Feed for category: consensus
Improving SPV Security With POW Fraud Proofs

Bitcoin full nodes require increasing computer resources that are not available to most of the public, therefore most users tend to use SPV. Simplified Payment Verification is a way for users to check the validity of a block without downloading the whole blockchain, only needing a copy of the block headers of the longest chain.

This schema makes SPV clients vulnerable to forks as it is secure under the assumption that the longest chain is valid and as attacks like Segwit2x have shown and this is not always a safe assumption. A new schema has been proposed on the Bitcoin-dev mailing list that allows invalid blocks to be rejected as long as there are enough honest miners to create a block within a reasonable time frame. The new schema doesn’t fully protect clients against dishonest miners but is an improvement over the current SPV.

The Great Consensus Cleanup
The great consensus cleanup is a new BIP suggested by developer Matt Corallo to address different issues in the current Bitcoin consensus, the new set of consensus changes aim at reducing complexity of Bitcoin implementations, improving worst-case validation times and fixing vulnerabilities like timewarp.
Mast and Schnorr Signatures
Bitcoin’s development effort for the past few years has been focused on a few key concepts, privacy, scalability and efficiency. One of the first improvements was Segregated witness which is ushering in the rest, Lightning Network followed but was an effort in a different direction as it took transactions off-chain rather than optimizing the on-chain process. Some of the upcoming technologies aimed at optimizing this process are Schnorr Signatures and Merkelized Abstract Syntax Trees or MAST for short.
PSBT (BIP 174) - Partially Signed Bitcoin Transactions

Multisig transactions 1 have been a great use case of Bitcoin for the past few years, they require unsigned or partially signed transactions to be passed between multiple parties to “co-sign” them. However, there is currently no unified format for how multiple parties may share these transactions between multiple signers, it depends on the particular implementation for each wallet making it hard to do among parties using different Bitcoin wallets.

A draft BIP (174), which was proposed last year by Andrew Chow, was recently a subject of interest among Bitcoin developers. It aims to create a standard extensible format that different clients can implement making Partially Signed Bitcoin Transactions (PSBT) easier to pass around users to sign and combine their signatures.

An Introduction to Segregated Witness ( Segwit )

If you’ve been around the cryptocurrency space in the last year or so, you had to notice the insane fees on Bitcoin around December and January. Bitcoin’s adoption has been growing along its price and so the amount of transactions done per day has been going up. There was a point where a day’s worth of transaction costs in USD reached 22 Million dollars. For perspective, it currently averages at 200 thousand dollars, that’s about 99% less.

Now while Bitcoin’s price and the cryptocurrency bear market had a toll on that, last year we saw a massive effort by the Bitcoin community to drive up the number of transactions per second the blockchain could handle. To achieve this goal two strategies were proposed, one of them was Bitcoin Core’s effort introducing SegWit, short for Segregated Witness, which was activated by a user activated soft fork (UASF), and the other was Bitcoin Cash’s user activated hard fork . To further explain this we need to touch on simple basic Bitcoin blockchain technical details.