Proof-of-work based signet faucet

This new functionality allows for complex operations such as direct on-chain Proof of Work (PoW) validation, where scripts can manipulate and verify hash bytes by concatenating and validating them within the transaction logic. Such advancements make it possible to create mechanisms for distributing coins based on actual PoW contributions, moving beyond the traditional reliance on allocations from block producers. The introduction of PoW-based coin distribution is exemplified by a proof-of-concept transaction and an accompanying Python script for claiming funds. Safeguards are in place to prevent reusing PoW across multiple claims or by unauthorized entities; cryptographic techniques ensure that each proof is uniquely bound to its claimant and can only be used once, leveraging signature verification and length commitments to secure the process. Emphasizing compatibility with Bitcoin ASICs aligns this system with existing mining infrastructure, and technical implementation details—such as scripting for difficulty, data concatenation, and preimage verification—ensure that only valid PoW submissions are rewarded.

Utilizing transaction hashes from mempool transactions as a method for PoW presents notable advantages in cryptocurrency operations. Security is inherently enhanced, as any alteration to a transaction modifies its hash, making theft or duplication virtually impossible. The uniqueness of these hashes means each transaction is essentially non-reusable except under rare circumstances, like coinbase transaction reuse, which typically signals deeper systemic issues. With relatively small transaction sizes (as low as 80 bytes), this approach remains compatible with ASIC hardware, especially when using signature forms like SIGHASH_SINGLE | SIGHASH_ANYONECANPAY. These signatures allow parts of the transaction to be signed so that the hash of the message (z-value) can have leading zeroes, meeting the PoW requirements. Efficiency gains are realized by enabling the claim of multiple coins in one transaction if the overall hash satisfies the required difficulty, as shown in this transaction example, thereby simplifying and streamlining reward collection.

Operational experiences with Bitcoin signet's PoW coin claims reveal the importance of adhering to predefined difficulty rules. Successful claims require meeting or exceeding the minimum difficulty threshold, with attempts below this threshold resulting in errors. Adjusting claim parameters to comply with these settings enables successful transactions, as evidenced by corresponding transaction IDs. This procedural clarity underscores the necessity of conforming to network requirements for efficient asset management on signet.

To further facilitate user participation, a standalone repository for mining PoW faucet coins is available at https://github.com/ajtowns/powcoins. This resource allows users to mine and claim coins without running an inquisition node locally, greatly lowering the entry barrier and offering a more accessible pathway to engage in mining activities.

On testnet4, a specific Pay to Proof of Work (P2W) address demonstrates an innovative scripting technique (address link). The script checks for DER signatures less than 60 bytes, creating a unique mechanism to adjust difficulty by reducing the size of the signature. This approach leverages the properties of DER signatures and P2WSH outputs, providing an effective way to implement PoW-linked addresses without changing consensus rules or adding new opcodes like OP_CAT. The preference for P2WSH over P2SH ensures standard transaction formats and broad compatibility, making this solution both elegant and practical for widespread adoption.

An important enhancement now allows users to claim coins directly on the mainnet, as illustrated by a recent transaction. This opens new avenues for interactive engagement and expands the system’s flexibility. Users can append PoW challenges to any output script, increasing security