AesEngine uses more memory and takes more time in .NET 10.0 than in .NET Framework 4.8.1

[paulomorgado]

I'm detecting that AesEngine uses more memory and takes more time in .NET 10.0 than in .NET Framework 4.8.1.

I've created this benchmark:

[MemoryDiagnoser]
[SimpleJob(RuntimeMoniker.Net10_0)]
[SimpleJob(RuntimeMoniker.Net481)]
[HideColumns(Column.Error, Column.StdDev, Column.Mean)]
public class AesEngineBenchmarks
{
    private KeyParameter key;
    private AesEngine aesForInit;
    private AesEngine aesForEncrypt;
    private byte[] output = new byte[256];
    private byte[] iv = new byte[] { 0x59, 0x5B, 0x69, 0x9B, 0xBD, 0x3B, 0xC0, 0xDF, 0x26, 0x06, 0x20, 0x93, 0xC1, 0xAD, 0x8F, 0x73 };

    [IterationSetup]
    public void IterationSetup()
    {
        key = new KeyParameter(new byte[] { 0x23, 0x48, 0x29, 0x00, 0x84, 0x67, 0xbe, 0x18, 0x6c, 0x3d, 0xe1, 0x4a, 0xae, 0x72, 0xd6, 0x2c });

        aesForInit = new AesEngine();

        aesForEncrypt = new AesEngine();
        aesForEncrypt.Init(true, key);
    }

    [Benchmark]
    public void Init()
    {
        aesForInit.Init(true, key);
    }

    [Benchmark]
    public void ProcessBlock()
    {
        aesForEncrypt.ProcessBlock(iv, 0, output, 16);
    }
}

and the results were:

BenchmarkDotNet v0.15.8, Windows 11 (10.0.26200.7705/25H2/2025Update/HudsonValley2)
13th Gen Intel Core i9-13900K 3.00GHz, 1 CPU, 32 logical and 24 physical cores
.NET SDK 10.0.102
  [Host]               : .NET 10.0.2 (10.0.2, 10.0.225.61305), X64 RyuJIT x86-64-v3
  .NET 10.0            : .NET 10.0.2 (10.0.2, 10.0.225.61305), X64 RyuJIT x86-64-v3
  .NET Framework 4.8.1 : .NET Framework 4.8.1 (4.8.9325.0), X64 RyuJIT VectorSize=256

InvocationCount=1  UnrollFactor=1

Method	Job	Runtime	Median	Allocated
Init	.NET 10.0	.NET 10.0	1,300.0 ns	832 B
ProcessBlock	.NET 10.0	.NET 10.0	800.0 ns	-
Init	.NET Framework 4.8.1	.NET Framework 4.8.1	1,200.0 ns	-
ProcessBlock	.NET Framework 4.8.1	.NET Framework 4.8.1	100.0 ns	-

What could be causing this?

[peterdettman]

I don't know why that would be, but in your case you probably could be using the much faster AES-NI implementation via Org.BouncyCastle.Crypto.Engines.AesUtilities.CreateEngine.

Or in general the higher level Org.BouncyCastle.Security.CipherUtilities, e.g.: CipherUtilities.GetCipher("AES/GCM").

[paulomorgado]

@peterdettman,

Using Org.BouncyCastle.Crypto.Engines.AesUtilities.CreateEngine makes it slightly better, but still worse than .NET Framework 4.8.1.

Method	Job	Runtime	Mean	Allocated
Init	.NET 10.0	.NET 10.0	785.4 ns	200 B
ProcessBlock	.NET 10.0	.NET 10.0	445.4 ns	-
Init	.NET Framework 4.8.1	.NET Framework 4.8.1	1,075.3 ns	-
ProcessBlock	.NET Framework 4.8.1	.NET Framework 4.8.1	151.0 ns	-

The allocation differences could be caused by .NET Framework 4.8.1 reporting allocations differently. But the time taken should not have that issue.