非对称加密--RSA

package test.util;

import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.util.HashMap;
import java.util.Map;

import javax.crypto.Cipher;

public class RSAUtil {
public static final String PUBLIC_KEY = "RSAPublicKey";
public static final String PRIVATE_KEY = "RSAPrivateKey";

/*
* 生成 RSA 的 公钥 和 私钥
*/
public static Map<String, Object> initKey() throws Exception{
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");
keyPairGenerator.initialize(1024); // 512-65536 & 64的倍数
KeyPair keyPair = keyPairGenerator.generateKeyPair();
RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();
RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();
Map<String, Object> keyMap = new HashMap<String, Object>();
keyMap.put(PUBLIC_KEY, publicKey);
keyMap.put(PRIVATE_KEY, privateKey);
return keyMap;
}

public static RSAPublicKey getPublicKey(Map<String, Object> keyMap){
RSAPublicKey publicKey = (RSAPublicKey) keyMap.get(PUBLIC_KEY);
return publicKey;
}
public static RSAPrivateKey getPrivateKey(Map<String, Object> keyMap){
RSAPrivateKey privateKey = (RSAPrivateKey) keyMap.get(PRIVATE_KEY);
return privateKey;
}

/*
* 公钥加密
*/
public static byte[] encrypt(byte[] data, RSAPublicKey publicKey) throws Exception{
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.ENCRYPT_MODE, publicKey);
byte[] cipherBytes = cipher.doFinal(data);
return cipherBytes;
}

/*
* 私钥解密
*/
public static byte[] decrypt(byte[] data, RSAPrivateKey privateKey) throws Exception{
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.DECRYPT_MODE, privateKey);
byte[] plainBytes = cipher.doFinal(data);
return plainBytes;
}

}