FIELD: computer engineering. SUBSTANCE: information characters, which are extended using orthogonal or bi- orthogonal code words, are set in correspondence to unique scrambling mask, which is chosen from set of scrambling masks, which have specific correlation properties. Set of scrambling masks corresponds to condition that correlation between modulo two sum of two scrambling masks with arbitrary code word is constant independently from code word and individual masks used for comparison. One claim of invention discloses method in which adding two masks using modulo two addition, so that Walsh transform of this sum provides maximally flat Walsh spectrum. For cellular telephone networks which use demodulation methods, the system of two-level encryption ensures protection at the level of cellular network due to use of code word, which is generated in pseudorandom fashion, for selection of one of scrambling masks, which is shared by all mobile stations in specific cell. In addition, method ensures protection of private channels at individual mobile user level due to use of encryption key, which is generated in pseudorandom fashion, for encryption of individual information signals before running scrambling operation. EFFECT: increased number of provided channels, decreased mutual noise between cells of cellular communication network. 50 cl, 9 dwg
