RSA非对称加密，公钥加密/私钥解密

非对称加密

package test;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.security.KeyStore;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.cert.CertificateException;
import java.security.cert.CertificateFactory;
import java.security.cert.X509Certificate;
import java.util.Base64;
import java.util.Enumeration;
import javax.crypto.Cipher;

/**
 * 公钥加密，私钥解密
 * @author jinzhm
 *
 */
public class RsaUtil {
    public final static String CIPHER_ALGORITHM = "RSA/ECB/PKCS1Padding";
    public final static String CHARSET_ENCODING = "UTF-8";
    
    /**
     * 加密
     * @param publicKeyPath
     * @param plainText
     * @return
     */
    private static byte[] encrypt(String publicKeyPath, String plainText) {
        if(publicKeyPath==null || plainText==null){
            return null;
        }
        try {
            PublicKey key = readPublic(publicKeyPath);
            Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
            cipher.init(Cipher.ENCRYPT_MODE, key);
            return cipher.doFinal(plainText.getBytes(CHARSET_ENCODING));
        } catch (Exception e) {
            e.printStackTrace();
            return null;
        }
    }
    
    /**
     * 解密
     * @param privateKeyPath
     * @param privateKeyPwd
     * @param encryptedText
     * @return
     */
    private static String decrypt(String privateKeyPath, String privateKeyPwd, String encryptedText) {
        if(privateKeyPath==null || privateKeyPwd==null || encryptedText==null){
            return null;
        }
        try {
            PrivateKey key = readPrivate(privateKeyPath, privateKeyPwd);
            Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
            cipher.init(Cipher.DECRYPT_MODE, key);
            return new String(cipher.doFinal(Base64.getDecoder().decode(encryptedText)));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }
    
    /**
     * 读取公钥
     * @param publicKeyPath
     * @return
     */
    private static PublicKey readPublic(String publicKeyPath){
        if(publicKeyPath==null){
            return null;
        }
        PublicKey pk = null;
        FileInputStream bais = null;
        try {
            CertificateFactory certificatefactory = CertificateFactory.getInstance("X.509");
            bais = new FileInputStream(publicKeyPath);
            X509Certificate cert = (X509Certificate)certificatefactory.generateCertificate(bais);
            pk = cert.getPublicKey();
        } catch (CertificateException e) {
            e.printStackTrace();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } finally{
            if(bais != null){
                try {
                    bais.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return pk;
    }
    
    /**
     * 读取私钥
     * @param path
     * @return
     */
    private static PrivateKey readPrivate(String privateKeyPath, String privateKeyPwd){
        if(privateKeyPath==null || privateKeyPwd==null){
            return null;
        }
        InputStream stream = null;
        try {
            // 获取JKS 服务器私有证书的私钥，取得标准的JKS的 KeyStore实例
            KeyStore store = KeyStore.getInstance("JKS");
            stream = new FileInputStream(new File(privateKeyPath));
            // jks文件密码，根据实际情况修改
            store.load(stream, privateKeyPwd.toCharArray());
            // 获取jks证书别名
            Enumeration en = store.aliases();
            String pName = null;
            while (en.hasMoreElements()) {
                String n = (String) en.nextElement();
                if (store.isKeyEntry(n)) {
                    pName = n;
                }
            }
            // 获取证书的私钥
            PrivateKey key = (PrivateKey) store.getKey(pName,
                    privateKeyPwd.toCharArray());
            return key;
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            if(stream != null){
                try {
                    stream.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        }
        return null;
    }
}