digitalsignature2example.java

用java实现的数字签名的例子

package cn.cncrypt.test;

/**
 *DigitalSignature2Example.java
 *Copyright 2005-2-16
 */
import java.security.Signature;
import java.security.KeyPairGenerator;
import java.security.KeyPair;
import java.security.SignatureException;

/**
 * 数字签名，使用RSA私钥对对消息摘要签名，然后使用公鈅验证 测试
 */
public class DigitalSignature2Example {
	public static void main(String[] args) throws Exception {
		if (args.length != 1) {
			System.err.println("Usage:java DigitalSignature2Example ");
			System.exit(1);
		}
		byte[] plainText = args[0].getBytes("UTF8");
		// 形成RSA公钥对
		System.out.println(" Start generating RSA key");
		KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
		keyGen.initialize(1024);
		KeyPair key = keyGen.generateKeyPair();
		System.out.println("Finish generating RSA key");
		// 使用私鈅签名
		Signature sig = Signature.getInstance("SHA1WithRSA");
		sig.initSign(key.getPrivate());
		sig.update(plainText);
		byte[] signature = sig.sign();
		System.out.println(sig.getProvider().getInfo());
		System.out.println(" Signature:");
		System.out.println(new String(signature, "UTF8"));
		// 使用公鈅验证
		System.out.println(" Start signature verification");
		
		Signature sig1 = Signature.getInstance("SHA1WithRSA");
		sig1.initVerify(key.getPublic());
		sig1.update(plainText);
		try {
			if (sig1.verify(signature)) {
				System.out.println("Signature verified");
			} else
				System.out.println("Signature failed");
		} catch (SignatureException e) {
			System.out.println("Signature failed");
		}
	}
}