| 摘要 |
PROBLEM TO BE SOLVED: To provide an additive encryption method and an apparatus in which a difficulty in decryption is compatible with high-speed processing. SOLUTION: In the additive encryption method and the apparatus, pseudo random numbers x<SB>0</SB>, x<SB>1</SB>,... are generated by an arbitrary pseudo random number generation algorithm A, buffers A<SB>0</SB>,..., A<SB>k-1</SB>are prepared, and first (k) random numbers are substituted into the buffers. When (xor) is defined as an exclusive OR, äC<SB>n</SB>} is defined as an encrypted sentence and äM<SB>n</SB>} is defined as a plain sentence on the conditions of n=0, x=x<SB>k</SB>and i=0, A<SB>i</SB>(xor)x is outputted and next encrypted as C<SB>n</SB>=A<SB>i</SB>(xor)x(xor)M<SB>n</SB>(1), conditions of A<SB>i</SB>=x and n=n+1 are set up (2) and conditions of i=x(mod k) and x=x<SB>k+n</SB>are set up (3). Thereafter, the steps (1) to (3) are repeated to encipher the plain sentence M<SB>n</SB>into the encrypted sentence C<SB>n</SB>. COPYRIGHT: (C)2004,JPO
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