SwiftSync - smarter synchronization with hints

In a recent discussion within the Bitcoin Development Mailing List, an intriguing cryptographic method was proposed that potentially offers a more efficient way of verifying transactions. The conversation initiated by Saint Wenhao and followed by Greg Maxwell delves into an alternative approach to the conventional hash function used in transaction validation. The participants are exploring the feasibility of using AES encryption, combined with modular arithmetic operations, as a substitute for the SHA-256 hashing algorithm commonly employed in blockchain technology.

The core of the proposal revolves around selecting a random symmetric key k and applying AES encryption to transaction outputs (UTXOs). By performing addition and subtraction on the encrypted outputs, the method aims to validate that either pairs of transactions match (A==C and B==D) or are swapped (A==D and B==C), without revealing the actual values of the transactions. This process is summarized in the equation: AES_k(UTXO_A) + AES_k(UTXO_B) - AES_k(UTXO_C) - AES_k(UTXO_D) == 0.

The proponents acknowledge that this concept is still theoretical and lacks a formal proof of its viability. However, the motivation behind this exploration is driven by the potential performance benefits. AES encryption is highlighted as being faster than SHA-256 hashing on most machines, which could lead to efficiency improvements in transaction processing times. This idea represents a novel approach in the ongoing effort to optimize cryptographic practices within the realm of blockchain development.