A Certificate Authority is the collection of hardware, software, and people responsible for issuing certificates in a hierarchical PKI. CAs may be public, as in SSL / TLS and government IDs, or private, as in corporate infrastructures. The primary responsibility of a public CA is to verify the ...

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179
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7answers
23k views

How do certification authorities store their private root keys?

Knowledge of a CA private key would allow MitM attackers to transparently supplant any certificates signed by that private key. It would also allow cyber criminals to start forging their own trusted ...
148
votes
4answers
17k views

Is there anything preventing the NSA from becoming a root CA?

There are now tons of Certification Authorities (CAs) that are trusted by default in major OS's, many of which are unrecognizable without online lookup or reference. While there have been attempts ...
111
votes
7answers
9k views

How do I report a security vulnerability about a trusted certificate authority? [duplicate]

I stumbled across a huge security vulnerability in a Certificate Authority that is trusted by all modern browsers and computers. Specifically, I am able to get a valid signed certificate for a domain ...
104
votes
13answers
27k views

Is there any technical security reason not to buy the cheapest SSL certificate you can find?

While shopping for a basic SSL cert for my blog, I found that many of the more well-known Certificate Authorities have an entry-level certificate (with less stringent validation of the purchaser's ...
81
votes
4answers
11k views

What prevents me from buying a SSL certificate for a domain I don't control?

Can I simply build a webserver, make its hostname "google.com", create a CSR off that server, and send that to a Certificate Authority for signing? Let's say I pick the cheapest and dodgiest outfit I ...
73
votes
10answers
20k views

Why do we not trust an SSL certificate that expired recently?

Every SSL certificate has an expiration date. Now suppose some site's certificate expired an hour ago or a day ago. All the software by default will either just refuse to connect to the site or issue ...
70
votes
4answers
27k views

Are all SSL Certificates equal?

After running a few tests from Qualsys' SSL Labs tool, I saw that there were quite significant rating differences between a GoDaddy and VeriSign certificate that I have tested against. Are all SSL ...
63
votes
12answers
8k views

How feasible is it for a CA to be hacked? Which default trusted root certificates should I remove?

This question has been revised & clarified significantly since the original version. If we look at each trusted certificate in my Trusted Root store, how much should I trust them? What factors ...
53
votes
2answers
3k views

Why does Windows Ship with Expired SSL Certificates?

I am cleaning up the certificate stores on my Windows machines, and considering which certificates I should keep, and which ones I should delete. Why does a fresh install of Windows Server 2012 R2 ...
42
votes
7answers
5k views

Is there any legitimate reason to install yourself as a root CA?

Follow up from comments on another question. Is there any reason as to why you might install yourself as a root CA on your own network? The only reason I can think of is forcing computers in the ...
38
votes
4answers
7k views

What alternatives are there to the existing Certificate Authority system for SSL?

Whilst the current CA system works very well for a lot of people, it does put a lot of power into individual CAs' hands, and makes a CA hack potentially devastating for customers and business. What ...
31
votes
6answers
8k views

Does it matter which Certificate Authority I source my SSL Certificate from?

To secure my web site with HTTPS, does it matter which company I source my SSL certificate from, or just that the browser recognizes it? From the Area51 proposal.
30
votes
3answers
8k views

Which CA issued certificate for https://www.google.com

I installed Kaspersky internet Security 2016 on my laptop; in Firefox and Edge the root issuer is Kaspersky Anti-Virus Personal Root Certificate. but in chrome the root issuer is GeoTrust. in my ...
30
votes
4answers
5k views

Corporate computers have own corporation's cert as trusted CA; should I consider all traffic compromised?

By my admittedly limited understanding of how HTTPS/TLS works, the end user (me) initiates a connection with a remote server which signs every one of its messages with a public key. This public key ...
30
votes
5answers
19k views

Where to get an SSL certificate for personal website?

I would like to use https to login to my personal webpage (which is on shared hosting). So I went over to google and started searching for sollutions. Eventualy I found out that I need an SSL ...
28
votes
2answers
4k views

Is it safe to send SSL certificates via email?

I just ordered a cheap Comodo PositiveSSL Certificate via a UK reseller, and I was rather surprised to find that the following files were emailed to me automatically, in a zip file: Root CA ...
28
votes
4answers
2k views

Can any CA sign any domain?

