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Simplified DES.py
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Simplified DES.py
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#Stefan Buys
#EHN 410 - Toets voorbereiding
#DES Algoritme vir Toetse
#April 2021
import numpy as np
def hexToBinary(string, length = -1):
mappingTable = {
'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" }
binary = ""
for i in range(len(string)):
binary = binary + mappingTable[string[i]]
#Remove leading zeros:
while binary[0] == '0':
binary = binary[1:]
if not(length == -1):
while (len(binary) < length):
binary = '0' + binary
return binary
#print(hexToBinary("ABC",20))
def binaryToHex(string, length = -1):
mappingTable = {
"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' }
#Fill in 0's at the front:
while not(len(string) % 4 == 0):
string = "0" + string
hexOut = ""
for i in range(0,len(string),4):
binary = ""
for j in range(4):
binary += string[i+j]
hexOut = hexOut + mappingTable[binary]
#Remove the leading 0's:
while hexOut[0] == '0':
hexOut = hexOut[1:]
if not(length == -1):
while (len(hexOut) < length):
hexOut = '0' + hexOut
return hexOut
#print(binaryToHex("00000000101010111100",5))
def shiftLeft(binary,num=1):
temp = ""
for numShifts in range(num):
for j in range(1,len(binary)):
temp = temp + binary[j]
temp = temp + binary[0]
binary = temp
temp = ""
return binary
def shiftRight(binary,num=1):
temp = ""
for numShifts in range(num):
temp = temp + binary[len(binary) - 1]
for j in range(0,len(binary)-1):
temp = temp + binary[j]
binary = temp
temp = ""
return binary
#print(shiftLeft("1010"))
def xor(a,b):
answer = ""
if not(len(a) == len(b)):
raise Exception("XOR with binary len (a) != binary len (b)")
for i in range(len(a)):
if a[i] == b[i]:
answer = answer + "0"
else:
answer = answer + "1"
if not(a[i] == "0" or a[i] == "1") or not(b[i] == "1" or b[i] == "0"):
raise Exception("XOR only works with binary, Hex inserted")
return answer
#print(xor("101","111"))
def permutation(permuteArrInput,binary,indexOrPosition = 0):
permuteArr = permuteArrInput.copy()
#If position, decrement all values in permuteArr:
if indexOrPosition == 1:
for i in range(len(permuteArr)):
if permuteArr[i] - 1 < 0:
print("WARNING: key permutation decremented resulted in a -1 index")
permuteArr[i] = permuteArr[i] - 1
#Check if there are enough values:
if (max(permuteArr) >= len(binary)):
raise Exception("Permutation, but too few indexes in binary array.")
output = ""
for i in range(len(permuteArr)):
output = output + binary[permuteArr[i]]
return output
#print(permutation([3,2,1],"110",1))
# Binary to decimal conversion
def binaryToDecimal(binaryIn):
binary = binaryIn
binary = int(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
#print(binaryToDecimal("1011"))
# Decimal to binary conversion
def decimalToBinaryForSsimplified(num):
res = bin(num).replace("0b", "")
if len(res) == 1:
res = '0' + res
# 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
#print(decimalToBinaryForSsimplified(3))
def sLookupSimplified(S, binary):
row = binary[0] + binary[3]
column = binary[1] + binary[2]
rowNum = binaryToDecimal(row)
columnNum = binaryToDecimal(column)
return decimalToBinaryForSsimplified(S[rowNum][columnNum])
#hello = "HelloHoeGaanDit"
#print(hello[0:5])
def permutationsToIndex(permutation):
output = []
for i in range(permutation):
output.append(permutation[i] - 1)
