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1f8a21d727
* Tighten up psf/black and flake8
* Fix some tests
* Fix some E741
* Fix some E741
* updating DIRECTORY.md
Co-authored-by: github-actions <${GITHUB_ACTOR}@users.noreply.github.com>
98 lines
2.6 KiB
Python
98 lines
2.6 KiB
Python
def apply_table(inp, table):
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"""
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>>> apply_table("0123456789", list(range(10)))
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'9012345678'
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>>> apply_table("0123456789", list(range(9, -1, -1)))
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'8765432109'
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"""
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res = ""
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for i in table:
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res += inp[i - 1]
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return res
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def left_shift(data):
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"""
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>>> left_shift("0123456789")
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'1234567890'
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"""
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return data[1:] + data[0]
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def XOR(a, b):
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"""
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>>> XOR("01010101", "00001111")
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'01011010'
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"""
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res = ""
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for i in range(len(a)):
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if a[i] == b[i]:
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res += "0"
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else:
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res += "1"
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return res
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def apply_sbox(s, data):
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row = int("0b" + data[0] + data[-1], 2)
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col = int("0b" + data[1:3], 2)
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return bin(s[row][col])[2:]
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def function(expansion, s0, s1, key, message):
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left = message[:4]
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right = message[4:]
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temp = apply_table(right, expansion)
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temp = XOR(temp, key)
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l = apply_sbox(s0, temp[:4]) # noqa: E741
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r = apply_sbox(s1, temp[4:])
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l = "0" * (2 - len(l)) + l # noqa: E741
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r = "0" * (2 - len(r)) + r
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temp = apply_table(l + r, p4_table)
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temp = XOR(left, temp)
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return temp + right
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if __name__ == "__main__":
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key = input("Enter 10 bit key: ")
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message = input("Enter 8 bit message: ")
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p8_table = [6, 3, 7, 4, 8, 5, 10, 9]
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p10_table = [3, 5, 2, 7, 4, 10, 1, 9, 8, 6]
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p4_table = [2, 4, 3, 1]
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IP = [2, 6, 3, 1, 4, 8, 5, 7]
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IP_inv = [4, 1, 3, 5, 7, 2, 8, 6]
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expansion = [4, 1, 2, 3, 2, 3, 4, 1]
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s0 = [[1, 0, 3, 2], [3, 2, 1, 0], [0, 2, 1, 3], [3, 1, 3, 2]]
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s1 = [[0, 1, 2, 3], [2, 0, 1, 3], [3, 0, 1, 0], [2, 1, 0, 3]]
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# key generation
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temp = apply_table(key, p10_table)
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left = temp[:5]
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right = temp[5:]
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left = left_shift(left)
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right = left_shift(right)
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key1 = apply_table(left + right, p8_table)
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left = left_shift(left)
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right = left_shift(right)
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left = left_shift(left)
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right = left_shift(right)
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key2 = apply_table(left + right, p8_table)
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# encryption
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temp = apply_table(message, IP)
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temp = function(expansion, s0, s1, key1, temp)
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temp = temp[4:] + temp[:4]
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temp = function(expansion, s0, s1, key2, temp)
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CT = apply_table(temp, IP_inv)
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print("Cipher text is:", CT)
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# decryption
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temp = apply_table(CT, IP)
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temp = function(expansion, s0, s1, key2, temp)
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temp = temp[4:] + temp[:4]
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temp = function(expansion, s0, s1, key1, temp)
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PT = apply_table(temp, IP_inv)
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print("Plain text after decypting is:", PT)
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