111 lines
3.4 KiB
Python
111 lines
3.4 KiB
Python
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import argparse
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def encode_shift_cipher(text, key):
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result = ""
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alphabet = 'abcdefghijklmnopqrstuvwxyz'
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shift_direction = 1
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shift_count = 0
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for char in text:
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if char.isalpha():
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shift = int(key[shift_count]) * shift_direction
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index = alphabet.index(char.lower())
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# Calculate the new index and wrap around if it's less than 0
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new_index = (index + shift) % 26
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if new_index < 0:
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new_index += 26 # Wrap around to 'z'
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result += alphabet[new_index]
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shift_direction *= -1
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shift_count = (shift_count + 1) % len(key)
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else:
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result += char
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return result
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def decode_shift_cipher(text, key):
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result = ""
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alphabet = 'abcdefghijklmnopqrstuvwxyz'
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shift_direction = 1
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shift_count = 0
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for char in text:
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if char.isalpha():
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shift = int(key[shift_count]) * shift_direction
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index = alphabet.index(char.lower())
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# Calculate the new index and wrap around if it's less than 0
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new_index = (index - shift) % 26
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if new_index < 0:
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new_index += 26 # Wrap around to 'z'
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result += alphabet[new_index]
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shift_direction *= -1
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shift_count = (shift_count + 1) % len(key)
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else:
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result += char
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return result
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def main():
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parser = argparse.ArgumentParser(description="Shift Cipher Encoder/Decoder")
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parser.add_argument("-e", "--encode", action="store_true", help="Encode the input")
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parser.add_argument("-d", "--decode", action="store_true", help="Decode the input")
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parser.add_argument("-k", "--key", required=True, help="Encryption/Decryption key (e.g., '1234')")
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parser.add_argument("-i", "--input", help="Input file to process")
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parser.add_argument("-o", "--output", help="Output file (optional)")
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parser.add_argument("-s", "--string", help="Input string to process")
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args = parser.parse_args()
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if not args.encode and not args.decode:
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print("Please specify whether to encode or decode using -e or -d.")
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return
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if args.encode and args.decode:
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print("Please choose either -e (encode) or -d (decode), not both.")
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return
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if args.input and args.string:
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print("Please choose either -i (input file) or -s (input string), not both.")
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return
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if args.input:
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# Read input from a file
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try:
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with open(args.input, "r") as file:
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input_text = file.read()
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except FileNotFoundError:
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print(f"Error: Input file '{args.input}' not found.")
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return
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elif args.string:
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# Use the input string
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input_text = args.string
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else:
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# Read input from the command line
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input_text = input("Enter the text to encode/decode: ")
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key = args.key
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if args.encode:
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output_text = encode_shift_cipher(input_text, key)
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else:
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output_text = decode_shift_cipher(input_text, key)
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if args.output:
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# Write the result to an output file
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with open(args.output, "w") as file:
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file.write(output_text)
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print(f"Output written to '{args.output}'")
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else:
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# Print the result to the console
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print("Result:")
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print(output_text)
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if __name__ == "__main__":
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main()
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