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function.py
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#this function converts a int number to 8 bit binary, the binary byte is a string
def dec_to_bin_8bit(val):
binary = '00000000'
if val >= 128:
binary = binary[:0] + '1' + binary[:7]
val -= 128
else:
binary = binary[:0] + '0' + binary[:7]
if val >= 64:
binary = binary[:1] + '1' + binary[:6]
val -= 64
else:
binary = binary[:1] + '0' + binary[:6]
if val >= 32:
binary = binary[:2] + '1' + binary[:5]
val -= 32
else:
binary = binary[:2] + '0' + binary[:5]
if val >= 16:
binary = binary[:3] + '1' + binary[:4]
val -= 16
else:
binary = binary[:3] + '0' + binary[:4]
if val >= 8:
binary = binary[:4] + '1' + binary[:3]
val -= 8
else:
binary = binary[:4] + '0' + binary[:3]
if val >= 4:
binary = binary[:5] + '1' + binary[:2]
val -= 4
else:
binary = binary[:5] + '0' + binary[:2]
if val >= 2:
binary = binary[:6] + '1' + binary[:1]
val -= 2
else:
binary = binary[:6] + '0' + binary[:1]
if val >= 1:
binary = binary[:7] + '1' + binary[:0]
val -= 1
else:
binary = binary[:7] + '0' + binary[:0]
return binary
def two_char_to_bin(val1, val2):
binary = '00000000'
if val1 >= 8:
binary = binary[:0] + '1' + binary[:7]
val1 -= 8
else:
binary = binary[:0] + '0' + binary[:7]
if val1 >= 4:
binary = binary[:1] + '1' + binary[:6]
val1 -= 4
else:
binary = binary[:1] + '0' + binary[:6]
if val1 >= 2:
binary = binary[:2] + '1' + binary[:5]
val1 -= 2
else:
binary = binary[:2] + '0' + binary[:5]
if val1 >= 1:
binary = binary[:3] + '1' + binary[:4]
val1 -= 1
else:
binary = binary[:3] + '0' + binary[:4]
if val2 >= 8:
binary = binary[:4] + '1' + binary[:3]
val2 -= 8
else:
binary = binary[:4] + '0' + binary[:3]
if val2 >= 4:
binary = binary[:5] + '1' + binary[:2]
val2 -= 4
else:
binary = binary[:5] + '0' + binary[:2]
if val2 >= 2:
binary = binary[:6] + '1' + binary[:1]
val2 -= 2
else:
binary = binary[:6] + '0' + binary[:1]
if val2 >= 1:
binary = binary[:7] + '1' + binary[:0]
val2 -= 1
else:
binary = binary[:7] + '0' + binary[:0]
return binary
#this function convert 8 bit binary or a byte to integer, here the binary argument is string of 8 char
# representing '1's and '0's
def bin_to_dec(binary):
val = 0
if binary[0] == '1':
val += 128
if binary[1] == '1':
val += 64
if binary[2] == '1':
val += 32
if binary[3] == '1':
val += 16
if binary[4] == '1':
val += 8
if binary[5] == '1':
val += 4
if binary[6] == '1':
val += 2
if binary[7] == '1':
val += 1
return val
#here the process of substitution is done for the encryption, meaning replacing a number with some another number,
# the tabel is given as follow
# 1 -> 14
# 2 -> 15
# 3 -> 5
# 4 -> 9
# 5 -> 11
# 6 -> 6
# 7 -> 13
# 8 -> 2
# 9 -> 4
# 10 -> 8
# 11 -> 1
# 12 -> 3
# 13 -> 10
# 14 -> 7
# 15 -> 12
def substitution(num):
if num == 1:
val = 14
elif num == 2:
val = 15
elif num == 3:
val = 5
elif num == 4:
val = 9
elif num == 5:
val = 11
elif num == 6:
val = 6
elif num == 7:
val = 13
elif num == 8:
val = 2
elif num == 9:
val = 4
elif num == 10:
