5 ms·

Asemica: An asemic Markov-chained cipher

38 points by photon12 6y ago

CodesInChaos 6y ago
I'd rather consider this an encoding than a cipher
- jchook 6y ago
  Why? It has a secret key. Doesn’t that qualify it as a cipher?
  - CodesInChaos 6y ago
    I'd treat that file as merely a style template, not as a key. Selling it as a cipher opens it up to criticism, since from the description it sounds like a simple substitution cipher with decoy symbols, which is obviously not secure.
deleted 6y ago
[deleted]
CodesInChaos 6y ago
If I wanted to produce plaintext like ciphertexts, I'd: 1. Encrypt the plaintext with a standard cipher, producing uniformly random bytes 2. Build a language model which predicts the probability of the next symbol (nowadays you'd probably use a neural network for that). 3. Run an arithmetic decoder (or similar) for that model on the ciphertext. This translates random bytes into language. The quality of the output depends on the quality of the language model.
MrXOR 6y ago
Interesting! You want secure asemic cipher? say hello to Format-preserving encryption. https://en.wikipedia.org/wiki/Format-preserving_encryption https://en.wikipedia.org/wiki/Format-preserving_encryption
daemonk 6y ago
I've wanted something like this for barcodes. My company depends on our users to enter in a 16 digit barcode correctly. It would be great if the 16 digit barcode can somehow be bi-directionally translated into a sentence (grammatically correct sentence would be even better). While this will probably take the user more keystrokes to type out, it should reduce entry errors.
- CodesInChaos 6y ago
  If you drop the grammar requirement, you can easily use one of the many dictionaries made for this purpose (e.g. diceware or a bip39 wordlist which even has support for many languages). If you feel fancy, you could make it order independent or add error correcting codes to compensate for a limited number of mistakes at the cost of an extra word or two.
prionassembly 6y ago
That's not what usually... https://en.wikipedia.org/wiki/Asemic_writing https://en.wikipedia.org/wiki/Asemic_writing

38 points by photon12 6y ago

CodesInChaos 6y ago

I'd rather consider this an encoding than a cipher

jchook 6y ago
Why? It has a secret key. Doesn’t that qualify it as a cipher?
- CodesInChaos 6y ago
  I'd treat that file as merely a style template, not as a key. Selling it as a cipher opens it up to criticism, since from the description it sounds like a simple substitution cipher with decoy symbols, which is obviously not secure.

deleted 6y ago

[deleted]

CodesInChaos 6y ago

If I wanted to produce plaintext like ciphertexts, I'd: 1. Encrypt the plaintext with a standard cipher, producing uniformly random bytes 2. Build a language model which predicts the probability of the next symbol (nowadays you'd probably use a neural network for that). 3. Run an arithmetic decoder (or similar) for that model on the ciphertext. This translates random bytes into language. The quality of the output depends on the quality of the language model.

MrXOR 6y ago

Interesting! You want secure asemic cipher? say hello to Format-preserving encryption. https://en.wikipedia.org/wiki/Format-preserving_encryption https://en.wikipedia.org/wiki/Format-preserving_encryption

daemonk 6y ago

I've wanted something like this for barcodes. My company depends on our users to enter in a 16 digit barcode correctly. It would be great if the 16 digit barcode can somehow be bi-directionally translated into a sentence (grammatically correct sentence would be even better). While this will probably take the user more keystrokes to type out, it should reduce entry errors.

CodesInChaos 6y ago
If you drop the grammar requirement, you can easily use one of the many dictionaries made for this purpose (e.g. diceware or a bip39 wordlist which even has support for many languages). If you feel fancy, you could make it order independent or add error correcting codes to compensate for a limited number of mistakes at the cost of an extra word or two.

prionassembly 6y ago

That's not what usually... https://en.wikipedia.org/wiki/Asemic_writing https://en.wikipedia.org/wiki/Asemic_writing