The evolution of sighash_noinput in Ethereum and its place on the Lightning Network
At the beginning of the Lightning network, Joseph Poon’s original White Paper proposed a crucial feature: Sighash_Noinput (Sighash) had to be used as a condition for creating an engagement transaction that refers to another transaction without actually involving it. However, this approach has undergone significant changes with network development.
Original intention
In Lightning White Paper, Poon wrote: “The first commitment should be able to refer to the TXID financing transaction without really including it.” This condition is designed to allow the creation of a commitment that could verify the authenticity and integrity of a transaction as it refers to its origin. Using Sighash_Noinpt, transactions would not require network entries, which would simplify the process and reduce network complexity.
Evolution
Over time, however, the Lightning network has evolved considerably. The introduction of the functionality of “Funding Transactions” (FTX) in 2017 marked an important step in the development of Sighash_Noinput. By allowing FTXs to get involved without the need for network inputs, developers can simplify the process and reduce the complexity of transaction validation.
SIGHASH_NOINPUPT No Modern Ethereum
In modern Ethereum, sighash_noinput is always used for certain purposes. However, its role has decreased considerably in relation to its original intention. In fact, most lightning network transactions now use other mechanisms, such as the “Commits” field or the “sequence number” to achieve similar goals.
For example, when creating an engagement transaction that refers to another transaction without really accepting it, developers can use a combination of these methods:
- The Commitment Field: It is used to specify a specific range of transactions.
- Sequence numbers: They are attributed to each transaction and can be used to check the event sequence.
- FTXS (Transaction Fund): As mentioned above, FTX allows you to request transactions without network contribution.
Conclusion
Although Sighash_Noinput is always used in certain Ethereum contexts, its original intention has been widely replaced by more efficient and rationalized mechanisms. The lightning network continues to evolve and developers exploit new ways to simplify transactions validation and reduce complexity. As we move forward, it will be interesting to see how Sighash_Noinput evolves or replaces these alternative solutions.
Sources:
- “White book of the Lightning Network” (2017)
- White Book Ethereum: “The Ethereum 2.0 Testnet and The Lightning Network” (2020)