/* ========================================================================
 * Copyright (c) 2005-2021 The OPC Foundation, Inc. All rights reserved.
 *
 * OPC Foundation MIT License 1.00
 * 
 * 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
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 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * The complete license agreement can be found here:
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 * ======================================================================*/

#if !NETSTANDARD2_1 && !NET472_OR_GREATER && !NET5_0_OR_GREATER
using System;
using System.Security.Cryptography;
using Org.BouncyCastle.Crypto.Prng;

namespace Opc.Ua.Security.Certificates.BouncyCastle
{
    /// <summary>
    /// Secure .Net Core Random Number generator wrapper for Bounce Castle.
    /// Creates an instance of RNGCryptoServiceProvider or an OpenSSL based version on other OS.
    /// </summary>
    public class CertificateFactoryRandomGenerator : IRandomGenerator, IDisposable
    {
        RandomNumberGenerator m_prg;

        /// <summary>
        /// Creates an instance of a crypthographic secure random number generator.
        /// </summary>
        public CertificateFactoryRandomGenerator()
        {
            m_prg = RandomNumberGenerator.Create();
        }

        /// <summary>
        /// Dispose the random number generator.
        /// </summary>
        public void Dispose()
        {
            m_prg.Dispose();
        }

        /// <summary>Add more seed material to the generator. Not needed here.</summary>
        public void AddSeedMaterial(byte[] seed) { }

        /// <summary>Add more seed material to the generator. Not needed here.</summary>
        public void AddSeedMaterial(long seed) { }

        /// <summary>
        /// Fills an array of bytes with a cryptographically strong
        /// random sequence of values.
        /// </summary>
        /// <param name="bytes">Array to be filled.</param>
        public void NextBytes(byte[] bytes)
        {
            m_prg.GetBytes(bytes);
        }

        /// <summary>
        /// Fills an array of bytes with a cryptographically strong
        /// random sequence of values.
        /// </summary>
        /// <param name="bytes">Array to receive bytes.</param>
        /// <param name="start">Index to start filling at.</param>
        /// <param name="len">Length of segment to fill.</param>
        public void NextBytes(byte[] bytes, int start, int len)
        {
            byte[] temp = new byte[len];
            m_prg.GetBytes(temp);
            Array.Copy(temp, 0, bytes, start, len);
        }
    }
}
#endif
