Ciphers

DES : Digital Encryption Standard

Developed by IBM in1970s

Originally a cryptographic cipher named Lucifer

NSA requested changes

Concern over changes ... controversy wondring if NSA requested backdoor

Technical Details

56 bit keys

Block cipher

Uses 64 bit blocks

DES Cracked

In 1998, a DES-encrypted message was cracked in 3 days

in 1999, a network of 10,000 desktop systems cracked a DES-encrypted message in less than 1 day

Triple DES

DES algo used three times

K1 is used to encrypt a message (P) resulting in C1 cipher text

K2 is used to decrypt C1 resulting in C2 cipher text

K3 is used to encrypt C2 rsulting in C3 cipher text

Technical Details

56 bit keys

Yields effective key length of 168 bits

AES : Advanced Encryption Standard

NIST requested proposal for AES

In 2001, NIST published an algo called Rijndael as AES

AES Technical Specifications

Rijndael specifies variable block sizes and key lengths, multipes of 32 bits

AES specifies a fixed 128 bit block size but key lengths of 128, 192 & 256 bits