Lattice Reduction Attack Research Articles

Guessing Bits: Improved Lattice Attacks on (EC)DSA with Nonce Leakage

The lattice reduction attack on (EC)DSA (and other Schnorr-like signature schemes) with partially known nonces, originally due to Howgrave-Graham and Smart, has been at the core of many concrete cryptanalytic works, side-channel based or otherwise, in the past 20 years. The attack itself has seen limited development, however: improved analyses have been carried out, and the use of stronger lattice reduction algorithms has pushed the range of practically vulnerable parameters further, but the lattice construction based on the signatures and known nonce bits remain the same.In this paper, we propose a new idea to improve the attack based on the same data in exchange for additional computation: carry out an exhaustive search on some bits of the secret key. This turns the problem from a single bounded distance decoding (BDD) instance in a certain lattice to multiple BDD instances in a fixed lattice of larger volume but with the same bound (making the BDD problem substantially easier). Furthermore, the fact that the lattice is fixed lets us use batch/preprocessing variants of BDD solvers that are far more efficient than repeated lattice reductions on non-preprocessed lattices of the same size. As a result, our analysis suggests that our technique is competitive or outperforms the state of the art for parameter ranges corresponding to the limit of what is achievable using lattice attacks so far (around 2-bit leakage on 160-bit groups, or 3-bit leakage on 256-bit groups).We also show that variants of this idea can also be applied to bits of the nonces (leading to a similar improvement) or to filtering signature data (leading to a data-time trade-off for the lattice attack). Finally, we use our technique to obtain an improved exploitation of the TPM–FAIL dataset similar to what was achieved in the Minerva attack.

Cryptanalysis of Merkle-Hellman Cipher Using Parallel Genetic Algorithm

In 1976, Whitfield Diffie and Martin Hellman introduced the public key cryptography or asymmetric cryptography standards. Two years later, an asymmetric cryptosystem was published by Ralph Merkle and Martin Hellman called $ \mathcal {M} \mathcal {H} $, based on a variant of knapsack problem known as the subset-sum problem which is proven to be NP -hard. Furthermore, over the last four decades, Metaheuristics have achieved remarkable progress in solving NP-hard optimization problems. However, the conception of these methods raises several challenges, mainly the adaptation and the parameters setting. In this paper, we propose a Parallel Genetic Algorithm (PGA) adapted to explore effectively the search space of considerable size in order to break the $ \mathcal {M} \mathcal {H} $ cipher. Experimental study is included, showing the performance of the proposed attacking scheme, and finally a concluding comparison with lattice reduction attacks.

On the Linear Complexity of the Power Generator

We obtain a lower bound on the linear complexity of the power generator of pseudo-random numbers, which in some special cases is also known as the RSA generator and as the Blum–Blum–Shub generator. In some very important cases this bound is essentially the best possible. In particular, this implies that lattice reduction attacks on such generators are not feasible.

On the linear complexity profile of the power generator

We obtain a lower bound on the linear complexity profile of the power generator of pseudo-random numbers modulo a Blum integer. A different method is also proposed to estimate the linear complexity profile of the Blum-Blum-Shub (1986) generator. In particular, these results imply that lattice reduction attacks on such generators are not feasible.