Can any CA sign any cert for any domain? If the answer is yes, what prevents having two different CAs creating a valid cert for the same domain? Does that mean that the whole TLS security has the ...
28
votes
4answers
39k views

Expired SSL Certificate Implications

What are the security implications of an expired SSL certificate? For example if an SSL certificate from a trusted CA has expired will the communication channel continue to remain secure?
28
votes
2answers
27k views

Why is Symantec/Verisign CA appearing as an invalid authority? [closed]

Typical browsing to www.BankOfAmerica.com got me an ERR_CERT_AUTHORITY_INVALID error. This was with an up-to-date production version of Google Chrome for Mac. I tried with Safari, and got the same ...
27
votes
4answers
12k views

Are there technical disadvantages in using free ssl certificates?

Note this question is related, except this one is about free SSL certs. There are providers who are offering totally free entry-level SSL certs (like StartSSL). I was wondering if they are ...
26
votes
4answers
35k views

how digital signature verification process works

I am not able to understand that how the digital signature is verified. I know that digital signature will be attached to the message and sent by sender to receiver. then receiver uses the public key ...
26
votes
1answer
50k views

Can a CSR be created in OpenSSL with SHA2?

Can a CSR be created in OpenSSL with SHA2? If so, what would the command be and what does this tell the CA, if anything? If you could create a CSR using SHA2 would it "tell" the signing CA to use it ...
25
votes
2answers
9k views

What are the advantages of EV Certificate?

What are the various advantages of using extended validation (EV) certificates than normal certificates which also provide comparatively high degree of encryption like RC4, 128 Bit? I know that the ...
22
votes
1answer
394 views

Are there security design weaknesses in the EFF Sovereign Keys proposal?

In response to SOPA and a number of high profile security breaches at certficate authourities in 2011, the EFF has released a soverign keys proposal: ...
21
votes
5answers
5k views

Are self-signed certificates actually more secure than CA signed certificates now?

Are self-signed certificates actually more secure than CA signed certificates now? I ask this because recent leaks about the NSA spy programs and the secret FISA courts mean that the US government ...
21
votes
1answer
24k views

Configure SSL Mutual (Two-way) Authentication

A lot of tutorials, a lot of pages, a lot of question and they differ in implementation of this issue "Configure SSL Mutual (Two-way) Authentication". I have to do it with Linux, and I don't know from ...
19
votes
7answers
4k views

Why are self signed certificates not trusted and is there a way to make them trusted?

I have locally made a Root CA certificate. I used the CA cert to sign the IA cert and used the IA cert to sign the server certificate. When I try to access the local server which uses the server ...
19
votes
4answers
3k views

Why does Facebook serve several SSL certificates?

Facebook seems to be alternately serving two SSL certificates, one from DigiCert and one from VeriSign. There are only two reasons for this that I can think of: They're in the middle of a ...
19
votes
3answers
3k views

Can a wildcard SSL certificate be issued for a second level domain?

Something like *.com or *.net? How about *.edu.au? The RFC 2818 does not say anything about this topic.
19
votes
1answer
23k views

What is the actual value of a certificate fingerprint?

In a x509 digital certificate there is a "certificate fingerprint" section. It contains md5, sha1 and sha256. How are these obtained, and during the SSL connection, how are these values checked for?
18
votes
4answers
15k views

Checklist on building an Offline Root & Intermediate Certificate Authority (CA)

Microsoft allows a CA to use Cryptography Next Generation (CNG) and advises of incompatibility issues for clients that do not support this suite. Here is an image of the default cryptography settings ...
18
votes
3answers
949 views

Can a nation-state adversary perform a MITM attack by compelling a CA to issue them with fake certs?

As I understand it, with any encryption system based on a trust chain / CAs (eg SSL, TLS, S/MIME), it would be possible for a nation-state adversary (such as the NSA) to compel the CA to issue them ...
18
votes
4answers
23k views

How are Chrome and Firefox validating SSL Certificates?

How are Chrome and Firefox validating SSL Certificates? Are they requesting data from an SSL certification website, like GeoTrust, to validate the certificate received from the web server?
17
votes
2answers
821 views

How can I prevent that my users get a certificate issued for my domain on my behalf?

