Digital certificates are divided into two categories. One type is stored in the computer and is called a "soft certificate"; the other type is stored in a USB key similar to a USB flash drive and is called a "hard certificate". For convenience and cost considerations, ordinary individual users prefer to use "soft certificates". "Soft certificates" have security risks. It does not force users to set a certificate and use a password, and other people can use it directly when logging in to the same computer. The private key of a "soft certificate" can be exported, giving Trojans an opportunity to copy the certificate to other computers for use. Previously, there were cases where banks' "soft certificates" were compromised, and some banks simply canceled the online payment function of "soft certificates" in 2008. The private key of a "soft certificate" can be exported, giving Trojans an opportunity to copy the certificate to other computers for use. Previously, there were cases where banks' "soft certificates" were compromised, and some banks simply canceled the online payment function of "soft certificates" in 2008.