公钥加密也称为非对称加密、速度慢、加密和解密的钥匙不相同，某一个人持有私钥，任何人都可以知道公钥

package com.stone.security;

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.util.Arrays;

import javax.crypto.Cipher;

/**
 * RSA算法 公钥加密 非对称加密
 * @author stone
 * @date 2014-03-11 00:28:38
 */
public class RSA {
	public static final String KEY_ALGORITHM = "RSA";
	public static final String CIPHER_ALGORITHM_ECB1 = "RSA/ECB/PKCS1Padding";
	public static final String CIPHER_ALGORITHM_ECB2 = "RSA/ECB/OAEPWithSHA-1AndMGF1Padding"; //不能用
	public static final String CIPHER_ALGORITHM_ECB3 = "OAEPWithSHA-256AndMGF1Padding";	//不能用
	
	static PublicKey publicKey;
	static PrivateKey privateKey;
	static Cipher cipher;
	static KeyPair keyPair;
	
	public static void main(String[] args) throws Exception {
		method1("斯柯达U*(Sfsad7f()*^%%$");
		method2("斯柯达U*(Sfsad7f()*^%%$");
		method3("斯柯达U*(Sfsad7f()*^%%$");
		
	}
	
	/**
	 * 公钥加密，私钥解密	使用默认CIPHER_ALGORITHM_ECB1
	 * @param str
	 * @throws Exception
	 */
	static void method1(String str) throws Exception {
		KeyPairGenerator keyGenerator = KeyPairGenerator.getInstance(KEY_ALGORITHM);
		KeyPair keyPair = keyGenerator.generateKeyPair();
		publicKey = keyPair.getPublic();
		privateKey = keyPair.getPrivate();
		cipher = Cipher.getInstance(KEY_ALGORITHM);
		cipher.init(Cipher.ENCRYPT_MODE, publicKey); //公钥加密
		byte[] encrypt = cipher.doFinal(str.getBytes());
		System.out.println("公钥加密后1：" + Arrays.toString(encrypt));
		
		cipher.init(Cipher.DECRYPT_MODE, privateKey);//私钥解密
		byte[] decrypt = cipher.doFinal(encrypt);
		System.out.println("私钥解密后1：" + new String(decrypt));
	}
	
	/**
	 * 私钥加密，公钥解密 	使用默认CIPHER_ALGORITHM_ECB1
	 * @param str
	 * @throws Exception
	 */
	static void method2(String str) throws Exception {
		KeyPairGenerator keyGenerator = KeyPairGenerator.getInstance(KEY_ALGORITHM);
		KeyPair keyPair = keyGenerator.generateKeyPair();
		publicKey = keyPair.getPublic();
		privateKey = keyPair.getPrivate();
		cipher = Cipher.getInstance(KEY_ALGORITHM);
		cipher.init(Cipher.ENCRYPT_MODE, privateKey); //私钥加密
		byte[] encrypt = cipher.doFinal(str.getBytes());
		System.out.println("私钥加密后2：" + Arrays.toString(encrypt));
		
		cipher.init(Cipher.DECRYPT_MODE, publicKey);//公钥解密
		byte[] decrypt = cipher.doFinal(encrypt);
		System.out.println("公钥解密后2：" + new String(decrypt));
	}
	
	/**
	 * 私钥加密，公钥解密 	使用CIPHER_ALGORITHM_ECB1 = RSA/ECB/PKCS1Padding
	 * @param str
	 * @throws Exception
	 */
	static void method3(String str) throws Exception {
		KeyPairGenerator keyGenerator = KeyPairGenerator.getInstance(KEY_ALGORITHM);
		KeyPair keyPair = keyGenerator.generateKeyPair();
		publicKey = keyPair.getPublic();
		privateKey = keyPair.getPrivate();
		cipher = Cipher.getInstance(CIPHER_ALGORITHM_ECB1);
		cipher.init(Cipher.ENCRYPT_MODE, privateKey); //私钥加密
		byte[] encrypt = cipher.doFinal(str.getBytes());
		System.out.println("私钥加密后3：" + Arrays.toString(encrypt));
		
		cipher.init(Cipher.DECRYPT_MODE, publicKey);//公钥解密
		byte[] decrypt = cipher.doFinal(encrypt);
		System.out.println("公钥解密后3：" + new String(decrypt));
	}
}