A method for encryption of file, comprising the steps of performing slide partition on source file block-by-block, each block being 128 bits; generating source key from user key by complementing the user key or by subjecting the user key to pseudo-random number processing; generating subkey from the source key through the use of compression permutation and logic shift; enciphering the blocks through the use of initial permutation, multiplicative conversion and inverse initial permutation, the multiplicative conversion using a cryptographic function including operations of extended conversion, exclusive OR of the subkey, box substitution and E conversion. The method is suitable for generating such digital information as voice and image etc... The executable file thus generated is provided to user in the form of software or being stored in memory, such as ROM and PROM, or being integrated into chips of various specifications, and is highly security and easy to use.
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