package com.ack.security;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.X509EncodedKeySpec;
import com.ack.security.ByteUtils;
/* Verify a DSA signature */
class VerifySignature {
public static void main( String[] args ) throws Exception {
final String publicKeyFile = "hello.pubkey";
final String signedDataFile = "hello.sig";
final String unsignedDataFile = "hello.txt";
// import the public key
byte[] encKey = com.ack.security.ByteUtils.loadBytesFromFile( publicKeyFile );
// start up the key fatory
System.out.println( "start up the key factory..." );
java.security.KeyFactory keyFactory = java.security.KeyFactory.getInstance( "DSA", "SUN" );
// get hold of the public key
java.security.spec.X509EncodedKeySpec pubKeySpec = new java.security.spec.X509EncodedKeySpec( encKey );
java.security.PublicKey pubKey = keyFactory.generatePublic( pubKeySpec );
System.out.println( "got the public key" );
// load the signed data
byte[] sigToVerify = com.ack.security.ByteUtils.loadBytesFromFile( signedDataFile );
System.out.println( "loaded the signed data..." );
// create a signature object with the supplied public key
java.security.Signature sig = java.security.Signature.getInstance( "SHA1withDSA", "SUN" );
sig.initVerify( pubKey );
System.out.println( "create a signature with supplied public key" );
// load original data into the signature
byte[] buffer = com.ack.security.ByteUtils.loadBytesFromFile( unsignedDataFile );
sig.update( buffer );
System.out.println( "loaded original data into the signature" );
// verify the two signatures
System.out.println( "about to verity signed data with newly created signature" );
boolean verifies = sig.verify( sigToVerify );
System.out.println( "signature verifies: " + verifies );
}
}