I would like to have the authentication and registration parts of my website encrypted (for obvious reason). This site is currently and older site which some friends and I started in middle school and still use today. I may or may not register it to be a Non-Profit Organization in the near future, but either way, a CA costs money and the organization doesn't have any and we are currently college kids.
Verisign is unreasonable and GoDaddy is $30/year. GoDaddy isn't too unreasonable, and I think their certs are accepted by most web browsers. The thing with GoDaddy is that I don't know why they have different SSL products (i.e.: why is it cheap to not verify me? does this have any implications on the cert and how the browser treats it if it just contains a domain name?)
Also, is there an issue with using my own cert? Could the login page be http, and have a line stating that I use a self-signed cert and here is it's fingerprint and then post the form to an https page? Safari's method isn't too bad or sound too scary. I'm afraid, however, that firefox 3's method will scare people away and give me a tonne of emails saying that my site is being hacked or something. I don't know how IE responds to self-signed certs. (There is also the issue of why pay for something I can create myself with no effort, but I'm not going to pose the philosophical part of it, this is a more practical question.)
In sum, do I give GoDaddy $30 a year or do I just tell people in a small paragraph what I'm doing and give the few people that will actually want my fingerprint it?
Edit: Some on a forum I was reading for more info mentioned that GoDaddy certs are only given if it's on a GoDaddy server, which this isn't. Two things: (1) is this true? and There are other CA's at about the same price, so the argument should still be the same.
The SSL certificate solves two purposes: encryption of traffic (for RSA key exchange, at least) and verification of trust. As you know, you can encrypt traffic with (or without, if we're talking SSL 3.0 or TLS) any self-signed certificate. But trust is accomplished through a chain of certificates. I don't know you, but I do trust verisign (or at least Microsoft does, because they've been paid lots of money to get it installed in their operating systems by default), and since Verisign trusts you, then I trust you too. As a result, there's no scary warning when I go to such an SSL page in my Web browser because somebody that I trust has said you are who you are.
Generally, the more expensive the certificate, the more investigating that the issuing certificate authority does. So for the Extended Validation certificates, the requesters have to submit more documents to prove that they are who they say they are, and in return they get a bright, happy green bar in modern Web browsers (I think Safari doesn't do anything with it quite yet).
Finally, some companies go with the big boys like Verisign purely for the brand name alone; they know that their customers have at least heard of Verisign and so that for people shopping on their online store, their seal looks a little less sketch-ball than, say, GoDaddy's.
If the branding is not important to you or if your site is not prone to phishing attacks, then the cheapest SSL cert that you can buy that has its root installed in most Web browsers by default will be fine. Usually, the only verification done is that you must be able to reply to an e-mail sent to the DNS's administrative contact, thus "proving" that you "own" that domain name.
You can use those cheap-o certificates on non-GoDaddy servers, sure, but you'll probably have to install an intermediate certificate on the server first. This is a certificate that sits between your cheap-o $30 certificate and the GoDaddy "real deal" root certificate. Web browsers visiting your site will be like "hmm, looks like this was signed with an intermediate, you got that?" which requires may require an extra trip. But then it'll request the intermediate from your server, see that it chains up to a trusted root certificate that it knows about, and there is no problem.
But if you are not allowed to install the intermediate on your server (such as in a shared hosting scenario), then you are out of luck. This is why most people say that GoDaddy certs can't be used on non-GoDaddy servers. Not true, but true enough for many scenarios.
(At work we use a Comodo certificate for our online store, and a cheapo $30 GoDaddy cert to secure the internal connection to the database.)
Edited in italics to reflect erickson's insightful clarifications below. Learn something new every day!
There's a common misconception that self-signed certificates are inherently less secure than those sold by commercial CA's like GoDaddy and Verisign, and that you have to live with browser warnings/exceptions if you use them; this is incorrect.
If you securely distribute a self-signed certificate (or CA cert, as bobince suggested) and install it in the browsers that will use your site, it's just as secure as one that's purchased and is not vulnerable to man-in-the-middle attacks and cert forgery. Obviously this means that it's only feasible if only a few people need secure access to your site (e.g., internal apps, personal blogs, etc.).
In the interest of increasing awareness and encouraging fellow small-time bloggers like myself to protect themselves, I've written up a entry-level tutorial that explains the concepts behind certificates and how to safely create and use your own self-signed cert (complete with code samples and screenshots) here.
Get a certificate from Let's Encrypt, a free CA this new decade, which is widely supported by browsers.
I haven't tried them yet, but StartCom was mentioned in a response to a similar question. Apparently you can get a one year certificate for free, and it's accepted by Firefox 3.
