Master Key Research Articles

Ban Non Wat: crucial research, but is it too soon for certainty?

As Charles Higham so rightly states, chronology is a major key to unlocking the prehistoric past, perhaps even the master key. Most readers nowadays will agree that the chronologies for the inceptions of farming and bronze working in north-east Thailand, as put forward in the 1970s, were in error, for the simple reason that archaeologists at that time were prone to sending small scattered fragments of charcoal to C14laboratories without really trying to understand exactly how and where the charcoal originated. I am sure I have been guilty of similar lapses, so apportioning blame is not on my mind and would indeed be pointless.

A Hybrid Key Management Approach for Secure Communication in Wireless Sensor Networks

Wireless Sensor Networks(WSN) used in a variety of applications are usually unattended in nature and are highly susceptible to attacks such as eavesdropping, hardware tampering and false messages. For secure communication among the nodes, Secret key cryptography is used since it provides high security with low computing power. Existing key management schemes does not guarantee the level of security and network performance. To handle such problems, random seed distribution with transitory cluster key, a hybrid approach is used which is the integration of both random key distribution and the transitory master key. The security analysis shows that our approach provides enhanced resilience and better connectivity by establishing secure channels among the communicating nodes in a hierarchical clustered wireless sensor network. It over persuades the state-of-the-art protocols by providing always the best security features.

A comprehensive study of algebraic fault analysis on PRINCE

PRINCE is a 64-bit lightweight block cipher with a 128-bit key published at ASIACRYPT 2012. Assuming one nibble fault is injected, previous different fault analysis (DFA) on PRINCE adopted the technique from DFA on AES and current results are different. This paper aims to make a comprehensive study of algebraic fault analysis (AFA) on PRINCE. How to build the equations for PRINCE and faults are explained. Extensive experiments are conducted. Under nibble-based fault model, AFA with three or four fault injections can succeed within 300 seconds with a very high probability. Under other fault models such as byte-based, half word-based, word-based fault models, the faults become overlapped in the last round and previous DFAs are difficult to work. Our results show that AFA can still succeed to recover the full master key. To evaluate security of PRINCE against fault attacks, we utilize AFA to calculate the reduced entropy of the secret key for given amount of fault injections. The results can interpret and compare the efficiency of previous work. Under nibble-based fault model, the master key of PRINCE can be reduced to 29.69 and 236.10 with 3 and 2 fault injections on average, respectively.

PRF-기반 키유도함수에서 카운터 입력 형태에 따른 증명가능 안전성

ABSTRACT The security of all cryptographic algorithms and protocols is b ased on the confidentiality of secret keys. Key management mechanism is an indispensable part of the cryptographic system and this deals with the generation, exchange, storage, use, and replacement of keys. Within the key management mechanism there are key derivation functions (KDFs) which derive one or more keys from a master key. NIST specifies three families of P RF-based KDFs in SP 800-108. In this paper, we examine the difference of security models between the KDFs and the encrypti on modes of operations. Moreover we focus on the provable security of PRF-based KDFs according to input types of counters , and show that the counter and feedback modes of KDFs using XOR of counters are insecure, while these modes using concatenation of counters are secure.Keywords: Key Derivation Functions, KDF, Provable Security, PRF, Encrypti on modes of operation. I.서 론 * 암호 알고리즘과 암호 프로토콜은 사용되는 키들의 접수일(2015년 3월 4일), 게재확정일(2015년 4월 27일)*본 연구는 2014년도 정부(미래창조과학부)의 재원으로 한국연구재단-차세대정보・컴퓨팅기술개발사업의 지원을

Certificate-based encryption resilient to key leakage

Certificate-based encryption (CBE) is an important class of public key encryption but the existing schemes are secure only under the premise that the decryption key (or private key) and master secret key are absolutely secret. In fact, a lot of side channel attacks and cold boot attacks can leak secret information of a cryptographic system. In this case, the security of the cryptographic system is destroyed, so a new model called leakage-resilient (LR) cryptography is introduced to solve this problem. While some traditional public key encryption and identity-based encryption with resilient-leakage schemes have been constructed, as far as we know, there is no leakage-resilient scheme in certificate-based cryptosystems. This paper puts forward the first certificate-based encryption scheme which can resist not only the decryption key leakage but also the master secret key leakage. Based on composite order bilinear group assumption, the security of the scheme is proved by using dual system encryption. The relative leakage rate of key is close to 1/3.

