FNV-1a

FNV-1a hash algorithm in C#

This small project is an implementation of the FNV-1a hash algorithm for 32-, 64-, 128-, 256-, 512- and 1024-bit variants. All implemented classes descend from the System.IO.Hashing's NonCryptographicHashAlgorithm, which should make for easy adoption.

Example:

namespace Fnv1aTest
{
    using System;
    using System.Globalization;
    using System.IO.Hashing;
    using System.Text;
    
    using Fnv1a;
    
    public static class Program
    {
        public static void Main()
        {
            NonCryptographicHashAlgorithm alg = new Fnv1a64();

            alg.Append(Encoding.UTF8.GetBytes("foobar"));
            Console.WriteLine(((ulong)BitConverter.ToInt64(alg.GetCurrentHash(), 0)).ToString("X8", CultureInfo.InvariantCulture));
        }
    }
}

This will output 85944171F73967E8 as the FNV-1a 64-bit hash of the string "foobar".

Benchmark Results

BenchmarkDotNet v0.15.8, Linux Ubuntu 24.04.5 LTS (Noble Numbat)
AMD EPYC 7763 2.45GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.401
  [Host]     : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3
  DefaultJob : .NET 10.0.12 (10.0.12, 10.0.1226.42308), X64 RyuJIT x86-64-v3

Method	PayloadLength	Mean	Error	StdDev	Ratio	RatioSD
Fnv1A32Block	32	55.40 ns	0.166 ns	0.147 ns	1.00	0.00
Fnv1A32SingleByte	32	98.14 ns	0.150 ns	0.133 ns	1.77	0.01
Fnv1A64Block	32	46.52 ns	0.186 ns	0.174 ns	0.84	0.00
Fnv1A64SingleByte	32	100.15 ns	0.173 ns	0.154 ns	1.81	0.01
Fnv1A128Block	32	234.44 ns	0.245 ns	0.204 ns	4.23	0.01
Fnv1A128SingleByte	32	209.67 ns	0.291 ns	0.258 ns	3.79	0.01
Fnv1A256Block	32	887.83 ns	0.793 ns	0.662 ns	16.03	0.04
Fnv1A256SingleByte	32	925.60 ns	1.354 ns	1.200 ns	16.71	0.05
Fnv1A512Block	32	2,189.70 ns	3.028 ns	2.832 ns	39.53	0.11
Fnv1A512SingleByte	32	2,205.52 ns	2.006 ns	1.675 ns	39.81	0.11
Fnv1A1024Block	32	22,394.22 ns	38.016 ns	31.745 ns	404.26	1.17
Fnv1A1024SingleByte	32	22,763.12 ns	68.925 ns	61.101 ns	410.92	1.50
Fnv1A32Block	1024	1,897.42 ns	0.893 ns	0.792 ns	1.00	0.00
Fnv1A32SingleByte	1024	3,261.41 ns	1.801 ns	1.406 ns	1.72	0.00
Fnv1A64Block	1024	1,552.87 ns	0.843 ns	0.658 ns	0.82	0.00
Fnv1A64SingleByte	1024	3,249.57 ns	1.699 ns	1.419 ns	1.71	0.00
Fnv1A128Block	1024	7,522.72 ns	12.036 ns	9.397 ns	3.96	0.01
Fnv1A128SingleByte	1024	6,695.46 ns	3.015 ns	2.354 ns	3.53	0.00
Fnv1A256Block	1024	27,610.77 ns	92.071 ns	81.618 ns	14.55	0.04
Fnv1A256SingleByte	1024	28,857.94 ns	9.198 ns	7.681 ns	15.21	0.01
Fnv1A512Block	1024	69,913.22 ns	152.061 ns	134.798 ns	36.85	0.07
Fnv1A512SingleByte	1024	72,050.12 ns	296.322 ns	277.180 ns	37.97	0.14
Fnv1A1024Block	1024	718,263.79 ns	709.576 ns	592.528 ns	378.55	0.34
Fnv1A1024SingleByte	1024	726,504.43 ns	1,289.493 ns	1,076.785 ns	382.89	0.57
Fnv1A32Block	65536	120,776.62 ns	21.601 ns	18.038 ns	1.00	0.00
Fnv1A32SingleByte	65536	207,514.00 ns	156.227 ns	146.135 ns	1.72	0.00
Fnv1A64Block	65536	99,453.35 ns	90.052 ns	79.828 ns	0.82	0.00
Fnv1A64SingleByte	65536	205,440.51 ns	213.681 ns	199.877 ns	1.70	0.00
Fnv1A128Block	65536	498,421.63 ns	779.690 ns	729.323 ns	4.13	0.01
Fnv1A128SingleByte	65536	378,891.90 ns	265.410 ns	207.214 ns	3.14	0.00
Fnv1A256Block	65536	1,757,220.07 ns	2,264.139 ns	2,007.100 ns	14.55	0.02
Fnv1A256SingleByte	65536	1,823,655.84 ns	946.122 ns	790.055 ns	15.10	0.01
Fnv1A512Block	65536	4,370,055.91 ns	6,558.820 ns	5,814.223 ns	36.18	0.05
Fnv1A512SingleByte	65536	4,451,021.02 ns	11,001.032 ns	10,290.372 ns	36.85	0.08
Fnv1A1024Block	65536	45,785,933.98 ns	71,835.493 ns	56,084.428 ns	379.10	0.45
Fnv1A1024SingleByte	65536	46,425,259.16 ns	36,342.892 ns	30,347.961 ns	384.39	0.25

Special thanks to crookseta for the missing-values project which allowed for the 256- and 512-bit variants to not have to use BigInteger, which was very slow.