Tag:Sequence cipher

  • Actual sequence cipher


    Using PRNG to construct cipher stream Many pnrgs have good statistical properties, which is necessary for strong sequence ciphers. If we make a statistical test on the key stream sequence, the behavior of the output result should be very similar to the bit sequence obtained by flipping a coin. Therefore, it is natural to assume […]

  • Encryption and decryption of sequence cipher


    Encryption and decryption of sequence cipher Plaintext, ciphertext and key sequence are composed of individual bits, namely x_{i}, y_{i},s_{i}\in \left\{0,1\right\} Encryption:y_i = e_{s_i}(x_i)\equiv x_i + s_i\ mod\ 2decrypt:x_i = d_{s_i}(y_i)\equiv y_i + s_i\ mod\ 2There are three points about the encryption and decryption functions of sequence cipher Why do encryption and decryption use the same […]

  • Sequence cipher and block cipher


    Sequence cipher The sequence cipher encrypts each bit individually. It is realized by adding each bit in the key sequence to each plaintext bit. The key sequence of synchronous sequence cipher only depends on the key, while the key sequence of asynchronous sequence cipher depends on the key and ciphertext. Most of the sequence ciphers […]