diff --git a/Crypto/src/crypto/parameters/DesParameters.cs b/Crypto/src/crypto/parameters/DesParameters.cs
new file mode 100644
index 000000000..ee37cd861
--- /dev/null
+++ b/Crypto/src/crypto/parameters/DesParameters.cs
@@ -0,0 +1,130 @@
+using System;
+
+namespace Org.BouncyCastle.Crypto.Parameters
+{
+ public class DesParameters
+ : KeyParameter
+ {
+ public DesParameters(
+ byte[] key)
+ : base(key)
+ {
+ if (IsWeakKey(key))
+ throw new ArgumentException("attempt to create weak DES key");
+ }
+
+ public DesParameters(
+ byte[] key,
+ int keyOff,
+ int keyLen)
+ : base(key, keyOff, keyLen)
+ {
+ if (IsWeakKey(key, keyOff))
+ throw new ArgumentException("attempt to create weak DES key");
+ }
+
+ /*
+ * DES Key Length in bytes.
+ */
+ public const int DesKeyLength = 8;
+
+ /*
+ * Table of weak and semi-weak keys taken from Schneier pp281
+ */
+ private const int N_DES_WEAK_KEYS = 16;
+
+ private static readonly 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.
+ * </p>
+ * @return true if the given DES key material is weak or semi-weak,
+ * false otherwise.
+ */
+ public static bool IsWeakKey(
+ byte[] key,
+ int offset)
+ {
+ if (key.Length - offset < DesKeyLength)
+ throw new ArgumentException("key material too short.");
+
+ //nextkey:
+ for (int i = 0; i < N_DES_WEAK_KEYS; i++)
+ {
+ bool unmatch = false;
+ for (int j = 0; j < DesKeyLength; j++)
+ {
+ if (key[j + offset] != DES_weak_keys[i * DesKeyLength + j])
+ {
+ //continue nextkey;
+ unmatch = true;
+ break;
+ }
+ }
+
+ if (!unmatch)
+ {
+ return true;
+ }
+ }
+
+ return false;
+ }
+
+ public static bool IsWeakKey(
+ byte[] key)
+ {
+ return IsWeakKey(key, 0);
+ }
+
+ /**
+ * 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));
+ }
+ }
+ }
+
+}
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