October 16, 2008, 5:40 AM — In my last post I discussed the Advanced Encryption Standard (AES). Another encryption standard is known as RC6. Its predecessors were RC4 and RC5. RC6 is a fast block cipher (cryptographic algorithm) designed by Ronald Rivest for RSA Data Security (now RSA Security) in 1994. RC by the way stands for Ron’s Code and/or Rivest’s Ciphers.
What a block cipher does is take clear text and then operate on chunks of that text known as blocks. The “operates on chunks of that text†means that an algorithm is applied to the block which performs an encryption on the input block using a secret key and outputs a corresponding block of ciphertext. The decryption process is similar in that a block of ciphertext has an algorithm applied to it, using the same secret key and produces the original block of plaintext.
A block cipher differs from a stream cipher, such as RC4, in that a block cipher works on “blocks†of cleartext and a stream cipher works on a stream of digits one at a time. Read the rest of this article
