Bitcoin Core: Improving Test Coverage Efficiency with Incremental Mutation Testing
Bruno Garcia introduced his work on improving mutation testing in Bitcoin Core. This technique evaluates testing effectiveness by intentionally adding systemic bugs (mutants) in the codebase: if a test fails, the mutant is “killed,” indicating the test can catch the error; if a test passes, the mutant “survives,” revealing insufficient coverage or gaps in the tests.
The goal of this work is to improve the efficiency of incremental mutation testing. Bruno Garcia validated his approach across eight pull requests, collecting feedback and suggesting changes to address mutants.
Bitcoin’s BIP Process Updated with BIP3
BIP3 defines the preparation and publication process for Bitcoin Improvement Proposals. A recently deployed update to BIP3 replaces BIP2 as the primary guideline for the BIP workflow.
While BIP3 retains most of the existing process, it introduces several simplifications and improvements. These include removing the comment system; reducing the number of BIP statuses from nine (Draft, Proposed, Active, Final, Rejected, Deferred, Withdrawn, Replaced, and Obsolete) to four (Draft, Complete, Deployed, and Closed); updating preamble headers; replacing Standards Track type with Specification type.
For more details see the change summary.
New Transaction Privacy Broadcasting Mechanism Merged into Bitcoin Core
A new transaction privacy broadcasting mechanism (GitHub PR) has been merged into Bitcoin Core. It allows locally submitted transactions (from the sendrawtransaction RPC) to be broadcast to the P2P network using Tor or I2P short-lived connections, or to IPv4/IPv6 peers via Tor, improving transaction-level privacy.
The Bitcoin Dev Project has released a SHA-256 visualization tool, Hash Explained, providing animated, interactive demonstrations of how cryptographic functions transform input text into hash values.
Users can step through each stage of the computation to gain an intuitive understanding of complex cryptographic concepts such as padding and compression.
For more details see the GitHub repo.
The Lockchain Protocol is a lightweight Bitcoin meta-protocol that enables efficient transaction discovery at zero marginal block space cost, and data verification without introducing any new on-chain storage mechanism.
The protocol repurposes the mandatory 4-byte nLockTime field in every transaction as a compact metadata header. By constraining its value to an unused range of past Unix timestamps (≥ 500,000,000), it encodes protocol signal, type, variant, and sequence identifier while remaining fully valid under the existing Bitcoin consensus and policies.
Its primary contribution lies in efficient transaction discovery: indexers only need to inspect a fixed-size header field to filter candidate transactions, independent of transaction payload size. Heavier data, such as OP_RETURN outputs or witness fields, can then be selectively parsed as needed. This approach requires no new cryptographic primitives or storage mechanisms.
See more details in the paper.
Researchers point out that while Elliptic Curve Cryptography (ECC) is widely deployed, it has seen limited systematic security testing. Exploits against ECC already exist, and with increasing computational power—alongside distributed, federated computing on the rise—the eventual erosion of ECC’s current security guarantees become inevitable.
The study explores the use of modern language model architecture in cracking the association between a known public key, and its associated private key, by reverse-engineering the public–private keypair generation process. It also evaluates whether modern machine learning models can memorize secp256r1 keypairs and whether such memorization could reverse engineer the keypair generation process. The work emphasizes that “proof-for” are equally valuable as “proof-against” for understanding ECC security.
For more details see the paper.
APoW: Auditable Proof-of-Work to Prevent Block Withholding Attacks
To address Block Withholding Attacks (BWAs) in pooled mining, Fairgate proposes APoW (Auditable Proof-of-Work), which elevates auditability to a first-class property, without relying on trusted hardware, interactive protocols, or centralized pool secrets.
At the core of APoW is v-diging (verification mining). Miners can be assigned to re-scan the same nonce space previously explored by another miner, using a modified PoW condition based on pattern matching rather than leading zeros. If a miner claims to have honestly searched a region, APoW provides a statistically meaningful chance of detecting withheld valid block solutions during verification.
Although APoW requires consensus-layer changes and poses challenges for existing ASICs, it opens a new design space for proof-of-work systems: one where mining effort itself is auditable, enabling stronger security guarantees and more robust decentralized coordination.
For more details see the paper.
BABE: Reducing BitVM3 Proof Costs by 1000×
A new proof verification protocol, BABE, introduces a low-cost verification scheme that preserves BitVM3’s on-chain cost advantages while reducing its off-chain storage and setup costs by approximately 1000×.
BABE uses witness encryption for linear pairing relations to verify Groth16 proofs, augmented with a secure two-party computation (2PC) protocol implemented using an efficient garbled circuit for scalar multiplication on elliptic curves. The garbled circuit design builds on recent work on Argo MAC (see below), which introduces an efficient garbling scheme for computing homomorphic MACs on such curves.
New Garbling Primitive Argo MAC: 1000× Efficiency Gain for Garbled SNARKs
Argo MAC is a new garbling primitive that efficiently translates from an encoding of the bit decomposition of a curve point to a homomorphic MAC of that point. This approach significantly simplifies SNARKs verification using garbled circuits and reduces circuit size by roughly 1000×.
