SegWit: What is it and how has it changed Bitcoин

SegWit (Segregated Witness) is a fundamental improvement to the architecture of Bitcoin, designed to address scaling issues and network vulnerabilities. This innovation has radically transformed the way the network processes and verifies transactions.

The mechanism of SegWit: how it really works

At the heart of SegWit lies a simple yet powerful idea: splitting the transaction structure into two components. The first part contains information about the transfer of funds, while the second includes cryptographic signatures, public keys, and other verification metadata.

The key difference is that the signature data (, so-called “witnesses” ), is physically separated from the main body of the transaction. This allowed the system to exclude them from the block size calculation. Thanks to this approach, the volume of one block effectively increased from 1 MB to approximately 4 MB, although the nominal limit remained the same.

History of Implementation and Evolution

The concept was developed in 2015 by developer Peter Willems together with the Bitcoin Core team. After two years of testing and discussion in the community, the update was deployed as a soft fork in August 2017. This meant that the change was backward compatible with older versions of the software.

Practical Impact on the Network

Without the implementation of this protocol, digital signatures can take up to 65% of the block size, creating a serious bottleneck for throughput. SegWit addressed this issue radically: by redistributing data, the network gained the ability to accommodate significantly more transactions per unit of time.

The results are impressive: the network's throughput has significantly increased, processing speed has accelerated, and the TPS ( transactions per second ) has shown a clear improvement. Moreover, the separation of signatures has eliminated a vulnerability known as the transaction malleability problem, where attackers could modify payment identifiers before their final confirmation.

This vulnerability was critical for the development of second-layer decentralized solutions, such as the Lightning Network, which require absolute stability of transaction identifiers.

Controversy in the crypto community

The implementation of SegWit did not go smoothly. An intense discussion about the feasibility and security of such an approach unfolded within the Bitcoin ecosystem. The disagreements were so deep that they led to a split in the community and the creation of Bitcoin Cash — a fork of Bitcoin that took an alternative path of increasing block size without the use of Segregated Witness.

Critics of SegWit pointed to potential risks: the complexity of implementation, possible vulnerabilities in the new architecture, and the theoretical danger that certain transactions could be spent by unauthorized parties. Despite skepticism, the majority of the network supported the upgrade, and it has been functioning successfully to this day.