/* ====================================================================
* Copyright (c) 1999, 2000 Ben Laurie. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by Ben Laurie
* for use in the Lucre project."
*
* 4. The name "Lucre" must not be used to
* endorse or promote products derived from this software without
* prior written permission.
*
* 5. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by Ben Laurie
* for use in the Lucre project."
*
* THIS SOFTWARE IS PROVIDED BY BEN LAURIE ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL BEN LAURIE OR
* HIS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* For more information on Lucre see http://anoncvs.aldigital.co.uk/lucre/.
*
*/
package uk.co.aldigital.ben.lucre;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.PrintStream;
import java.math.BigInteger;
import java.security.NoSuchAlgorithmException;
class Bank extends PublicBank {
private BigInteger m_biPrivateKey;
Bank(int nPrimeLengthBits) {
assert nPrimeLengthBits >= MIN_COIN_LENGTH+DIGEST_LENGTH;
m_biGenerator=BigInteger.valueOf(4);
m_biPrime=Util.generateGermainPrime(nPrimeLengthBits,20);
m_biPrivateKey=generateExponent();
m_biPublicKey=m_biGenerator.modPow(m_biPrivateKey,m_biPrime);
verifyGenerator();
}
Bank(BufferedReader rdr)
throws IOException {
super(rdr);
m_biPrivateKey=Util.readNumber(rdr,"private=");
}
Bank(String szFile)
throws IOException {
this(Util.newBufferedFileReader(szFile));
}
BigInteger generateExponent() {
return Util.random(getPrimeLengthBits()-1,
getExponentGroupOrder()
.subtract(BigInteger.valueOf(getPrimeLengthBits()
+2+1)));
}
private void verifyGenerator() {
// The generator is supposed to yield g^2 != 1 (mod p)
// and g^((p-1)/2) = 1 (mod p)
assert !m_biGenerator.modPow(Util.TWO,m_biPrime).equals(Util.ONE)
: "g^2 != 1 (mod p)";
assert m_biGenerator.modPow(m_biPrime.shiftRight(1),
m_biPrime).equals(Util.ONE)
: "g^((p-1)/2) = 1 (mod p)";
}
public void write(PrintStream out) {
writePublic(out);
Util.dumpNumber(out,"private=",m_biPrivateKey);
}
public void writePublic(PrintStream out) {
super.write(out);
}
public void dump(PrintStream out) {
super.dump(out);
Util.dumpNumber(out,"k= ",m_biPrivateKey);
}
public BigInteger getPrivateKey() {
return m_biPrivateKey;
}
public BigInteger signRequest(PublicCoinRequest req) {
BigInteger BtoA=req.getRequest().modPow(getPrivateKey(),getPrime());
Util.dumpNumber("B->A= ",BtoA);
return BtoA;
}
public boolean verify(Coin coin)
throws NoSuchAlgorithmException {
BigInteger t=coin.generateCoinNumber(this);
if(t == null)
return false;
t=t.modPow(getPrivateKey(),getPrime());
Util.dumpNumber("y^k= ",t);
return t.equals(coin.getSignature());
}
public static void main(String args[])
throws IOException {
if(args.length < 1) {
System.err.println("... <prime length>");
System.exit(1);
}
Bank bank=new Bank(Integer.valueOf(args[0]).intValue());
bank.dump(System.out);
}
}