Developing DES

- [Instructor] In 1973, … the National Institute of Standards and Technology or NIST … issued a public request for an encryption algorithm. … It had to meet several criteria … that included a high level security, … be easily understood, adaptable, economical, … efficient and exportable. … In 1974, IBM submitted Lucifer, … a block cipher developed by Feistel and his colleagues. … Lucifer was evaluated … by the National Security Agency … who then reduced the key length from 128 bits to 56 bits … and changed the inner workings. … This then became the Data Encryption Standard or DES … and was adopted in 1977 as the government standard … for encrypting data. … It's also known as Data Encryption Algorithm or DEA. … The publication of DES … prompted a lot of research in cryptography. … So let's talk about DES. … DES is a minor variation of the Feistel cipher. … It encrypts a 64-bit block of data using a 56-bit key. … From the 56-bit key, 16 sub keys are generated … and a corresponding 16 rounds of processing …