Efficient block masking for counting-based secret sharing

This paper discusses how to recover RSA secret keys from their noisy version observed by side-channel attacks. At CRYPTO2009, Heninger and Shacham proposed a polynomial time algorithm which recovers an original secret key from some fraction of secret key bits. Then, at CRYPTO2010, Henecka et al. proposed a polynomial time algorithm recovering a correct secret key from the noisy secret key bits with some errors. Then they gave the bound such that the secret key can be recovered in polynomial time. At PKC2013, Kunihiro et al. presented a key-recovery algorithm from the erroneous version of secret key bits with erasures and errors. They also gave a condition for recovering the secret key and its theoretical bound. They pointed out that there is a small gap between their derived condition and the theoretical bound and closing the gap is an open problem. In this paper, we first improve the bound and reduce the computational cost by introducing tighter inequalities than the Hoeffding bound and choosing aggressive parameter settings. Our obtained bound is asymptotically optimal. Further, we show a practical countermeasure against the secret key extraction attack based on our analysis. In the countermeasure, some of the bits in the secret key are intentionally flipped and then the secret key with errors is stored in the memory. With the help of the intentionally added errors, the security is enhanced. For example, it results to be secure against the attacker extracting the secret key with an error rate 0.13 by intentionally adding a 0.15 fraction of errors. Finally, we revisit asymmetric error cases and give a provable bound for crossover probabilities.

In this paper, we discuss how to recover the RSA secret key from a noisy version of the secret key obtained through physical attacks such as cold boot and side channel attacks. For example, consider a cold boot attack to extract the RSA secret key stored in the memory. The attacker can obtain a degraded version of the secret key so that some bits are erased. In principle, if many erasures occur, the key recovery for the secret key becomes rather difficult. To date, many noise models other than the erasure model have been introduced. For the discrete noise case, the binary erasure model, binary error model, and binary erasure and error model have been introduced. Effective algorithms have been proposed for each noise model, and the conditions for noise which the original secret key can be recovered in polynomial time have been derived. Research has also been conducted on models that can obtain continuous leakage. In this case, several algorithms have been proposed according to the degree of knowledge of the leakage model. Many studies have been conducted on by taking heuristic approaches. In this paper, we provide a survey of existing research and then attempt to explain it within a unified framework.

In this paper, we propose a new chaos-based encryption scheme for medical images. It is based on a combination of chaos and DNA computing under the scenario of two encryption rounds, preceded by a key generation layer, and follows the permutation-substitution-diffusion structure. The SHA-256 hash function alongside the initial secret keys is employed to produce the secret keys of the chaotic systems. Each round of the proposed algorithm involves six steps, i.e., block-based permutation, pixel-based substitution, DNA encoding, bit-level substitution (i.e., DNA complementing), DNA decoding, and bit-level diffusion. A thorough search of the relevant literature yielded only this time the pixel-based substitution and the bit-level substitution are used in cascade for image encryption. The key-streams in the bit-level substitution are based on the logistic-Chebyshev map, while the sine-Chebyshev map allows producing the key-streams in the bit-level diffusion. The final encrypted image is obtained by repeating once the previous steps using new secret keys. Security analyses and computer simulations both confirm that the proposed scheme is robust enough against all kinds of attacks. Its low complexity indicates its high potential for real-time and secure image applications.

The expansion of wireless communication introduces security vulnerabilities, emphasizing the essential need for secure systems that prioritize confidentiality, integrity, and other key aspects of data protection. Since computational security acknowledges the possibility of breaches when adequate computational resources are available, that is why information-theoretic security is being explored, which suggests the existence of unbreakable cryptographic systems even in the presence of limitless processing power. Secret key exchange has traditionally relied on RSA or DH protocols, but researchers are now exploring innovative approaches for sharing secret keys among wireless network devices, leveraging physical or link layer characteristics. This research seeks to revolutionize secure multi-party key acquisition in wireless networks, capitalizing on information-theoretic security and collaborative data extraction. The proposed secret key generation framework comprehensively organizes and explains the information-theoretic aspects of secret key generation within the lower layers of wireless networks, especially the link layer, proposes a novel information-theoretic SKG framework for the dynamic acquisition of symmetric secret keys, and responds to contemporary information security challenges by relying on information-theory principles rather than vulnerable mathematical relationships in the post-quantum period. A new cryptographic key can be generated using a straightforward method, and when it is combined (XORed) with the previous key, it creates a continuously changing secret for encryption and decryption. This approach enhances security because, as attackers attempt to break the encryption, the system generates fresh, dynamic keys, making it progressively more challenging for them to succeed. The research work in question integrates key renewal, or how often keys are updated (dynamic keys), with a security off-period. It introduces a framework for determining the best key refresh rate based on the anticipated rate at which keys might be compromised. Furthermore, the proposed framework is scalable, allowing new nodes to quickly join the existing network. The system was tested with multiple nodes equipped with IEEE 802.11 interfaces, which were set in monitor mode to capture frames at the link layer. Nodes map their on-time frames onto their Bloom filters. Nodes exchange these Bloom filters in a feedback mechanism. Nodes extract those frames from their .pcap files, which are present in all Bloom filters; these are common frames among all nodes. These frames are used to form a shared secret that is passed to HMAC Key Derivation Function by each node to acquire the final encryption key of the required length. The validation of this encryption key is performed using a simple challenge-response protocol; upon successful validation, encrypted communication begins. Otherwise, the key generation process is restarted.

