meerkat-java/mixer/src/main/java/verifier/VerifyTable.java

package verifier;

import com.google.protobuf.InvalidProtocolBufferException;
import meerkat.crypto.mixnet.Mix2ZeroKnowledgeVerifier;
import meerkat.crypto.mixnet.MixerOutput;
import meerkat.protobuf.Crypto;
import meerkat.protobuf.Mixing;

import java.util.Arrays;

/**
 * Created by Tzlil on 12/30/2015.
 */
public final class VerifyTable {

    public static boolean verifyTable(Mix2ZeroKnowledgeVerifier verifier,int n,MixerOutput mixerOutput)
            throws InvalidProtocolBufferException {
        int index1,index2,layer;

        //assert n = 2^k
        if ( (n &(n-1)) != 0)
            throw new IllegalArgumentException("n");

        int layers = 2*(int)(Math.log(n) / Math.log(2)) - 1;
        //initialize locationChecksum table
        // use for check BeneshNet validity
        boolean[][] locationChecksum = new boolean[layers][n];
        for (boolean[] locationChecksumLayer: locationChecksum) {
            Arrays.fill(locationChecksumLayer,false);
        }

        Mixing.ZeroKnowledgeProof[][] zeroKnowledgeProofs = mixerOutput.getProofs();
        Crypto.RerandomizableEncryptedMessage[][] rerandomizableEncryptedMessages = mixerOutput.getEncryptedMessages();

        for (int i = 0; i < zeroKnowledgeProofs.length ; i++){
            for (int j = 0; j < zeroKnowledgeProofs[i].length ; j ++){
                Mixing.ZeroKnowledgeProof zkp = zeroKnowledgeProofs[i][j];
                if(zkp == null){
                    int ttt = 1;
                    ttt++;
                }
                Mixing.ZeroKnowledgeProof.Location location = zkp.getLocation();
                index1 = location.getI();
                index2 = location.getJ();
                layer = location.getLayer();

                // check location validity
                if (layer > layers >> 1) {
                    if (index2 - index1 != n >> (layers - layer))
                        return false;
                }
                else{
                    if (index2 - index1 != n >> (layer + 1))
                        return false;
                }

                // mark location in table
                locationChecksum[layer][index1] = true;
                locationChecksum[layer][index2] = true;

                // verify proof
                if(!verifier.verify(rerandomizableEncryptedMessages[layer][index1],
                        rerandomizableEncryptedMessages[layer][index2],
                        rerandomizableEncryptedMessages[layer + 1][index1],
                        rerandomizableEncryptedMessages[layer + 1][index2],
                        zkp)) {

                    verifier.verify(rerandomizableEncryptedMessages[layer][index1],
                            rerandomizableEncryptedMessages[layer][index2],
                            rerandomizableEncryptedMessages[layer + 1][index1],
                            rerandomizableEncryptedMessages[layer + 1][index2],
                            zkp);
                    System.out.print("\n\n\nlayer " + layer + " i , j " + index1 + " , " + index2 + "\n\n\n");
                    return false;
                }
            }
        }

        // verify all necessary locations for BeneshNet were proved
        for (boolean[] checksumLayer: locationChecksum) {
            for (boolean locationBoolean: checksumLayer) {
                if (!locationBoolean)
                    return false;
            }
        }
        return true;
    }
}