3 ms·

This cipher is just 4 rounds of Vigenere with progressively shorter keys...

• billpg 16y ago
  Exactly. It's a very flawed cipher which I invented when I was young and naive.
  • swolchok 16y ago
    I realized that; I was just hoping that this observation would lead to an attack, but it's not clear to me that there's a particularly easy/reliable extension of the Vigenere attacks...
    • billpg 16y ago
      Gotcha. The vulnerability I thought of could be applied to Vigenere but in a roundabout sort of way.