val = 8
elif num == 11:
val = 1
elif num == 12:
val = 3
elif num == 13:
val = 10
elif num == 14:
val = 7
elif num == 15:
val = 12
else:
val = 0
return val
#here the process of permutation is done aka interchanging the places of bit in a byte,
# the sequence of binary arrangement as follow
# 1 -> 5
# 2 -> 8
# 3 -> 6
# 4 -> 3
# 5 -> 2
# 6 -> 4
# 7 -> 1
# 8 -> 7
def permutation(binaryIn):
binary = '00000000'
binary = binary[:0] + binaryIn[4] + binary[:7]
binary = binary[:1] + binaryIn[7] + binary[:6]
binary = binary[:2] + binaryIn[5] + binary[:5]
binary = binary[:3] + binaryIn[2] + binary[:4]
binary = binary[:4] + binaryIn[1] + binary[:3]
binary = binary[:5] + binaryIn[3] + binary[:2]
binary = binary[:6] + binaryIn[0] + binary[:1]
binary = binary[:7] + binaryIn[6] + binary[:0]
return binary
#it converts 4 bit binary to int, again the binary is a string of '0' and '1'
def bin_to_dec_4bit(binary):
val = 0
if binary[0] == '1':
val += 8
if binary[1] == '1':
val += 4
if binary[2] == '1':
val += 2
if binary[3] == '1':
val += 1
return val
#it converts int to 4 bit binary, the return binary is in form of a string
def dec_to_bin_4bit(val):
binary = '0000'
if val >= 8:
binary = binary[:0] + '1' + binary[:3]
val -= 8
else:
binary = binary[:0] + '0' + binary[:3]
if val >= 4:
binary = binary[:1] + '1' + binary[:2]
val -= 4
else:
binary = binary[:1] + '0' + binary[:2]
if val >= 2:
binary = binary[:2] + '1' + binary[:1]
val -= 2
else:
binary = binary[:2] + '0' + binary[:1]
if val >= 1:
binary = binary[:3] + '1' + binary[:0]
val -= 1
else:
binary = binary[:3] + '0' + binary[:0]
return binary
#here the process of reverse permutation is done for the decryption. It shoud be exact reverse of
# the perutation process, binary interchange sequence as follow
# 1 -> 7
# 2 -> 5
# 3 -> 4
# 4 -> 6
# 5 -> 1
# 6 -> 3
# 7 -> 8
# 8 -> 2
def reverse_permutation(binaryIn):
binary = '00000000'
binary = binary[:0] + binaryIn[6] + binary[:7]
binary = binary[:1] + binaryIn[4] + binary[:6]
binary = binary[:2] + binaryIn[3] + binary[:5]
binary = binary[:3] + binaryIn[5] + binary[:4]
binary = binary[:4] + binaryIn[0] + binary[:3]
binary = binary[:5] + binaryIn[2] + binary[:2]
binary = binary[:6] + binaryIn[7] + binary[:1]
binary = binary[:7] + binaryIn[1] + binary[:0]
return binary
#here the process of reverse substitution is done for the decryption. Make sure it is exact
# reverse if the substitution process. Sequence of number interchange as follow
# 1 -> 11
# 2 -> 8
# 3 -> 12
# 4 -> 9
# 5 -> 3
# 6 -> 6
# 7 -> 14
# 8 -> 10
# 9 -> 4
# 10 -> 13
# 11 -> 5
# 12 -> 15
# 13 -> 7
# 14 -> 1
# 15 -> 2
def reverse_substitution(num):
if num == 1:
val = 11
elif num == 2:
val = 8
elif num == 3:
val = 12
elif num == 4:
val = 9
elif num == 5:
val = 3
elif num == 6:
val = 6
elif num == 7:
val = 14
elif num == 8:
val = 10
elif num == 9:
val = 4
elif num == 10:
val = 13
elif num == 11:
val = 5
elif num == 12:
val = 15
elif num == 13:
val = 7
elif num == 14:
val = 1
elif num == 15:
val = 2
else:
val = 0
return val