In the Internet of Things (IoT) systems, it is often required to deliver a secure message to a group of devices. The public key broadcast encryption is an efficient primitive to handle IoT ...broadcasts, by allowing a user (or a device) to broadcast encrypted messages to a group of legitimate devices. This paper proposes an IoT-friendly subset representation called Combinatorial Subset Difference (CSD), which generalizes the existing subset difference (SD) method by allowing wildcards (*) in any position of the bitstring. Based on the CSD representation, we first propose an algorithm to construct the CSD subset, and a CSD-based public key broadcast encryption scheme. By providing the most general subset representation, the proposed CSD-based construction achieves a minimal header size among the existing broadcast encryption. The experimental result shows that our CSD saves the header size by 17% on average and more than 1000 times when assuming a specific IoT example of IP address with 20 wildcards and 2 20 total users, compared to the SD-based broadcast encryption. We prove the semantic security of CSD-based broadcast encryption under the standard l-BDHE assumption, and extend the construction to a chosen-ciphertext-attack (CCA)-secure version.
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With the rapid growth of the blockchain market, privacy and security issues for digital assets are becoming more important. In the most widely used public blockchains, such as Bitcoin and Ethereum, ...all activities on user accounts are publicly disclosed, which violates privacy regulations such as EU GDPR. Encryption of accounts and transactions may protect privacy, but it also raises issues of validity and transparency. While encrypted information can protect privacy, it cannot alone verify the validity of a transaction. Additionally, encryption makes it difficult to meet anti-money laundering regulations, such as auditability. In this paper, we propose <inline-formula> <tex-math notation="LaTeX">{\sf Azeroth} </tex-math></inline-formula>, an auditable zero-knowledge transfer framework. <inline-formula> <tex-math notation="LaTeX">{\sf Azeroth} </tex-math></inline-formula> connects a zero-knowledge proof to an encrypted transaction, enabling it to check its validation while protecting its privacy. <inline-formula> <tex-math notation="LaTeX">{\sf Azeroth} </tex-math></inline-formula> also allows authorized auditors to audit transactions. <inline-formula> <tex-math notation="LaTeX">{\sf Azeroth} </tex-math></inline-formula> is designed as a smart contract for flexible deployment on existing blockchains. We implement the <inline-formula> <tex-math notation="LaTeX">{\sf Azeroth} </tex-math></inline-formula> smart contract, and execute it on various platforms including an Ethereum testnet blockchain, and measure the time to show the practicality of our proposal. The end-to-end latency of a privacy-preserving transfer takes about <inline-formula> <tex-math notation="LaTeX">4.4s </tex-math></inline-formula>. In particular, the client's transaction generation time with a proof only takes about <inline-formula> <tex-math notation="LaTeX">0.9s </tex-math></inline-formula>. The security of <inline-formula> <tex-math notation="LaTeX">{\sf Azeroth} </tex-math></inline-formula> is proven under the cryptographic assumptions.
As a solution to mitigate the key exposure problems in the digital signature, the forward security has been proposed. The forward security guarantees the integrity of the messages generated in the ...past despite leaks of a current time period secret key by evolving a secret key on each time period. In this paper, we propose a new forward secure aggregate signature scheme utilizing recursive zk-SNARKs (zero knowledge Succinct Non-interactive ARguments of Knowledge). Our proposal has constant complexities in key/signature sizes, signature generation, and verification time. The proposed forward secure signature scheme can aggregate signatures generated by multiple users as well as a single user. The security of the proposed scheme is formally proven under zero-knowledge assumption and random oracle model. The experiment results show that our signature scheme yields 12 s for signing time, 1 ms for verification time, 25 s for aggregation time, with the 1.6 KB secret key size and signature size independent of the number of time periods.
Among the zero-knowledge succinct non-interactive arguments of knowledge (zk-SNARK), the simulation-extractable zk-SNARK (SE-SNARK) introduces a security notion of non-malleability. The existing ...pairing-based zk-SNARKs designed from linear encoding are known to be vulnerable to algebraic manipulation of the proof. The latest SE-SNARKs check the proof consistency by increasing the proof size and the verification cost. In particular, the number of pairings increases almost doubles due to further verification. In this paper, we propose two novel SE-SNARK constructions with a single verification. The consistency check is subsumed in a single verification through employing a hash function. The proof size and verification time of the proposed SE-SNARK schemes are minimal in that it is the same as the state-of-the-art zk-SNARK without non-malleability. The proof in our SE-SNARK constructions comprises only three group elements (type III) in the QAP-based scheme and two group elements (type I) in the SAP-based scheme. The verification time in both requires only 3 pairings. The soundness of the proposed schemes is proven under the hash-algebraic knowledge (HAK) assumption and the (linear) collision-resistant hash assumption.
