AES ECB one-shot vs TransformFinalBlock BenchmarkDotNet repro

README.md

AES ECB one-shot vs TransformFinalBlock benchmark

This is the exact BenchmarkDotNet project used for the .NET 10 run of dotnet/runtime issue 58784's benchmark.

Note

This gist was prepared and published with GitHub Copilot.

AesIssue58784BenchNet10.csproj

<Project Sdk="Microsoft.NET.Sdk">

  <PropertyGroup>
    <OutputType>Exe</OutputType>
    <TargetFramework>net10.0</TargetFramework>
    <ImplicitUsings>enable</ImplicitUsings>
    <Nullable>enable</Nullable>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="BenchmarkDotNet" Version="0.15.8" />
  </ItemGroup>

</Project>

global.json

{
  "sdk": {
    "version": "10.0.301",
    "rollForward": "latestFeature"
  }
}

Program.cs

using System.Security.Cryptography;
using System.Text;
using BenchmarkDotNet.Attributes;
using BenchmarkDotNet.Running;

BenchmarkRunner.Run<Bench>();

public class Bench
{
    byte[] _key, _plaintext, _ciphertext;

    [GlobalSetup]
    public void Setup()
    {
        _key = RandomNumberGenerator.GetBytes(32);
        _plaintext = Encoding.UTF8.GetBytes("This is a test. This is a test. ");

        using var tempAes = Aes.Create();
        tempAes.Key = _key;
        _ciphertext = tempAes.EncryptEcb(_plaintext, PaddingMode.None);
    }

    [Benchmark(Baseline = true)]
    public byte[] Old_Enc()
    {
        using Aes aes = Aes.Create();
        aes.Padding = PaddingMode.None;
        aes.Mode = CipherMode.ECB;

        using var transform = aes.CreateEncryptor(_key, null);
        return transform.TransformFinalBlock(_plaintext, 0, _plaintext.Length);
    }

    [Benchmark]
    public byte[] Old_Dec()
    {
        using Aes aes = Aes.Create();
        aes.Padding = PaddingMode.None;
        aes.Mode = CipherMode.ECB;

        using var transform = aes.CreateDecryptor(_key, null);
        return transform.TransformFinalBlock(_ciphertext, 0, _ciphertext.Length);
    }

    [Benchmark]
    public byte[] New_Enc()
    {
        using Aes aes = Aes.Create();
        aes.Key = _key;
        return aes.EncryptEcb((ReadOnlySpan<byte>)_plaintext, PaddingMode.None);
    }

    [Benchmark]
    public byte[] New_Dec()
    {
        using Aes aes = Aes.Create();
        aes.Key = _key;
        return aes.DecryptEcb((ReadOnlySpan<byte>)_ciphertext, PaddingMode.None);
    }
}