在密码学中，公开密钥认证（英语：Public key certificate），又称公开密钥凭证、公钥凭证、数字凭证（digital certificate）、数字认证、身份凭证（identity certificate）或安全证书，是一种电子文档，用来证明公开密钥所有者的身份。认证中，包含了密钥信息，拥有者身份信息，以及这份文档的数字签章，以保证这个文档的整体内容正确无误。如果签章是正确的，而用户可以相信签署者，之后用户就知道他们可以使用这个密钥，来与密钥的拥有者进行通信。在X.509中规范了这个认证的过程与标准。

In cryptography, a public key certificate (also known as a digital certificate or identity certificate) is an electronic document used to prove ownership of a public key. The certificate includes information about the key, information about its owner's identity, and the digital signature of an entity that has verified the certificate's contents are correct. If the signature is valid, and the person examining the certificate trusts the signer, then they know they can use that key to communicate with its owner.