Cryptanalysis of the MEM Mode of Operation

The MEM mode is a nonce-based enciphering mode of operation proposed by Chakraborty and Sarkar, which was claimed to be secure against symmetric nonce respecting adversaries. We show that this is not correct by using two very simple attcks. One attack need one decryption and one decryption queries, and the other only need one encryption query

A Novel Approach to Communicate Secret Message Between Users Using Sponge Function Technique on NTRU

This paper presents a novel approach for a (key distribution) for secret message communication among a group (G). In order to increase security to distribute secret message (key), we introduce sponge functions using these at a specific permutation. We generate a key and distribute this key using (PKCS)(public key crypto systems), the absorbing, squeezing functions are used. In this paper an introduction part which briefs regarding sponge functions, key distribution centre, group communication and NTRU, key generation authentication, in literature review we describe about the research states of sponge functions, lightweight hash functions-KDC – NTRU. In proposed work we propose how the group communication establishes registration of users, entry and exit of a user. The encryption and decryption algorithm are used between sender and receiver. The entire proposed work is verified in VHDL and ‘MATLABS'. doi: http://dx.doi.org/10.12777/ijse.4.2.2013.44-51 [How to cite this article: Varaprasad, S., Rao, K. V., & Avadhani, P. S. (2013). A Novel Approach to Communicate Secret Message between Users Using Sponge Function Technique on NTRU. INTERNATIONAL JOURNAL OF SCIENCE AND ENGINEERING, 4(2), 44-51; doi: http://dx.doi.org/10.12777/ijse.4.2.2013.44-51

Collision Attack on GRINDAHL

Hash functions have been among the most scrutinized cryptographic primitives in the previous decade, mainly due to the cryptanalysis breakthroughs on MD-SHA family and the NIST SHA3 competition that followed. GRINDAHL is a hash function proposed at FSE 2007 that inspired several SHA3 candidates. One of its particularities is that it follows the RIJNDAEL design strategy, with an efficiency comparable to SHA2. This paper provides the first cryptanalytic work on this scheme and we show that the 256-bit version of GRINDAHL is not collision resistant. Our attack uses byte-level truncated differentials and leverages a counterintuitive method (reaching an internal state where all bytes are active) in order to ease the construction of good differential paths. Then, by a careful utilization of the freedom degrees inserted every round, and with a work effort of approximatively $2^{112}$ hash computations, an attacker can generate a collision for the full 256-bit version of GRINDAHL

Provable Security of (Tweakable) Block Ciphers Based on Substitution-Permutation Networks

Substitution-Permutation Networks (SPNs) refer to a family of constructions which build a wn-bit block cipher from n-bit public permutations (often called S-boxes), which alternate keyless and “local” substitution steps utilizing such S-boxes, with keyed and “global” permu- tation steps which are non-cryptographic. Many widely deployed block ciphers are constructed based on the SPNs, but there are essentially no provable-security results about SPNs. In this work, we initiate a comprehensive study of the provable security of SPNs as (possibly tweakable) wn-bit block ciphers, when the underlying n-bit permutation is modeled as a public random permutation. When the permutation step is linear (which is the case for most existing designs), we show that 3 SPN rounds are necessary and sufficient for security. On the other hand, even 1-round SPNs can be secure when non-linearity is allowed. Moreover, 2-round non-linear SPNs can achieve “beyond- birthday” (up to 2 2n/3 adversarial queries) security, and, as the number of non-linear rounds increases, our bounds are meaningful for the number of queries approaching 2 n . Finally, our non-linear SPNs can be made tweakable by incorporating the tweak into the permutation layer, and provide good multi-user security. As an application, our construction can turn two public n-bit permuta- tions (or fixed-key block ciphers) into a tweakable block cipher working on wn-bit inputs, 6n-bit key and an n-bit tweak (for any w ≥ 2); the tweakable block cipher provides security up to 2 2n/3 adversarial queries in the random permutation model, while only requiring w calls to each permutation, and 3w field multiplications for each wn-bit input

Cryptanalysis of RadioGatun

In this paper we study the security of the RadioGatun family of hash functions, and more precisely the collision resistance of this proposal. We show that it is possible to find differential paths with acceptable probability of success. Then, by using the freedom degrees available from the incoming message words, we provide a significant improvement over the best previously known cryptanalysis. As a proof of concept, we provide a colliding pair of messages for RadioGatun with 2-bit words. We finally argue that, under some light assumption, our technique is very likely to provide the first collision attack on RadioGatun

Merkle-Damgård Construction Method and Alternatives: A Review

Cryptographic hash function is an important cryptographic tool in the field of information security. Design of most widely used hash functions such as MD5 and SHA-1 is based on the iterations of compression function by Merkle-Damgård construction method with constant initialization vector. Merkle-Damgård construction showed that the security of hash function depends on the security of the compression function. Several attacks on Merkle-Damgård construction based hash functions motivated researchers to propose different cryptographic constructions to enhance the security of hash functions against the differential and generic attacks. Cryptographic community had been looking for replacements for these weak hash functions and they have proposed new hash functions based on different variants of Merkle-Damgård construction. As a result of an open competition NIST announced Keccak as a SHA-3 standard. This paper provides a review of cryptographic hash function, its security requirements and different design methods of compression function

