信息加密之非对称加密算法RSA

9/6/2015来源:Java教程人气:1454

信息加密之非对称加密算法RSA

  前面为大家已经总结了,基于密钥交换的DH算法,现在就为大家再介绍一种基于因子分解的RSA算法,这种加密算法有两种实现形式:1、公钥加密,私钥解密;2、私钥加密,公钥解密。下面就为大家分析一下实现代码,相对于DH算法,RSA显得有些简单。初始化密钥:

KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("RSA");            keyPairGenerator.initialize(512);            KeyPair keyPair = keyPairGenerator.generateKeyPair();            RSAPRivateKey rsaprivateKey = (RSAPrivateKey)keyPair.getPrivate();//私有密钥            RSAPublicKey rsapublicKey = (RSAPublicKey)keyPair.getPublic();//公有密钥            System.out.println("privateKey : "+Base64.encodeBase64String(rsaprivateKey.getEncoded()));            System.out.println("publicKey : "+Base64.encodeBase64String(rsapublicKey.getEncoded()));

1、私钥加密,公钥解密:

//私钥加密,公钥解密--加密            PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaprivateKey.getEncoded());            KeyFactory privateKeyFactory = KeyFactory.getInstance("RSA");            PrivateKey privateKey = privateKeyFactory.generatePrivate(pkcs8EncodedKeySpec);            Cipher privateCipher = Cipher.getInstance("RSA");            privateCipher.init(Cipher.ENCRYPT_MODE, privateKey);            byte[] result = privateCipher.doFinal(src.getBytes());            System.out.println("私钥加密,公钥解密--加密:"+Base64.encodeBase64String(result));                        //私钥加密,公钥解密--解密            X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsapublicKey.getEncoded());            KeyFactory publicKeyFactory = KeyFactory.getInstance("RSA");            PublicKey publicKey = publicKeyFactory.generatePublic(x509EncodedKeySpec);            Cipher publicCipher = Cipher.getInstance("RSA");            publicCipher.init(Cipher.DECRYPT_MODE, publicKey);            result = publicCipher.doFinal(result);            System.out.println("私钥加密,公钥解密--解密:"+new String(result));

2、公钥加密,私钥解密:

//公钥加密,私钥解密---加密            x509EncodedKeySpec = new X509EncodedKeySpec(rsapublicKey.getEncoded());            publicKeyFactory = KeyFactory.getInstance("RSA");            publicKey = publicKeyFactory.generatePublic(x509EncodedKeySpec);            publicCipher = Cipher.getInstance("RSA");            publicCipher.init(Cipher.ENCRYPT_MODE, publicKey);            result = publicCipher.doFinal(src.getBytes());            System.out.println("公钥加密,私钥解密---加密:"+Base64.encodeBase64String(result));                        //公钥加密,私钥解密---解密            pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaprivateKey.getEncoded());            privateKeyFactory = KeyFactory.getInstance("RSA");            privateKey = privateKeyFactory.generatePrivate(pkcs8EncodedKeySpec);            privateCipher = Cipher.getInstance("RSA");            privateCipher.init(Cipher.DECRYPT_MODE, privateKey);            result = privateCipher.doFinal(result);            System.out.println("公钥加密,私钥解密---解密:"+new String(result));

  根据输出的结果不难发现,公钥和私钥并不一致,私钥的长度要大于公钥。

  到今天对于信息的加密算法:Base64、对称加密算法、消息摘要加密算法、非对称加密算法就全部总结完毕。