DH密鑰交換主要是兩個公式的編寫，即：

? ? ·公鑰計算公式；

? ? ·密鑰計算公式；

生成隨機數作為私鑰

截圖如下：

?

源碼如下：

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;//構造函數隨機私鑰public DH(){Random r = new Random();mPriKey = r.nextInt(20);System.out.println("dh priKey is : " + mPriKey);}//公鑰計算公式計算出公鑰public int getPublicKey(){return (int) (Math.pow(dhG, mPriKey) % dhP);}//使用對方公鑰與自己私鑰生成密鑰//在把結果轉256字節，AES密鑰需要128字節或256字節public byte[] getSecretKey(long publicKey){int buf = (int) (Math.pow(publicKey, mPriKey) % dhP);return sha256(buf);}//轉換成byte[256]類型，作為AES密鑰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 {//查密鑰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 + " ");}}

總結

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