hashserv

[] (https://travis-ci.org/Storj/hashserv)

What is this?

We want to prove some data existed at a certain point and time, we call this Proof of Existence. We can do that by finding the cryptographic hash of some data, then inserting that hash into the Bitcoin blockchain. Since the Bitcoin blockchain is an immutable and secure public ledger, we can prove that the data existed at the time of insertion, like a mathematical notary. Unfortunately that insertion costs money, around $0.03, so it becomes expensive if I wanted to do this for 10,000+ documents.

Instead we can take that data and put it in a Merkle tree, and insert the Merkle root into the Bitcoin blockchain. For any of the items in the Merkle tree, as long as we have the Merkle proof, we can prove that it is contained in that Merkle root notarized in the Bitcoin blockchain.

Therefore we can notarize 10,000 documents for $0.03 instead of $300. It is recommended that the party notarizing their document or data hold on to the Merkle proof "receipt." This allows that party to prove that their document has been notarized in a specific Bitcoin transaction in the absence of any other data.

tldr; A federated server for building blockchain notarized Merkle trees, and returning the Merkle proof as a receipt.

Setup

In order to run you need to have a python config file in hashserv/config.py By default hashserv/config.py is set to run on testnet with a test wallet.

virtualenv -p /usr/bin/python3 venv # install virtualenv
source venv/bin/activate # activate virtualenv
python setup.py develop # install dependencies
python -c 'from hashserv.app import init_db; init_db()' # init database
python hashserv/app.py # start server

API

Add a hash to the queue for the next block. Returns the block number that the data will be inserted into. In some cases the hash is a duplicate, so the API will return the block number that the hash is in.

GET /api/submit/<sha256_hash>/
    Parameters:
    - sha256_hash
    Returns:
    - block_num

Sample Output:

47

Returns the content of a particular block.

GET /api/block/<block_num>/
	Parameters:
	- block_num
	Returns:
	- Block data

Sample Output:

{
  "block_num": 1,
  "closed": true,
  "leaves": [
    "e1566f09e0deea437826514431be6e4bdb4fe10aa54d75aecf0b4cdc1bc4320c",
    "2f7f9092b2d6c5c17cfe2bcf33fc38a41f2e4d4485b198c2b1074bba067e7168",
    "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
  ],
  "merkle_root": "6a9a3c86d47f1fe12648c86368ecd9723ff12e3fc34f6ae219d4d9d3e0d60667",
  "tx_id": "012fdc0eb5ebae181e1197b4e9307731473118b0634d3ede749a562e9d11809e"
}

The latest block on this federated server.

GET /api/block/latest_block/
    Returns:
    - Block number of the latest block

Sample Output:

78

Return a Merkle proof for an inserted item with a closed block.

GET /api/proof/<sha256_hash>/
     Parameters:
    - sha256_hash
    Returns:
    - Merkle proof and other JSON data

Sample Output:

{
  "merkle_root": "6a9a3c86d47f1fe12648c86368ecd9723ff12e3fc34f6ae219d4d9d3e0d60667",
  "proof": [
    {
      "left": "e1566f09e0deea437826514431be6e4bdb4fe10aa54d75aecf0b4cdc1bc4320c",
      "parent": "0fdd6b6895e15115c262f6acb9a6ae0c73248568b740454ab21591f8a533dd7f",
      "right": "2f7f9092b2d6c5c17cfe2bcf33fc38a41f2e4d4485b198c2b1074bba067e7168"
    },
    {
      "left": "0fdd6b6895e15115c262f6acb9a6ae0c73248568b740454ab21591f8a533dd7f",
      "parent": "6a9a3c86d47f1fe12648c86368ecd9723ff12e3fc34f6ae219d4d9d3e0d60667",
      "right": "3b7546ed79e3e5a7907381b093c5a182cbf364c5dd0443dfa956c8cca271cc33"
    }
  ],
  "target": "2f7f9092b2d6c5c17cfe2bcf33fc38a41f2e4d4485b198c2b1074bba067e7168",
  "tx_id": "012fdc0eb5ebae181e1197b4e9307731473118b0634d3ede749a562e9d11809e"
}

Notarize the current block, and start a new one.

GET /api/block/generate/
    Returns:
    - Number of block written in the blockchain

Sample Output:

Block 3 Built.