A reciprocal cipher is a type of cipher where the same algorithm is used for both encryption and decryption. This means that if you encrypt a plaintext message to get a ciphertext, you can use the same process to decrypt the ciphertext back into the plaintext. Here are some examples of reciprocal ciphers:
ROT13: This is a simple substitution cipher where each letter of the alphabet is replaced by the letter 13 positions after it in the alphabet. For example, 'A' becomes 'N', 'B' becomes 'O', and so on. Since the alphabet has 26 letters, applying ROT13 twice returns the original text, making it a reciprocal cipher[1][3][8].
XOR Cipher: This cipher uses the XOR (exclusive OR) operation to encrypt and decrypt data. If you XOR a plaintext with a key to get the ciphertext, you can XOR the ciphertext with the same key to get back the plaintext. This property makes the XOR cipher a reciprocal cipher[1][4].
Enigma Machine: The Enigma machine, used during World War II, is a more complex example of a reciprocal cipher. It used a series of rotors to encrypt messages. The sam...
