自簽名證書：由服務器自己頒發給自己，用於證明自己身份的東西，非權威頒發機構發布，默認客戶端都是不信任的，主要目的是用來加密和保證數據的完整性和不可抵賴性,與簽名證書相同.
詳細具體解釋見下面英文。
When you're building an ecommerce site one of the first things you'll need to set up is a security certificate so that your server data will be secure. When you set this up, you have the option of creating a self-signed cerficate or creating a certificate approved by a certificate authority.
Similarities Between Signed and Self-Signed Certificates
Whether you get your certificate signed by a certificate authority or sign it yourself, there is one thing that is exactly the same on both:
Both certificates will generate a site that cannot be read by third-parties. The data sent over an monly used Certificate Authority is Verisign. Depending upon which CA is used, the domain is verified and a certificate is issued. Verisign and other more trusted CAs will verify the existence of the business in question and the ownership of the domain to provide a bit more security that the site in question is legitimate.
The problem with using a self-signed certificate is that nearly every Web browser checks that an es down to is trust. When you use a self-signed certificate, you are saying to your customers "trust me - I am who I say I am." When you use a certificate signed by a CA, you are saying, "Trust me - Verisign agrees I am who I say I am."
If You're Doing Ecommerce You Need a Signed Certificate
While it is possible your customers will forgive you a self-signed certificate if all they use it for is to login to your website. But if you're asking them to input their credit card or Paypal information, then you really need a signed certificate. Most people trust the signed certificates and won't do business over an HTTPS server without one. So if you're trying to sell something on your website, invest in that certificate. It's just a cost of doing business.