| The existing traditional public-key cryptosystems such as RSA and ECC will migrate to the post-quantum cryptography（PQC）systems because the development of large-scale quantum computers is threating the security of the traditional public-key cryptosystems.The lattice-based cryptography（LBC）has become the most promising cryptographic scheme due to its high security,simple structure,fast computation speed and good scalability.Although LBC has the advantage of resisting quantum attacks,it still faces the threat of side-channel analysis（SCA）in the process of implementation,which is just like traditional public key cryptosystems.In this thesis,we focus on the side-channel security of LBC.Specifically,the power analysis attacks and the related protection techniques are studied on the embedded platform implementation.On this basis,the key modules are selected and extended to hardware implementation.The specific research work of this thesis is summarized as follows:Firstly,the power analysis of LBC implemented on embedded devices is studied,and a template attack method based on cyclic message rotation is proposed.The Incremental-Storage vulnerability is found in the Decode function by analyzing the decapsulation stage of LBC.The leakage of this vulnerability is closely related to the Hamming weight value for secret messages.Based on the Incremental-Storage vulnerability,Normalized Inter-Class Variance（NICV）is used to build classification templates for the Hamming weight of secret messages’intermediate states.The recovery of the secret message by bytes can be realized by identifying the cyclic message rotation property of the LBC.Experiments on CRYSTAL-Kyber and Saber show that the proposed method is able to complete the template construction with fewer power traces,and only 32 power traces are required to complete the attack while maintaining a high success rate of secret message recovery.Secondly,a high-order masking scheme based on bitslice is proposed with Saber as an example.On one hand,a ciphertext comparison method based on zero-test is proposed.The proofs of correctness and security under the t-probing model are given,and the generality of the proposed ciphertext comparison method is analyzed.On the other hand,the throughput of A2B transform and central binomial sampling in decapsulation stage is improved by using bitslice technique for the case of Saber with a large amount of data parallelism.Some functions are specially designed according to the parameters of Saber.The performance of each security level of the proposed masking scheme is analyzed,and the security is evaluated using TVLA.The results show that the proposed masking scheme can resist high-order SCA and effectively reduce the time overhead and storage overhead caused by masking.Finally,a hardware unit of SHA-3 based on Domain-Oriented Masking（DOM）in the central binomial sampler is proposed after the consideration of hardware masking design.To address the problem that the threshold implementation does not have high-order generality and the design is complicated,the DOM is used such that the masked components with correlation are operated separately in different domains.The non-completeness of the masked circuit is achieved by adding and changing registers’positions.At the same time,the masked structure is optimized to achieve a pipeline structure while simplifying the storage of round constants.Experiments show that the area overhead factors of the 2nd-order masked implementation and the 3rd-order masked implementation of this design are 1.95x and 3.2x,respectively,which are smaller than the area overhead factors of existing schemes,indicating that the overhead brought by this design is acceptable under the demand of high-order security level. |
