Patent ID: 8280044

Claim:
A stream encryption method using an encryptor and a decoder, wherein the encryptor performs: generating a 2 L -bit long bit pattern (L is N or more) for every channel of N channels by using N number of pseudo random sequences for respective channel of the N channels; determining the bit pattern generated for the respective channel of the N channels whether to apply the bit pattern as it is or apply the bit pattern inverted by using independently a plaintext of N number of 1-bit input signal sequences; calculating a logical product of the respective bit of the bit pattern determined whether to apply the bit pattern as it is or apply the bit pattern inverted; generating a L-bit encryption symbol corresponding to a number of a bit where the result of calculation of the logical product is “1”; and outputting the generated encryption symbol to the decoder, and the decoder performs: inputting the encryption symbol output from the encryptor; selecting a number of the bit indicated by the encryption symbol input by the encryptor among the bit pattern generated by the N number of pseudo random sequences; and decoding independently the plaintext input to the encryptor to a plaintext for respective channel by using the same pseudo random sequences used in the encryptor.