## F

2.5.1 Description of the Encryption Algorithm DDP-64 is a ten-round iterated block cipher, operating on 64-bit data blocks and using a 128-bit key. The general encryption scheme of DDP-64 is the same as that of Cobra-H64 (see Figure 2.8a ) except for the key scheduling. The encryption and decryption functions of DDP-64 can be described by the following equations Y F(e 0)(X, K) and X F(e 1)(Y, K) (2.27) where X is the input data block (it is plaintext for encryption), Y is the output data block...

## Ek0 Ek1 EK2 EK2n

Where EK(M) is an encryption function controlled with the key K. The key specifies what kind of substitution table is implemented by the encryption algorithm. Actually, it is impossible to construct such a table because of the large value of n (usually for practically used ciphers we have n 64 or 128 bits). However, selecting an algorithm and a key, we define a substitution table that sets the correspondence between plaintext blocks, M, and ciphertext blocks, C EK(M). For a given key, one...

## VTV0 VTVJJ and Vtvj Vtv0J49

We will call the reversible RSDDOs simply SDDOs or reversible DDOs (RDDOs). The formal presentation of the reversible controlled operations uses the following definitions Definition 4.1. Let F0, Fj, , F2m-J be some set of the single-type operations defined by the formula Y Fi Fi(X), where i J, 2, , 2m-J, Xis an n-bit input binary vector, and Y is the output. Then, the V-dependent operation F(V) defined by the formula Y F(V) (X ) FV(X), where Vis an m-bit controlling vector, is called the...

## Design of the BPI for Cryptographic Applications

From the point of view of construction of encryption algorithms and hash functions, it is not necessary to perform some prescribed bit permutations. It is sufficient to specify the permutations that provide good avalanche effect and sufficient uniformity of the probability distribution of the bit transpositions. The P3V96 operation used in the design of COBRA-F64a and COBRA-F64b block ciphers 48 is an example of such command. An alternative variant of the specialized BPI is the P32 128...

## References

Advanced Encryption Standard. 1997. Proceedings of the 4th International Workshop, Fast Software Encryption FSE '97, Ed. Eli Biham. Springer Verlag LNCS 1267 83-87. 2. Becker, W. 1979. Method and system for machine enciphering and deciphering. U.S. Patent 4157454. 3. Benes, V.E. 1962. Algebraic and topological properties of connecting networks. Bell Systems Technical Journal 41 1249-74. 4. Benes, V.E. 1965. Mathematical theory of connecting networks and telephone traffic. New York Academic...