Bitcoin: Is there an idiomatic way to prove ownership of an (extended) public key?
Is there an idiomatic way to prove ownership of a public key other than spending coins?
In the world of cryptocurrencies like Bitcoin, it’s not uncommon for users to be asked to prove ownership of their private keys or public addresses. However, traditional methods like spending coins aren’t always enough. In this article, we’ll explore idiomatic ways to verify ownership of an extended public key without using coins.
What are extended public keys?
Extended public keys refer to any type of public key that includes additional information beyond the standard 32 bytes (256 bits) associated with a regular public key. This can include various identifiers, such as account balances, transaction IDs, or even IP addresses. While these extended keys offer more flexibility and convenience, they also introduce new security challenges.
Idiomatic Methods for Verifying Ownership
Here are some idiomatic ways to verify ownership of an extended public key without spending coins:
- Domain Name System (DNS) Record: If you have a website or online service associated with your private key, you can use DNS records to indicate that the owner’s identity is tied to that key. This approach does not require any cryptocurrency transactions.
- IP Address Verification: If you have an IP address associated with your private key, you can verify ownership using tools like Whois or IP Whois services. These services allow users to look up and validate domain names, including those used for public keys.
- OpenID Connect: OpenID Connect (OIDC) is a standard identity layer that allows users to associate their public key with an email address or username. By verifying ownership through OIDC, you can create a secure link between your private key and the associated account information.
- Hash-based verification: A hash-based approach involves generating a digital fingerprint of your private key using a cryptographic algorithm such as SHA-256 or BLAKE2b. This hash value can be used to verify the identity of someone who possesses an extended public key.
Producing a transaction as proof
For methods that require spending coins, you can create a transaction to prove ownership by producing a specific output with a large amount of cryptocurrency (e.g., 100 BTC or 10 million Nubits). This approach is commonly used on decentralized finance (DeFi) platforms such as Uniswap.
Here is an example of how to produce such a transaction:
- Create a new contract instance using your public key.
- Set the output value and associated gas limit for the transaction.
- Include any input addresses or parameters needed to satisfy the transaction requirements.
- Execute the transaction, which will create a new block on the blockchain.
Conclusion
While traditional methods such as coin-spending may not be suitable for verifying ownership of extended public keys without using coins, these idiomatic approaches offer more flexibility and security. By leveraging DNS records, IP address verification, OpenID Connect, hash-based verification, or producing transactions as proof, you can ensure that your private key is tied to the associated identity, minimizing the need for cryptocurrency spending.
Keep in mind that these methods can have different levels of complexity and usability depending on the specific use case. Be sure to evaluate each approach carefully before selecting the solution that best suits your needs.