Confounding Effect in Clinical Research of Otolaryngology and Its Control.

Confounding effect is a critical issue in clinical research of otolaryngology because it can distort the research's conclusion. In this review, we introduce the definition of confounding effect, the methods of verifying and controlling the effect. Confounding effect can be prevented by research's design, and adjusted by data analysis. Clinicians would be aware and cautious about confounding effect in their research. They would be able to set up a research's design in which appropriate methods have been applied to prevent this effect.They would know how to adjust confounding effect after data collection. It is important to remember that sometimes it is impossible to eliminate confounding effect completely, and statistical method is not a master key. Solid research knowledge and critical thinking of our brain are the most important in controlling confounding effect.

128비트 경량 블록암호 LEA의 저면적 하드웨어 설계

This paper describes an efficient hardware design of Lightweight Encryption Algorithm (LEA) developed by National Security Research Institute(NSRI). The LEA crypto-processor supports for master key of 128-bit. To achieve small-area and low-power implementation, an efficient hardware sharing is employed, which shares hardware resources for encryption and decryption in round transformation block and key scheduler. The designed LEA crypto-processor was verified by FPGA implementation. The LEA core synthesized with Xilinx ISE has 1,498 slice elements, and the estimated throughput is 216.24 Mbps with 135.15 MHz.

Design and Evaluation of a New Scheme Based on Secret Sharing Mechanisms that Increases the Security of Conditional Access Systems in Satellite Pay-TV

This paper introduces a new scheme that confronts one of the critical flaws of conditional access (CA) systems employed in satellite pay-TV, the long or infinite cryptoperiod of a master key (MK). ...

A Meet in the Middle Attack on Reduced Round Kuznyechik

In this letter, we present a meet-in-the-middle attack on the 5-round reduced Kuznyechik cipher which has been recently chosen to be standardized by the Russian federation. Our attack is based on the differential enumeration approach. However, the application of the exact approach is not successful on Kuznyechik due to its optimal round diffusion properties. Accordingly, we adopt an equivalent representation for the last round where we can efficiently filter ciphertext pairs and launch the attack in the chosen ciphertext setting. We also utilize partial sequence matching which further reduces the memory and time complexities. For the 5-round reduced cipher, the 256-bit master key is recovered with an online time complexity of 2140.3, a memory complexity of 2153.3, and a data complexity of 2113.

Related-Key Differential Attacks on CHESS-64

With limited computing and storage resources, many network applications of encryption algorithms require low power devices and fast computing components. CHESS-64 is designed by employing simple key scheduling and Data-Dependent operations (DDO) as main cryptographic components. Hardware performance for Field Programmable Gate Arrays (FPGA) and for Application Specific Integrated Circuits (ASIC) proves that CHESS-64 is a very flexible and powerful new cipher. In this paper, the security of CHESS-64 block cipher under related-key differential cryptanalysis is studied. Based on the differential properties of DDOs, we construct two types of related-key differential characteristics with one-bit difference in the master key. To recover 74 bits key, two key recovery algorithms are proposed based on the two types of related-key differential characteristics, and the corresponding data complexity is about 2 42.9 chosen-plaintexts, computing complexity is about 2 42.9 CHESS-64 encryptions, storage complexity is about 2 26.6 bits of storage resources. To break the cipher, an exhaustive attack is implemented to recover the rest 54 bits key. These works demonstrate an effective and general way to attack DDO-based ciphers.

An Authenticated Key Agreement Scheme for Wireless Sensor Networks

We propose a new authenticated key agreement scheme based on Blom’s scheme, but using multiple master keys and public keys in permutations to compute the private keys in each node. The computations are over a small prime field, and by storing them in a random order in the node, the private-public-master-key associations (PPMka) of the private keys are lost. If a node is captured, the PPMka of the private keys cannot be determined with certainty, making it difficult to begin to attack the scheme. We obtained analytical results to show that, using suitable keying parameters, the probability of discovering the correct PPMka can be made so small, that a very powerful adversary needs to capture the entire network of tens of thousands of nodes or expend an infeasible amount of effort to try all of the possible solutions. We verified our results using computer-simulated attacks on the scheme. The unknown PPMka enables our scheme to break free from the capture threshold of the original Blom’s scheme, so that it can be used in large networks of low-resource devices, such as sensor nodes.