Development of a cryptography model based on improved filtering, compression and encryption techniques for ECG signal processing

Electrocardiography is the process of producing an electrocardiogram (ECG) which is a convenient tool for identifying people with potential heart diseases which may need immediate referral to a hospital or emergency medical services in E-healthcare. The ECG signal remote monitoring application in the healthcare services face many challenges related to the real-time diagnosis. The noise cancellation of the ECG signal is critical for accurate extraction of useful heart data from ECG. Additionally, the continuous flow of signals may lead to a sheer increase in the volume of the data, the ECG data needs a large memory storage device. At the same time, security and privacy of the data is considered as a significant aspect of remote diagnosis medical application that further increases the volume of data sharing, including the risk factor. This research work proposed a model to combine approaches for ECG denoising, data encoding, and encryption. Further, improved ECG signal processing based on improved filtering, an adaptive lossless compression mechanism, and hybrid cryptography are proposed. For the denoising of the ECG signal, an enhanced and extended Kalman and adaptive Recursive Least Square (RLS) filtering have been used for signal filtering along with Discrete Wavelet Transform (DWT). The compression mechanism is performed using adaptive lossless compression based on Huffman encoding. Furthermore, to increase security, a cryptography mechanism has been employed using the Advanced Encryption Standard (AES) algorithm and Cipher Block Chaining (CBC) operation mode scheme with a 256-bit key. The Diffie-Hellman key exchange and Rivest Shamir Adleman (RSA) key generation algorithms have been used to authenticate the receiver, and key generation for encrypting and decrypting processes, respectively. Consequently, the main contributions of this research work include a high level of security, privacy, encoding with low error reconstruction along with reduced noise and processing time for the ECG signal in e-healthcare services. The proposed model is for denoising, assuring data security, and compression performance for ECG data storage and transmission on MIT-BIH and PTB Diagnostic ECG dataset. The experimental results show that the proposed system model is successfully the denoising, and secure storage and transmission of ECG data. Based on the simulation results show a decrease for SNR by SNRimp of 55 in dB, a significant improvement of 21.92 for MSE and good accuracy for PSNR and CC. Furthermore, the throughput average of CR is enhanced by 26.66 and 0.8416 for PRD compared with existing different compression schemes for the ECG signal. Finally, the proposed system model is utilized for high-level security against for various kinds of attacks such as denial-of-service (DoS), Distributed DoS, privacy attack, and Man-in-the-middle (MitM)

Forkcipher: A New Primitive for Authenticated Encryption of Very Short Messages

This is an extended version of the article with the same title accepted at Asiacrypt 2019.International audienceHighly efficient encryption and authentication of short messages is an essential requirement for enabling security in constrained scenarios such as the CAN FD in automotive systems (max. message size 64 bytes), massive IoT, critical communication domains of 5G, and Narrowband IoT, to mention a few. In addition, one of the NIST lightweight cryptography project requirements is that AEAD schemes shall be “optimized to be efficient for short messages (e.g., as short as 8 bytes)”. In this work we introduce and formalize a novel primitive in symmetric cryptography called a forkcipher. A forkcipher is a keyed function expanding a fixed-length input to a fixed-length output. We define its security as indistinguishability under chosen ciphertext attack. We give a generic construction validation via the new iterate-fork-iterate design paradigm. We then propose ForkSkinny as a concrete forkcipher instance with a public tweak and based on SKINNY: a tweakable lightweight block cipher constructed using the TWEAKEY framework. We conduct extensive cryptanalysis of ForkSkinny against classical and structure-specific attacks. We demonstrate the applicability of forkciphers by designing three new provably-secure, nonce-based AEAD modes which offer performance and security tradeoffs and are optimized for efficiency of very short messages. Considering a reference block size of 16 bytes, and ignoring possible hardware optimizations, our new AEAD schemes beat the best SKINNY-based AEAD modes. More generally, we show forkciphers are suited for lightweight applications dealing with predominantly short messages, while at the same time allowing handling arbitrary messages sizes. Furthermore, our hardware implementation results show that when we exploit the inherent parallelism of ForkSkinny we achieve the best performance when directly compared with the most efficient mode instantiated with the SKINNY block cipher

Security Enhancement of the Vortex Family of Hash Functions

Vortex is a new family of one-way hash functions which has been submitted to the NIST SHA-3 competition. Its design is based on using the Rijndael block cipher round as a building block, and using a multiplication-based merging function to support fast mixing in a small number of steps. Vortex is designed to be a fast hash function, when running on a processor that has AES acceleration and has a proven collision resistance [2]. Several attacks on Vortex have been recently published [3, 4, 5, 6] exploiting some structural properties of its design, as presented in the version submitted to the SHA-3 competition. These are mainly ¯rst and second preimage attacks with time complexity below the ideal, as well as attempts to distinguish the Vortex output from random. In this paper we study the root-cause of the attacks and propose few amendments to the Vortex structure, which eliminate the attacks without a®ecting its collision resistance and performance