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java实现非对称加密算法的过程

发布时间:2021-05-14 发布时间:
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  1. 什么是对称式加密和非对称式加密

  对称式加密:解密方式是加密方式的逆运算,即加密和解密使用的是同一个密钥(初等加密算法)。

  非对称式加密:加密和解密需要两个密钥进行,这两个密钥是公钥和私钥(高等加密算法)。

  2. 对称式加密和非对称式加密的主要实现方式

  对称式加密主要实现方式:

  1) DES(Data Encryption Standard):安全性较差,一般不建议使用。

  2) 3DES:三重DES,针对DES密钥长度较短的问题,3DES可以实现最少112位、最高168位密钥长度。

  3) AES:相比于3DES拥有更好的安全性。

  4) PBE(Password Based Encryption):基于口令的加密,结合了DES和AES的优点。

  非对称式加密主要实现方式:

  1) DH(Diffie-Hellman):密钥交换算法。

  2) RSA:基于因子分解。

  3) ElGamal:基于离散对数。

  4) ECC(Elliptical Curve Cryptography):椭圆曲线加密。

  3. 对称式加密在JAVA中的实现(PBE加密):

  [java] view plain copypublic class PBE {

  private static String src=“security with PBE”;

  public static void main(String[] args){

  jdkPBE();

  }

  public static void jdkPBE(){

  try {

  //初始化盐(扰码)

  SecureRandom random=new SecureRandom();

  byte[] salt=random.generateSeed(8);

  //口令与密钥

  String password=“CSDN”;

  PBEKeySpec pbeKeySpec=new PBEKeySpec(password.toCharArray());

  SecretKeyFactory factory=SecretKeyFactory.getInstance(“PBEWITHMD5andEDS”);

  Key key=factory.generateSecret(pbeKeySpec);

  //加密

  PBEParameterSpec pbeParameterSpec=new PBEParameterSpec(salt,100);//参数1.盐,参数2.迭代次数

  Cipher cipher=Cipher.getInstance(“PBEWITHMD5andEDS”);

  cipher.init(Cipher.ENCRYPT_MODE,key,pbeParameterSpec);

  byte[] result=cipher.doFinal(src.getBytes());

  System.out.println(“jdk pbe encrypt:” + Base64.encodeToString(result,1));

  //解密

  cipher.init(Cipher.DECRYPT_MODE,key,pbeParameterSpec);

  result=cipher.doFinal(result);

  System.out.println(“jdk pbe decrypt:”+new String(result));

  } catch (Exception e) {

  e.printStackTrace();

  }

  }

  }

  4. 非对称式加密在JAVA中的实现(DH加密):

  [java] view plain copypublic class DH {

  private static String src=“security with DH”;

  public static void main(String[] args){

  jdkDH();

  }

  public static void jdkDH(){

  try {

  //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();

  //初始化接收方密钥

  KeyFactory receiverKeyFactory=KeyFactory.getInstance(“DH”);

  X509EncodedKeySpec x509EncodedKeySpec=new X509EncodedKeySpec(senderPublicKeyEnc);

  PublicKey receiverPublicKey=receiverKeyFactory.generatePublic(x509EncodedKeySpec);

  DHParameterSpec dhParameterSpec=((DHPublicKey)receiverPublicKey).getParams();

  KeyPairGenerator receiverKeyPairGenerator=KeyPairGenerator.getInstance(“DH”);

  receiverKeyPairGenerator.initialize(dhParameterSpec);

  KeyPair receiverKeyPair=receiverKeyPairGenerator.generateKeyPair();

  PrivateKey receiverPrivateKey=receiverKeyPair.getPrivate();

  byte[] receiverPublicKeyEnc =receiverKeyPair.getPublic().getEncoded();

  //密钥构建

  KeyAgreement receiverKeyAgreement = KeyAgreement.getInstance(“DH”);

  receiverKeyAgreement.init(receiverPrivateKey);

  receiverKeyAgreement.doPhase(receiverPublicKey, true);

  SecretKey receiverDesKey=receiverKeyAgreement.generateSecret(“DES”);

  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.encodeToString(result,1));

  //解密

  cipher=Cipher.getInstance(“DES”);

  cipher.init(Cipher.DECRYPT_MODE,receiverDesKey);

  result=cipher.doFinal(result);

  System.out.println(“jdk dh encrypt:”+new String(result));

  } catch (Exception e) {

  e.printStackTrace();