Efficient Design of Certificateless Chameleon Signature from Bilinear Pairing

Certificateless public key cryptography (CL-PKC), does not require the use of the certificate to guarantee the authenticity of public keys. It does rely upon the use of a trusted third party (TTP), who is in possession of a master key. CL-PKC does not suffer from the key escrow property. Thus, CL-PKC can be seen as a model for the use in public key cryptography. In this paper, we proposed a new certificateless Chameleon signature scheme based on bilinear pairings. The proposed scheme is more efficient than AL-Riyami and Pateson [10] schemes. And our scheme is un-forgeable under the hardness assumption of the q-strong Diffie-Hellman problem and Computational Diffie-Hellman problem.

Multidimensional meet-in-the-middle attack and its applications to KATAN32/48/64

This paper investigates a new framework to analyze symmetric ciphers by guessing intermediate states and dividing algorithms into consecutive sub-ciphers. It is suitable for lightweight ciphers with simple key schedules and block sizes smaller than key lengths. New attacks on the block cipher family KATAN are proposed by adopting this framework. Our new attacks can recover the master keys of 175-round KATAN32, 130-round KATAN48 and 112-round KATAN64 faster than exhaustive search, and thus reach many more rounds than previous attacks. We also provide new attacks on 115-round KATAN32 and 100-round KATAN48 in order to demonstrate this new kind of attacks can be more time-efficient and memory-efficient than existing attacks.

Secure Deduplication with Efficient and Reliable Convergent Key Management

Data deduplication is a technique for eliminating duplicate copies of data, and has been widely used in cloud storage to reduce storage space and upload bandwidth. Promising as it is, an arising challenge is to perform secure deduplication in cloud storage. Although convergent encryption has been extensively adopted for secure deduplication, a critical issue of making convergent encryption practical is to efficiently and reliably manage a huge number of convergent keys. This paper makes the first attempt to formally address the problem of achieving efficient and reliable key management in secure deduplication. We first introduce a baseline approach in which each user holds an independent master key for encrypting the convergent keys and outsourcing them to the cloud. However, such a baseline key management scheme generates an enormous number of keys with the increasing number of users and requires users to dedicatedly protect the master keys. To this end, we propose Dekey , a new construction in which users do not need to manage any keys on their own but instead securely distribute the convergent key shares across multiple servers. Security analysis demonstrates that Dekey is secure in terms of the definitions specified in the proposed security model. As a proof of concept, we implement Dekey using the Ramp secret sharing scheme and demonstrate that Dekey incurs limited overhead in realistic environments.

Analysing the EAP-TLS Handshake and the 4-Way Handshake of the 802.11i Standard

The IEEE 802.11i standard has been designed to enhance security in wireless networks. The EAP-TLS handshake aims to provide mutual authentication between supplicant and authentication server, and then derive the Pairwise Master Key (PMK). In the 4 -way handshake the supplicant and the authenticator use PMK to derive a fresh pairwise transient key (PTK). The PMK is not used directly for security while assuming the supplicant and authenticator have the same PMK before running 4- way handshake. In this paper, the EAP-TLS handshake and the 4-way handshake phases have been analysed with a proposed framework using Isabelle tool. In the analysis, we have found a new Denial-of-Service (DoS) attack in the 4-way handshake. The attack prevents the authenticator from receiving message 4 after the supplicant sends it out. This attack forces the authenticator to re-send the message 3 until time out and subsequently to de-authenticate supplicant. This paper has proposed improvements to the 4-way handshake to avoid the Denial-of-Service attack.

What is the effective key length for a block cipher: an attack on every practical block cipher

Recently, several important block ciphers are considered to be broken by the brute-force-like cryptanalysis, with a time complexity faster than the exhaustive key search by going over the entire key space but performing less than a full encryption for each possible key. Motivated by this observation, we describe a meetin-the-middle attack that can always be successfully mounted against any practical block ciphers with success probability one. The data complexity of this attack is the smallest according to the unicity distance. The time complexity can be written as 2 k (1 − ∈), where ∈ > 0 for all practical block ciphers. Previously, the security bound that is commonly accepted is the length k of the given master key. From our result we point out that actually this k-bit security is always overestimated and can never be reached because of the inevitable loss of the key bits. No amount of clever design can prevent it, but increments of the number of rounds can reduce this key loss as much as possible. We give more insight into the problem of the upper bound of effective key bits in block ciphers, and show a more accurate bound. A suggestion about the relationship between the key size and block size is given. That is, when the number of rounds is fixed, it is better to take a key size equal to the block size. Also, effective key bits of many well-known block ciphers are calculated and analyzed, which also confirms their lower security margins than thought before. The results in this article motivate us to reconsider the real complexity that a valid attack should compare to.

