METHOD FOR DATA PROTECTION IN RADIO AND LOCAL COMPUTER NETWORK Russian patent published in 2005 - IPC

FIELD: cryptographic data protection in radio and local computer networks.

SUBSTANCE: data protection method in radio and local computer networks with limitations on access to network clients, is characterized by encryption of text portion of packet with keys, individual for each pair of clients by means of two-parameter encrypting transformation v_i=F(u_i,ξ_i) and decrypting transformation u_i=F_-1(v_i,ξ_i) on basis of random replacement table T_k having length of 2^l symbols, where ^l - length of alphabet element, u_i - combination, transformed during encryption, v_i - encryption result, ξ_i - transformation parameter, for encryption of next information combination u_i, transferred from client with number t to client with number g, source value u_i is found in table T_k, difference of values of addresses of clients Δ=g-t is calculated by module 2^l, value Δ is masked by randomly filled masking table T_m, for which purpose from table T_m at address Δ result of masking Δ_M is read, value Δ_M is used as transformation parameter ξ_i of symbol u_i subjected to encryption, while encrypting transformation of symbol is performed using table T_k and additional addresses table T_a, in which in row with address u_i address of combination u_i in table T_k is stored, address of combination u_i is determined, address of transformation result is calculated as sum by module 2^l of address of combination u_i and value Δ_M and transformation result v_i is read by calculated address from table T_k, decrypting transformation of symbol is performed using table T_k and additional addresses table T_a, in which in a row with address v_i an address of combination v_i in table T_k is stored, address of combination v_i is determined, address of transformation result u_i is determined as difference by module 2^l of combination^{address v_i and value Δ_M and transformation result u_i is read by calculated address from table T_k.}

EFFECT: encryption of information by keys, individual for each pair of clients, with fast realization of cryptographic transformation.

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