// Default authentication provider (empty class).// Copyright (C) 2008-2010 Malcolm Crowe, Lex Li, and other contributors.// // Permission is hereby granted, free of charge, to any person obtaining a copy of this// software and associated documentation files (the "Software"), to deal in the Software// without restriction, including without limitation the rights to use, copy, modify, merge,// publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons// to whom the Software is furnished to do so, subject to the following conditions:// // The above copyright notice and this permission notice shall be included in all copies or// substantial portions of the Software.// // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,// INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE// FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER// DEALINGS IN THE SOFTWARE. using System; namespace GSF.Net.Snmp.Security{    /// <summary>    /// Default authentication provider.    /// </summary>    public sealed class DefaultAuthenticationProvider : IAuthenticationProvider    {        private DefaultAuthenticationProvider()        {        }         private static IAuthenticationProvider _instance;         /// <summary>        /// Gets the instance.        /// </summary>        /// <value>The instance.</value>        public static IAuthenticationProvider Instance        {            get { return _instance ?? (_instance = new DefaultAuthenticationProvider()); }        }         #region IAuthenticationProvider Members         /// <summary>        /// Computes the hash.        /// </summary>        /// <param name="version">The version.</param>        /// <param name="header">The header.</param>        /// <param name="parameters">The parameters.</param>        /// <param name="data">The scope data.</param>        /// <param name="privacy">The privacy provider.</param>        /// <param name="length">The length bytes.</param>        /// <returns></returns>        public OctetString ComputeHash(VersionCode version, ISegment header, SecurityParameters parameters, ISnmpData data, IPrivacyProvider privacy, byte[] length)        {            if (header == null)            {                throw new ArgumentNullException(nameof(header));            }             if (parameters == null)            {                throw new ArgumentNullException(nameof(parameters));            }             if (data == null)            {                throw new ArgumentNullException(nameof(data));            }             if (privacy == null)            {                throw new ArgumentNullException(nameof(privacy));            }             return OctetString.Empty;        }         /// <summary>        /// Computes the hash.        /// </summary>        /// <returns></returns>        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Performance", "CA1822:MarkMembersAsStatic")]        public OctetString ComputeHash(byte[] buffer, OctetString engineId)        {            if (buffer == null)            {                throw new ArgumentNullException(nameof(buffer));            }             if (engineId == null)            {                throw new ArgumentNullException(nameof(engineId));            }             return OctetString.Empty;        }         /// <summary>        /// Gets the clean digest.        /// </summary>        /// <value>The clean digest.</value>        public OctetString CleanDigest        {            get { return OctetString.Empty; }        }         /// <summary>        /// Converts password to key.        /// </summary>        /// <param name="password"></param>        /// <param name="engineId"></param>        /// <returns></returns>        public byte[] PasswordToKey(byte[] password, byte[] engineId)        {            if (password == null)            {                throw new ArgumentNullException(nameof(password));            }                        if (engineId == null)            {                throw new ArgumentNullException(nameof(engineId));            }                        // IMPORTANT: this function is not used.            return new byte[0];        }         /// <summary>        /// Gets the length of the digest.        /// </summary>        /// <value>The length of the digest.</value>        public int DigestLength => 0;         #endregion         /// <summary>        /// Returns a <see cref="System.String"/> that represents this instance.        /// </summary>        /// <returns>        /// A <see cref="System.String"/> that represents this instance.        /// </returns>        public override string ToString()        {            return "Default authentication provider";        }    }}