = hex2bin(key)
+
+# --parity bit drop table
+keyp = [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]
+
+# getting 56 bit key from 64 bit using the parity bits
+key = permute(key, keyp, 56)
+
+# Number of bit shifts
+shift_table = [1, 1, 2, 2,
+			2, 2, 2, 2,
+			1, 2, 2, 2,
+			2, 2, 2, 1]
+
+# Key- Compression Table : Compression of key from 56 bits to 48 bits
+key_comp = [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]
+
+# Splitting
+left = key[0:28] # rkb for RoundKeys in binary
+right = key[28:56] # rk for RoundKeys in hexadecimal
+
+rkb = []
+rk = []
+for i in range(0, 16):
+	# Shifting the bits by nth shifts by checking from shift table
+	left = shift_left(left, shift_table[i])
+	right = shift_left(right, shift_table[i])
+
+	# Combination of left and right string
+	combine_str = left + right
+
+	# Compression of key from 56 to 48 bits
+	round_key = permute(combine_str, key_comp, 48)
+
+	rkb.append(round_key)
+	rk.append(bin2hex(round_key))
+
+print("Encryption")
+cipher_text = bin2hex(encrypt(pt, rkb, rk))
+print("Cipher Text : ", cipher_text)
+
+print("Decryption")
+rkb_rev = rkb[::-1]
+rk_rev = rk[::-1]
+text = bin2hex(encrypt(cipher_text, rkb_rev, rk_rev))
+print("Plain Text : ", text)
+
+