The electronic evidence authentication and protection scheme is based on the lattice cryptosystem, and other illegal users or attackers are unable to obtain the original electronic evidence data in the whole process of the electronic evidence protection system, which well protects the security of the original electronic evidence and increases the overall security of the scheme.

The authentication sizes corresponding to different safety grade coefficients (such as 64bits, 128bits, 256bits and 512bits) can be calculated when the selected system parameter is n=512bits, q=2**64. The results are shown in the file named "the data of this article.xlsx". The algorithm authentication size corresponding to different safety grade coefficients of our proposed lat-tice-based cipher scheme and RSA and ECC authentication algorithms is given. As shown in the file named "the data of this article.xlsx"

The meaning of "Safety grade coefficient " in this data file is as follows: a parameter of a security level, in which the higher the parameter, the more secure the scheme.

The meaning of "RSA algorithm " in this data file is as follows: a widely used asymmetric cryptographic algorithm. The corresponding data below represent the computational complexity of the algorithm. The higher the numerical value, the higher the complexity, and the higher the security level of the scheme.

The meaning of "ECC algorithm " in this data file is as follows: a widely used symmetric cryptographic algorithm. The corresponding data below represent the computational complexity of the algorithm. The higher the numerical value, the higher the complexity, and the higher the security level of the scheme.

The meaning of "Our algorithm " in this data file is as follows: the scheme proposed in this paper. The corresponding data below represent the computational complexity of the algorithm. The higher the numerical value, the higher the complexity, and the higher the security level of the scheme.