> In Applied Cryptography Schneier says that the DSA algorithm is
> covered by two patents: the Diffie-Hellman patent and the Schnorr
> patent. Now, the first of these expired in April 1997, but the
> second is valid until some time in 2008. But Bruce also goes on to
> say that the issue was still undecided.
The Schnorr patent #4995082 only covers a very specific application of DSA
with smart cards. OpenSSL doesn't violate it. There is only one independent
claim in the patent, and it describes a long sequence of operations, all
of which must be reproduced to violate the patent (which is regarded as a
"scare-crow" patent and is useless against software implementations).
The text of claim 1 follows my .signature.
--
Clifford Heath http://www.osa.com.au/~cjh
Open Software Associates Limited mailto:[EMAIL PROTECTED]
29 Ringwood Street / PO Box 4414 Phone +613 9871 1694
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Deploying Solutions to the Enterprise
--
In a method for mutual identification of subscribers in a data exchange
system working with processor chip cards and using identification data
coded into the cards by a card-issuing center including subscriber-related
public keys and stored in the respective chip cards along with private
keys which have a logical relationship to the public keys, whereby random
number-dependent check data are exchanged between the subscribers,
comprising the steps of:
- transmitting from a chip card the coded identification data together
with a signature of the center to a subscriber entering into an
information exchange with the chip card;
- at the subscriber checking the correctness of the coded identification
data with reference to known information including a public list or
reference to the signature of the center;
- forming in the chip card a x value proceeding from a random, discrete
logarithm r.epsilon.(1, . . . , p-1), where p is a declared prime number
modulus, and according to the rule x:=2^r (mod p):
- transmitting the x value to the subscriber;
- transmitting from the subscriber a random bit sequence
e=(el,l. . . ,et,k).epsilon.{0,1}^kt
to the chip card;
- multiplying the stored, private key sj representing a discrete logarithm
with a binary number formed from the bits of the random bit sequence e
transmitted from the subscriber to the chip card and adding the random
number r allocated to the previously-transmitted x value to
- calculate, at the chip card, a number y according to the rule [Figure]
transmitting the number y to the subscriber; at the subscriber,
calculating a number x with reference to the number y according to the
rule [Figure] checking the identity of the chip card user by comparing
the calculated number x and the x value previously communicated to the
subscriber.
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