To sign a document digitally, you need a personal key, the certificate. A personal key is stored on your computer as a combination of a private key, which must be kept secret, and a public key, which you add to your documents when you sign them.
要对文档进行数字签名，需要个人密钥和证书。个人密钥以私钥和公钥的组合形式存储在您的计算机上，前者必须保密，而后者需要在签署文档时将其添加到其中。