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 24.04.3 LTS (Noble Numbat)
AMD EPYC 7763 2.45GHz, 1 CPU, 4 logical and 2 physical cores
.NET SDK 10.0.102
  [Host]     : .NET 10.0.2 (10.0.2, 10.0.225.61305), X64 RyuJIT x86-64-v3
  DefaultJob : .NET 10.0.2 (10.0.2, 10.0.225.61305), X64 RyuJIT x86-64-v3

Method	PayloadLength	Mean	Error	StdDev	Ratio	RatioSD
Fnv1A32Block	32	51.40 ns	0.129 ns	0.114 ns	1.00	0.00
Fnv1A32SingleByte	32	104.00 ns	0.198 ns	0.165 ns	2.02	0.01
Fnv1A64Block	32	45.47 ns	0.389 ns	0.364 ns	0.88	0.01
Fnv1A64SingleByte	32	102.70 ns	0.247 ns	0.231 ns	2.00	0.01
Fnv1A128Block	32	232.16 ns	0.185 ns	0.154 ns	4.52	0.01
Fnv1A128SingleByte	32	183.46 ns	0.256 ns	0.240 ns	3.57	0.01
Fnv1A256Block	32	881.68 ns	0.473 ns	0.369 ns	17.15	0.04
Fnv1A256SingleByte	32	925.48 ns	0.646 ns	0.540 ns	18.00	0.04
Fnv1A512Block	32	2,199.22 ns	2.361 ns	1.843 ns	42.78	0.10
Fnv1A512SingleByte	32	2,209.79 ns	2.459 ns	2.054 ns	42.99	0.10
Fnv1A1024Block	32	22,662.06 ns	25.452 ns	22.562 ns	440.87	1.04
Fnv1A1024SingleByte	32	22,361.64 ns	8.785 ns	7.336 ns	435.02	0.94
Fnv1A32Block	1024	1,824.70 ns	0.527 ns	0.411 ns	1.00	0.00
Fnv1A32SingleByte	1024	3,335.86 ns	1.242 ns	1.101 ns	1.83	0.00
Fnv1A64Block	1024	1,551.64 ns	2.794 ns	2.477 ns	0.85	0.00
Fnv1A64SingleByte	1024	3,280.27 ns	5.973 ns	5.587 ns	1.80	0.00
Fnv1A128Block	1024	7,505.65 ns	14.720 ns	12.292 ns	4.11	0.01
Fnv1A128SingleByte	1024	6,699.54 ns	8.626 ns	7.203 ns	3.67	0.00
Fnv1A256Block	1024	27,622.35 ns	4.264 ns	3.329 ns	15.14	0.00
Fnv1A256SingleByte	1024	28,971.42 ns	5.264 ns	4.395 ns	15.88	0.00
Fnv1A512Block	1024	68,376.71 ns	116.513 ns	97.293 ns	37.47	0.05
Fnv1A512SingleByte	1024	70,705.70 ns	145.422 ns	128.913 ns	38.75	0.07
Fnv1A1024Block	1024	724,792.79 ns	1,498.557 ns	1,328.432 ns	397.21	0.71
Fnv1A1024SingleByte	1024	715,605.56 ns	339.826 ns	301.247 ns	392.18	0.18
Fnv1A32Block	65536	116,459.35 ns	27.407 ns	22.886 ns	1.00	0.00
Fnv1A32SingleByte	65536	207,938.78 ns	256.201 ns	213.939 ns	1.79	0.00
Fnv1A64Block	65536	99,176.16 ns	17.502 ns	15.515 ns	0.85	0.00
Fnv1A64SingleByte	65536	209,497.21 ns	171.765 ns	143.432 ns	1.80	0.00
Fnv1A128Block	65536	480,519.81 ns	258.369 ns	201.717 ns	4.13	0.00
Fnv1A128SingleByte	65536	386,017.04 ns	152.126 ns	142.299 ns	3.31	0.00
Fnv1A256Block	65536	1,766,838.49 ns	325.950 ns	272.183 ns	15.17	0.00
Fnv1A256SingleByte	65536	1,879,842.11 ns	262.729 ns	232.902 ns	16.14	0.00
Fnv1A512Block	65536	4,392,293.09 ns	3,646.681 ns	3,232.688 ns	37.72	0.03
Fnv1A512SingleByte	65536	4,423,738.27 ns	6,647.503 ns	5,892.838 ns	37.99	0.05
Fnv1A1024Block	65536	46,356,388.15 ns	12,217.543 ns	10,202.202 ns	398.05	0.11
Fnv1A1024SingleByte	65536	45,820,265.71 ns	124,585.155 ns	104,034.247 ns	393.44	0.86

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.