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Non malleable encryption method and apparatus using key-encryption keys and digital signature

  • US 6,931,126 B1
  • Filed: 01/19/2000
  • Issued: 08/16/2005
  • Est. Priority Date: 01/27/1999
  • Status: Expired due to Fees
First Claim
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1. A method comprising the steps of:

  • encrypting a data message m at a transmitter processor using a primary transmitter secret key z, wherein z is known to the transmitter processor but not to a receiver processor, to form a quantity E;

    preparing a quadruplet (anew, bnew,snew, E) at the transmitter processor where;


    anew=z*ycmodulo p;


    bnew=gcmodulo p;


    snew=signaturec(anew,bnew,E);

    where y=gxmodulo p, c is a random number, x is a receiver secret key of the receiver processor, and the parameters g, x, and p are picked using a known encryption method;

    wherein snew is a signature which is determined by using the same random number c that was used to determine anew and bnew;

    transmitting the quadruplet (anew, bnew,snew, E) from the transmitter processor to the receiver processor;

    verifying the signature snew at the receiver processor;

    decrypting anew and bnew at the receiver processor by using the receiver secret key x to get the primary transmitter secret key z;

    using the primary transmitter secret key z to decrypt the quantity E and thereby obtaining the message m at the receiver processor.

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