myibu · myibu · Sep 10, 2021 · Sep 10, 2021
diff --git a/build.gradle b/build.gradle
@@ -26,7 +26,7 @@ tasks.withType(JavaCompile) { options.encoding = "UTF-8" }
 
 group = 'com.github.myibu'
 archivesBaseName = "algorithm-java"
-version = "0.0.1"
+version = "0.0.1a"
 
 repositories {
     mavenCentral()

diff --git a/readme.md b/readme.md
@@ -16,7 +16,7 @@ Reference to: [SHA256.pdf](./docs/SHA256.pdf)
 <dependency>
   <groupId>com.github.myibu</groupId>
   <artifactId>algorithm-java</artifactId>
-  <version>0.0.1</version>
+  <version>0.0.1a</version>
 </dependency>
 ```
 

diff --git a/src/main/java/com/github/myibu/algorithm/hash/SipHash.java b/src/main/java/com/github/myibu/algorithm/hash/SipHash.java
@@ -1,15 +1,53 @@
 package com.github.myibu.algorithm.hash;
 
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+import java.lang.management.ManagementFactory;
+import java.nio.file.Paths;
+
 /**
  * SipHash 2-4 algorithm
  * @author myibu
  * Created on 2021/9/8
  */
 public class SipHash {
     protected byte[] hashSeed;
-    private final int c;
-    private final int d;
+    protected int c;
+    protected int d;
     protected static final int DEFAULT_SEED_SIZE = 128 / 8;
+    private static final String LINUX_RANDOM_FILE = "/dev/urandom";
+
+    public SipHash() {
+        this.hashSeed = generateHashSeed();
+        this.c = 2;
+        this.d = 4;
+    }
+
+    private byte[] generateHashSeed() {
+        byte[] seed = new byte[DEFAULT_SEED_SIZE];
+        boolean seedInitialized = false;
+        File randomFile = Paths.get(LINUX_RANDOM_FILE).toFile();
+        if (randomFile.exists() && randomFile.canRead()) {
+            try {
+                FileInputStream fis = new FileInputStream(randomFile);
+                if (fis.read(seed, 0, seed.length) == DEFAULT_SEED_SIZE) {
+                    seedInitialized = true;
+                }
+            } catch (IOException e) {
+
+            }
+        }
+        if (!seedInitialized) {
+            for (int j = 0; j < seed.length; j++) {
+                long sec = System.currentTimeMillis() / 1000;
+                long usec = System.nanoTime();
+                long pid = Integer.parseInt(ManagementFactory.getRuntimeMXBean().getName().split("@")[0]);
+                seed[j] = (byte)(sec ^  usec ^ pid);
+            }
+        }
+        return seed;
+    }
 
     public SipHash(byte[] seed) {
         this(seed, 2, 4);

diff --git a/src/main/java/com/github/myibu/algorithm/hash/SipHash13.java b/src/main/java/com/github/myibu/algorithm/hash/SipHash13.java
@@ -6,6 +6,12 @@
  * Created on 2021/9/8
  */
 public class SipHash13 extends SipHash {
+    public SipHash13() {
+        super();
+        this.c = 1;
+        this.d = 3;
+    }
+
     public SipHash13(byte[] seed) {
         super(seed, 1, 3);
     }

diff --git a/src/test/java/com/github/myibu/algorithm/AlgorithmTest.java b/src/test/java/com/github/myibu/algorithm/AlgorithmTest.java
@@ -19,6 +19,13 @@ public void testSHA256() throws Exception {
                 ByteOperator.byteArrayToHexString(bs));
     }
 
+    @Test
+    public void testDefaultSipHash() throws Exception {
+        SipHash sipHash = new SipHash();
+        long hashRes = sipHash.hash("12345678");
+        System.out.println(Long.toHexString(hashRes));
+    }
+
     @Test
     public void testSipHash() throws Exception {
         byte[] hashSeed = new byte[]{