xxHash convert resulting in hash too long

Question

I'm using xxHash for C# to hash a value for consistency. ComputeHash returns a byte[], but I need to store the results in a long.

I'm able to convert the results into an int32 using the BitConverter. Here is what I've tried:

var xxHash = new System.Data.HashFunction.xxHash();
byte[] hashedValue = xxHash.ComputeHash(Encoding.UTF8.GetBytes(valueItem));
long value = BitConverter.ToInt64(hashedValue, 0);

When I use int this works fine, but when I change to ToInt64 it fails.

Here's the exception I get:

Destination array is not long enough to copy all the items in the collection. Check array index and length.

Answer 1

Adding a new answer because current implementation of xxHash from Brandon Dahler uses a hashing factory where you initialize the factory with a configuration containing hashsize and seed:

using System.Data.HashFunction.xxHash;

//can also set seed here, (ulong) Seed=234567
xxHashConfig config = new xxHashConfig() { HashSizeInBits = 64 };
var factory = xxHashFactory.Instance.Create(config);
byte[] hashedValue = factory.ComputeHash(Encoding.UTF8.GetBytes(valueItem)).Hash;