X.509 Digital Certification

创建数字认证的过程如下：

1.Alice sends a signed certificate request containing her name, her public key, and perhaps some additional information to a CA.

2.The CA creates a message, m, from Alice's request. The CA signs the message with its private key, creating a separate signature message, sig. The CA returns the message, m, and the signature, sig, to Alice. Together, m and sig form Alice's certificate.

3.Alice sends both parts of her certificate to Bob to give him access to her public key.

4.Bob verifies the signature, sig using the CA's public key. If the signature proves valid, he accepts the public key in the certificate as Alice's public key.