Importance

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Abstract

In a data exchange system working with processor chip cards, a chip card transmits coded identification data I, v and, proceeding from a random, discrete logarithm r, an exponential value x=2.sup.r (mod p) to the subscriber who, in turn, generates and transmits a random bit sequence e to the chip card. By multiplication of a stored, private key s with the bit sequence e and by addition of the random number r, the chip card calculates a y value and transmits the y value to the subscriber who, in turn, calculates an x value from the information y, v.sub.j and e and checks whether the calculated x value coincides with the transmitted x value. For an electronic signature, a hash value e is first calculated from an x value and from the message m to be signed and a y value is subsequently calculated from the information r, s.sub.j and e. The numbers x and y then yield the electronic signature of the message m.

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First Claim