BCryptAeadHandleCache.cs

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using System;
using System.Threading;
using Internal.NativeCrypto;
 
namespace Internal.Cryptography;
 
internal static class BCryptAeadHandleCache
{
    private static SafeAlgorithmHandle s_aesCcm;
 
    private static SafeAlgorithmHandle s_aesGcm;
 
    private static SafeAlgorithmHandle s_chaCha20Poly1305;
 
    internal static SafeAlgorithmHandle AesCcm => GetCachedAlgorithmHandle(ref s_aesCcm, "AES", "ChainingModeCCM");
 
    internal static SafeAlgorithmHandle AesGcm => GetCachedAlgorithmHandle(ref s_aesGcm, "AES", "ChainingModeGCM");
 
    internal static bool IsChaCha20Poly1305Supported { get; } = OperatingSystem.IsWindowsVersionAtLeast(10, 0, 20142);
 
 
    internal static SafeAlgorithmHandle ChaCha20Poly1305 => GetCachedAlgorithmHandle(ref s_chaCha20Poly1305, "CHACHA20_POLY1305");
 
    private static SafeAlgorithmHandle GetCachedAlgorithmHandle(ref SafeAlgorithmHandle handle, string algId, string chainingMode = null)
    {
        SafeAlgorithmHandle safeAlgorithmHandle = Volatile.Read(ref handle);
        if (safeAlgorithmHandle != null)
        {
            return safeAlgorithmHandle;
        }
        SafeAlgorithmHandle safeAlgorithmHandle2 = Cng.BCryptOpenAlgorithmProvider(algId, null, Cng.OpenAlgorithmProviderFlags.NONE);
        if (chainingMode != null)
        {
            safeAlgorithmHandle2.SetCipherMode(chainingMode);
        }
        safeAlgorithmHandle = Interlocked.CompareExchange(ref handle, safeAlgorithmHandle2, null);
        if (safeAlgorithmHandle != null)
        {
            safeAlgorithmHandle2.Dispose();
            return safeAlgorithmHandle;
        }
        return safeAlgorithmHandle2;
    }
}