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Java SDK for Hyperledger fabric project
/*
*
* Copyright 2017, 2018 IBM Corp. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
* http://www.apache.org/licenses/LICENSE-2.0
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/
package org.hyperledger.fabric.sdk.idemix;
import java.util.Arrays;
import java.util.HashSet;
import java.util.Set;
import com.google.protobuf.ByteString;
import org.apache.milagro.amcl.FP256BN.BIG;
import org.apache.milagro.amcl.FP256BN.ECP;
import org.apache.milagro.amcl.FP256BN.ECP2;
import org.apache.milagro.amcl.RAND;
import org.hyperledger.fabric.protos.idemix.Idemix;
/**
* IdemixIssuerPublicKey represents the idemix public key of an issuer (Certificate Authority).
*/
public class IdemixIssuerPublicKey {
private final String[] AttributeNames;
private final ECP Hsk;
private final ECP HRand;
private final ECP[] HAttrs;
private final ECP2 W;
private final ECP BarG1;
private final ECP BarG2;
private final BIG ProofC;
private final BIG ProofS;
private byte[] Hash = new byte[0];
/**
* Constructor
*
* @param attributeNames the names of attributes as String array (must not contain duplicates)
* @param isk the issuer secret key
*/
IdemixIssuerPublicKey(String[] attributeNames, BIG isk) {
// check null input
if (attributeNames == null || isk == null) {
throw new IllegalArgumentException("Cannot create IdemixIssuerPublicKey from null input");
}
// Checking if attribute names are unique
Set map = new HashSet<>();
for (String item : attributeNames) {
if (!map.add(item)) {
throw new IllegalArgumentException("Attribute " + item + " appears multiple times in attributeNames");
}
}
final RAND rng = IdemixUtils.getRand();
// Attaching Attribute Names array correctly
AttributeNames = attributeNames;
// Computing W value
W = IdemixUtils.genG2.mul(isk);
// Filling up HAttributes correctly in Issuer Public Key, length
// preserving
HAttrs = new ECP[attributeNames.length];
for (int i = 0; i < attributeNames.length; i++) {
HAttrs[i] = IdemixUtils.genG1.mul(IdemixUtils.randModOrder(rng));
}
// Generating Hsk value
Hsk = IdemixUtils.genG1.mul(IdemixUtils.randModOrder(rng));
// Generating HRand value
HRand = IdemixUtils.genG1.mul(IdemixUtils.randModOrder(rng));
// Generating BarG1 value
BarG1 = IdemixUtils.genG1.mul(IdemixUtils.randModOrder(rng));
// Generating BarG2 value
BarG2 = BarG1.mul(isk);
// Zero Knowledge Proofs
// Computing t1 and t2 values with random local variable r for later use
BIG r = IdemixUtils.randModOrder(rng);
ECP2 t1 = IdemixUtils.genG2.mul(r);
ECP t2 = BarG1.mul(r);
// Generating proofData that will contain 3 elements in G1 (of size 2*FIELD_BYTES+1)and 3 elements in G2 (of size 4 * FIELD_BYTES)
byte[] proofData = new byte[0];
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(t1));
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(t2));
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(IdemixUtils.genG2));
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(BarG1));
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(W));
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(BarG2));
// Hashing proofData to proofC
ProofC = IdemixUtils.hashModOrder(proofData);
// Computing ProofS = (ProofC*isk) + r mod GROUP_ORDER
ProofS = BIG.modmul(ProofC, isk, IdemixUtils.GROUP_ORDER).plus(r);
ProofS.mod(IdemixUtils.GROUP_ORDER);
// Compute Hash of IdemixIssuerPublicKey
byte[] serializedIpk = toProto().toByteArray();
Hash = IdemixUtils.bigToBytes(IdemixUtils.hashModOrder(serializedIpk));
}
/**
* Construct an IdemixIssuerPublicKey from a serialized issuer public key
*
* @param proto a protobuf representation of an issuer public key
*/
public IdemixIssuerPublicKey(Idemix.IssuerPublicKey proto) {
