Block Headers Service

The Block Headers Service is a standalone service that communicates with the Bitcoin network using the P2P protocol. It is used to retrieve block headers and data related to them.

Table of Contents

How it is used in the SPV Wallet ecosystem

The Block Headers Service (BHS) is used by the SPV Wallet to verify the validity of merkle roots.

This service exposes a REST API with multiple endpoints, the most important from the SPV Wallet user perspective is:

GET /chain/merkleroots/verify

How merkle roots are verified

The SPV Wallet sends a request to the BHS with an array of merkle roots and the block height.

[
  {
    "blockHeight": 0,
    "merkleRoot": "string"
  }
]

The BHS should return an object which contains general information about confirmation process called confirmationState and an array of validated merkle roots with blockHash, blockHeight, confirmation state and merkleRoot.

[
  {
    "confirmationState": "CONFIRMED",
    "confirmations": [
      {
        "blockHash": "string",
        "blockHeight": 0,
        "confirmation": "CONFIRMED",
        "merkleRoot": "string"
      }
    ]
  }
]

Confirmation passes only if both - blockHeight and merkleRoot are valid pair.

⚠️ Note: BHS only checks for merkle roots in Longest Chain. It does not check for merkle roots in Side Chains.

⚠️ Note: There might be a case that merkle root is valid but BHS does not have it in its database. It happens when the block is freshly mined and BHS did not receive it yet.

Authentication

Block Headers Service API needs a valid Bearer token to be used. You can set the token in config.yaml file.

When running this service from start.sh script, the token would be default and properly set on both spv-wallet and block-headers-service.

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