×

Non-deterministic public key encrypton system

  • US 5,799,088 A
  • Filed: 09/23/1996
  • Issued: 08/25/1998
  • Est. Priority Date: 12/01/1993
  • Status: Expired due to Fees
First Claim
Patent Images

1. A public-key encryption system wherein a message sender encrypts a plaintext message P using a publicly known key unique to a message receiver and the message receiver decrypts the encrypted message using a secret private key from which the public key has been derived, characterised in that:

  • (1) a private key (D) is selected which comprises a plurality of binary numbers D1 to n ;

    (2) a public key (E) is computed by exponentiation (as hereinbefore defined) using the private key by, for each of the said numbers D1 to n, calculating the state of a pseudo-random binary number generator from a given and known initial state after a number of clock pulses or state transitions equal to the corresponding number given by the private key D1 to n and providing each of the calculated binary states E1 to n as a component of the public key E;

    (3) the message sender(a) generates a random initialisation key (R) comprising a set of binary numbers R1 to n and computes by exponentiation an open key Q by, for each of the numbers R1 to n, calculating the state of a pseudo-random binary number generator from a given and known initial state after a number of clock pulses or state transitions equal to the corresponding number given by the random initialisation key R1 to n and providing each of the calculated binary states O1 to n as a component of the open key Q,(b) exponentiates the components of the public key E by the components of the random initialisation key R to produce generator initialisation states K1 to n by, for each of the said numbers E1 to n and R1 to n, calculating the state of a pseudo-random binary number generator that would result from applying the process defined in step (2) a number of times equal to the corresponding binary number R1 to n,(c) loads a set (n) of pseudo-random binary number generators, the outputs of which are combined to form a first mixture generator, with initial values K1 to n,(d) clocks the first mixture generator to obtain a keystream serial output,(e) combines said keystream output with the binary plaintext message P to produce an encrypted bit stream ciphertext C,(f) adds the ciphertext C to the open key Q to produce a message stream,(g) transmits the message to the message receiver;

    (4) the message receiver(a) extracts the open key Q from the message stream,(b) exponentiates the open key Q by the private key D to derive generator initialisation states K1 to n by, for each of the said numbers Q1 to n and D1 to n, calculating the state of a pseudo-random binary number generator that would result from applying the process defined in step (3)(a) a number of times equal to the corresponding binary number D1 to n,(c) loads a second set (n) of pseudo-random binary number generators, the outputs of which are combined to form a mixture generator, with the generator initialisation states K1 to n,(d) clocks the mixture generator to obtain a keystream serial output and combines this output with the received encrypted bit stream to produce the sender'"'"'s plaintext message.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×