Java笔记-DH密钥交换

桃扇骨 2022-09-05 04:20 210阅读 0赞

DH密钥交换主要是两个公式的编写，即：

·公钥计算公式；

·密钥计算公式；

生成随机数作为私钥

截图如下：

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3FxNzg0NDI3NjE_size_16_color_FFFFFF_t_70][]

源码如下：

DH.java

package cn.it1995.tool;
    
    import java.security.MessageDigest;
    import java.security.NoSuchAlgorithmException;
    import java.util.Random;
    
    public class DH {
    
        private static final int dhP = 45;
        private static final  int dhG = 9;
    
        private int mPriKey;
    
        //构造函数随机私钥
        public DH(){
    
            Random r = new Random();
            mPriKey = r.nextInt(20);
            System.out.println("dh priKey is : " + mPriKey);
        }
    
        //公钥计算公式计算出公钥
        public int getPublicKey(){
    
            return (int) (Math.pow(dhG, mPriKey) % dhP);
        }
    
        //使用对方公钥与自己私钥生成密钥
        //在把结果转256字节，AES密钥需要128字节或256字节
        public byte[] getSecretKey(long publicKey){
    
            int buf = (int) (Math.pow(publicKey, mPriKey) % dhP);
            return sha256(buf);
        }
    
        //转换成byte[256]类型，作为AES密钥
        private byte[] sha256(int data){
    
            try {
    
                MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
                messageDigest.update(DataSecret.int2Byte(data));
                return messageDigest.digest();
            }
            catch (NoSuchAlgorithmException e) {
                
                e.printStackTrace();
            }
    
            return new byte[]{-1};
        }
    }

DataSecret.java

package cn.it1995.tool;
    
    import org.apache.commons.codec.binary.Base64;
    
    import java.io.UnsupportedEncodingException;
    import java.nio.ByteBuffer;
    
    public class DataSecret {
    
    
        public static byte[] encode(byte[] txt) throws UnsupportedEncodingException {
    
            return Base64.encodeBase64(txt);
        }
    
        public static byte[] decode(String txt){
    
            return Base64.decodeBase64(txt);
        }
    
        public static byte[] int2Byte(int data){
    
            ByteBuffer byteBuffer = ByteBuffer.allocate(4);
            byteBuffer.putInt(data);
            return byteBuffer.array();
        }
    }

Main.java

public static void main(String[] args) throws UnsupportedEncodingException {
    
    
         //查密钥
         DH dhC = new DH();
         DH dhS = new DH();
    
         int publicKeyC = dhC.getPublicKey();
         int publicKeyS = dhS.getPublicKey();
    
         byte[] secretC = dhC.getSecretKey(publicKeyS);
         byte[] secretS = dhS.getSecretKey(publicKeyC);
    
         System.out.println("client's secrete is : ");
         for(byte i : secretC){
    
             System.out.print(i + " ");
         }
         System.out.println("\nserver's secrete is : ");
         for(byte i : secretS){
    
             System.out.print(i + " ");
         }
     }

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