您可以从证书颁发机构获取证书。不论您选择政府机构还是私营公司，这项服务——例如让他们证明您的身份——通常是要收费的。其他很少几家机构会无偿颁发证书，如开源项目 CAcert 基于知名可靠的 Web of Trust 模型，且正日益普及。
If you are using Linux, macOS or Solaris, you must install a recent version of Thunderbird or Firefox. LibreOffice will then access their certificate storage.
If you have created different profiles in Thunderbird or Firefox and you want to use certificates from one specific user profile, select the profile in Tools - Options - Security - Certificate Path. Alternatively, you can set the environment variable MOZILLA_CERTIFICATE_FOLDER to point to the folder containing that profile.
Open your web browser’s preferences, select the Advanced section, click on the Certificates tab, and then choose View Certificates. The Certificate Manager dialog will appear.
导入您的新根证书，然后选择并编辑此证书。启用此根证书至少使其能够为 Web 和电子邮件访问所信任。这能确保此证书可以对您的文档进行签名。您可以用同样的方式编辑任何中间证书，但是中间证书对于签名文档不是必需的。
On Windows systems, LibreOffice will access the system certificate storage.
Your private key for the digital signature will usually be generated and securely stored by Windows as part of the signature-issuance process. Once the issuing Certificate Authority is satisfied that your computer produced the private key and you have satisfied any other identification requirements, the corresponding public key is signed by the Certificate Authority. For personal keys obtained over the Internet, the private key is generated by your browser and it is not shared with the Certificate Authority.
If a private key is received by other means or you transfer it from another computer, you can install it on your Windows PC by double-clicking on the private key certificate and providing any required password. This private key may be known to others (such as an organizational or governmental security administration) depending on how it was issued to you.
Public keys of other people used to verify document digital signatures, or encrypt documents for their eyes only, are usually stored in your system with digital certificate-management applications. In some cases you will need to manage those public-key certificates yourself.
The general management of public and private keys on your PC will vary depending on the version of Windows you are operating. For more information, use the "Help and Support" topic of your Windows version and search for "digital signature".
Choose File - Digital Signatures - Digital Signatures.
In the Select Certificate dialog, select your certificate and click OK.
You see again the Digital Signatures dialog, where you can add more certificates if you want. Click OK to add the public key to the saved file.
A signed document shows an icon in the status bar. You can double-click the icon in the status bar to view the certificate.
The result of the signature validation is displayed in the status bar and within the Digital Signature dialog. Several documents and macro signatures can exist inside an ODF document. If there is a problem with one signature, then the validation result of that one signature is assumed for all signatures. That is, if there are ten valid signatures and one invalid signature, then the status bar and the status field in the dialog will flag the signature as invalid.
选择工具 - 宏 - 数字签名。
When you open the Basic IDE that contains signed macros, you see an icon in the status bar. You can double-click the icon in the status bar to view the certificate.