package de.bablokb.crypto;

import java.io.*;
import java.security.*;
import sun.misc.*;
import org.gnu.readline.*;

public class SignAndVerify {
    
    private static final int BUF_SIZE = 8192;
    
    private String iAlgo = "DSA";
    private String iFile = null;
    private boolean iSign;
    private Signature iSig = null;
    
    private void updateSignature() throws Exception {
	FileInputStream stream = new FileInputStream(iFile);
	byte[] sbuf = new byte[BUF_SIZE];
	int length;
	while ((length=stream.read(sbuf)) != -1)
	    iSig.update(sbuf,0,length);
	stream.close();
    }
    
    private void getSignature() throws Exception {
	iSig = Signature.getInstance(iAlgo);
	KeyStore ks = KeyStore.getInstance("JKS");
	String ksName  = Readline.readline("Keystore file: ");
	String ksPass  = Readline.readline("Keystore passphrase: ");
	ks.load(new FileInputStream(ksName.trim()),ksPass.toCharArray());
	
	if (iSign) {
	    String alias   = Readline.readline("Key alias: ");
	    String keyPass = Readline.readline("Key passphrase: ");
	    iSig.initSign((PrivateKey) ks.getKey(alias,keyPass.toCharArray()));
	} else {
	    String alias   = Readline.readline("Certificate alias: ");
	    iSig.initVerify(ks.getCertificate(alias).getPublicKey());
	}
    }
    
    private void printSignature() throws Exception {
	BASE64Encoder enc = new BASE64Encoder();
	String out = enc.encode(iSig.sign());
	System.err.println("Signature ("+iAlgo+"):");
	System.out.println(out);
	FileOutputStream stream = new FileOutputStream(iFile+"."+iAlgo);
	PrintWriter writer = new PrintWriter(stream); 
	writer.print(out);
	writer.flush();
	stream.close();
    }
    
    private boolean checkSignature() throws Exception {
	String filename = Readline.readline("Signature file: ");
	FileInputStream stream = new FileInputStream(filename.trim());
	byte[] data64 = new byte[stream.available()];
	BufferedInputStream bis = new BufferedInputStream(stream);
	bis.read(data64,0,data64.length);
	stream.close();
	BASE64Decoder decoder = new BASE64Decoder();
	byte[] data = decoder.decodeBuffer(new String(data64));
	return iSig.verify(data);
    }
}