A method, comprising: receiving first handwriting information associated with handwriting entered by a user; in response to receiving the first handwriting information, processing the first handwriting information, the processing of the first handwriting information comprising performing a dimension normalization to reduce the effect of wobbling inherent in the handwriting entered by the user; determining whether to associate the first handwriting information with an account corresponding to the user, comprising: computing (120, 330) a degree of complexity of the first handwriting information, wherein the degree of complexity is based at least in part on one or more characteristic values extracted from the first handwriting information; and the one or more characteristic values are based at least in part on one or more of: a number of strokes; a spatial distribution of the handwriting; and a gradient distribution of the handwriting; and determining whether the degree of complexity of the first handwriting information satisfies one or more preset conditions, the one or more preset conditions including: the degree of complexity being greater than a minimum complexity threshold, and the degree of complexity being less than a maximum complexity threshold; and in response to a determination that the degree of complexity of the first handwriting information satisfies the one or more preset conditions, associating the first handwriting information with identity registration information corresponding to the user. receiving first handwriting information associated with handwriting entered by a user; in response to receiving the first handwriting information, processing the first handwriting information, the processing of the first handwriting information comprising performing a dimension normalization to reduce the effect of wobbling inherent in the handwriting entered by the user; determining whether to associate the first handwriting information with an account corresponding to the user, comprising: computing (120, 330) a degree of complexity of the first handwriting information, wherein the degree of complexity is based at least in part on one or more characteristic values extracted from the first handwriting information; and the one or more characteristic values are based at least in part on one or more of: a number of strokes; a spatial distribution of the handwriting; and a gradient distribution of the handwriting; and determining whether the degree of complexity of the first handwriting information satisfies one or more preset conditions, the one or more preset conditions including: the degree of complexity being greater than a minimum complexity threshold, and the degree of complexity being less than a maximum complexity threshold; and computing (120, 330) a degree of complexity of the first handwriting information, wherein the degree of complexity is based at least in part on one or more characteristic values extracted from the first handwriting information; and the one or more characteristic values are based at least in part on one or more of: a number of strokes; a spatial distribution of the handwriting; and a gradient distribution of the handwriting; and the degree of complexity is based at least in part on one or more characteristic values extracted from the first handwriting information; and the one or more characteristic values are based at least in part on one or more of: a number of strokes; a spatial distribution of the handwriting; and a gradient distribution of the handwriting; and a number of strokes; a spatial distribution of the handwriting; and a gradient distribution of the handwriting; and determining whether the degree of complexity of the first handwriting information satisfies one or more preset conditions, the one or more preset conditions including: the degree of complexity being greater than a minimum complexity threshold, and the degree of complexity being less than a maximum complexity threshold; and in response to a determination that the degree of complexity of the first handwriting information satisfies the one or more preset conditions, associating the first handwriting information with identity registration information corresponding to the user.