125 lines
3.5 KiB
Python
125 lines
3.5 KiB
Python
## ptext = plaintext
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## ctext = ciphertext
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## mk = multiplicative key
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## ak = additive key
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def add_cipher_en(ptext, ak):
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result = ""
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for ch in ptext:
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if ch.isalpha():
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base = ord('A') if ch.isupper() else ord('a')
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result += chr((ord(ch) - base + ak) % 26 + base)
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else:
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result += ch
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return result
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def add_cipher_de(ctext, ak):
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result = ""
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for ch in ctext:
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if ch.isalpha():
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base = ord('A') if ch.isupper() else ord('a')
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result += chr((ord(ch) - base - ak) % 26 + base)
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else:
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result += ch
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return result
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def mult_cipher_en(ptext, mk):
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result = ""
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for ch in ptext:
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if ch.isalpha():
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base = ord('A') if ch.isupper() else ord('a')
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x = ord(ch) - base
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result += chr((x * mk) % 26 + base)
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else:
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result += ch
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return result
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def mult_cipher_de(ctext, mk):
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result = ""
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inverse = pow(mk, -1, 26)
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for ch in ctext:
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if ch.isalpha():
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base = ord('A') if ch.isupper() else ord('a')
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x = ord(ch) - base
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result += chr((x * inverse) % 26 + base)
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else:
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result += ch
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return result
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def affine_en(ptext, ak, mk):
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result = ""
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for ch in ptext:
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if ch.isalpha():
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base = ord('A') if ch.isupper() else ord('a')
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x = ord(ch) - base
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result += chr(((x * mk + ak) % 26) + base)
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else:
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result += ch
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return result
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def affine_de(ctext, ak, mk):
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result = ""
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inverse = pow(mk, -1, 26)
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for ch in ctext:
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if ch.isalpha():
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base = ord('A') if ch.isupper() else ord('a')
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x = ord(ch) - base
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result += chr((((x - ak) * inverse) % 26) + base)
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else:
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result += ch
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return result
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def mult_inverse(mk):
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inverse = pow(mk, -1, 26)
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return inverse
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def operator(argument,ptext,ak,mk):
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match argument:
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case '1':
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print("Additive Cipher")
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print("Plaintext: ", ptext)
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print("Additive Key: ", ak)
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ctext = add_cipher_en(ptext, ak)
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print("Ciphertext: ", ctext)
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print("Decrypted Text: ", add_cipher_de(ctext, ak))
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case '2':
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print("Multiplicative Cipher")
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print("Plaintext: ", ptext)
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print("Multiplicative Key: ", mk)
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ctext = mult_cipher_en(ptext, mk)
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print("Ciphertext: ", ctext)
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print("Multiplicative Inverse: ", mult_inverse(mk))
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print("Decrypted Text: ", mult_cipher_de(ctext, mk))
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case '3':
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print("Affine Cipher")
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print("Plaintext: ", ptext)
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print("Additive Key: ", ak)
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print("Multiplicative Key: ", mk)
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ctext = affine_en(ptext, ak, mk)
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print("Ciphertext: ", ctext)
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print("Affine Inverse: ", mult_inverse(mk))
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print("Decrypted Text: ", affine_de(ctext, ak, mk))
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case '4':
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print("Goodbye")
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exit()
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case _:
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print("Invalid Choice, please try again.")
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def main():
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ptext = input("Kindly enter your desired plaintext: ")
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ak = 20
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mk = 15
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print("Welcome to the substitution cipher system.")
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print("Enter your choice of algorithm")
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print("1. Additive Cipher")
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print("2. Multiplicative Cipher")
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print("3. Affine Cipher")
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print("4. Exit")
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while True:
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op = input("Enter your choice of operation: ")
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operator(op, ptext, ak, mk)
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if __name__ == '__main__':
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main()
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