Universally Composable Bitcoin Ledger

The podcast explores the security of the Bitcoin protocol using the universal composability (UC) framework. A UC security proof for Bitcoin is presented, specifying its goal as a parametrizable ledger functionality. A new, weaker but implementable ledger functionality is proposed, demonstrating that an abstraction of the Bitcoin protocol securely achieves it under certain assumptions (global clock, random oracle, and idealized network). It shows how previous property-based approaches can be viewed as special cases of this UC treatment, and discusses the implications for composition with other protocols. Finally, the improvement of security guarantees by incorporating public key cryptography is analyzed.