## The twofish encryption algorithm: a 128-bit block cipherThe first and only guide to one of today's most important new cryptography algorithms The Twofish Encryption Algorithm A symmetric block cipher that accepts keys of any length, up to 256 bits, Twofish is among the new encryption algorithms being considered by the National Institute of Science and Technology (NIST) as a replacement for the DES algorithm. Highly secure and flexible, Twofish works extremely well with large microprocessors, 8-bit smart card microprocessors, and dedicated hardware. Now from the team who developed Twofish, this book provides you with your first detailed look at: * All aspects of Twofish's design and anatomy * Twofish performance and testing results * Step-by-step instructions on how to use it in your systems * Complete source code, in C, for implementing Twofish On the companion Web site you'll find: * A direct link to Counterpane Systems for updates on Twofish * A link to the National Institute of Science and Technology (NIST) for ongoing information about the competing technologies being considered for the Advanced Encryption Standard (AES) for the next millennium For updates on Twofish and the AES process, visit these sites: * www.wiley.com/compbooks/schneier * www.counterpane.com * www.nist.gov/aes Wiley Computer Publishing Timely.Practical.Reliable Visit our Web site at www.wiley.com/compbooks/ Visit the companion Web site at www.wiley.com/compbooks/schneier |

### From inside the book

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Page 79

We also have a differential attack which breaks five rounds of full Twofish with

2232 work and 241

This attack involves choosing 160 bits of a pair of keys, K, K* , with the remaining

bits ...

We also have a differential attack which breaks five rounds of full Twofish with

2232 work and 241

**chosen**-**plaintext**queries. • We have a chosen-key attack.This attack involves choosing 160 bits of a pair of keys, K, K* , with the remaining

bits ...

Page 104

A conventional attack is usually judged in terms of the number of plaintexts or

ciphertexts needed for the attack, and the level of access to the cipher needed to

get those texts (i.e., known plaintext,

A conventional attack is usually judged in terms of the number of plaintexts or

ciphertexts needed for the attack, and the level of access to the cipher needed to

get those texts (i.e., known plaintext,

**chosen plaintext**, adaptive**chosen plaintext**).Page 183

... 80, 121 design criteria 3, 42 process 1,117,130 standard 30 Akelarre 36

algebraic degree 103 Alpha CPU 29 assembly 19, 20, 22-25, 121, 157 attack

brute-force 42, 98 chosen ciphertext 38 chosen key 79 partial 109

... 80, 121 design criteria 3, 42 process 1,117,130 standard 30 Akelarre 36

algebraic degree 103 Alpha CPU 29 assembly 19, 20, 22-25, 121, 157 attack

brute-force 42, 98 chosen ciphertext 38 chosen key 79 partial 109

**chosen****plaintext**4, 38, ...### What people are saying - Write a review

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### Common terms and phrases

16 rounds 32-bit words active S-boxes addition Advances in Cryptology analysis batch bits of key block cipher Blowfish byte sequences chosen plaintexts ciphertext clock cycles compute Counterpane Systems CPUs cryptographic define difference sequence differential attack differential characteristic Differential Cryptanalysis differential patterns differential probabilities DPmax DWORD encryption and decryption endif F function family key Fast Software Encryption Feistel network fixed S-boxes four S-boxes guess Hamming weight hardware hash function implementations input difference International Workshop Proceedings key bytes key length key material key schedule key setup key sizes key-dependent S-boxes linear cryptanalysis LPmax MDS matrix MDS matrix multiply number of rounds output difference p#efine pair of keys Pentium performance permutations possible PPro/II precomputed properties qo and q random related-key attack right pair round function round subkeys smart card speed Springer-Verlag structure Table Twofish Twofish variant weak keys whitening XOR difference XORed zero