中文摘要：

为实现数字签名在匿名性与可追踪性之间更多、更好的均衡，在原有K次条件群签名的基础之上，提出了一种新的数字签名概念：K＋L次条件群签名，可广泛应用于电子货币、电子投票及匿名认证等领域。给出了K＋L次条件群签名的定义与安全性需求，并在原有K次条件群签名构建的基础之上，在随机预言模型（ROM）下，基于d-BDH、qSDH及DDH等数学假设构建了一个具体的安全K＋L次条件群签名方案。

英文摘要：

To achieve more and better tradeoffs between anonymity and traceability for digital signatures, a new digital signature concept is presented, i. e. K＋L times conditional group signature, which is based on the concept of K times conditional group signature. It can be applied in many scenarios such as e-cash, e-voting and anonymous credentials etc. The definition and security requirements of K＋L times conditional group signature are given. Based on old g times conditional group signature scheme, a concrete scheme are also given, whose security is based on d-BDH, q-SDH and DDH assumptions and random oracle model （ROM）.