Rollback Attacks Research Articles

SvTPM: SGX-Based Virtual Trusted Platform Modules for Cloud Computing

Virtual Trusted Platform Modules (vTPMs) are widely used in commercial cloud platforms (e.g., VMware Cloud, Google Cloud, and Microsoft Azure) to provide virtual root-of-trust and security services for virtual machines. Unfortunately, current state-of-the-art vTPM implementations for cloud computing cannot provide strong protection for vTPMs at run-time and suffer from poor performance under binding vTPMs to a physical TPM. In this paper, we propose SvTPM, an SGX-based virtual trusted platform module, which provides complete life cycle protection of vTPMs in the cloud and does not rely on the physical TPM. SvTPM provides strong isolation protection so malicious cloud tenants or even cloud administrators cannot access vTPM's private keys or any other sensitive data. In this paper, we implement a prototype of SvTPM, which identifies and solves a couple of critical security challenges for vTPM protection with SGX, such as NVRAM rollback attacks, NVRAM binding attacks, and vTPM rollback attacks. SvTPM also shows how to establish trust between vTPM and SGX Platform. Our performance evaluation shows that the NVRAM launch time of SvTPM is <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$1700\times$</tex-math></inline-formula> faster than vTPM built upon hardware TPM. In TPM standard command evaluation, we find that SvTPM incurs negligible performance overhead while providing strong isolation and protection. To our knowledge, SvTPM is the first practical work to solve the critical security challenges of securing vTPM using SGX.

L2chain

With the rapid development of blockchain, the concept of decentralized applications (DApps), built upon smart contracts, has attracted much attention in academia and industry. However, significant issues w.r.t. system throughput, transaction confidentiality, and the security guarantee of the DApp transaction execution and order correctness hinder the border adoption of blockchain DApps. To address these issues, we propose L2chain, a novel blockchain framework aiming to scale the system through a layer-2 network where DApps process transactions in the layer-2 network and only the system state digest, acting as the state integrity proof, is maintained on-chain. To achieve high performance, we introduce the split-execute-merge (SEM) transaction processing workflow with the help of the RSA accumulator, allowing DApps to lock and update a part of the state digest in parallel. We also design a witness cache mechanism for DApp executors to reduce the transaction processing latency. To fulfill confidentiality, we leverage the trusted execution environment (TEE) for DApps to execute encrypted transactions off-chain. To ensure transaction execution and order correctness, we propose a two-step execution process for DApps to prevent attacks ( i.e. , rollback attacks) from subverting the state transition. Extensive experiments have demonstrated that L2chain can achieve 1.5X to 42.2X and 7.1X to 8.9X throughput improvements in permissioned and permissionless settings respectively.

A revocable multi-authority fine-grained access control architecture against ciphertext rollback attack for mobile edge computing

Mobile edge computing is an emerging decentralized cloud paradigm that can provide real-time mobile services for users. But there are some limitations in the existing access control architectures for mobile edge computing, such as low efficiency, poor expansibility and high algorithm complexity. Therefore in this paper, we propose a decentralized ciphertext-policy attribute-based encryption scheme which with mutually verifiable outsourced decryption and non-delegated computing mode attribute revocation as the fine-grained access control model for the mobile edge cloud. Compared with the state-of-art access control models with revocation function, first, our scheme is based on Type-3 pairing, which has higher efficiency and stronger security. Second, our outsourcing decryption algorithm can realize mutual verification, that is, not only the server can verify the validity of the user’s outsourcing key, but also the user can verify the correctness of the decrypted plaintext. Thirdly, our revocation algorithm can not only resist ciphertext rollback attacks to achieve the genuine backward and forward security, but also does not need the assistance of any intermediate proxy server, which greatly simplifies the network topology.

SPChain: Blockchain-based medical data sharing and privacy-preserving eHealth system

The sharing of electronic medical records (EMRs) has great positive significance for research on disease and epidemic prevention. Recently, blockchain-based eHealth systems have achieved great success in terms of EMRs sharing and management, but there still remain some challenges. Permissioned blockchain-based solutions provide high throughput and scalability, but may suffer from rollback attacks and lead to privacy leakage. Designs based on the public blockchain, on the other hand, are more open and secure, but sacrifice scalability and have no incentives for medical institutions to join into the systems. Moreover, data retrieval in blockchain-based eHealth systems is inefficient because of the basic blockchain structure. To solve the above problems, we propose a blockchain-based medical data sharing and privacy-preserving eHealth system named SPChain. To achieve quick retrieval, we devise special keyblocks and microblocks for patients to store their EMRs. A reputation system is also constructed to motivate medical institutions to participate in SPChain. By using proxy re-encryption schemes, SPChain achieves medical data sharing for patients in a privacy-preserving manner. To evaluate SPChain, we leverage the distribution of miners in the real world to test the system’s performance and ability to resist mentioned attacks. The results show that SPChain can achieve high throughput (220 TPS) with low storage overhead. Compared with the existing schemes, SPChain achieves lower time complexity in terms of data retrieving, and can resist proposed blockchain attacks as well as SPChain attacks.

A Hybrid Multi-level Mechanism for Application Integrity Checking

The protection of the integrity of the computer system, although not able to deal with all security threats, is still essential to enhance the overall security of the system. Integrity check may be a reasonable way to protect application from tampering with low cost. This paper designs a multi-level check mechanism of application integrity with multiple inspection methods, which can better display the advantages of different inspection methods. Hybrid checking method may be utilized for different file integrity checking demands. The paper also demonstrate the implementation of a high-performance Linux page-level integrity checking method, in reference to the design in NetBSD system. Experiment results show that it may better deal with the application file rollback attacks. And on machine with limited resource, for example, thin client, the overhead of integrity checking can be lower than 10%.