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 ...

learn more… | top users | synonyms (1)

65
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 ...
26
votes
2answers
10k 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 ...
17
votes
9answers
7k 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 ...
107
votes
14answers
29k 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 ...
72
votes
4answers
28k 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 ...
19
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 ...
74
votes
10answers
21k 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 ...
181
votes
7answers
24k 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 ...
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, ...
4
votes
4answers
700 views

Why self-signed https is less trustworthy than unencrypted http?

It wouldn't be far-fetched to guesstimate that at least 50% of the web traffic can be intercepted in 2014. However, a guesstimate of active interception attacks is likely an order of magnitude lower&...
12
votes
6answers
3k views

Is it possible for corporation to intercept and decrypt SSL/TLS traffic? [duplicate]

I found there are some companies claim that they offer service that can eliminate SSL/TLS blind spot, such as Blue Coat and Gigamon. Are they talking about some way of decipher the https content (...
18
votes
2answers
898 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? ...
30
votes
5answers
20k 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 ...
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 ...
13
votes
1answer
17k views

SSL Certificate framework 101: How does the browser actually verify the validity of a given server certificate? [duplicate]

Sorry I know this is a complete noob question and at the risk of posting a somewhat duplicate topic. I have a basic understanding of public/private key, hashing, digital signature... I have been ...
18
votes
3answers
969 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 ...
9
votes
2answers
793 views

What kind of certificate do I need to be able to sign my own subdomain certificates?

We are making a web-based application that will be installed in intranets as a virtual machine image (we send the user a CD with the virtual machine image, user runs it in a VMWare/VirtualBox/...). ...
6
votes
1answer
12k views

Should the thumbprint be SHA2 in addition to the Signature Hash Algorithm?

I'm looking at a Windows PKI and see that the Thumbprint is SHA1, while the Signature is SHA2 (SHA256). Is this an acceptable configuration? Should I recommend that the client update to SHA2 for a ...
2
votes
2answers
512 views

Are there other roots of trust on my computer aside from these 46 root certificates?

I've heard many people imply that modern browsers and OSes trust a myriad of root certificates. The implication is that it is impossible to ensure the private keys of all of the root certificates ...
151
votes
4answers
18k 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 ...
26
votes
4answers
38k 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 ...
8
votes
1answer
14k views

SSL certificate chain verification

After reading many articles and watching many tutorials I decided to be specific because there are some things about SSL certificate chain verification and SSL cetificate verification in general that ...
20
votes
1answer
25k 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?
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 ...
7
votes
3answers
8k views

How do I check that I have a direct SSL connection to a website?

I always thought that if I had an SSL connection there would be no MITM attacks. Now it appears that isn't true (see comments in this question Is it okay from a security perspective to read foreign (...
21
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.
9
votes
5answers
3k views

Understanding SSL certificate signing

I am trying to understand how SSL certificate and signing and the chain of trust works. I know about root CAs and that they are used to sign intermediate CAs that sign the end certificates that are ...
23
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 ...
15
votes
4answers
9k views

What Trusted Root Certification Authorities should I trust? [duplicate]

After two recent Slashdot articles (#1 #2) about questionable Root Certificates installed on machines, I decided to take a closer look at what I have installed on my machines. (I use current versions ...
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 ...
32
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.
9
votes
8answers
6k views

Is Spoofing a CA signed certificate possible?

I had never thought about this situation before, I may be completely wrong but I am going to have to clarify it anyway. When a communication starts with a server, during the client handshake, the ...
28
votes
4answers
41k 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?
13
votes
1answer
1k views

How secure is “Let's Encrypt”?

I just configured and installed a free SSL certificate from Let's Encrypt. It's great, and very easy to set up. However in this post-Snowden era, I was wondering how secure this really is. For ...
9
votes
2answers
412 views

I want trusted SMIME certificates for 3rd parties. Is this a reasonable configuration?

I want to send out SMIME certificates with my emails, and want to deploy the following PKI Root01 (All EKU, All Constrants, No Restrictions) PolicyInt01 (Internal applications, not trusted by 3rd ...
15
votes
2answers
557 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 ...
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 ...
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 ...
5
votes
1answer
3k views

google certificates correct CA [closed]

I view certificates of https://www.google.com.ua/ So I thought, when requesting via cURL, if I point by CURLOPT_CAINFO to those certificates (GeoTrust Global CA and Google Internet Authority G2 in ...
3
votes
2answers
391 views

Explicitly prohibit an intermediate CA certificate on OpenSSL

How do you explicitly not trust a particular certificate (especially, CA certificate) for OpenSSL? On NSS-based applications, one can install the cert with trustarg p: prohibited (explicitly ...
3
votes
3answers
715 views

Where can I find all SSL CA certificates

I am working on an SSL implementation project and ofcourse I need to verify the certificate presented by the server. To do that I need CA certificates or at least root CA certificates (correct me I am ...
4
votes
4answers
401 views

Should name constraints be present on a subordinate CA issued to an organization?

I was looking at Google's Internet Authority G2. Its a subordinate CA (critical, CA:TRUE, pathlen:0) certified by GeoTrust. The dump is below. Presumably, GeoTrust certified that CA for Google so ...
3
votes
2answers
485 views

Can I buy a signing-valid certificate for internal use?

So now that I have to implement "secure transport" as defined by The Direct Project (not to mention reinventing a bunch of wheels, but that's another story for SO), I find myself staring down the ...
2
votes
1answer
523 views

Security Certificates - Tools to Generate Security Certificates

I want to create a self-signed certificate that will be installed as a trusted certificate authority. I then want to create another two certificates which are signed using the private key of the self-...
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 ...
28
votes
4answers
13k 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 ...
14
votes
1answer
6k 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 ...
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 ...
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 ...
27
votes
1answer
52k 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 ...