Black-Box Constructions of Signature Schemes in the Bounded Leakage Setting

To simplify the certificate management procedures, Shamir introduced the concept of identity-based cryptography (IBC). However, the key escrow problem is inherent in IBC. To get rid of it, Al-Riyami and Paterson introduced in 2003 the notion of certificateless cryptography (CLC). However, if a cryptosystem is not perfectly implemented, adversaries would be able to obtain part of the system\u27s secret state via side-channel attacks, and thus may break the system. This is not considered in the security model of traditional cryptographic primitives. Leakage-resilient cryptography was then proposed to prevent adversaries from doing so. There are fruitful works on leakage-resilient encryption schemes, while there are not many on signature schemes in the leakage setting. In this work, we review the folklore generic constructions of identity-based signature and certificateless signature, and show that if the underlying primitives are leakage-resilient, so are the resulting identity-based signature scheme and certificateless signature scheme. The leakage rate follows the minimum one of the underlying primitives. We also show some instantiations of these generic constructions

Leakage-resilient biometric-based remote user authentication with fuzzy extractors

National Research Foundation (NRF) Singapor

Stacco: Differentially Analyzing Side-Channel Traces for Detecting SSL/TLS Vulnerabilities in Secure Enclaves

Intel Software Guard Extension (SGX) offers software applications enclave to protect their confidentiality and integrity from malicious operating systems. The SSL/TLS protocol, which is the de facto standard for protecting transport-layer network communications, has been broadly deployed for a secure communication channel. However, in this paper, we show that the marriage between SGX and SSL may not be smooth sailing. Particularly, we consider a category of side-channel attacks against SSL/TLS implementations in secure enclaves, which we call the control-flow inference attacks. In these attacks, the malicious operating system kernel may perform a powerful man-in-the-kernel attack to collect execution traces of the enclave programs at page, cacheline, or branch level, while positioning itself in the middle of the two communicating parties. At the center of our work is a differential analysis framework, dubbed Stacco, to dynamically analyze the SSL/TLS implementations and detect vulnerabilities that can be exploited as decryption oracles. Surprisingly, we found exploitable vulnerabilities in the latest versions of all the SSL/TLS libraries we have examined. To validate the detected vulnerabilities, we developed a man-in-the-kernel adversary to demonstrate Bleichenbacher attacks against the latest OpenSSL library running in the SGX enclave (with the help of Graphene) and completely broke the PreMasterSecret encrypted by a 4096-bit RSA public key with only 57286 queries. We also conducted CBC padding oracle attacks against the latest GnuTLS running in Graphene-SGX and an open-source SGX-implementation of mbedTLS (i.e., mbedTLS-SGX) that runs directly inside the enclave, and showed that it only needs 48388 and 25717 queries, respectively, to break one block of AES ciphertext. Empirical evaluation suggests these man-in-the-kernel attacks can be completed within 1 or 2 hours.Comment: CCS 17, October 30-November 3, 2017, Dallas, TX, US

Unbounded Leakage-Resilience and Leakage-Detection in a Quantum World

Side-channel attacks, which aim to leak side information on secret system components, are ubiquitous. Even simple attacks, such as measuring time elapsed or radiation emitted during encryption and decryption procedures, completely break textbook versions of many cryptographic schemes. This has prompted the study of leakage-resilient cryptography, which remains secure in the presence of side-channel attacks. Classical leakage-resilient cryptography must necessarily impose restrictions on the type of leakage one aims to protect against. As a notable example, the most well-studied leakage model is that of bounded leakage, where it is assumed that an adversary learns at most $\ell$ bits of leakage on secret components, for some leakage bound $\ell$. Although this leakage bound is necessary, it is unclear if such a bound is realistic in practice since many practical side-channel attacks cannot be captured by bounded leakage. In this work, we investigate the possibility of designing cryptographic schemes that provide guarantees against arbitrary side-channel attacks: - Using techniques from uncloneable quantum cryptography, we design several basic leakage-resilient primitives, such as secret sharing, (weak) pseudorandom functions, digital signatures, and public- and private-key encryption, which remain secure under (polynomially) unbounded classical leakage. In particular, this leakage can be much longer than the (quantum) secret being leaked upon. In our view, leakage is the result of observations of quantities such as power consumption and hence is most naturally viewed as classical information. - In the even stronger adversarial setting where the adversary is allowed to obtain unbounded quantum leakage (and thus leakage-resilience is impossible), we design schemes for many cryptographic tasks which support leakage-detection. This means that we can efficiently check whether the security of such a scheme has been compromised by a side-channel attack. These schemes are based on techniques from cryptography with certified deletion. - We also initiate a study of classical cryptographic schemes with (bounded) post-quantum leakage-resilience. These schemes resist side-channel attacks performed by adversaries with quantum capabilities which may even share arbitrary entangled quantum states. That is, even if such adversaries are non-communicating, they can still have spooky communication via entangled states

On the Non-malleability of the Fiat-Shamir Transform

The Fiat-Shamir transform is a well studied paradigm for removing interaction from public-coin protocols. We investigate whether the resulting non-interactive zero-knowledge (NIZK) proof systems also exhibit non-malleability properties that have up to now only been studied for NIZK proof systems in the common reference string model: first, we formally define simulation soundness and a weak form of simulation extraction in the random oracle model (ROM). Second, we show that in the ROM the Fiat-Shamir transform meets these properties under lenient conditions. A consequence of our result is that, in the ROM, we obtain truly efficient non malleable NIZK proof systems essentially for free. Our definitions are sufficient for instantiating the Naor-Yung paradigm for CCA2-secure encryption, as well as a generic construction for signature schemes from hard relations and simulation-extractable NIZK proof systems. These two constructions are interesting as the former preserves both the leakage resilience and key-dependent message security of the underlying CPA-secure encryption scheme, while the latter lifts the leakage resilience of the hard relation to the leakage resilience of the resulting signature scheme

A Lightweight Security Protocol for NFC-based Mobile Payments

© 2016 Published by Elsevier B.V. In this work, we describe a security solution that can be used to securely establish mobile payment transactions over the Near-Field Communication (NFC) radio interface. The proposed solution is very lightweight one; it uses symmetric cryptographic primitives on devices having memory and CPU resources limitations. We show that our approach maintains the security of NFC communications and we further demonstrate that our solution is simple, scalable, cost-effective, and incurs minimal computational processing overheads

Leakage-Resilient Group Signature: Definitions and Constructions

Group signature scheme provides group members a way to sign messages without revealing their identities. Anonymity and traceability are two essential properties in a group signature system. However, these two security properties hold based on the assumption that all the signing keys are perfectly secret and leakage-free. On the another hand, on account of the physical imperfection of cryptosystems in practice, malicious attackers can learn fraction of secret state (including secret keys and intermediate randomness) of the cryptosystem via side-channel attacks, and thus breaking the security of whole system. To address this issue, Ono et al. introduced a new security model of group signature, which captures randomness exposure attacks. They proved that their proposed construction satisfies the security require-ments of group signature scheme. Nevertheless, their scheme is only provably secure against randomness exposure and supposes the secret keys remains leakage-free. In this work, we focus on the security model of leakage-resilient group signature based on bounded leakage setting and propose three new black-box constructions of leakage-resilient group signature secure under the proposed security models