1 files changed, 151 insertions, 0 deletions
diff --git a/core/src/main/java/org/spongycastle/pqc/crypto/gmss/util/GMSSUtil.java b/core/src/main/java/org/spongycastle/pqc/crypto/gmss/util/GMSSUtil.java
new file mode 100644
index 00000000..57678d85
--- /dev/null
+++ b/core/src/main/java/org/spongycastle/pqc/crypto/gmss/util/GMSSUtil.java
@@ -0,0 +1,151 @@
+package org.spongycastle.pqc.crypto.gmss.util;
+
+/**
+ * This class provides several methods that are required by the GMSS classes.
+ */
+public class GMSSUtil
+{
+    /**
+     * Converts a 32 bit integer into a byte array beginning at
+     * <code>offset</code> (little-endian representation)
+     *
+     * @param value the integer to convert
+     */
+    public byte[] intToBytesLittleEndian(int value)
+    {
+        byte[] bytes = new byte[4];
+
+        bytes[0] = (byte)((value) & 0xff);
+        bytes[1] = (byte)((value >> 8) & 0xff);
+        bytes[2] = (byte)((value >> 16) & 0xff);
+        bytes[3] = (byte)((value >> 24) & 0xff);
+        return bytes;
+    }
+
+    /**
+     * Converts a byte array beginning at <code>offset</code> into a 32 bit
+     * integer (little-endian representation)
+     *
+     * @param bytes the byte array
+     * @return The resulting integer
+     */
+    public int bytesToIntLittleEndian(byte[] bytes)
+    {
+
+        return ((bytes[0] & 0xff)) | ((bytes[1] & 0xff) << 8)
+            | ((bytes[2] & 0xff) << 16) | ((bytes[3] & 0xff)) << 24;
+    }
+
+    /**
+     * Converts a byte array beginning at <code>offset</code> into a 32 bit
+     * integer (little-endian representation)
+     *
+     * @param bytes  the byte array
+     * @param offset the integer offset into the byte array
+     * @return The resulting integer
+     */
+    public int bytesToIntLittleEndian(byte[] bytes, int offset)
+    {
+        return ((bytes[offset++] & 0xff)) | ((bytes[offset++] & 0xff) << 8)
+            | ((bytes[offset++] & 0xff) << 16)
+            | ((bytes[offset] & 0xff)) << 24;
+    }
+
+    /**
+     * This method concatenates a 2-dimensional byte array into a 1-dimensional
+     * byte array
+     *
+     * @param arraycp a 2-dimensional byte array.
+     * @return 1-dimensional byte array with concatenated input array
+     */
+    public byte[] concatenateArray(byte[][] arraycp)
+    {
+        byte[] dest = new byte[arraycp.length * arraycp[0].length];
+        int indx = 0;
+        for (int i = 0; i < arraycp.length; i++)
+        {
+            System.arraycopy(arraycp[i], 0, dest, indx, arraycp[i].length);
+            indx = indx + arraycp[i].length;
+        }
+        return dest;
+    }
+
+    /**
+     * This method prints the values of a 2-dimensional byte array
+     *
+     * @param text  a String
+     * @param array a 2-dimensional byte array
+     */
+    public void printArray(String text, byte[][] array)
+    {
+        System.out.println(text);
+        int counter = 0;
+        for (int i = 0; i < array.length; i++)
+        {
+            for (int j = 0; j < array[0].length; j++)
+            {
+                System.out.println(counter + "; " + array[i][j]);
+                counter++;
+            }
+        }
+    }
+
+    /**
+     * This method prints the values of a 1-dimensional byte array
+     *
+     * @param text  a String
+     * @param array a 1-dimensional byte array.
+     */
+    public void printArray(String text, byte[] array)
+    {
+        System.out.println(text);
+        int counter = 0;
+        for (int i = 0; i < array.length; i++)
+        {
+            System.out.println(counter + "; " + array[i]);
+            counter++;
+        }
+    }
+
+    /**
+     * This method tests if an integer is a power of 2.
+     *
+     * @param testValue an integer
+     * @return <code>TRUE</code> if <code>testValue</code> is a power of 2,
+     *         <code>FALSE</code> otherwise
+     */
+    public boolean testPowerOfTwo(int testValue)
+    {
+        int a = 1;
+        while (a < testValue)
+        {
+            a <<= 1;
+        }
+        if (testValue == a)
+        {
+            return true;
+        }
+
+        return false;
+    }
+
+    /**
+     * This method returns the least integer that is greater or equal to the
+     * logarithm to the base 2 of an integer <code>intValue</code>.
+     *
+     * @param intValue an integer
+     * @return The least integer greater or equal to the logarithm to the base 2
+     *         of <code>intValue</code>
+     */
+    public int getLog(int intValue)
+    {
+        int log = 1;
+        int i = 2;
+        while (i < intValue)
+        {
+            i <<= 1;
+            log++;
+        }
+        return log;
+    }
+}