I have a domain, where some other users have access to upload files, use email, use XMPP, etc. How can I prevent that these users go to a certificate authority and get a certificate for my domain? ...
17
votes
3answers
2k views

What are the risks of a Certificate Authority hack for 'the average user'?

Recently the DigiNotar CA was hacked, and rogue certificates were issued. Since they also issue certificates on behalf of the Dutch government, the government made a statement about it as well, ...
17
votes
9answers
6k views

How does SSL/TLS PKI work?

We have lots of questions that address portions of SSL/TLS as it relates to PKI, but none of them seem to bring everything together. A canonical answer that we can point people to I think would be ...
16
votes
3answers
3k views

What happens when an Intermediate CA is revoked?

Currently I'm working on a certificate manager that allows our product to securely connect to remote webservices (over TLS/SSL). For security, we use Certificate Revocation List checking (or ...
15
votes
5answers
2k views

What is the difference between http and https with a self-signed SSL certificate?

A colleague of mine has told me he doesn't see why there is a warning when visiting a HTTPS website with a self-signed certificate saying that the security may be compromised, but there is no warning ...
15
votes
6answers
2k views

What's the point of the CA?

So a Certificate Authority certifies that a website corresponds to a given organization. Why is this necessary? When I interact with a business or organization, I do it one of a couple ways: I ...
15
votes
3answers
2k views

Why are CA-issued certificates considered so much more secure than self-signed certificates

I looked at other Stack Exchange posts explaining why self-signed certificates are not as secure as CA-issued certificates, and most of these pages say the same thing: If it's self-signed, and the ...
15
votes
3answers
4k views

Are there any downsides to using Let's Encrypt for a website's SSL certificates?

On the advantages side, I see several benefits to using the Let's Encrypt service (e.g., the service is free, easy to setup, and easy to maintain). I'm wondering what, if any, are the disadvantages to ...
15
votes
2answers
420 views

How much of a problem is it that Windows “hides” some of the trusted root CA certs?

Based on information on this page, Windows actually trusts many more root CA certificates than what are displayed when a user launches certmgr.msc and navigates to Trusted Root Certification ...
14
votes
4answers
7k views

SSL root certificate optional?

I may have been under the wrong impression on how servers should be setup and what certificates actually get sent over during the server hello certificate message. I came across this today from ...
14
votes
1answer
5k views

How does OCSP stapling work?

I've been looking into OCSP stapling for HTTPS, which looks pretty interesting. From what I can tell, it's essentially a way of offloading CRLs from the CA to the server, allowing for everything to be ...
14
votes
3answers
278 views

Domain name expiration and TLS

If I purchase a domain name that has expired, do I have any assurance that the previous owner does not have a valid HTTPS certificate for the site? In other words, do CAs check domain name expiration ...
14
votes
1answer
360 views

Yubikey / GPG with OpenSSH signed key

I am currently looking into the possibility of using Yubikey (NEO)'s to store the private SSH keys of my users. By searching the internet I've found several places that explain how you can generate a ...
13
votes
3answers
1k views

Should I be concerned that Google no longer trusts specific Symantec root CA cert that is also on my Windows system?

This is related to this other question which refers to Google moving to distrust the "Class 3 Public Primary CA" root certificate operated by Symantec Corporation, across Chrome, Android, and Google ...
13
votes
3answers
8k views

Why is my Positive SSL certificate deemed insecure by Google Chrome? [duplicate]

We run a website over HTTPS with a wildcard certificate from Positive SSL. Today, when I opened Google Chrome (v. 42.0.2311.90 m) and navigated to the site, I noticed a red cross through the https ...
13
votes
4answers
1k views

How do certificate issuers become trusted?

From what I understand, the certificate scheme that TLS/SSL relies on works because your computer has trust for major CA issuers built into it. That is, your OS is installed with certificates for ...
13
votes
2answers
4k views

How does DNSSec work? Are there known limitations or issues?

Based on information from this site, DNSSec is needed to protect us from a number of DNS and SSL / TLS hacks, including: DNS spoofing, especially on wifi or shared medium Registrars that abuse their ...