CryptoBytes.cs

using System;
using System.Runtime.CompilerServices;

namespace Chaos.NaCl
{
    internal static class CryptoBytes
    {
        public static void Wipe(byte[] data)
        {
            if (data == null)
                throw new ArgumentNullException("data");
            InternalWipe(data, 0, data.Length);
        }

        // Secure wiping is hard
        // * the GC can move around and copy memory
        //   Perhaps this can be avoided by using unmanaged memory or by fixing the position of the array in memory
        // * Swap files and error dumps can contain secret information
        //   It seems possible to lock memory in RAM, no idea about error dumps
        // * Compiler could optimize out the wiping if it knows that data won't be read back
        //   I hope this is enough, suppressing inlining
        //   but perhaps `RtlSecureZeroMemory` is needed
        [MethodImpl(MethodImplOptions.NoInlining)]
        internal static void InternalWipe(byte[] data, int offset, int count)
        {
            Array.Clear(data, offset, count);
        }

        // shallow wipe of structs
        [MethodImpl(MethodImplOptions.NoInlining)]
        internal static void InternalWipe<T>(ref T data)
            where T : struct
        {
            data = default(T);
        }
    }
}