java 私钥加密解密的例子

package com.rsa.zpl;
import java.io.FileOutputStream; 
import java.security.KeyPair; 
import java.security.KeyPairGenerator; 
import java.security.SecureRandom; 
import java.util.Date;
/**
 * 生成公钥和私钥
 * @author zpl
 *
 */
public class GenKeys {
    public static void main(String[] args) throws Exception {
        KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA"); 
        SecureRandom secureRandom = new SecureRandom(new Date().toString().getBytes());
        keyPairGenerator.initialize(1024, secureRandom);
        KeyPair keyPair = keyPairGenerator.genKeyPair();
        String publicKeyFilename = "D:/publicKeyFile";
        byte[] publicKeyBytes = keyPair.getPublic().getEncoded();
        FileOutputStream fos = new FileOutputStream(publicKeyFilename); 
        fos.write(publicKeyBytes); 
        fos.close();
        String privateKeyFilename = "D:/privateKeyFile"; 
        byte[] privateKeyBytes = keyPair.getPrivate().getEncoded();
        fos = new FileOutputStream(privateKeyFilename); 
        fos.write(privateKeyBytes); 
        fos.close();
    }
}

package com.rsa.zpl;

import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.PKCS8EncodedKeySpec;
/**
 * 获取私钥
 * @author zpl
 *
 */
public class PrivateKeyReader {    
    public static PrivateKey get(String filename)throws Exception {
        File f = new File(filename);
        FileInputStream fis = new FileInputStream(f);
        DataInputStream dis = new DataInputStream(fis);
        byte[] keyBytes = new byte[(int)f.length()];
        dis.readFully(keyBytes);
        dis.close();
        PKCS8EncodedKeySpec spec =new PKCS8EncodedKeySpec(keyBytes);
        KeyFactory kf = KeyFactory.getInstance("RSA");
        return kf.generatePrivate(spec);
      }

    
    public static void main(String[] args) throws Exception, InvalidKeySpecException, IOException {
        System.out.println(PrivateKeyReader.get("d:/privateKeyFile"));
    }
}


package com.rsa.zpl;

import java.io.DataInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.security.PublicKey;
import java.security.spec.X509EncodedKeySpec;
import java.security.KeyFactory;
/**
 * 获取私钥
 * @author zpl
 *
 */
public class PublicKeyReader {    
    public static PublicKey get(String filename) throws Exception {
        File f = new File(filename);
        FileInputStream fis = new FileInputStream(f); 
        DataInputStream dis = new DataInputStream(fis);
        byte[] keyBytes = new byte[(int)f.length()]; 
        dis.readFully(keyBytes); 
        dis.close();
        X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);
        KeyFactory kf = KeyFactory.getInstance("RSA"); 
        return kf.generatePublic(spec);
    }
    public static void main(String[] args) {
    	try {
			System.out.println(get("D:\\publicKeyFile"));
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}


}


package com.rsa.zpl;

import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import javax.crypto.Cipher;
/**
 * 公钥加密，私钥解密
 * @author zpl
 *
 */
public class TestEncryptAndDecrypt {    
    public static void main(String[] args) throws Exception {
    	//测试公钥加密，私钥解密
        String input = "thisIsMyPassword$7788";
        RSAPublicKey pubKey = (RSAPublicKey) PublicKeyReader.get("d:/publicKeyFile");
        
        
        Cipher cipher = Cipher.getInstance("RSA");        
        cipher.init(Cipher.ENCRYPT_MODE, pubKey);
        byte[] cipherText = cipher.doFinal(input.getBytes());
        //加密后的东西
//        System.out.println("cipher: " + new String(cipherText));
        
        Cipher cipher1 = Cipher.getInstance("RSA");  
        RSAPrivateKey privKey = (RSAPrivateKey) PrivateKeyReader.get("d:/privateKeyFile");
        //开始解密
        cipher1.init(Cipher.DECRYPT_MODE, privKey); 
        byte[] plainText = cipher1.doFinal(cipherText);
        System.out.println("plain : " + new String(plainText));
    }

}




package com.rsa.zpl;

import java.io.InputStream;
import java.security.KeyFactory;
import java.security.PublicKey;
import java.security.interfaces.RSAPrivateKey;
import java.security.interfaces.RSAPublicKey;
import java.security.spec.X509EncodedKeySpec;

import javax.crypto.Cipher;

import org.apache.commons.io.IOUtils;
/**
 * 公钥解密，私钥加密
 * @author zpl
 *
 */
public class TestEncryptAndDecrypt {    
    public static void main(String[] args) throws Exception {
    	//加密部分*****************************************************8
        String input = "thisIsMyPassword$zpl";
        //RSAPublicKey pubKey = (RSAPublicKey) PublicKeyReader.get("d:/publicKeyFile");// 这是公钥加密的
        RSAPrivateKey privKey = (RSAPrivateKey) PrivateKeyReader.get("D:/privateKeyFile");// 这是私钥加密的
        Cipher cipher = Cipher.getInstance("RSA");        
        cipher.init(Cipher.ENCRYPT_MODE, privKey);
        byte[] cipherText = cipher.doFinal(input.getBytes());
        //加密后的东西
        System.out.println("******************以上是加密部分cipher: " + new String(cipherText));
        
        
        // 解密部分 *****************************************************
        Cipher cipher1 = Cipher.getInstance("RSA"); 
        RSAPublicKey pubKey = (RSAPublicKey)get(TestEncryptAndDecrypt.class.getResourceAsStream("publicKeyFile"));// 公钥解密
//        RSAPublicKey pubKey = (RSAPublicKey) PublicKeyReader.get("d:/publicKeyFile");// 公钥解密
       // RSAPrivateKey privKey = (RSAPrivateKey) PrivateKeyReader.get("d:/privateKeyFile");//私钥解密用这个
        //开始解密
        cipher1.init(Cipher.DECRYPT_MODE, pubKey); 
        byte[] plainText = cipher1.doFinal(cipherText);
        System.out.println("plain : " + new String(plainText));
    }
    
    public static PublicKey get(InputStream inputStream) throws Exception {
 	byte[] keyBytes = IOUtils.toByteArray(inputStream);
      X509EncodedKeySpec spec = new X509EncodedKeySpec(keyBytes);
      KeyFactory kf = KeyFactory.getInstance("RSA"); 
      return kf.generatePublic(spec);
  }

}

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plain : thisIsMyPassword$zpl

生成这样,说明是正确的