HashedAuthenticationMechanism.cs

using System;
 
namespace Waher.Networking.SASL
{
    public abstract class HashedAuthenticationMechanism : AuthenticationMechanism 
    {
        public HashedAuthenticationMechanism()
        {
        }
 
        public abstract byte[] H(byte[] Data);
 
        public virtual byte[] H(string s)
        {
            return this.H(System.Text.Encoding.UTF8.GetBytes(s));
        }
 
        protected byte[] HMAC(byte[] Key, byte[] Text)
        {
            byte[] A1 = Key;
            if (A1.Length > 64)
                A1 = this.H(A1);
 
            if (A1.Length < 64)
                Array.Resize(ref A1, 64);
 
            byte[] A3 = (byte[])A1.Clone();
            int i;
 
            for (i = 0; i < 64; i++)
            {
                A1[i] ^= 0x5c;    // opad
                A3[i] ^= 0x36;    // ipad
            }
 
            return this.H(CONCAT(A1, this.H(CONCAT(A3, Text))));
        }
 
        protected byte[] KD(string k, string s)
        {
            return this.H(CONCAT(k, ":", s));
        }
    }
}