Implementation of Shamir's Secret Sharing on Proactive Network

For most cryptosystems, by using a single-system master key there is a need to protect many important encryption and decryption keys used to achieve data security. There are three major drawbacks under this single-master key arrangement. First, if the master key is disclosed to the public by accident, then the entire system has no secrecy at all. Second, if the master key is lost, then all the keys under protection become inaccessible. Third, if the owner of the master key becomes disloyal, then all important information becomes completely available to the opponents. The secret sharing scheme was designed to overcome these problems. Shamir’s (t, n)-threshold scheme is one of the most wellknown examples of secret sharing schemes which provides a very simple and efficient way to share a secret among any t of the n participants. The primary goal of our research is to study the terminology and protocols behind secret sharing schemes and implement Shamir’s scheme using Java. In addition, we have also introduced a new scheme for extending the Shamir’s scheme on proactive network.

New differential fault analysis on PRESENT

Abstract In this paper, we present two differential fault analyses on PRESENT-80 which is a lightweight block cipher. The first attack is a basic attack which induces a fault on only one bit of intermediate states, and we can obtain the last subkey of the block cipher, given 48 faulty cipher texts on average. The second attack can retrieve the master key of the block cipher, given 18 faulty cipher texts on average. In the latter attack, we assume that we can induce faults on a single nibble of intermediate states. Given those faulty cipher texts, the computational complexity of attacks is negligible.

Key Management for Multiple Multicast Groups in Wireless Networks

With the emergence of diverse group-based services, multiple multicast groups are likely to coexist in a single network, and users may subscribe to multiple groups simultaneously. However, the existing group key management (GKM) schemes, aiming to secure communication within a single group, are not suitable in multiple multicast group environments because of inefficient use of keys, and much larger rekeying overheads. In this paper, we propose a new GKM scheme for multiple multicast groups, called the master-key-encryption-based multiple group key management (MKE-MGKM) scheme. The MKE-MGKM scheme exploits asymmetric keys, i.e., a master key and multiple slave keys, which are generated from the proposed master key encryption (MKE) algorithm and is used for efficient distribution of the group key. It alleviates the rekeying overhead by using the asymmetry of the master and slave keys, i.e., even if one of the slave keys is updated, the remaining ones can still be unchanged by modifying only the master key. Through numerical analysis and simulations, it is shown that the MKE-MGKM scheme can reduce the storage overhead of a key distribution center (KDC) by 75 percent and the storage overhead of a user by up to 85 percent, and 60 percent of the communication overhead at most, compared to the existing schemes.

Architectures of flexible symmetric key crypto engines—a survey

Throughput, flexibility, and security form the design trilogy of reconfigurable crypto engines; they must be carefully considered without reducing the major role of classical design constraints, such as surface, power consumption, dependability, and cost. Applications such as network security, Virtual Private Networks (VPN), Digital Rights Management (DRM), and pay per view have drawn attention to these three constraints. For more than ten years, many studies in the field of cryptographic engineering have focused on the design of optimized high-throughput hardware cryptographic cores (e.g., symmetric and asymmetric key block ciphers, stream ciphers, and hash functions). The flexibility of cryptographic systems plays a very important role in their practical application. Reconfigurable hardware systems can evolve with algorithms, face up to new types of attacks, and guarantee interoperability between countries and institutions. The flexibility of reconfigurable crypto processors and crypto coprocessors has reached new levels with the emergence of dynamically reconfigurable hardware architectures and tools. Last but not least, the security of systems that handle confidential information needs to be thoroughly evaluated at the design stage in order to meet security objectives that depend on the importance of the information to be protected and on the cost of protection. Usually, designers tackle security problems at the same time as other design constraints and in many cases target only one security objective, for example, a side-channel attack countermeasures, fault tolerance capability, or the monitoring of the device environment. Only a few authors have addressed all three design constraints at the same time. In particular, key management security (e.g., secure key generation and transmission, the use of a hierarchical key structure composed of session keys and master keys) has frequently been neglected to the benefit of performance and/or flexibility. Nevertheless, a few authors propose original processor architectures based on multi-crypto-processor structures and reconfigurable cryptographic arrays. In this article, we review published works on symmetric key crypto engines and present current trends and design challenges.