FasterBase64

An implementation of a fast base64 encoding algorithm in C#. The algorithm is described in Faster Base64 Encoding and Decoding Using AVX2 Instructions by Wojciech Muła and Daniel Lemire.

Benchmarks (see below) show that this implementation is about 8-10 times faster than the standard .NET implementation in System.Convert.TryToBase64Chars() and System.Convert.TryFromBase64Chars(). We provide re-implementations of these two methods within a static class FasterBase64.Convert.

• FasterBase64.Convert.TryToBase64Chars() works the same way as System.Convert.TryToBase64Chars();
• FasterBase64.FasterBase64.TryFromBase64Chars() works the same way asSystem.Convert.TryFromBase64Chars(), if the input does not contain whitespace. The standard .NET implementation differs from the RFC4648 standard in that it allows whitespace in the data. If you need an implementation that skips whitespace, it is easy to copy the data, omitting whitespace, and then call System.FasterBase64.TryFromBase64Chars(). We believe that (in all reasonable cases) this is still faster than using the standard implementation.

Benchmarks for encoding

AMD Ryzen 9 3950X 16-Core Processor, 3493 Mhz, Windows 10.0.22509, .NET 6.0.0 (6.0.21.52210)

Method	N	Mean	Error	StdDev
Old	100	95.05 ns	0.758 ns	0.672 ns
New	100	25.06 ns	0.507 ns	0.498 ns
Old	1000	872.76 ns	11.321 ns	10.036 ns
New	1000	92.05 ns	0.633 ns	0.592 ns
Old	10000	8,723.65 ns	79.673 ns	74.526 ns
New	10000	724.58 ns	9.693 ns	9.067 ns

Here "Old" denotes usage of System.Convert.TryToBase64Chars(), "New" denotes usage of FasterBase64.Convert.TryToBase64Chars(), "N" is the size of input byte array.

Benchmarks for decoding

AMD Ryzen 9 3950X 16-Core Processor, 3493 Mhz, Windows 10.0.22509, .NET 6.0.0 (6.0.21.52210)

Method	N	Mean	Error	StdDev
Old	100	94.66 ns	0.839 ns	0.743 ns
New	100	54.08 ns	0.547 ns	0.457 ns
Old	1000	831.63 ns	9.560 ns	8.474 ns
New	1000	131.31 ns	1.085 ns	0.906 ns
Old	10000	8,254.94 ns	64.406 ns	57.094 ns
New	10000	1,011.61 ns	6.320 ns	5.602 ns

Here "Old" denotes usage of System.Convert.TryFromBase64Chars(), "New" denotes usage of FasterBase64.Convert.TryFromBase64Chars(), "N" is the size of byte array, that is then encoded in base64 using System.Convert.TryToBase64Chars() to form input to the benchmarked methods.

Caveats

• Although we believe the implementation to be reasonably well tested, there might still be bugs.
• The implementation uses AVX2 instructions, but does not check if AVX2 is available. AVX2 support can be easily checked by querying the property System.Runtime.Intrinsics.X86.Avx2.IsSupported.

TODO

• NuGet package.

License

• Copyright (c) Alexander Luzgarev, 2021, under the GPL license.