ByteArrayEqualityComparer.cs

using System;
using System.Collections.Generic;

public class ByteArrayEqualityComparer : IEqualityComparer<byte[]>
{
    // FNV1-1a 32bit https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
    public int GetHashCode(byte[] obj)
    {
        uint hash = 0;
        if (obj != null)
        {
            hash = 2166136261;
            for (int i = 0; i < obj.Length; i++)
            {
                hash = unchecked((obj[i] ^ hash) * 16777619);
            }
        }

        return unchecked((int)hash);
    }

    public bool Equals(byte[] xs, byte[] ys)
    {
        if (object.ReferenceEquals(xs, ys)) return true;
        if (xs == null) return false;
        if (ys == null) return false;
        if (xs.Length != ys.Length) return false;

        for (int i = 0; i < xs.Length; i++)
        {
            if (xs[i] != ys[i]) return false;
        }
        return true;
    }
}

class Program
{
    static void Main(string[] args)
    {
        var xs = new byte[] { 1, 10, 100 };
        var ys = new byte[] { 1, 10, 100 };
        var zs = new byte[] { 1, 10, 150 };

        var dict = new Dictionary<byte[], int>(new ByteArrayEqualityComparer());
        dict.Add(xs, 0);
        Console.WriteLine(dict.ContainsKey(ys)); // true;
        Console.WriteLine(dict.ContainsKey(zs)); // false
    }
}