java RSA公钥加密,私钥解密算法例子
RSA算法原理http://www.ruanyifeng.com/blog/2013/06/rsa_algorithm_part_one.html
"非对称加密算法"。
(1)乙方生成两把密钥(公钥和私钥)。公钥是公开的,任何人都可以获得,私钥则是保密的。
(2)甲方获取乙方的公钥,然后用它对信息加密。
(3)乙方得到加密后的信息,用私钥解密。
如果公钥加密的信息只有私钥解得开,那么只要私钥不泄漏,通信就是安全的。公钥用于加密,私钥用于解密.
原文:http://my.oschina.net/u/2284972/blog/525301
RSA是一种非对称加密算法,一般很难破解,因此一些要求比较高的系统通常会采用rsa加密算法,一般来说用RSA加密有如下几个步骤.
1.生成公钥与私钥
2.用公钥对需要加密的字符串等进行加密
3.在需要解密的地方,用私钥进行解密
下面对上面的几个部分贴出代码.
1.生成公钥与私钥
package com.rsa; import java.io.FileOutputStream; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.SecureRandom; import java.util.Date; 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(); } }
2.读取公钥方法
package com.rsa; 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; 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); } }
3.读取私钥方法
package com.rsa; 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; 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 { PrivateKeyReader.get("d:/privateKeyFile"); } }
4.测试公钥加密,私钥解密
package com.rsa; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import javax.crypto.Cipher; public class TestEncryptAndDecrypt { public static void main(String[] args) throws Exception { String input = "thisIsMyPassword$7788"; Cipher cipher = Cipher.getInstance("RSA"); RSAPublicKey pubKey = (RSAPublicKey) PublicKeyReader.get("d:/publicKeyFile"); RSAPrivateKey privKey = (RSAPrivateKey) PrivateKeyReader.get("d:/privateKeyFile"); cipher.init(Cipher.ENCRYPT_MODE, pubKey); byte[] cipherText = cipher.doFinal(input.getBytes()); //加密后的东西 System.out.println("cipher: " + new String(cipherText)); //开始解密 cipher.init(Cipher.DECRYPT_MODE, privKey); byte[] plainText = cipher.doFinal(cipherText); System.out.println("plain : " + new String(plainText)); } }
查看结果:
程序代码程序代码
cipher:J���
�nE��J�b9��CO��I�?�g[B{�w��u0����}�r6
�Q��Xa��ٝ�͊��N}n�]�@��_9!D��_�|k�ͪ&g�^��ɿ�XTa$�7��*�{7�R���v�S
plain:thisIsMyPassword$7788
说明加密解密成功。
备注,这里记录的只是测试方法,当然在实际使用过程中,可能还需要对加密后的byte[]采用base64编码,转换成字符串存储起来,在解密的时候,先通过base64还原成byte,然后在解密,这样会更好。详细的方法,
可以参考这篇文章:http://www.yihaomen.com/article/java/376.htm