Limitations of the computational and energy capabilities of IoT devices provide new challenges in securing communication between devices. Physical layer security (PHYSEC) is one of the solutions that can be used to solve the communication security challenges. In this paper, we conducted an investigation on PHYSEC which utilizes channel reciprocity in generating a secret key, commonly known as secret key generation (SKG) schemes. Our research focused on the efforts to get a simple SKG scheme by eliminating the information reconciliation stage so as to reduce the high computational and communication cost. We exploited the pre-processing method by proposing a modified Kalman (MK) and performing a combination of the method with a multilevel quantization, i.e., combined multilevel quantization (CMQ). Our approach produces a simple SKG scheme for its significant increase in reciprocity so that an identical secret key between two legitimate users can be obtained without going through the information reconciliation stage.

A new group signature with one time secret key is proposed. The main merits are that it only needs the trusted center issuing the partial secret key one time for each group member; and that the group member can generate his different secret key each time when he wants to sign a message. The group public key is constant and the size of the signature is independent of the number of group members. The total computation cost of signature and verification requires only 8 modular exponentiations.

This paper introduces a best approach for Least Significant Bit (LSB) based on image steganography that enhances the existing LSB substitution techniques to improve the security level of hidden information. It is a new approach to substitute LSB of RGB true color image. The new security conception hides secret information within the LSB of image where a secret key encrypts the hidden information to protect it from unauthorized users. In general, in LSB methods, hidden information is stored into a specific position of LSB of image. For this reason, knowing the retrieval methods, anyone can extract the hidden information. In our paper, hidden information is stored into different position of LSB of image depending on the secret key. As a result, it is difficult to extract the hidden information knowing the retrieval methods. We have used the Peak Signal-to-Noise Ratio (PSNR) to measure the quality of the stego images. The value of PSNR gives better result because our proposed method changes very small number of bits of the image. The obtained results show that the proposed method results in LSB based image steganography using secret key which provides good security issue and PSNR value than general LSB based image steganography methods.

Problem statement: A cryptosystem is a way for a sender and a receiver to communicate digitally by which the sender can send receiver any confidential or private message by first encrypting it using the receiver’s public key. Upon receiving the encrypted message, the receiver can confirm the originality of the message’s contents using his own secret key. Up to now, most of the existing cryptosystems were developed based on a single cryptographic assumption like factoring, discrete logarithms, quadratic residue or elliptic curve discrete logarithm. Although these schemes remain secure today, one day in a near future they may be broken if one finds a polynomial algorithm that can efficiently solve the underlying cryptographic assumption. Approach: By this motivation, we designed a new cryptosystem based on two cryptographic assumptions; quadratic residue and discrete logarithms. We integrated these two assumptions in our encrypting and decrypting equations so that the former depends on one public key whereas the latter depends on one corresponding secret key and two secret numbers. Each of public and secret keys in our scheme determines the assumptions we use. Results: The newly developed cryptosystem is shown secure against the three common considering algebraic attacks using a heuristic security technique. The efficiency performance of our scheme requires 2Texp+2Tmul +Thash time complexity for encryption and Texp+2Tmul +Tsrt time complexity for decryption and this magnitude of complexity is considered minimal for multiple cryptographic assumptions-like cryptosystems. Conclusion: The new cryptosystem based on multiple cryptographic assumptions offers a greater security level than that schemes based on a single cryptographic assumption. The adversary has to solve the two assumptions simultaneously to recover the original message from the received corresponding encrypted message but this is very unlikely to happen.

In this paper we propose a new protocol for multiparty secret key sharing by using quantum entanglement swapping. Quantum Entanglement swapping is a process that allows two non-interacting quantum systems to be entangled. Further, to increase the security level and to make sure that the users are legitimate, authentication for both parties will be required by a trusted third party. In this protocol, a trusted third party will authenticate the sender and the receiver and help them forming a secret key. Furthermore, the proposed protocol will perform entanglement swapping between the sender and the receiver. The result from the entanglement swapping will be an Einstein-Podolsky-Rosen (EPR) pair that will help them in forming and sending the secret key without having the sender to send any physical quantum states to the receiver. This protocol will provide the required authentication of all parties to the trusted party and it will provide the required secure method in transmitting the secret key.

