/* ====================================================================
* 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 CoinRequest extends PublicCoinRequest {
private BigInteger m_biBlindingFactor;
private UnsignedCoin m_coin=new UnsignedCoin();
CoinRequest(PublicBank bank)
throws NoSuchAlgorithmException {
BigInteger y;
m_coin.random(bank);
y=m_coin.generateCoinNumber(bank);
// choose b
m_biBlindingFactor=Util.random(1,bank.getPrime().subtract(Util.ONE));
Util.dumpNumber("b= ",m_biBlindingFactor);
// calculate A->B: y g^b
m_biCoinRequest=bank.getGenerator().modPow(m_biBlindingFactor,
bank.getPrime());
m_biCoinRequest=m_biCoinRequest.multiply(y).mod(bank.getPrime());
Util.dumpNumber("A->B= ",m_biCoinRequest);
}
CoinRequest(BufferedReader rdr)
throws IOException {
read(rdr);
}
CoinRequest(String szFile)
throws IOException {
this(Util.newBufferedFileReader(szFile));
}
public void write(PrintStream str) {
super.writePublic(str);
m_coin.write(str);
Util.dumpNumber(str,"blinding=",m_biBlindingFactor);
}
public void read(BufferedReader rdr)
throws IOException {
super.read(rdr);
m_coin.read(rdr);
m_biBlindingFactor=Util.readNumber(rdr,"blinding=");
}
BigInteger unblind(BigInteger biSignedCoin,PublicBank bank) {
BigInteger z=bank.getPublicKey().modPow(m_biBlindingFactor,
bank.getPrime());
z=z.modInverse(bank.getPrime());
z=z.multiply(biSignedCoin);
z=z.mod(bank.getPrime());
return z;
}
Coin processResponse(PublicBank bank,
BigInteger biSignedCoinRequest) {
BigInteger biCoinSignature=unblind(biSignedCoinRequest,bank);
Util.dumpNumber("z= ",biCoinSignature);
return new Coin(m_coin,biCoinSignature);
}
}