The verifiable computation paradigm has been studied extensively as a means to verifying the result of outsourced computation. In said scheme, the verifier requests computation from the prover and ...verifies the result by checking the output and proof received from the prover. Although they have great potential for various critical applications, verifiable computations have not been widely used in practice, because of their significant performance overhead. Existing cryptography-based approaches incur significant overhead, because a cryptography-based mathematical frame needs to be constructed, which prevents deviation from the correct computation. The proposed approach is to reduce the overhead by trusting the computing hardware platform where the computation is outsourced. If one trusts the hardware to do the computation, the hardware can take the place of the cryptographic computing frame, thereby guaranteeing correct computation. The key challenge of this approach is to define what exactly the hardware should guarantee for verifiable computation. For this, we introduce the concept of Correct Execution Environment (CEE), which guarantees instruction correctness and state preservation. We prove that these two requirements are satisfactory conditions for a correct output. By employing a CEE, the verifiable computation scheme can be simplified, and its overhead can be reduced drastically. The presented experimental results demonstrate that the execution time is approximately 1.7 million times faster and the verification time over 50 times faster than a state-of-the-art cryptographic approach.
This paper defines a non-linear cost compression problem, proposes an efficient algorithm, and applies it to a real application of multi level cell memory to minimize energy consumption and latency. ...The non-linear cost compression problem extends the traditional cost compression problem to allow a non-linear cost function of symbol frequencies, while it is a weighted linear combination of symbol frequencies in the cost compression problem. In order to solve the non-linear cost compression problem efficiently, we propose an encoding symbol frequency based approach. We first compute frequencies of encoding symbols to minimize a cost function. To achieve the computed frequencies of a cost-compressed message, we deploy existing size-decompression algorithms. The proposed algorithm is optimal and as fast as the existing size compression algorithms. Our experimental results show that it reduces the energy consumption and latency by 70 percent for a text file in multi level cell memory. Furthermore, it increases the lifetime of endurance limited memory.
The rapid increase in data generation has led to outsourcing computation to cloud service providers, allowing clients to handle large tasks without investing resources. However, this brings up ...security concerns, and while there are solutions like fully homomorphic encryption and specific task-oriented methods, challenges in optimizing performance and enhancing security models remain for widespread industry adoption. Outsourcing computations to an untrusted remote computer can be risky, but attestation techniques and verifiable computation schemes aim to ensure the correct execution of outsourced computations. Nevertheless, the latter approach incurs significant overhead in generating a proof for the client. To minimize this overhead, the concept of a Correct Execution Environment (CEE) has been proposed (CEEv1), which omits proof generation for trusted parts of the prover. This paper proposes a new hardware-based CEE (CEEv2) that supports virtual memory and uses an inverted page table mechanism to detect, or prevent, illegal modifications to page mappings. The proposed mechanism supports virtual memory and thwarts virtual-to-physical mapping attacks, while minimizing software modifications. The paper also compares the proposed mechanism to other similar mechanisms used in AMD's SEV-SNP and Intel's SGX.
Even though dataflow models are good at exploiting task-level parallelism of an application, it is difficult to exploit the parallelism of loop structures since they are not explicitly specified in ...existent dataflow models. To overcome this drawback, we propose a novel extension to the SDF model, called SDF/L graph, specifying the loop structures explicitly in a hierarchical fashion. With a given SDF/L graph specification and the mapping and scheduling information, an application can be automatically parallelized on a multicore system. The enhanced expression capability by the proposed extension is verified with two applications, k-means clustering and deep neural network application.
Audit logs are an elemental part of computer systems due to their forensic value. Safeguarding audit logs on a physically unprotected machine are a challenging work, especially in the presence of ...active adversaries. Forward security is necessary for such a logging system. In this paper, we propose a new Forward secure sequential Aggregate Signature (FAS) scheme with optimal storage and communication for keys and signatures. To the best of our knowledge, our FAS scheme is the only scheme that has constant-sized public and secret keys as well as constant-sized aggregate signatures. Our proposed scheme supports aggregation of consecutive signatures by a third party. We prove the security of our proposed scheme under the hardness of factoring assumption, in the random oracle model.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
With the continuous scaling of semiconductor technology, failure rate is increasing significantly so that reliability becomes an important issue in multiprocessor system-on-chip (MPSoC) design. We ...propose an optimal checkpoint selection with task duplication hardening to tolerate transient faults. A target application is specified in a task graph, and the schedule/checkpoint placements are determined at design time. The proposed optimal algorithm minimizes the checkpoint overhead with a latency constraint. Experimental results show that the proposed algorithm effectively reduces the minimum end-to-end latency to perform a fault-tolerant schedule. In addition, the proposed algorithm dramatically decreases the checkpointing overhead on uniprocessor and multiprocessor systems compared with a greedy approach and an equidistant algorithm.
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