In this case, I am assuming that a verified E-mail address is sufficient to establish a user's identity.
在这种情况中，我们假设一个经过验证的电子邮件地址就足以建立用户的身份。
2
Secure Multipurpose Internet Mail Extensions (S/MIME) allows digital signatures to be attached to e-mail messages, such that the recipient can verify the identity of the signer.
安全多用途 Internet 邮件扩展（Secure Multipurpose Internet Mail Extensions，S/MIME）允许将数字签名附加到电子邮件消息上，这样接收方就可以验证签名者的身份。
3
With OpenID, end users can own an identity without externalizing information they would prefer to protect, such as their E-mail address.