Weak coin flipping is a cryptographic primitive in which two mutually distrustful parties generate a shared random bit to agree on a winner via remote communication. While a stand-alone secure weak coin flipping protocol can be constructed from noiseless communication channels, its composability has not been explored. In this work, we demonstrate that no weak coin flipping protocol can be abstracted into a black box resource with composable security. Despite this, we also establish the overall stand-alone security of weak coin flipping protocols under sequential composition.

翻译：弱硬币翻转是一种密码学原语,其中两个互不信任的方通过远程通信生成一个共享随机比特以决定获胜者。虽然基于无噪声通信信道可以构造独立安全的弱硬币翻转协议,但其可组合性尚未被探索。在本文中,我们证明了任何弱硬币翻转协议都无法抽象为具有可组合安全性的黑盒资源。尽管如此,我们也在顺序组合下确立了弱硬币翻转协议的整体独立安全性。