diff --git a/OpenSim.Framework/Remoting.cs b/OpenSim.Framework/Remoting.cs
new file mode 100644
index 0000000000..88f559862c
--- /dev/null
+++ b/OpenSim.Framework/Remoting.cs
@@ -0,0 +1,90 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Security.Cryptography;
+
+namespace OpenSim.Framework
+{
+ ///
+ /// NEEDS AUDIT.
+ ///
+ ///
+ /// Suggested implementation
+ /// Store two digests for each foreign host. A local copy of the local hash using the local challenge (when issued), and a local copy of the remote hash using the remote challenge.
+ /// When sending data to the foreign host - run 'Sign' on the data and affix the returned byte[] to the message.
+ /// When recieving data from the foreign host - run 'Authenticate' against the data and the attached byte[].
+ /// Both hosts should be performing these operations for this to be effective.
+ ///
+ class RemoteDigest
+ {
+ private byte[] currentHash;
+ private byte[] secret;
+
+ private SHA512Managed SHA512;
+
+ ///
+ /// Initialises a new RemoteDigest authentication mechanism
+ ///
+ /// Needs an audit by a cryptographic professional - was not "roll your own"'d by choice but rather a serious lack of decent authentication mechanisms in .NET remoting
+ /// The shared secret between systems (for inter-sim, this is provided in encrypted form during connection, for grid this is input manually in setup)
+ /// Binary salt - some common value - to be decided what
+ /// The challenge key provided by the third party
+ public RemoteDigest(string sharedSecret, byte[] salt, string challenge)
+ {
+ SHA512 = new SHA512Managed();
+ Rfc2898DeriveBytes RFC2898 = new Rfc2898DeriveBytes(sharedSecret,salt);
+ secret = RFC2898.GetBytes(512);
+ ASCIIEncoding ASCII = new ASCIIEncoding();
+
+ currentHash = SHA512.ComputeHash(AppendArrays(secret, ASCII.GetBytes(challenge)));
+ }
+
+ ///
+ /// Authenticates a piece of incoming data against the local digest. Upon successful authentication, digest string is incremented.
+ ///
+ /// The incoming data
+ /// The remote digest
+ ///
+ public bool Authenticate(byte[] data, byte[] digest)
+ {
+ byte[] newHash = SHA512.ComputeHash(AppendArrays(AppendArrays(currentHash, secret), data));
+ if (digest == newHash)
+ {
+ currentHash = newHash;
+ return true;
+ }
+ else
+ {
+ throw new Exception("Hash comparison failed. Key resync required.");
+ }
+ }
+
+ ///
+ /// Signs a new bit of data with the current hash. Returns a byte array which should be affixed to the message.
+ /// Signing a piece of data will automatically increment the hash - if you sign data and do not send it, the
+ /// hashes will get out of sync and throw an exception when validation is attempted.
+ ///
+ /// The outgoing data
+ /// The local digest
+ public byte[] Sign(byte[] data)
+ {
+ currentHash = SHA512.ComputeHash(AppendArrays(AppendArrays(currentHash, secret), data));
+ return currentHash;
+ }
+
+ ///
+ /// Helper function, merges two byte arrays
+ ///
+ /// A
+ /// B
+ /// C
+ private byte[] AppendArrays(byte[] a, byte[] b)
+ {
+ byte[] c = new byte[a.Length + b.Length];
+ Buffer.BlockCopy(a, 0, c, 0, a.Length);
+ Buffer.BlockCopy(b, 0, c, a.Length, b.Length);
+ return c;
+ }
+
+ }
+}