E. Filliol started his presentation with a short introduction to misimplementation of crypto systems and basiys in cryptography. First the different type of ciper systems were presented

  • stream ciphers – working on a stream of bits or Bytes, most likely performing a xor operation on the message with at (pseudo) random vector. The vector is created based on a key.
  • block ciphers – work on defined blocks of a message. For example the message is devided in this parts of 64 Bit. These blocks are encrypted with a key.

After the introduction a short presentation of his project Mediggo. A Library to analyse crypto.

To analyse ciphertext he took the following steps:

  1. detection – detect the cypher system
  2. build a corpus – get a statistical model of the plaintext language
  3. decrypt – try to recover the original message.

Interested to learn more? have a look at the Google-Code project Mediggo. Slides are included there.