Universal Composition with Responsive Environments
Universal Composition with Responsive Environments
复制标题
DOI：
10.1007/978-3-662-53890-6_27
复制
发表时间：
2016-12
期刊：
影响因子：
--
通讯作者：
J. Camenisch;Robert R. Enderlein;S. Krenn;Ralf Küsters;Daniel Rausch
中科院分区：
文献类型：
--
作者：
J. Camenisch;Robert R. Enderlein;S. Krenn;Ralf Küsters;Daniel Rausch
在通用可组合性框架中，对手(或环境)和协议/理想功能通常必须在网络接口上交换元信息，例如算法、密钥、签名、密文、信令信息和与损坏相关的消息。对于这些不反映实际网络通信的纯粹与建模相关的消息，对手/环境通常非常合理和自然地立即提供所请求的信息，或者在接收到某些信息之后立即将控制权交还给协议/功能。然而，在现有的通用可组合性模型中，没有一种模型能保证这一点。我们称之为无响应性问题。正如我们将在本文中讨论的那样，尽管形式上的非响应性不会使任何通用的可组合性模型失效，但它有许多缺点，如不必要的复杂规范和较低的表现力。此外，这个问题在文献中经常被忽视，导致规范定义不明确和有缺陷。协议设计者真的不应该关心这个问题，但目前他们不得不关心：给对手/环境不立即响应建模相关请求的选项并不能转化为任何真实的攻击场景，通过完全避免这种人工建模问题，完全解决了无响应问题及其负面后果。我们提出了响应环境和对手的新概念。在激活任何其他协议/功能之前，此类环境和对手必须提供对与建模相关的请求的有效响应。因此，协议设计人员不必再担心由于此类请求未得到及时响应而导致的人工产物。我们的概念适用于所有现有的通用可组合性模型，如UC、GNUC和IITM模型，并为IITM模型提供了完整的定义和证明(模拟关系、传递性、各种模拟概念的等价性和合成定理)。
In universal composability frameworks, adversaries (or environments) and protocols/ideal functionalities often have to exchange meta-information on the network interface, such as algorithms, keys, signatures, ciphertexts, signaling information, and corruption-related messages. For these purely modeling-related messages, which do not reflect actual network communication, it would often be very reasonable and natural for adversaries/environments to provide the requested information immediately or give control back to the protocol/functionality immediately after having received some information. However, in none of the existing models for universal composability is this guaranteed. We call this thenon-responsiveness problem. As we will discuss in the paper, while formally non-responsiveness does not invalidate any of the universal composability models, it has many disadvantages, such as unnecessarily complex specifications and less expressivity. Also, this problem has often been ignored in the literature, leading to ill-defined and flawed specifications. Protocol designers really should not have to care about this problem at all, but currently they have to: giving the adversary/environment the option to not respond immediately to modeling-related requests does not translate to any real attack scenario.This paper solves the non-responsiveness problem and its negative consequences completely, by avoiding this artificial modeling problem altogether. We propose the new concepts of responsive environments and adversaries. Such environments and adversaries must provide a valid response to modeling-related requests before any other protocol/functionality is activated. Hence, protocol designers do no longer have to worry about artifacts resulting from such requests not being answered promptly. Our concepts apply to all existing models for universal composability, as exemplified for the UC, GNUC, and IITM models, with full definitions and proofs (simulation relations, transitivity, equivalence of various simulation notions, and composition theorems) provided for the IITM model.