MASON ECE 646 - Lecture 7 Data Encryption Standard and its extensions (22 pages)

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Lecture 7 Data Encryption Standard and its extensions



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Lecture 7 Data Encryption Standard and its extensions

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Lecture Notes


Pages:
22
School:
George Mason University
Course:
Ece 646 - Cryptography and Computer Network Security
Cryptography and Computer Network Security Documents

Unformatted text preview:

ECE 646 Lecture 7 Data Encryption Standard and its extensions DES 3DES DES X NBS public request for a standard cryptographic algorithm May 15 1973 August 27 1974 The algorithm must be secure public completely specified easy to understand available to all users economic and efficient in hardware able to be validated exportable 1 DES chronicle of events 1973 NBS issues a public request for proposals for a standard cryptographic algorithm 1975 first publication of the IBM s algorithm and request for comments 1976 NBS organizes two workshops to evaluate the algorithm 1977 official publication as FIPS PUB 46 Data Encryption Standard 1983 1987 1993 recertification of the algorithm for another five years 1993 software implementations allowed to be validated Controversies surrounding DES Unknown design criteria Most criteria reconstructed from cipher analysis 1990 Reinvention of differential cryptanalysis Slow in software Only hardware implementations certified 1993 Software firmware and hardware treated equally Too short key Theoretical designs of DES breaking machines 1998 Practical DES cracker built 2 Life of DES 1970 2000 1990 1980 Time transision to a new standard DES developed by IBM and NSA In common use for over 20 years Federal and banking standard Over 130 validated implementations De facto world wide standard Most popular secret key ciphers 1980 1990 2000 2030 112 168 bit keys Triple DES AES Rijndael DES Other popular algorithms 2020 1999 1977 American standards 2010 56 bit key AES 2001 contest IDEA Serpent RC5 Twofish 128 192 and 256 bit keys Blowfish RC6 CAST Mars 3 DES external look plaintext block 64 bits DES key 56 bits 64 bits ciphertext block DES high level internal structure 4 IP 1 L0 DES Main Loop Feistel Structure R0 K1 f R1 L1 K2 f Ln 1 Rn Rn 1 Ln f Rn Kn 1 R2 L2 L15 R15 K16 f L16 R16 IP 1 Feistel Structure Encryption Decryption Ln Ln Rn f Ln 1 Kn 1 Rn f Rn 1 Ln 1 Ln 1 Rn 1 Rn 1 f Ln Rn Kn 1 Kn 1 5 Feistel Structure Encryption Decryption Ln Ln Rn f Kn



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