1 files changed, 107 insertions, 0 deletions
diff --git a/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/params/DESParameters.java b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/params/DESParameters.java
new file mode 100644
index 000000000..6c9c3985d
--- /dev/null
+++ b/libraries/spongycastle/core/src/main/java/org/spongycastle/crypto/params/DESParameters.java
@@ -0,0 +1,107 @@
+package org.spongycastle.crypto.params;
+
+public class DESParameters
+    extends KeyParameter
+{
+    public DESParameters(
+        byte[]  key)
+    {
+        super(key);
+
+        if (isWeakKey(key, 0))
+        {
+            throw new IllegalArgumentException("attempt to create weak DES key");
+        }
+    }
+
+    /*
+     * DES Key length in bytes.
+     */
+    static public final int DES_KEY_LENGTH = 8;
+
+    /*
+     * Table of weak and semi-weak keys taken from Schneier pp281
+     */
+    static private final int N_DES_WEAK_KEYS = 16;
+
+    static private byte[] DES_weak_keys =
+    {
+        /* weak keys */
+        (byte)0x01,(byte)0x01,(byte)0x01,(byte)0x01, (byte)0x01,(byte)0x01,(byte)0x01,(byte)0x01,
+        (byte)0x1f,(byte)0x1f,(byte)0x1f,(byte)0x1f, (byte)0x0e,(byte)0x0e,(byte)0x0e,(byte)0x0e,
+        (byte)0xe0,(byte)0xe0,(byte)0xe0,(byte)0xe0, (byte)0xf1,(byte)0xf1,(byte)0xf1,(byte)0xf1,
+        (byte)0xfe,(byte)0xfe,(byte)0xfe,(byte)0xfe, (byte)0xfe,(byte)0xfe,(byte)0xfe,(byte)0xfe,
+
+        /* semi-weak keys */
+        (byte)0x01,(byte)0xfe,(byte)0x01,(byte)0xfe, (byte)0x01,(byte)0xfe,(byte)0x01,(byte)0xfe,
+        (byte)0x1f,(byte)0xe0,(byte)0x1f,(byte)0xe0, (byte)0x0e,(byte)0xf1,(byte)0x0e,(byte)0xf1,
+        (byte)0x01,(byte)0xe0,(byte)0x01,(byte)0xe0, (byte)0x01,(byte)0xf1,(byte)0x01,(byte)0xf1,
+        (byte)0x1f,(byte)0xfe,(byte)0x1f,(byte)0xfe, (byte)0x0e,(byte)0xfe,(byte)0x0e,(byte)0xfe,
+        (byte)0x01,(byte)0x1f,(byte)0x01,(byte)0x1f, (byte)0x01,(byte)0x0e,(byte)0x01,(byte)0x0e,
+        (byte)0xe0,(byte)0xfe,(byte)0xe0,(byte)0xfe, (byte)0xf1,(byte)0xfe,(byte)0xf1,(byte)0xfe,
+        (byte)0xfe,(byte)0x01,(byte)0xfe,(byte)0x01, (byte)0xfe,(byte)0x01,(byte)0xfe,(byte)0x01,
+        (byte)0xe0,(byte)0x1f,(byte)0xe0,(byte)0x1f, (byte)0xf1,(byte)0x0e,(byte)0xf1,(byte)0x0e,
+        (byte)0xe0,(byte)0x01,(byte)0xe0,(byte)0x01, (byte)0xf1,(byte)0x01,(byte)0xf1,(byte)0x01,
+        (byte)0xfe,(byte)0x1f,(byte)0xfe,(byte)0x1f, (byte)0xfe,(byte)0x0e,(byte)0xfe,(byte)0x0e,
+        (byte)0x1f,(byte)0x01,(byte)0x1f,(byte)0x01, (byte)0x0e,(byte)0x01,(byte)0x0e,(byte)0x01,
+        (byte)0xfe,(byte)0xe0,(byte)0xfe,(byte)0xe0, (byte)0xfe,(byte)0xf1,(byte)0xfe,(byte)0xf1
+    };
+
+    /**
+     * DES has 16 weak keys.  This method will check
+     * if the given DES key material is weak or semi-weak.
+     * Key material that is too short is regarded as weak.
+     * <p>
+     * See <a href="http://www.counterpane.com/applied.html">"Applied
+     * Cryptography"</a> by Bruce Schneier for more information.
+     *
+     * @return true if the given DES key material is weak or semi-weak,
+     *     false otherwise.
+     */
+    public static boolean isWeakKey(
+        byte[] key,
+        int offset)
+    {
+        if (key.length - offset < DES_KEY_LENGTH)
+        {
+            throw new IllegalArgumentException("key material too short.");
+        }
+
+        nextkey: for (int i = 0; i < N_DES_WEAK_KEYS; i++)
+        {
+            for (int j = 0; j < DES_KEY_LENGTH; j++)
+            {
+                if (key[j + offset] != DES_weak_keys[i * DES_KEY_LENGTH + j])
+                {
+                    continue nextkey;
+                }
+            }
+
+            return true;
+        }
+        return false;
+    }
+
+    /**
+     * DES Keys use the LSB as the odd parity bit.  This can
+     * be used to check for corrupt keys.
+     *
+     * @param bytes the byte array to set the parity on.
+     */
+    public static void setOddParity(
+        byte[] bytes)
+    {
+        for (int i = 0; i < bytes.length; i++)
+        {
+            int b = bytes[i];
+            bytes[i] = (byte)((b & 0xfe) |
+                            ((((b >> 1) ^
+                            (b >> 2) ^
+                            (b >> 3) ^
+                            (b >> 4) ^
+                            (b >> 5) ^
+                            (b >> 6) ^
+                            (b >> 7)) ^ 0x01) & 0x01));
+        }
+    }
+}