Formal Analysis of Enhanced Authorization in the TPM 2.0

Abstract

The Trusted Platform Module (TPM) is a system component that provides a hardware-based approach to establish trust in a platform by providing protected storage, robust platform integrity measurement, secure platform attestation and other secure functionalities. The access to TPM commands and TPM-resident key objects are protected via an authorization mechanism. Enhanced Authorization (EA) is a new mechanism introduced by the TPM 2.0 to provide a rich authorization model for specifying flexible access control policies for TPM-resident objects.In our paper, we conduct a formal verification of the EA mechanism. Firstly, we propose a model of the TPM 2.0 EA mechanism in a variant of the applied pi calculus. Secondly, we identify and formalize the security properties of the EA mechanism (Prop.1 and 2) in its design. We also give out a misuse problem that is easily to be neglected (Lemma 7). Thirdly, using the SAPIC tool and the tamarin prover, we have verified both the two security properties. Meanwhile, we have found 3 misuse cases and one of them leads to an attack on the application in [12].

Symbolic Models for Isolated Execution Environments

“…In [19], [20], Delaune et al analyse parts of the Trusted Platform Module (TPM) [21] instruction set using ProVerif. In [22], Shao et al model the enhanced authorization mechanism introduced in the TPM 2.0 specification and analyse it using SAPIC. These approaches are however different in the sense that they model some instructions offered by the TPM, while we directly add a report mechanism to the language.…”

Automated Analysis of Security Protocols with Global State

“…In our modelling of the Yubikey the server can handle several requests from different devices in parallel, which was not possible in the direct modelling in [21]. Another example is the model of the enhanced authorization mechanism introduced in the TPM 2.0 specification by Shao et al [32]. In this work, a model of the TPM that executes API commands sequentially is compared to one that executes them in parallel, finding flaws in the parallel version.…”

“…The present calculus and verification method have been used to verify a configuration of the key-management API PKCS#11 [20] and was extended with loops to allow for the analysis of the streaming protocol TESLA [25]. In [32], Shao et al used our tool to analyse the enhanced authorization mechanism introduced in the TPM 2.0 specification.…”

“…Related work complements these case studies with an analysis of a more complete model of PKCS#11 [20], and the enhanced authorisation mechanism in the TPM 2.0 [32], as well as an extension of SAPIC that allows for the analysis of stream protocols such as TESLA [25].…”

Trusted computing theory and technology in innovation-driven development

“…HMAC 授权会话方面, 我们在计算模型下使用安全协议验 证工具 CryptoVerif 分析了 TPM 2.0 的 HMAC 授权, 证明 HMAC 授权会话满足认证性 [17] . 策略授 权方面, 采用应用 Pi 演算形式化分析了 TPM 2.0 的策略授权安全机制, 通过 Tarmarin 自动化验证工 具我们发现 NV 策略授权存在 TOCTOU 攻击 [18] . DAA 协议接口方面, 我们发现 TPM 2.0 规范所实 现的 DAA 协议 API 存在 Static DH oracle 攻击的风险 [19] , 并且基于进程代数对 DAA 协议实现建模 分析, 利用进程演算验证工具 ProVerif 自动化分析发现 DAA 协议不满足前向匿名性.…”