RobinReinecke / Monoalphabetic-and-Vigenere-Cipher

Encrypt and break monoalphabetic and vigenère cipher using n-gram analysis

Monoalphabetic-and-Vigenere-Cipher

Encrypt and break monoalphabetic and vigenère cipher using n-gram analysis.

Monoalphabetic cipher

Usage of encryption and decryption module

mono.py [-h] (-e/--encrypt KEY | -d/--decrypt KEY) [-o/--out OUT] FILE

Usage of breaking module

break_mono.py [-h] [-o/--out OUT] FILE

Example: Encryption

Encrypt a given plaintext with a chosen key.

$ python3 ./src/mono/mono.py -e ZEBRASCDFGHIJKLMNOPQTUVWXY ./examples/mono.plaintext -o ./examples/mono.ciphertext2

Example: Decryption

Decrypt a given ciphertext with the correct key.

$ python3 ./src/mono/mono.py -d ZEBRASCDFGHIJKLMNOPQTUVWXY ./examples/mono.ciphertext -o ./examples/mono.plaintext2

Example: Breaking

The breaker uses an evolutionary algorithm to iteratively improve the key. Multithreading is used by default. Amount of threads is adjustable. But depending on the used hardware, the breaking takes a while.

$ python3 ./src/mono/break_mono.py ./examples/mono.ciphertext -o ./examples/mono.key2

Vigenère cipher

Usage of encryption and decryption module

vig.py [-h] (-e/--encrypt KEY | -d/--decrypt KEY) [-o/--out OUT] FILE

Usage of breaking module

break_vig.py [-h] -k/--keylen KEYLEN [-o/--out OUT] FILE

Example: Encryption

Encrypt a given plaintext with a chosen key.

$ python3 ./src/vig/vig.py -e hardkey ./examples/vig.plaintext -o ./examples/vig.ciphertext2

Example: Decryption

Decrypt a given ciphertext with the correct key.

$ python3 ./src/vig/vig.py -d hardkey ./examples/vig.ciphertext -o ./examples/mono.plaintext2

Example: Breaking

The breaker uses bigram analysis and needs the correct key length. The Kasiski examination and Friedman test can help to determine the key length.

$ python3 ./src/vig/break_vig.py -k 7 ./examples/vig.ciphertext -o ./examples/vig.key2

Thanks

Special thanks to the Python genius @TrueKuehli