| | ipedia.com: Block cipher Article (Site not responding. Last check: 2007-09-23) |
 | | Block sizess are typically 64 or 128 bits, though some ciphers have a variable block size. |
| | Lucifer is considered by many to be the first civilian block cipher, developed at IBM in the 1970s based on work done by Horst Feistel. |
| | The technique is called differential cryptanalysis and remains one of the few general attacks against block ciphers; linear cryptanalysis is another, but was probably unknown, even to NSA, prior to its publication by Mitsuru Matsui. |
| www.ipedia.com /block_cipher.html (627 words) |
