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 54
... MDS Matrix The four bytes output from the four S - boxes are multiplied by a 4 - by - 4 MDS matrix over GF ( 28 ) . This matrix multiply is the principal diffusion mecha- nism in Twofish . The MDS property guarantees that the number of ...
... MDS Matrix The four bytes output from the four S - boxes are multiplied by a 4 - by - 4 MDS matrix over GF ( 28 ) . This matrix multiply is the principal diffusion mecha- nism in Twofish . The MDS property guarantees that the number of ...
Page 55
... MDS properties for three of the bytes are still fully guaranteed with ... matrix will change all four output bytes , which affect the round function output , but after rotation there is no such guarantee . If a byte value difference of 1 is ...
... MDS properties for three of the bytes are still fully guaranteed with ... matrix will change all four output bytes , which affect the round function output , but after rotation there is no such guarantee . If a byte value difference of 1 is ...
Page 72
... MDS matrix multiply , which uses the XOR operation , it is difficult to analyze the full F1 value due to the ... MDS matrix element that maps the S - box output is a simple linear transformation ( i.e. , multiplication by a GF ( 28 ) ...
... MDS matrix multiply , which uses the XOR operation , it is difficult to analyze the full F1 value due to the ... MDS matrix element that maps the S - box output is a simple linear transformation ( i.e. , multiplication by a GF ( 28 ) ...
Common terms and phrases
active actually addition algorithm allow alternative analysis applications approximation attack bits block cipher bound choose chosen ciphertext clock compute consider constant construction CPUs cryptanalysis cryptographic cycles decryption define dependent derive difference sequence differential differential attack DWORD effect eight elements encryption example expect F function Feistel network fixed four give given guess hardware identical implementations improve input key bytes key material key schedule key-dependent S-boxes known larger least length linear MDS matrix mode multiply Note operations output Page Pages pattern Pentium performance permutations plaintext possible probability Proceedings properties random related-key attack right pair rotations round function round subkeys sequence simple single smart cards Software specific speed Springer-Verlag structure Table tion Twofish values variant weak whitening Workshop XOR difference XORed zero