非对称加密DH/RSA/ElGamal

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BouncyCastle简称 BC 是第三方包，需下载
DH

public class DHTest {    private static String src="dddd顶顶顶";    public static void main(String[] args) {        jdkDH();    }    public static void jdkDH(){        try{            //note:需要对方的公钥解密，对方发送过来的加密数据            //初始化发送方密钥            KeyPairGenerator senderKeyPairGenerator=KeyPairGenerator.getInstance("DH");            senderKeyPairGenerator.initialize(512);            KeyPair senderKeyPair=senderKeyPairGenerator.generateKeyPair();            byte[] senderPublicKeyEnc=senderKeyPair.getPublic().getEncoded();//发送方公钥，需要发送给接受方（网络，文件....）            //使用发送方公钥，初始化接受方密钥            KeyFactory receiverKeyFactory=KeyFactory.getInstance("DH");            X509EncodedKeySpec x509EncodedKeySpec=new X509EncodedKeySpec(senderPublicKeyEnc);            DHPublicKey receiverPublicKey=(DHPublicKey)receiverKeyFactory.generatePublic(x509EncodedKeySpec);            DHParameterSpec dhParameterSpec=receiverPublicKey.getParams();            KeyPairGenerator receiverKeyPairGenerator=KeyPairGenerator.getInstance("DH");            receiverKeyPairGenerator.initialize(dhParameterSpec);            KeyPair receiverKeyPair=receiverKeyPairGenerator.generateKeyPair();            PrivateKey receiverPrivateKey=receiverKeyPair.getPrivate();            byte[] receiverPublicKeyEnc=receiverKeyPair.getPublic().getEncoded();//接受方公钥，需要发送给发送方（网络，文件....）            //密钥构建            //构建接受方的加解密密钥，            KeyAgreement receiverKeyAgreement=KeyAgreement.getInstance("DH");            receiverKeyAgreement.init(receiverPrivateKey);            receiverKeyAgreement.doPhase(receiverPublicKey,true);            SecretKey receiverDESKey=receiverKeyAgreement.generateSecret("DES");            //构建发送方的加解密密钥            KeyFactory senderKeyFactory=KeyFactory.getInstance("DH");            x509EncodedKeySpec=new X509EncodedKeySpec(receiverPublicKeyEnc);            PublicKey senderPublicKey=senderKeyFactory.generatePublic(x509EncodedKeySpec);            KeyAgreement senderKeyAgreement=KeyAgreement.getInstance("DH");            senderKeyAgreement.init(senderKeyPair.getPrivate());            senderKeyAgreement.doPhase(senderPublicKey,true);            SecretKey senderDESKey=senderKeyAgreement.generateSecret("DES");            if(Objects.equals(receiverDESKey,senderDESKey))                System.out.println("双方密钥相同");            //加密            Cipher cipher=Cipher.getInstance("DES");            cipher.init(Cipher.ENCRYPT_MODE,senderDESKey);            byte[] result=cipher.doFinal(src.getBytes());            System.out.println("jdk DH encrypt: "+ Base64.encodeBase64String(result));            //解密            cipher.init(Cipher.DECRYPT_MODE,receiverDESKey);            result=cipher.doFinal(result);            System.out.println("jdk DH decrypt: "+new String(result));        }catch (Exception e){            e.printStackTrace();        }    }}

