According to Zhihu's inquiry, Beijing CA signature can be signed by Alipay and WeChat scan code. This method is convenient and efficient, and it can also avoid a series of problems caused by the loss and expiration of certificates. No matter which way you choose, you need to ensure the security and validity of the digital certificate. At the same time, when signing important documents, it is recommended to check the original paper or electronic documents to ensure the accuracy and legality of signing.