https://github.com/isaaccorley/quipster-automatic-cipher-solver

Implementation of the QUIPSTER Substitution Cipher Solving Algorithm from "Solving Substitution Ciphers" - Hasinoff (2003)
https://github.com/isaaccorley/quipster-automatic-cipher-solver

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Implementation of the QUIPSTER Substitution Cipher Solving Algorithm from "Solving Substitution Ciphers" - Hasinoff (2003)

• Host: GitHub
• URL: https://github.com/isaaccorley/quipster-automatic-cipher-solver
• Owner: isaaccorley
• Created: 2020-01-30T04:11:23.000Z (almost 5 years ago)
• Default Branch: master
• Last Pushed: 2020-02-04T17:43:42.000Z (almost 5 years ago)
• Last Synced: 2024-10-14T10:15:27.990Z (3 months ago)
• Language: Python
• Size: 466 KB
• Stars: 2
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

        
# QUIPSTER-Automatic-Cipher-Solver

Implementation of the QUIPSTER Substitution Cipher Solving Algorithm from ["Solving Substitution Ciphers" - Hasinoff (2003)](https://people.csail.mit.edu/hasinoff/pubs/hasinoff-quipster-2003.pdf)

Some modifications have been made to the original algorithm and a different dictionary is utilized for assessing the N-gram based scoring metric.

The most notably difficult part about this cryptoalgorithm (and language based cryptoalgorithms in general) is that it easily falls into a local minima and never escapes due to:

- Only swapping 2 characters in the key on every iteration

- Using a scoring metric which can be biased based on your corpus

- Using a corpus which has notably different distributions of language than the plaintext (Even if from the same language)

Therefore to assist in unlocking the perfect mapping of the key, a CLI user interface is added to allow the user to manually make updates to the key based on their own knowledge and viewing the ciphertext compared to the decrypted plaintext.

## Break a ciphertext

```

python main.py \

    --ciphertext_path data/ciphertexts/ciphertext2.txt \

    --output plaintext.txt \

    --num_trials 500 \

    --num_swaps 1000 \

    --converge_swaps 5

```

## Generating a random ciphertext from a plaintext and break it

```

python main.py \

    --plaintext_path data/plaintexts/plaintext0.txt \

    --output plaintext.txt \

    --num_trials 500 \

    --num_swaps 1000 \

    --converge_swaps 5

```