/*
 * VerifyHandler.java
 *
 * Created on den 9 januari 2005, 11:20
 */

import java.security.*;
import java.io.*;

/**
 *
 * @author Henrik Johansson
 */
public class VerifyHandler {
    private String dataName;
    private String publicKeyName;
    private String signatureName;
    private String signatureAlgorithm = "SHA1withDSA";
    private int bufSize = 1024;
    
    /** Creates a new instance of VerifyHandler */
    public VerifyHandler() {
    }
    
    /** Creates a new instance of VerifyHandler */
    public VerifyHandler(String dataName, String publicKeyName, String signatureName) {
        this.setDataName(dataName);
        this.setPublicKeyName(publicKeyName);
        this.setSignatureName(signatureName);
    }
    
    public boolean verifySignature() {
        try {
            // ladda nyckeln
            FileInputStream keyfis = new FileInputStream(getPublicKeyName());
            ObjectInputStream key = new ObjectInputStream(keyfis);
            PublicKey pk = (PublicKey) key.readObject();
            key.close();
            key.close();
            
            // ladda signatur
            FileInputStream sigfis = new FileInputStream(getSignatureName());
            byte[] signature = new byte[1024];
            int length = sigfis.read(signature);
            // verifiera signatur
            Signature s = Signature.getInstance(getSignatureAlgorithm());
            s.initVerify(pk);
            FileInputStream input = new FileInputStream(getDataName());
            byte[] buf = new byte[getBufSize()];
            int count = 0;
            while((count = input.read(buf, 0, getBufSize())) != -1) {
                s.update(buf, 0, count);
            }
            input.close();
            return s.verify(signature, 0, length);
        } catch(Exception e) {
            e.printStackTrace();
        }
        return false;
    }
    
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        if(args.length != 3) {
            System.err.println("SignHandler måste anropas med tre argument, <data> <publicKey> <signature>.");
            System.exit(1);
        }
        VerifyHandler vh = new VerifyHandler(args[0], args[1], args[2]);
        if(vh.verifySignature()) {
            System.out.println(args[0] + " kunde verifieras");
        } else {
            System.out.println(args[0] + " kunde INTE verifieras");
        }
    }

    public String getDataName() {
        return dataName;
    }

    public void setDataName(String dataName) {
        this.dataName = dataName;
    }

    public String getPublicKeyName() {
        return publicKeyName;
    }

    public void setPublicKeyName(String publicKeyName) {
        this.publicKeyName = publicKeyName;
    }

    public String getSignatureName() {
        return signatureName;
    }

    public void setSignatureName(String signatureName) {
        this.signatureName = signatureName;
    }

    public String getSignatureAlgorithm() {
        return signatureAlgorithm;
    }

    public void setSignatureAlgorithm(String signatureAlgorithm) {
        this.signatureAlgorithm = signatureAlgorithm;
    }

    public int getBufSize() {
        return bufSize;
    }

    public void setBufSize(int bufSize) {
        this.bufSize = bufSize;
    }
}