if permutation[i] - 1 < 0:
print("WARNING: key permutation decremented resulted in a -1 index")
return permutation
return output
###############################################################################
# S-BOXES DEFINE
###############################################################################
S0 = [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]
S1 = [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]
S2 = [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]
###############################################################################
# SIMPLIFIED DES ALGORITME BEGIN
###############################################################################
###############################################################################
# ENCRYPTION
###############################################################################
#10-bit key:
key = "1100011110"
keyPermuteP10 = [3,5,2,7,4,10,1,9,8,6]
keyPermuteP8 = [6,3,7,4,8,5,10,9]
#8-bit plaintext
plaintext = "00101000" #plaintext was: 00101000
plaintextPermuteIP = [2,6,3,1,4,8,5,7]
#### KEY GENERATION ##########################
subkey = ['1']*2
permutedKeyP10 = permutation(keyPermuteP10,key,1)
leftHalfKey = permutedKeyP10[0:5]
rightHalfKey = permutedKeyP10[5:10]
#Calculating subkey 1
leftHalfKeyLS1 = shiftLeft(leftHalfKey,1)
rightHalfKeyLS1 = shiftLeft(rightHalfKey,1)
subkey1 = leftHalfKeyLS1 + rightHalfKeyLS1
subkey1 = permutation(keyPermuteP8,subkey1,1)
subkey[0] = subkey1
#Calculating subkey 2
leftHalfKeyLS2 = shiftLeft(leftHalfKey,3)
rightHalfKeyLS2 = shiftLeft(rightHalfKey,3)
subkey2 = leftHalfKeyLS2 + rightHalfKeyLS2
subkey2 = permutation(keyPermuteP8,subkey2,1)
subkey[1] = subkey2
#NBNBNB Uncomment for encryption:
#NBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNB
#Uncomment for decryption
#For decryption:
#subKeyTemp = subkey
#subkey = []
#for i in range(len(subKeyTemp)-1,-1,-1):
# subkey.append(subKeyTemp[i])
#NBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNBNB
################################################
#Perform the initial permutation:
plaintextPerm = permutation(plaintextPermuteIP,plaintext,1)
LHS = plaintextPerm[0:4]
RHS = plaintextPerm[4:8]
EP = [4,1,2,3,2,3,4,1]
S0 = [[1,0,3,2],[3,2,1,0],[0,2,1,3],[3,1,3,2]]
S1 = [[0,1,2,3],[2,0,1,3],[3,0,1,0],[2,1,0,3]]
#Do the mapping F:
RHSexpandedPermuted = permutation(EP,RHS,1)
RHSexpandedPermuted = xor(RHSexpandedPermuted,subkey[0])
RHSleftbit = sLookupSimplified(S0,RHSexpandedPermuted[0:4])
RHSleftbit = RHSleftbit + sLookupSimplified(S1,RHSexpandedPermuted[4:8])
P4 = [2,4,3,1]
Foutput = permutation(P4,RHSleftbit,1)
Stage1out = xor(LHS,Foutput) + RHS
#########################################
Switch = Stage1out[4:8] + Stage1out[0:4]
#########################################
LHS = Switch[0:4]
RHS = Switch[4:8]
EP = [4,1,2,3,2,3,4,1]
S0 = [[1,0,3,2],[3,2,1,0],[0,2,1,3],[3,1,3,2]]
S1 = [[0,1,2,3],[2,0,1,3],[3,0,1,0],[2,1,0,3]]
#Do the mapping F:
RHSexpandedPermuted = permutation(EP,RHS,1)
RHSexpandedPermuted = xor(RHSexpandedPermuted,subkey[1])
RHSleftbit = sLookupSimplified(S0,RHSexpandedPermuted[0:4])
RHSleftbit = RHSleftbit + sLookupSimplified(S1,RHSexpandedPermuted[4:8])
P4 = [2,4,3,1]
Foutput = permutation(P4,RHSleftbit,1)
Stage2out = xor(LHS,Foutput) + RHS
#######################################
invIP = [4,1,3,5,7,2,8,6]
ciphertext = permutation(invIP,Stage2out,1)
print(ciphertext)