chainpoint

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.

Chainpoint Standard Receipt

A standardized Chainpoint receipt format allows any system to verify a receipt by checking a Bitcoin transaction and using math to verify the data.

Table Breakdown

Header
chainpoint_version	version of the Chainpoint standard
hash_type	hashing algorithm used to encrypt target data (sha-256)
merkle_root	root of the Merkle Tree that is published in the blockchain
tx_id	transaction id where the Merkle Root is stored
timestamp	non-authoritative Unix timestamp of the target

Target
target_hash	hash of the target that is being recorded in the blockchain
target_proof	Merkle proof used to prove target_hash is part of Merkle tree
URI (optional)	path to the target

Extra
custom (optional)	hash of the target that is being recorded in the blockchain
...	...

Sample JSON

{
    "header": {
        "chainpoint_version": "1.0",
        "hash_type": "SHA-256",
        "merkle_root": "6a9a3c86d47f1fe12648c86368ecd9723ff12e3fc34f6ae219d4d9d3e0d60667",
        "tx_id": "012fdc0eb5ebae181e1197b4e9307731473118b0634d3ede749a562e9d11809e",
        "local_timestamp": "1436172703"
    },
    "target": {
        "target_hash": "2f7f9092b2d6c5c17cfe2bcf33fc38a41f2e4d4485b198c2b1074bba067e7168",
        "target_URI": "http://blockchainreciept.com/target_name",
        "target_proof": [
            {
                "left": "e1566f09e0deea437826514431be6e4bdb4fe10aa54d75aecf0b4cdc1bc4320c",
                "parent": "0fdd6b6895e15115c262f6acb9a6ae0c73248568b740454ab21591f8a533dd7f",
                "right": "2f7f9092b2d6c5c17cfe2bcf33fc38a41f2e4d4485b198c2b1074bba067e7168"
            },
            {
                "left": "0fdd6b6895e15115c262f6acb9a6ae0c73248568b740454ab21591f8a533dd7f",
                "parent": "6a9a3c86d47f1fe12648c86368ecd9723ff12e3fc34f6ae219d4d9d3e0d60667",
                "right": "3b7546ed79e3e5a7907381b093c5a182cbf364c5dd0443dfa956c8cca271cc33"
            }
        ]
    },
    "extra": [
        { "custom_key_1": "value_1"},
        { "custom_key_2": "value_2"}
    ]
}

Chainpoint Standard Block

A standardized Chainpoint block is a collection of data items which are summarized and inserted into the Bitcoin blockchain.

Table Breakdown

Block
block_num	number of block on local database
closed	can more data items be added to this block
leaves	list of hash of all the data items in this block
merkle_root	the cryptographic summary of all the data items in the block
tx_id	bitcoin transaction id in which the merkle_root was included

Sample JSON

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