Stability and style variation are important characteristics in handwriting analysis and recognition. This paper describes a stability modeling technique of handwritings in the context of on-line signature verification. With this technique, the stability and style-variation characteristics of the reference samples are deduced from the dynamic warping relationship between the sequences of basic handwriting strokes. Reliability measures of the extracted signature features are incorporated into the signature segmentation, model building, and verification algorithms, so that stable handwriting features are emphasized in the signature matching process, while style variations for less stable features are intentionally tolerated. The generated signature model consists of a structure description graph of the handwriting components and their stability information. A signature is accepted by the model if it is close to a permissible path within the weighted graph. A novel feature of the technique is its ability to refine the correspondence relation of the handwriting during model building and signature verification. This ability enables the verification and partial correction of segmentation errors to reduce the number of false rejections while maintaining the system security level and keeping the number of reference samples manageable.