Enforcement Rules of the Electronic Signatures Act Article 11

The expression "to provide services for issuing certificates" as set forth in Paragraph 1, Article 12 of the Act shall mean that a certificate issued by a certification authority may be used by the certificate subscriber as a proof to sign an electronic record with a third party other than the certification authority.
中文原文 電子簽章法施行細則第11條
本法第十二條第一項所稱提供簽發憑證服務,係指憑證機構簽發之憑證,可供憑證用戶作為其與憑證機構以外之第三人簽署電子文件時證明之用者。

English translation for reference only; the Chinese text prevails. Not legal advice.