Concatenate the Hashes

What does Concatenate the Hashes mean?

A simple, important, and boring piece of the hashing toolkit.

Introduction:

If you don’t know anything about hashes, Geeq Demystifies : The Hardworking Hash is an introduction for you.

If you have never seen a hash in blockchain before, you can try it in less than 15 seconds. Go to the Geeq Data app and use the sample file in Step 1. Then do Step 2. You will see the hash of the sample file represented as this long set of characters, called an alphanumeric string:

a7804a7d6d67a1e17b03b8560b5f5467477dd4996cde55771ddcb9a91ab9ff23

Here is the same information presented as an equation:

Hash (sample) = a7804a7d6d67a1e17b03b8560b5f5467477dd4996cde55771ddcb9a91ab9ff23

Sometimes the beginning and end of a hash are written to save space, although you should always be able to verify the entire string if you expand it:

Hash (sample) = a7804…9ff23

Sometimes the left hand side is written like this: Hash_sample or H_sample

Hash_sample = a7804…9ff23
H_sample = a7804…9ff23

Main Idea:

Concatenating two hashes means taking the hash of each object separately and then literally putting the two results side by side without spaces. We’ll hash this One Pager with the Geeq Data app.

Geeq uses the Blake3 algorithm so each hash is 32 bytes.

1. Take the hash of (sample) = a7804…9ff23.
   
2. Take the hash of (OnePager) = 33107fc26223f03e38ce804d753269d4cdc5f7ad8cbe258607146506d1c3c52e
   
   We can abbreviate the second hash like this: Hash (OnePager) = 33107…3c52e
   
3. To concatenate the hashes, we want the hash of (a7804…9ff2333107…3c52e) or the hash of (a7804a7d6d67a1e17b03b8560b5f5467477dd4996cde55771ddcb9a91ab9ff2333107fc26223f03e38ce804d753269d4cdc5f7ad8cbe258607146506d1c3c52e)
   
   which is: c936a1f69058dc9538592a22231a90da86fddc31872f59fc06253b8d9522396a
   
4. The concatenation we just calculated is written like as an equation like this:
   
   hash (H_sample | H_OnePager) = c936a…2396a

Conclusion:

It is very easy for a computer to calculate a hash. Geeq is data-agnostic. That means you can adapt Geeq Data to suit any application you want. For example, instead of the Geeq Data app we support, you could write an app to upload a video or song which are other forms of digitized data. Perhaps you would like to send those exact versions to a Geeq chain to capture exactly what they were to preserve evidence.

In every case, the protocol running behind the scenes will be generating hashes and concatenating hashes to produce Geeq’s durable proofs.

The Geeq Difference:

Blockchain protocols concatenate hashes frequently, because that is the technique used to calculate merkle roots, merkle trees, and merkle proofs. Geeq uses the same methods to produce its durable proofs. However, Geeq’s 1 kb proof is parsimonious because Geeq’s data records are structured so it is easy to find the very small pieces of data that have to be hashed.

Used in a Sentence (and this is Important):

Be careful to notice the order in which the hashes are concatenated. We calculated the
hash (H_sample | H_OnePager) = c936a…2396a.

You will get an entirely different result if you hash (H_OnePager | H_sample) =
498877b977ac73f984fbe283e14335b45c37436c2b5c9b2f4bfe4dd3fa858c13.

If you are trying to verify a proof on your own, you will need to follow the same order as the protocol does when you concatenate the hashes. Fortunately, Geeq’s protocol provides clear and standardized sets of instructions.

Last Updated: November 15, 2023