The DES Algorithm
As an example of the first official
deployment of encryption, we'll consider
the Data Encryption Standard, DES.
In 1977 the US Government adopted a product cipher from IBM and later that
year was defined as as the official encryption standard by the US
Standards Bureau.
DES software is publicly available
(see
DES-crypt.c),
but is more efficiently implemented in hardware.
Users are confident of its security (they will openly say when it is in
use - for example, Unix passwords).
- Data is encrypted in 64 bit blocks.
- Ciphertext is output in 64 bit blocks.
- A 56 bit key is used.
- The same key is used for both encryption and decryption.
CITS3002 Computer Networks, Lecture 12, Cryptography's role in networking, p7, 22nd May 2024.
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CITS3002