Vehicle Ad hoc Networks (VANETs) are an emergent wireless communication technology that has the potential to reduce the risk of accidents caused by drivers and provide a wide range of entertainment facilities. Because of the nature of VANETs' open-access environment, security attacks can affect the messages broadcast by a vehicle. VANET is therefore vulnerable to security and privacy issues. Recently, many schemes for addressing these problems of VANET have been proposed. However, most of them are affected by massive computation overhead and security issues. In this paper, we propose a scheme named efficient conditional privacy preservation with mutual authentication to address the problems mentioned above in VANET. This scheme depends on the division of geographical areas into a number domains and their distribution, where each domain stores the Certificate Revocation List (CRL) in all Road-side Units (RSUs) located inside the domain. During the mutual authentication phase, the vehicle should authenticate with the TA. After the vehicle obtains a pool of pseudo-identities and the corresponding secret keys from RSU, it is allowed to transmit a message to the other components in the VANET. Because our scheme does not use the bilinear pairing, the performance evaluation shows that our scheme has a lower system cost in terms of computation and communication than other existing methods. Meanwhile, the proposed scheme reduces the computation costs of signing the message and verifying the message by 99.85% and 99.93%, respectively. While the proposed scheme reduces the communication costs of the message size by 13.3%.

In this paper, we attack Kyber’s key-generation algorithm using power analysis and lattice reduction. More specifically, we target the Centered Binomial Distribution (CBD) sampler which generates the secret data of the underlying Learning With Error (LWE) instance. From a side-channel perspective, our attack uses a single trace, leveraging classifiers developed through supervised learning. We enhance the classification with the AdaBoost strategy, which provides more reliable results and exploitable statistics, enabling the identification of error-free classified samples. In optimal scenarios, our classifiers, combined with the outputted statistics, allow us to recover up to 68% of the secret key’s coefficients from the trace, ensuring that these recovered coefficients are error-free. In such cases, we show that the secret keys can be recovered by Gaussian elimination over a finite field in a few seconds. For less advantageous cases, we assess the block-size in lattice reduction that would complete the key recovery, providing a fine-grained trade-offs between the correctly guessed proportion and the block-size, based on standard estimates. Finally, we conducted large-scale experiments, from power traces to secret key recovery (for most of the instances) under a threshold of 18 hours, targeting all three Kyber’s security levels. Our average rate of success across all security level is more than 96%.

Anonymous channel tickets have been proposed as a way to provide user anonymity and to reduce the overhead of re-authentication for authentication in wireless environments. Chen et al. proposed a secure and efficient protocol, based on a protocol proposed by Yang et al., which is resistant to guessing attacks on networks from which users’ secret keys are easy to obtain. However, their scheme is time-consuming in the phases of ticket issuing and authentication. Furthermore, a malicious attacker can utilize the expired time, Texp, to launch a denial of authentication (DoA) attack, which is a type of denial of service attack. Because Texp is exposed to any user, it would be easy to launch a DoA attack that could make the scheme impractical. To resist against DoAs that the scheme of Chen et al. might suffer, we propose an improved scheme based on elliptic curve cryptography in this paper. Our scheme not only reduces time cost but also enhances security. The basis of the proposed scheme is the elliptic curve discrete logarithm problem. The operations of points of an elliptic curve are faster and use fewer bits to achieve the same level of security. Therefore, our scheme is more suitable for mobile devices, which have limited computing power and storage. Copyright © 2012 John Wiley & Sons, Ltd.

It has long been known that cryptographic schemes offering provably unbreakable security exist, namely the One Time Pad (OTP). The OTP, however, comes at the cost of a very long secret key - as long as the plain-text itself. In this paper we propose an encryption scheme which we (boldly) claim offers the same level of security as the OTP, while allowing for much shorter keys, of size polylogarithmic in the computing power available to the adversary. The Scheme requires a large sequence of truly random words, of length polynomial in the both plain-text size and the logarithm of the computing power the adversary has. We claim that it ensures such an attacker cannot discern the cipher output from random data, except with small probability. We also show how it can be adapted to allow for several plain-texts to be encrypted in the same cipher output, with almost independent keys. Also, we describe how it can be used in lieu of a One Way Function.

AC-RRNS: Anti-collusion secured data sharing scheme for cloud storage

Designated Verifier Signature (DVS) guarantees that only a verifier designated by a signer can verify the “validity of a signature”. In this paper, we propose a new variant of DVS; Proxiable Designated Verifier Signature (PDVS) where the verifier can make a third party (i.e. the proxy) substitute some process of the verification. In the PDVS system, the verifier can reduce his computational cost by delegating some process of the verification without revealing the validity of the signature to the proxy. In all DVS systems, the validity of a signature means that a signature satisfies both properties that (1) the signature is judged “accept” by a decision algorithm and (2) the signature is confirmed at it is generated by the signer. So in the PDVS system, the verifier can make the proxy substitute checking only the property of (1). In the proposed PDVS model, we divide verifier's secret keys into two parts; one is a key for performing the decision algorithm, and the other is a key for generating a dummy signature, which prevents a third party from convincing the property (2). We also define security requirements for the PDVS, and propose a PDVS scheme which satisfies all security requirements we define.