METHOD FOR BLOCK ENCRYPTION OF INFORMATION Russian patent published in 2005 - IPC

FIELD: cryptography and data protection technologies.

SUBSTANCE: method for encryption and decryption of information includes use of block mutually reversible unambiguous two-parameter encrypting and decrypting transformations on basis of tables with random filling having size of N rows each with participation of series of gamma from data-independent random numbers generator, while for encryption block α bytes long additional gamma series α bytes long is produced, alternating for each block, while each byte is transformed using two-parameter bytes transformation v_i=F(u_i,ξ_i) with participation of pseudo-random values to gamma series ξ_i 1 byte long, then in two steps operation for forming an encryption block is performed by bytes concatenation, while encrypting transformation of concatenation of first step bytes with numbers input, having values from 1 to α, is performed by summing certain source u_i and transformed values v_i bytes: a_i=v_i+v_i+1+u_i for i=1,...,(α-1), a_α=v_α+u₁+u₂+...+u_α, encrypting transformation of concatenation of bytes of second step a_i with numbers i having values from 1 to α, is performed in form of recurrent operations F as follows: χ_i=F(a_i, a_i+1) for input=1,...,(α-1), χ_α=a_α, decrypting transformations of bytes are performed in reversed order, firstly, second step decrypting transformation is performed for values of each received byte χ'_i with number i, having values from 1 to α, in form of recurrent operations F^-1 in following way: a'_α=χ'_α; a'_i=F^-1(χ'_i,a'_i+1) for i=α-1, α-2,..., 1 then first step decrypting transformation is performed for values of each byte a_i with number i, having values from 1 to α in form of recurrent operations F^-1 as follows: , for i=1,...,α.

EFFECT: high data processing speed and a pseudo-random series of signals provided after encryption independently from statistics of separate letters in source text.

4 cl