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1. How to Break FF3 on Large Domains

   https://doi.org/https://doi.org/10.1007/978-3-030-17656-3_4  

   Hoang, V.T.; Miller, D.; Trieu, Ni (May 2019, Advances in Cryptology – EUROCRYPT 2019)

   We improve the attack of Durak and Vaudenay (CRYPTO'17) on NIST Format-Preserving Encryption standard FF3, reducing the running time from $O(N^5)$ to $$O(N^{17/6})$$ for domain $$Z_N \times Z_N$$. Concretely, DV's attack needs about $$2^{50}$$ operations to recover encrypted 6-digit PINs, whereas ours only spends about $$2^{30}$$ operations. In realizing this goal, we provide a pedagogical example of how to use distinguishing attacks to speed up slide attacks. In addition, we improve the running time of DV's known-plaintext attack on 4-round Feistel of domain $$Z_N \times Z_N$$ from $O(N^3)$ time to just $$O(N^{5/3})$$ time. We also generalize our attacks to a general domain $$Z_M \times Z_N$$, allowing one to recover encrypted SSNs using about $$2^{50}$$ operations. Finally, we provide some proof-of-concept implementations to empirically validate our results. 

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2. On Quantum Chosen-Ciphertext Attacks and Learning with Errors

   Alagic, Gorjan; Jeffery, Stacey; Ozols, Maris; Poremba, Alexander (January 2019, Theory of Quantum Computing, Communication, and Cryptography 2019)

   Large-scale quantum computing is a significant threat to classical public-key cryptography. In strong "quantum access" security models, numerous symmetric-key cryptosystems are also vulnerable. We consider classical encryption in a model which grants the adversary quantum oracle access to encryption and decryption, but where the latter is restricted to non-adaptive (i.e., pre-challenge) queries only. We define this model formally using appropriate notions of ciphertext indistinguishability and semantic security (which are equivalent by standard arguments) and call it QCCA1 in analogy to the classical CCA1 security model. Using a bound on quantum random-access codes, we show that the standard PRF- and PRP-based encryption schemes are QCCA1-secure when instantiated with quantum-secure primitives. We then revisit standard IND-CPA-secure Learning with Errors (LWE) encryption and show that leaking just one quantum decryption query (and no other queries or leakage of any kind) allows the adversary to recover the full secret key with constant success probability. In the classical setting, by contrast, recovering the key uses a linear number of decryption queries, and this is optimal. The algorithm at the core of our attack is a (large-modulus version of) the well-known Bernstein-Vazirani algorithm. We emphasize that our results should *not* be interpreted as a weakness of these cryptosystems in their stated security setting (i.e., post-quantum chosen-plaintext secrecy). Rather, our results mean that, if these cryptosystems are exposed to chosen-ciphertext attacks (e.g., as a result of deployment in an inappropriate real-world setting) then quantum attacks are even more devastating than classical ones. 

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3. Distributed Logic Encryption: Essential Security Requirements and Low-Overhead Implementation

   https://doi.org/10.1145/3526241.3530372  

   Afsharmazayejani, Raheel; Sayadi, Hossein; Rezaei, Amin (June 2022, In Proceedings of Great Lakes Symposium on VLSI (GLSVLSI))

   Due to outsource manufacturing, the semiconductor industry must deal with various hardware threats such as piracy and overproduction. To prevent illegal electronic products from functioning, the circuit can be encrypted using a protected key only known to the designer. However, an attacker can still decipher the secret key utilizing a functioning circuit bought from the market, and the encrypted layout leaked from an untrusted foundry. In this paper, after introducing essential conformity and mutuality features for secure logic encryption, we propose DLE, a novel Distributed Logic Encryption design that resists against all known oracle guided and structural attacks including the newly proposed fault-aided SAT-based attack that iteratively injects a single stuck-at fault to thwart the locking effect. DLE forces the attacker to insert multiple stuck-at faults simultaneously in critical points to achieve a smaller but meaningful encrypted circuit; thus, exponentially reducing the chance to hit all the critical points with properly located stuck-at fault injections. Our experiments confirm that DLE maintains an exponentially high degree of security under diverse attacks with the polynomial area and linear performance overheads. 

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4. PWRLEAK: Exploiting Power Reporting Interface for Side-channel Attacks on AMD SEV

   Wang, Wubing; Li, Mengyuan; Zhang, Yinqian; Lin, Zhiqiang (July 2023, roceedings of the 20th Conference on Detection of Intrusions and Malware & Vulnerability Assessment)

   An increasing number of Trusted Execution Environment (TEE) is adopting to a variety of commercial products for protecting data security on the cloud. However, TEEs are still exposed to various side-channel vulnerabilities, such as execution order-based, timing-based, and power-based vulnerabilities. While recent hardware is applying various techniques to mitigate order-based and timing-based side-channel vulnerabilities, power-based side-channel attacks remain a concern of hardware security, especially for the confidential computing settings where the server machines are beyond the control of cloud users. In this paper, we present PWRLEAK, an attack framework that exploits AMD’s power reporting interfaces to build power side-channel attacks against AMD Secure Encrypted Virtualization (SEV)-protected VM. We design and implement the attack framework with three general steps: (1) identify the instruction running inside AMD SEV, (2) apply a power interpolator to amplify power consumption, including an emulation-based interpolator for analyzing purposes and a moregeneral interrupt-based interpolator, and (3) infer secrets with various analysis approaches. A case study of using the emulation-based interpolator to infer the whole JPEG images processed by libjpeg demonstrates its ability to help analyze power consumption inside SEV VM. Our end-to-end attacks against Intel’s Integrated Performance Primitives (Intel IPP) library indicates that PWRLEAK can be exploited to infer RSA private keys with over 80% accuracy using the interrupt based interpolator. 

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5. Flexible Password-Based Encryption: Securing Cloud Storage and Provably Resisting Partitioning-Oracle Attacks

   https://doi.org/10.1007/978-3-031-30872-7_23  

   Bellare, Mihir; Shea, Laura (April 2023, Topics in Cryptology - CT-RSA 2023 - Cryptographers' Track at the RSA Conference 2023)

   Rosulek, Mike (Ed.)

   We introduce flexible password-based encryption (FPBE), an extension of traditional password-based encryption designed to meet the operational and security needs of contemporary applications like end-to-end secure cloud storage. Operationally, FPBE supports nonces, associated data and salt reuse. Security-wise, it strengthens the usual privacy requirement, and, most importantly, adds an authenticity requirement, crucial because end-to-end security must protect against a malicious server. We give an FPBE scheme called DtE that is not only proven secure, but with good bounds. The challenge, with regard to the latter, is in circumventing partitioning-oracle attacks, which is done by leveraging key-robust (also called key-committing) encryption and a notion of authenticity with corruptions. DtE can be instantiated to yield an efficient and practical FPBE scheme for the target applications. 

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