Crypto Terms

  • Confusion - Each bit of the ciphertext should be produced from a combination of parts from the key.
    This makes the identification of the relevant portions of the key difficult to find.

  • Diffusion - A small change in the plaintext data will spread changes to the ciphertext. (change to 50% of the output bits)

  • Avalanche Effect - interchangeable with diffusion

  • SP Boxes / Networks - Substitution and Permutation Functions that are called cyclically (and are reversable)

    • Substitution Boxes - A(n invertible) mapping function to provide an output given an input
    • Permutation Boxes - A shuffling function to output a rearranged version of an input

  • Fiestal Networks - A sort of one-way version of SP Boxes, where given the output it is difficult to find the input.

    • Given a reversed order of keys, it is able to decrypt with the same processes in encrypting.

  • Block Ciphers - A cipher method which operates on blocks of data.
    The last block may need to be padded to match the required block size.

  • Stream Ciphers - Each plaintext character is encrypted on a per-character basis (one at a time)