diff --git a/crypto/src/crypto/generators/SCrypt.cs b/crypto/src/crypto/generators/SCrypt.cs
index efa74d735..64a36df63 100644
--- a/crypto/src/crypto/generators/SCrypt.cs
+++ b/crypto/src/crypto/generators/SCrypt.cs
@@ -8,12 +8,46 @@ using Org.BouncyCastle.Crypto.Utilities;
namespace Org.BouncyCastle.Crypto.Generators
{
- public class SCrypt
+ /// <summary>Implementation of the scrypt a password-based key derivation function.</summary>
+ /// <remarks>
+ /// Scrypt was created by Colin Percival and is specified in
+ /// <a href="http://tools.ietf.org/html/draft-josefsson-scrypt-kdf-01">draft-josefsson-scrypt-kd</a>.
+ /// </remarks>
+ public class SCrypt
{
- // TODO Validate arguments
- public static byte[] Generate(byte[] P, byte[] S, int N, int r, int p, int dkLen)
+ /// <summary>Generate a key using the scrypt key derivation function.</summary>
+ /// <param name="P">the bytes of the pass phrase.</param>
+ /// <param name="S">the salt to use for this invocation.</param>
+ /// <param name="N">CPU/Memory cost parameter. Must be larger than 1, a power of 2 and less than
+ /// <code>2^(128 * r / 8)</code>.</param>
+ /// <param name="r">the block size, must be >= 1.</param>
+ /// <param name="p">Parallelization parameter. Must be a positive integer less than or equal to
+ /// <code>Int32.MaxValue / (128 * r * 8)</code>.</param>
+ /// <param name="dkLen">the length of the key to generate.</param>
+ /// <returns>the generated key.</returns>
+ public static byte[] Generate(byte[] P, byte[] S, int N, int r, int p, int dkLen)
{
- return MFcrypt(P, S, N, r, p, dkLen);
+ if (P == null)
+ throw new ArgumentNullException("Passphrase P must be provided.");
+ if (S == null)
+ throw new ArgumentNullException("Salt S must be provided.");
+ if (N <= 1)
+ throw new ArgumentException("Cost parameter N must be > 1.");
+ // Only value of r that cost (as an int) could be exceeded for is 1
+ if (r == 1 && N >= 65536)
+ throw new ArgumentException("Cost parameter N must be > 1 and < 65536.");
+ if (r < 1)
+ throw new ArgumentException("Block size r must be >= 1.");
+ int maxParallel = Int32.MaxValue / (128 * r * 8);
+ if (p < 1 || p > maxParallel)
+ {
+ throw new ArgumentException("Parallelisation parameter p must be >= 1 and <= " + maxParallel
+ + " (based on block size r of " + r + ")");
+ }
+ if (dkLen < 1)
+ throw new ArgumentException("Generated key length dkLen must be >= 1.");
+
+ return MFcrypt(P, S, N, r, p, dkLen);
}
private static byte[] MFcrypt(byte[] P, byte[] S, int N, int r, int p, int dkLen)
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