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Cryptographic apparatus and method

  • US 7,177,424 B1
  • Filed: 05/17/2000
  • Issued: 02/13/2007
  • Est. Priority Date: 06/22/1999
  • Status: Expired due to Fees
First Claim
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1. Encryption apparatus for performing symmetric encryption, comprising:

  • means (KS) for generating a keystream block (S(i)) in response to an encryption key (K), the keystream block comprising a plurality of bits (s) of a pseudo-random number sequence; and

    means (MX) for combining the keystream block (i) with a plaintext block (P(i)) comprising a plurality of bits (b) to produce a ciphertext block (C(i));

    wherein the number of bits (s) in the keystream block exceeds the number of bits (b) in the plaintext block.

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