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Caesar Cipher
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| """ | |
| Simple implementation of the Caesar cipher that works for the English alphabet | |
| """ | |
| alphabet = [chr(letter) for letter in range(97, 123)] | |
| def caesar_cipher(text, key): | |
| """ | |
| Enciphers/deciphers a text. | |
| @param text: to encipher/decipher | |
| @param key: use a positive number to encipher and a negative to decipher | |
| """ | |
| text_ = "" | |
| for c in text: | |
| text_ += shift(c.lower(), key) | |
| return text_ | |
| def shift(char, n): | |
| """ Shifts a letter by `n` letters and wraps at z to a.""" | |
| try: | |
| index = alphabet.index(char) | |
| except ValueError: | |
| return char # unknown letter | |
| index += n | |
| if index > 25: index = index - 26 | |
| return alphabet[index] | |
| text = "Hello, my name is CasperCL" | |
| code = caesar_cipher(text, 13) | |
| deciphered = caesar_cipher(code, -13) | |
| assert text.lower() == deciphered |
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