Account abstraction allows a contract wallet to initiate transaction execution. Thus, account abstraction is useful for preserving the privacy of externally owned accounts (EOAs) because it can remove a transaction issued from an EOA to the contract wallet and hides who issued the transaction by additionally employing anonymous authentication procedures such as ring signatures. However, unconditional anonymity is undesirable in practice because it prevents to reveal who is accountable for a problem when it arises. Thus, maintaining a balancing between anonymity and accountability is important. In this paper, we propose an anonymous yet accountable contract wallet system. In addition to account abstraction, the proposed system also utilizes accountable ring signatures (Bootle et al., ESORICS 2015). The proposed system provides (1) anonymity of a transaction issuer that hides who agreed with running the contract wallet, and (2) accountability of the issuer, which allows the issuer to prove they agreed with running the contract wallet. Moreover, due to a security requirement of accountable ring signatures, the transaction issuer cannot claim that someone else issued the transaction. This functionality allows us to clarify the accountability involved in issuing a transaction. In addition, the proposed system allows an issuer to employ a typical signature scheme, e.g., ECDSA, together with the ring signature scheme. This functionality can be considered an extension of the common multi-signatures that require a certain number of ECDSA signatures to run a contract wallet. The proposed system was implemented using zkSync (Solidity). We discuss several potential applications of the proposed system, i.e., medical information sharing and asset management.

翻译：账户抽象允许合约钱包主动发起交易执行。因此，账户抽象有助于保护外部拥有账户（EOA）的隐私，因为它可以消除从EOA发往合约钱包的交易记录，并通过额外采用环签名等匿名认证程序来隐藏交易发起者身份。然而，无条件匿名在实践中并不可取，因为当问题出现时，这会阻碍确定责任方。因此，在匿名性与可追责性之间保持平衡至关重要。本文提出了一种匿名且可追责的合约钱包系统。除账户抽象外，该系统还采用了可追责环签名（Bootle等人，ESORICS 2015）。所提系统具备以下特性：（1）交易发起者的匿名性——隐藏同意执行合约钱包的具体身份；（2）发起者的可追责性——允许发起者证明自己曾同意执行合约钱包。此外，基于可追责环签名的安全要求，交易发起者无法否认交易行为或声称交易由他人发起。该功能使我们能够明确交易发起过程中的责任归属。同时，所提系统允许发起者将典型签名方案（如ECDSA）与环签名方案结合使用。此功能可视为对常规多重签名的扩展——后者通常要求特定数量的ECDSA签名才能执行合约钱包。我们使用zkSync（Solidity）实现了所提系统，并探讨了其在医疗信息共享与资产管理等领域的潜在应用场景。