// check for bad input
if (proto == null) {
throw new IllegalArgumentException("Cannot create IdemixIssuerPublicKey from null input");
}
if (proto.getHAttrsCount() < proto.getAttributeNamesCount()) {
throw new IllegalArgumentException("Serialized IPk does not contain enough HAttr values");
}
AttributeNames = new String[proto.getAttributeNamesCount()];
for (int i = 0; i < proto.getAttributeNamesCount(); i++) {
AttributeNames[i] = proto.getAttributeNames(i);
}
HAttrs = new ECP[proto.getHAttrsCount()];
for (int i = 0; i < proto.getHAttrsCount(); i++) {
HAttrs[i] = IdemixUtils.transformFromProto(proto.getHAttrs(i));
}
BarG1 = IdemixUtils.transformFromProto(proto.getBarG1());
BarG2 = IdemixUtils.transformFromProto(proto.getBarG2());
HRand = IdemixUtils.transformFromProto(proto.getHRand());
Hsk = IdemixUtils.transformFromProto(proto.getHSk());
ProofC = BIG.fromBytes(proto.getProofC().toByteArray());
ProofS = BIG.fromBytes(proto.getProofS().toByteArray());
W = IdemixUtils.transformFromProto(proto.getW());
// Compute Hash of IdemixIssuerPublicKey
byte[] serializedIpk = toProto().toByteArray();
Hash = IdemixUtils.bigToBytes(IdemixUtils.hashModOrder(serializedIpk));
}
/**
* check whether the issuer public key is correct
*
* @return true iff valid
*/
public boolean check() {
// check formalities of IdemixIssuerPublicKey
if (AttributeNames == null || Hsk == null || HRand == null || HAttrs == null
|| BarG1 == null || BarG1.is_infinity() || BarG2 == null
|| HAttrs.length < AttributeNames.length) {
return false;
}
for (int i = 0; i < AttributeNames.length; i++) {
if (HAttrs[i] == null) {
return false;
}
}
// check proofs
ECP2 t1 = IdemixUtils.genG2.mul(ProofS);
ECP t2 = BarG1.mul(ProofS);
t1.add(W.mul(BIG.modneg(ProofC, IdemixUtils.GROUP_ORDER)));
t2.add(BarG2.mul(BIG.modneg(ProofC, IdemixUtils.GROUP_ORDER)));
// Generating proofData that will contain 3 elements in G1 (of size 2*FIELD_BYTES+1)and 3 elements in G2 (of size 4 * FIELD_BYTES)
byte[] proofData = new byte[0];
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(t1));
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(t2));
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(IdemixUtils.genG2));
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(BarG1));
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(W));
proofData = IdemixUtils.append(proofData, IdemixUtils.ecpToBytes(BarG2));
// Hash proofData to hproofdata and compare with proofC
return Arrays.equals(IdemixUtils.bigToBytes(IdemixUtils.hashModOrder(proofData)), IdemixUtils.bigToBytes(ProofC));
}
/**
* @return A proto version of this issuer public key
*/
Idemix.IssuerPublicKey toProto() {
Idemix.ECP[] ipkHAttrs = new Idemix.ECP[HAttrs.length];
for (int i = 0; i < HAttrs.length; i++) {
ipkHAttrs[i] = IdemixUtils.transformToProto(HAttrs[i]);
}
return Idemix.IssuerPublicKey.newBuilder()
.setProofC(ByteString.copyFrom(IdemixUtils.bigToBytes(ProofC)))
.setProofS(ByteString.copyFrom(IdemixUtils.bigToBytes(ProofS)))
.setW(IdemixUtils.transformToProto(W))
.setHSk(IdemixUtils.transformToProto(Hsk))
.setHRand(IdemixUtils.transformToProto(HRand))
.addAllAttributeNames(Arrays.asList(AttributeNames))
.setHash(ByteString.copyFrom(Hash))
.setBarG1(IdemixUtils.transformToProto(BarG1))
.setBarG2(IdemixUtils.transformToProto(BarG2))
.addAllHAttrs(Arrays.asList(ipkHAttrs))
.build();
}
/**
* @return The names of the attributes certified with this issuer public key
*/
public String[] getAttributeNames() {
return AttributeNames;
}
protected ECP getHsk() {
return Hsk;
}
protected ECP getHRand() {
return HRand;
}
protected ECP[] getHAttrs() {
return HAttrs;
}
protected ECP2 getW() {
return W;
}
/**
* @return A digest of this issuer public key
*/
public byte[] getHash() {
return Hash;
}
}