Unlike many schemes, RC5 has a variable block size (32, 64 or 128 bits), key size (0 to 2040 bits) and number of rounds (0 to 255). The original suggested choice of parameters were a block size of 64 bits, a 128-bit key and 12 rounds.
There are two entrypoint script: encrypt and decrypt with the same interface.
usage: encrypt.py [-h] -i INPUT_FILE -k KEY_FILE -o OUTPUT_FILE
[-w BLOCK_SIZE] [-r ROUND_SIZE]
Required arguments:
-i INPUT_FILE, --input-file INPUT_FILE
Path to data file
-k KEY_FILE, --key-file KEY_FILE
Path to key file
-o OUTPUT_FILE, --output-file OUTPUT_FILE
Path to result file.
Optional arguments:
-w BLOCK_SIZE, --block-size BLOCK_SIZE
RC5 block size. (32, 64 or 128 bits)
-r ROUND_SIZE, --round-size ROUND_SIZE
RC5 round count. (0 to 255)For example, assume that we have source.txt and key.rc5 files, then:
python encrypt.py -i source.txt -o encrypted.txt -k key
python decrypt.py -i encrypted.txt -o decrypted.txt -k key