Even if you have to pay, I would suggest using a CA rather than self-signed certificates. Some people won't see your explanation, and a fake site could post their own fake certificate's fingerprint just like you propose. I doubt the average user knows what a certificate fingerprint is or how to check it.
Instead of creating a self-signed cert, create a self-signed CA, and sign your HTTPS certificate with that. It's easier to ask users to install a CA than a single server cert, and you can create new certs (eg. for subdomains, or to update expired certs) without users having to install a server cert again.
You can then decide later whether it's worth the $30 to switch from a cert signed by your own CA to the same cert signed by GoDaddy or whoever.
Either way, don't have an HTTP page with a form posted to HTTPS. The user cannot see that that's where it's going; they'd have to view source to check the form hasn't been hijacked to point elsewhere and no-one's going to do that. You would have to have an HTTP front page with the CA link and a separate link to the HTTPS login form.
Asking users to install a CA with a cert downloaded via plain HTTP is a bit naughty: if there were a man-in-the-middle they could replace your CA on the fly and hijack the ensuing HTTPS connections. The chances of this actually happening are quite low as it would have to be a targeted attack as opposed to plain old automated sniffing, but really you ought to be hosting the CA download link on some other HTTPS-protected service.
Customer acceptance is a matter only you can answer, knowing who your users are. Certainly the Firefox interface is excessively scary. If CAs like GoDaddy are down to $30 these days I would probably go for it; it used to be a lot, lot worse.
Assuming support on old and niche browsers is not much of an issue, just go for the cheapest CA available. You are supposed to be paying to have the CA properly verify who you are, but in practice that's not the way it works and it never has been, so paying extra for more thorough checks gets you almost nothing. Verisign's extortionate prices survive through corporate inertia alone.
CAs are there to receive money for doing nothing but owning a few hundred bits of private key. The identity-verifying stuff that was supposed to have been part of the CA mandate has been moved to EV certificates. Which are even more of a rip-off. Joy.
Self-signed certificates are insecure. Yes, really. "At least it's encrypted" isn't helping at all. From the article:
World-class encryption * zero authentication = zero security
If your website is for you and a few of your friends, then you might create your own CA and distribute your certificate to friends.
Otherwise either get a certificate from known CA (for free) or don't bother with self-signed certificates at all, because all you'd get is a false sense of security.
Why just encrypted traffic is not secure? You're always allowing the other end to decrypt your traffic (you have to, otherwise you'd be sending gibberish).
If you don't check who's on the other end, you're allowing anybody to decrypt your traffic. It doesn't make a difference if you send data to an attacker securely or not securely — the attacker gets the data anyway.
I'm not talking about checking whether e.g. paypal.com belongs to a trustworthy financial institution (that's a bigger problem). I'm talking about checking whether you're sending data to the paypal.com, or just to a van around the corner that sends a certificate saying "yeah, I'm like totally paypal.com and you have my word that it's true!"
I just finally broke down and switched my server from self-signed to a GoDaddy cert last night and it wasn't that big a deal, aside from their process not being as clear as it could be. $30/year is a reasonable cost and using the cert on a non-GoDaddy server is not an issue.
If you're going to be talking SSL to the public, get a real cert signed by a real CA. Even if you're working for minimum wage, you'll save more than $30/year worth of wasted time in dealing with user fears or distrust, and that's even before considering any possible lost revenue due to them being scared away from your site.
To answer your question about Internet Explorer, it will warn users about any site whose certificate is not signed by an IE-known (unfortunately called "trusted") CA. This includes for your own CA and for self-signed certificates. It will also make a warning if the domain in the certificate is not the one being accessed.
If this is a private site, you may not care so long as you are getting link-level encryption (and are you that fearful of someone sniffing your traffic?). If there is public access and you want SSL, then get a signed certificate from a recognized CA, as others have already advised.
If that van around the corner is capable of hijacking your internet connection already, you've got worse problems than self-signed certificates.
Banks should use client certificates for authentication. That would make it impossible for that van to do anything.... since it doesn't have the banks private key.
Self-signed certs are perfectly fine... assuming your internet connection hasn't been compromised. If your connection has been compromised... you're probably dogged anyway.
GoDaddy is giving SSL Certificates for $15 a year via this the buy now link on this site. Don't apply coupon codes because then the price goes back to $30 a year and discounts from there.
http://www.sslshopper.com/ssl-certificate-comparison.html?ids=17,25,34,37,62
来源：https://stackoverflow.com/questions/292732/self-signed-ssl-cert-or-ca