Add new unsecureRandom() constructor to create fast and/or deterministic pseudo random values

Author: patrickfav

CHANGELOG

@@ -1,5 +1,9 @@
 # Releases
 
+## v1.1.0
+
+* add `unsecureRandom()` constructor which creates random for e.g. tests or deterministic randoms
+
 ## v1.0.0
 
 * add `append()` method supporting multiple byte arrays #26

README.md

@@ -145,12 +145,18 @@ Bytes.allocate(4, (byte) 1); //fill with 0x01
 Bytes.empty(); //creates zero length byte array
 ```
 
-Creating **random** byte arrays for e.g. testing:
+Creating cryptographically secure **random** byte arrays:
 
 ```java
 Bytes.random(12);
 ```
 
+Creating cryptographically unsecure **random** byte arrays for e.g. testing:
+
+```java
+Bytes.unsecureRandom(12, 12345L); // using seed makes it deterministic
+```
+
 Reading byte content of encoded `String`s:
 
 ```java

src/main/java/at/favre/lib/bytes/Bytes.java

@@ -662,6 +662,35 @@ public static Bytes random(int length) {
         return random(length, new SecureRandom());
     }
 
+    /**
+     * A new instance with pseudo random bytes using an unsecure random number generator.
+     * This may be used in e.g. tests. In production code use {@link #random(int)} per default.
+     * <p>
+     * <strong>ONLY USE IN NON-SECURITY RELEVANT CONTEXT!</strong>
+     *
+     * @param length desired array length
+     * @return random instance
+     */
+    public static Bytes unsecureRandom(int length) {
+        return random(length, new Random());
+    }
+
+    /**
+     * A new instance with pseudo random bytes using an unsecure random number generator.
+     * This may be used in e.g. tests to create predictable numbers.
+     * <p>
+     * In production code use {@link #random(int)} per default.
+     * <p>
+     * <strong>ONLY USE IN NON-SECURITY RELEVANT CONTEXT!</strong>
+     *
+     * @param length desired array length
+     * @param seed   used to seed random number generator - using same seed will generate same numbers
+     * @return random instance
+     */
+    public static Bytes unsecureRandom(int length, long seed) {
+        return random(length, new Random(seed));
+    }
+
     /**
      * A new instance with random bytes.
      *

src/test/java/at/favre/lib/bytes/BytesConstructorTests.java

@@ -34,6 +34,7 @@
 import java.nio.IntBuffer;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
+import java.security.SecureRandom;
 import java.text.Normalizer;
 import java.util.Arrays;
 import java.util.BitSet;
@@ -547,4 +548,25 @@ private void testUUID(UUID uuid) {
     public void fromUUIDNullArgument() {
         Bytes.from((UUID) null);
     }
+
+    @Test
+    public void createSecureRandom() {
+        assertNotEquals(Bytes.random(16), Bytes.random(16));
+    }
+
+    @Test
+    public void createSecureRandomWithExplicitSecureRandom() {
+        assertNotEquals(Bytes.random(16, new SecureRandom()), Bytes.random(16, new SecureRandom()));
+    }
+
+    @Test
+    public void createUnsecureRandom() {
+        assertNotEquals(Bytes.unsecureRandom(128), Bytes.unsecureRandom(128));
+    }
+
+    @Test
+    public void createUnsecureRandomWithSeed() {
+        assertEquals(Bytes.unsecureRandom(128, 4L), Bytes.unsecureRandom(128, 4L));
+        assertNotEquals(Bytes.unsecureRandom(4, 3L), Bytes.unsecureRandom(4, 4L));
+    }
 }