RSA加解密代碼示例

import javax.crypto.Cipher;
import java.security.*;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.HashMap;
import java.util.Map;

public class RSAEncrypt {
    //用於封裝隨機產生的公鑰與私鑰
    private static Map<Integer, String> keyMap = new HashMap<Integer, String>();
    public static void main(String[] args) throws Exception {
        /**
         * 在程序中，我們首先利用genKeyPair()函數生成公鑰和私鑰並將其保存到Map集合中。
         * 然后，基於產生的公鑰對明文進行加密。
         * 針對已經已經加密的密文，我們再次使用私鑰解密，得到明文
         * */
        //生成公鑰和私鑰
        genKeyPair();

        //獲取當前系統時間
        long start = System.currentTimeMillis();
        int counts = 100000;
        for (int i = 0; i < counts; i++) {
            //加密字符串
            String message = "張三123zhangsan";
            System.out.println("隨機生成的公鑰為:" + keyMap.get(0) + "\n" + "公鑰長度:" + keyMap.get(0).length());
            System.out.println("隨機生成的私鑰為:" + keyMap.get(1) + "\n" + "私鑰長度:" + keyMap.get(1).length());
            String messageEn = encrypt(message,keyMap.get(0));
            System.out.println(message + "\t加密后的字符串為:" + messageEn + "\n" + "加密后的字符串長度：" + messageEn.length());
            String messageDe = decrypt(messageEn,keyMap.get(1));
            System.out.println("還原后的字符串為:" + messageDe);
        }
        long end = System.currentTimeMillis();
        System.out.println("10萬條數據平均耗時:" + (end - start) / counts + "ms。");
        System.out.println("10萬條數據總共耗時:" + (end - start) + "ms。");
    }

    /**
     * 隨機生成密鑰對
     * @throws NoSuchAlgorithmException
     */
    public static void genKeyPair() throws NoSuchAlgorithmException {
        // KeyPairGenerator類用於生成公鑰和私鑰對，基於RSA算法生成對象
        KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA");
        // 初始化密鑰對生成器，密鑰大小為96-1024位
        keyPairGen.initialize(1024,new SecureRandom());
        // 生成一個密鑰對，保存在keyPair中
        KeyPair keyPair = keyPairGen.generateKeyPair();
        RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate();   // 得到私鑰
        RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic();  // 得到公鑰
        String publicKeyString = new String(Base64.encodeBase64(publicKey.getEncoded()));
        // 得到私鑰字符串
        String privateKeyString = new String(Base64.encodeBase64((privateKey.getEncoded())));
        // 將公鑰和私鑰保存到Map
        keyMap.put(0,publicKeyString);  //0表示公鑰
        keyMap.put(1,privateKeyString);  //1表示私鑰
    }
    /**
     * RSA公鑰加密
     *
     * @param str
     *            加密字符串
     * @param publicKey
     *            公鑰
     * @return 密文
     * @throws Exception
     *             加密過程中的異常信息
     */
    public static String encrypt( String str, String publicKey ) throws Exception{
        //base64編碼的公鑰
        byte[] decoded = Base64.decodeBase64(publicKey);
        RSAPublicKey pubKey = (RSAPublicKey) KeyFactory.getInstance("RSA").generatePublic(new X509EncodedKeySpec(decoded));
        //RSA加密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.ENCRYPT_MODE, pubKey);
        String outStr = Base64.encodeBase64String(cipher.doFinal(str.getBytes("UTF-8")));
        return outStr;
    }

    /**
     * RSA私鑰解密
     *
     * @param str
     *            加密字符串
     * @param privateKey
     *            私鑰
     * @return 銘文
     * @throws Exception
     *             解密過程中的異常信息
     */
    public static String decrypt(String str, String privateKey) throws Exception{
        //64位解碼加密后的字符串
        byte[] inputByte = Base64.decodeBase64(str.getBytes("UTF-8"));
        //base64編碼的私鑰
        byte[] decoded = Base64.decodeBase64(privateKey);
        RSAPrivateKey priKey = (RSAPrivateKey) KeyFactory.getInstance("RSA").generatePrivate(new PKCS8EncodedKeySpec(decoded));
        //RSA解密
        Cipher cipher = Cipher.getInstance("RSA");
        cipher.init(Cipher.DECRYPT_MODE, priKey);
        String outStr = new String(cipher.doFinal(inputByte));
        return outStr;
    }
}