Unlike Ethereum, which was conceived as a general-purpose smart-contract platform, Bitcoin was designed primarily as a transaction ledger for its native currency, which limits programmability for conditional applications. This constraint is particularly evident when considering oracles, mechanisms that enable Bitcoin contracts to depend on exogenous events. This paper investigates whether new oracle designs have emerged for Bitcoin Layer 1 since the 2015 transition to the Ethereum smart contracts era and whether subsequent Bitcoin improvement proposals have expanded oracles' implementability. Using Scopus and Web of Science searches, complemented by Google Scholar to capture protocol proposals, we observe that the indexed academic coverage remains limited, and many contributions circulate outside journal venues. Within the retrieved corpus, the main post-2015 shift is from multisig-style, which envisioned oracles as co-signers, toward attestation-based designs, mainly represented by Discreet Log Contracts (DLCs), which show stronger Bitcoin community compliance, tool support, and evidence of practical implementations in real-world scenarios such as betting and prediction-market mechanisms.

翻译：与以太坊被构想为通用智能合约平台不同，比特币主要被设计为其原生货币的交易账本，这限制了其在条件性应用方面的可编程性。在考虑预言机——使比特币合约能够依赖于外部事件的机制——时，这一约束尤为明显。本文研究了自2015年进入以太坊智能合约时代以来，比特币Layer 1是否出现了新的预言机设计，以及随后的比特币改进提案是否扩展了预言机的可实现性。通过使用Scopus和Web of科学数据库进行检索，并辅以谷歌学术以捕获协议提案，我们观察到，索引的学术覆盖仍然有限，许多贡献在期刊渠道之外流通。在检索到的文献中，2015年后的主要转变是从多重签名风格（将预言机设想为共同签名者）转向基于证明的设计，主要以离散对数合约（DLCs）为代表。DLCs显示出更强的比特币社区合规性、工具支持以及在现实世界场景（如博彩和预测市场机制）中实际实施的证据。