  }

  }

  }

  

  5. 非对称式加密在JAVA中的实现(RSA加密):

  [java] view plain copypublic class RSA {

  private static String src=“security with rsa”;

  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);//64的整倍数,512~65536

  KeyPair keyPair=keyPairGenerator.generateKeyPair();

  RSAPrivateKey rsaPrivateKey= (RSAPrivateKey) keyPair.getPrivate();

  RSAPublicKey rsaPublicKey= (RSAPublicKey) keyPair.getPublic();

  System.out.println(“Public key:”+ Base64.encodeToString(rsaPrivateKey.getEncoded(),1));

  System.out.println(“Private key:”+ Base64.encodeToString(rsaPrivateKey.getEncoded(),1));

  //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.encodeToString(result,1));

  //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(new String(result));

  //公钥加密,私钥解密——加密

  x509EncodedKeySpec=new X509EncodedKeySpec(rsaPublicKey.getEncoded());

  keyFactory=KeyFactory.getInstance(“RSA”);

  publicKey=keyFactory.generatePublic(x509EncodedKeySpec);

  cipher=Cipher.getInstance(“RSA”);

  cipher.init(Cipher.ENCRYPT_MODE,publicKey);

  result=cipher.doFinal(src.getBytes());

  System.out.println(“钥加密,私钥解密——加密:”+Base64.encodeToString(result,1));

  //公钥加密,私钥解密——解密

  pkcs8EncodedKeySpec=new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());

  keyFactory=KeyFactory.getInstance(“RSA”);

  privateKey=keyFactory.generatePrivate(pkcs8EncodedKeySpec);

  cipher=Cipher.getInstance(“RSA”);

  cipher.init(Cipher.DECRYPT_MODE,privateKey);

  cipher.doFinal(result);

  System.out.println(“公钥加密,私钥解密——解密:” + Base64.encodeToString(result, 1));

  } catch (Exception e) {

  e.printStackTrace();

  }

  }

  }

  

  6、RSA非对称加密算法

  唯一广泛接受并实现

  数据加密&数字签名

  既可公钥加密,私钥解密

  又可私钥加密,公钥解密

  

  代码实现

  try {

  //初始化秘钥

  KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance(“RSA”);

  keyPairGenerator.initialize(512);

  KeyPair keyPair = keyPairGenerator.generateKeyPair();

  RSAPublicKey rsaPublicKey = (RSAPublicKey)keyPair.getPublic();

  RSAPrivateKey rsaPrivateKey = (RSAPrivateKey)keyPair.getPrivate();

  //私钥加密,公钥解密--加密

  PKCS8EncodedKeySpec pkcs8EncodedKeySpec = new PKCS8EncodedKeySpec(rsaPrivateKey.getEncoded());

  KeyFactory factory = KeyFactory.getInstance(“RSA”);

  PrivateKey privateKey = factory.generatePrivate(pkcs8EncodedKeySpec);

  Cipher cipher = Cipher.getInstance(“RSA”);

  cipher.init(Cipher.ENCRYPT_MODE, privateKey);

  byte[] result = cipher.doFinal(str.getBytes());

  System.out.println(“私加公解 rsa en:”+Base64.toBase64String(result));

  //私钥加密,公钥解密--解密

  X509EncodedKeySpec x509EncodedKeySpec = new X509EncodedKeySpec(rsaPublicKey.getEncoded());

  factory = KeyFactory.getInstance(“RSA”);

  PublicKey publicKey = factory.generatePublic(x509EncodedKeySpec);

  cipher = Cipher.getInstance(“RSA”);

  cipher.init(Cipher.DECRYPT_MODE, publicKey);

  byte[] raw = cipher.doFinal(result);

  System.out.println(“私加公解 rsa de:”+ new String(raw));

  //公钥加密,私钥解密--加密

  cipher.init(Cipher.ENCRYPT_MODE, publicKey);

  byte[] result2 = cipher.doFinal(str.getBytes());

  System.out.println(“公加私解 rsa en:”+Base64.toBase64String(result2));

  //公钥加密,私钥解密--解密

  cipher.init(Cipher.DECRYPT_MODE, privateKey);

  byte[] raw2 = cipher.doFinal(result2);

  System.out.println(“公加私解 rsa de:” + new String (raw2));

  } catch (Exception e) {

  // TODO Auto-generated catch block

  e.printStackTrace();

  }


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