RSA

public class RSATest {    private static String src="dddddd ddd  订单";    public static void main(String[] args) {        jdkRSA();    }    public static void jdkRSA(){        try {            //初始化密钥            KeyPairGenerator keyPairGenerator=KeyPairGenerator.getInstance("RSA");            keyPairGenerator.initialize(512);            KeyPair keyPair=keyPairGenerator.generateKeyPair();            RSAPublicKey rsaPublicKey=(RSAPublicKey)keyPair.getPublic();            RSAPrivateKey rsaPrivateKey=(RSAPrivateKey)keyPair.getPrivate();            System.out.println("Public Key: "+ Base64.encodeBase64String(rsaPublicKey.getEncoded()));            System.out.println("Private Key: "+ Base64.encodeBase64String(rsaPrivateKey.getEncoded()));            //私钥加密，公钥解密--加密            PKCS8EncodedKeySpec pkcs8EncodedKeySpec=new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());            KeyFactory keyFactory=KeyFactory.getInstance("RSA");            PrivateKey privateKey=keyFactory.generatePrivate(pkcs8EncodedKeySpec);            Cipher cipher=Cipher.getInstance("RSA");            cipher.init(Cipher.ENCRYPT_MODE,privateKey);            byte[] result=cipher.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=KeyFactory.getInstance("RSA");            PublicKey publicKey=keyFactory.generatePublic(x509EncodedKeySpec);            cipher=Cipher.getInstance("RSA");            cipher.init(Cipher.DECRYPT_MODE,publicKey);            result=cipher.doFinal(result);            System.out.println("私钥加密，公钥解密--解密 :"+new String(result));            //公钥加密，私钥解密--加密            //公钥加密，私钥解密--解密        } catch (Exception e) {            e.printStackTrace();        }    }    public static void bcRSA(){        //重新设置Security.addProvider(new BouncyCastleProvider());        //剩下的基本一致；所有的 getInstance()指定provider    }}

ElGamal

public class ElGamalTest {    public static void main(String[] args) {        bcElGamal();    }    /*    只有 Bouncy Castle 提供,仅支持公钥加密，私钥解密    PKCS8EncodedKeySpec（私钥） X509EncodedKeySpec（公钥）  将密钥的字节数组转成密钥对象     */    public static void bcElGamal(){        try {            Security.addProvider(new BouncyCastleProvider());            //初始化密钥            AlgorithmParameterGenerator algorithmParameterGenerator=AlgorithmParameterGenerator.getInstance("ElGamal");            algorithmParameterGenerator.init(256);            AlgorithmParameters algorithmParameters=algorithmParameterGenerator.generateParameters();            DHParameterSpec dhParameterSpec=algorithmParameters.getParameterSpec(DHParameterSpec.class);            KeyPairGenerator keyPairGenerator=KeyPairGenerator.getInstance("ElGamal");            keyPairGenerator.initialize(dhParameterSpec,new SecureRandom());            KeyPair keyPair=keyPairGenerator.generateKeyPair();            PublicKey elGamalPublicKey=keyPair.getPublic();            PrivateKey elGamalPrivateKey=keyPair.getPrivate();            System.out.println("Public Key: "+ Base64.encodeBase64String(elGamalPublicKey.getEncoded()));            System.out.println("Private Key: "+ Base64.encodeBase64String(elGamalPrivateKey.getEncoded()));            //转换密钥，公钥加密            X509EncodedKeySpec x509EncodedKeySpec=new X509EncodedKeySpec(elGamalPublicKey.getEncoded());            KeyFactory keyFactory=KeyFactory.getInstance("ElGamal");            elGamalPublicKey=keyFactory.generatePublic(x509EncodedKeySpec);            Cipher cipher=Cipher.getInstance("ElGamal");            cipher.init(Cipher.ENCRYPT_MODE,elGamalPublicKey);            byte[] result=cipher.doFinal("是了解对方拉".getBytes());            System.out.println("加密:"+Base64.encodeBase64String(result));            //私钥解密            PKCS8EncodedKeySpec pkcs8EncodedKeySpec=new PKCS8EncodedKeySpec(elGamalPrivateKey.getEncoded());            keyFactory=KeyFactory.getInstance("ElGamal");            elGamalPrivateKey=keyFactory.generatePrivate(pkcs8EncodedKeySpec);            cipher.init(Cipher.DECRYPT_MODE,elGamalPrivateKey);            result=cipher.doFinal(result);            System.out.println("解密："+new String(result));        } catch (Exception e) {            e.printStackTrace();        }    }}

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