A piece of data used in public key cryptography that contains identifying information (i.e. email address or web address), a hash of a public key, and a digital signature that authenticates the data in the certificate.

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23
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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 ...
21
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3answers
7k views

Is SHA1 weak for SSL?

I noticed that today after I scanned a site on the Qualys SSL Labs site that SSL ciphersuites which use SHA1 are now highlighted as being "Weak". It seems this has just happened; I scan sites pretty ...
21
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5answers
3k views

Are login “certificates” more secure than standard username + password authentication?

I just opened a new bank account which comes with internet banking. Unlike the others I have used so far, this one requires a personal certificate (a .p12 file stored on my computer) + password for ...
21
votes
4answers
2k views

Cloudflare's free SSL options require trusting them; what could they do to change that?

Cloudflare offers 3 free SSL options: Flexible SSL, Full SSL, and Full Strict SSL. The article “CloudFlare’s great new features and why I won’t use them” explores the shortcomings of the Flexible and ...
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
2answers
30k views

Advantages of client certificates for client authentication?

I'm no security expert, so please just ask in a comment if I haven't made my question clear enough for an answer. The Scenario We have a server running WCF services, and a number of clients ...
19
votes
1answer
21k 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
2answers
19k views

Chrome SSL Warning: “You cannot proceed because the website operator has requested heightened security for this domain. ”

I'm trying to go to the URL below, and Chrome warns me that the wildcard certificate is not valid for this domain. ...
18
votes
4answers
14k 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
7answers
10k views

How do I check if a gmail/gtalk SSL certificate is valid?

Pidgin started prompting me to accept/reject new gtalk SSL certificate a few days ago and I am not able at the moment to tunnel the traffic to check if it would continue to happen or if it wouldn't ...
17
votes
4answers
4k views

What is the potential impact of these SSL certificate validation vulnerabilities?

I just finished reading through this paper by Georgiev et al, which demonstrates a wide range of serious security flaws in SSL certificate validation in various non-browser software, libraries and ...
17
votes
2answers
2k views

How can you prevent employees of your company from creating valid ssl certs? [duplicate]

When registering for an SSL cert, I was able to validate that I "owned" the domain I was creating the cert for by having a valid @domain.com email address. If I worked for a large company, say ...
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
1answer
13k views

4096 bit RSA encryption keys vs 2048

Where do 4096 bit RSA keys for SSL certs currently stand in terms of things like CA support, browser support, etc? In the overall scheme of things is the increased security worth the risk of 4096 bit ...
17
votes
4answers
21k 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?
16
votes
3answers
2k views

Multi-tenancy, SSL Certificates, and Subject Alternative Name

The X509 specification allows a CA to issue a single certificate for multiple hostnames, by using the "Subject Alternative Name" extension. From the spec: The subject alternative name ...
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 ...
16
votes
4answers
2k views

Broken SSL on every website [duplicate]

One of my friends called me saying every website anyone in her family goes to has untrusted SSL certificates. From any computer in her house, HTTPS is broken and Firefox or Chrome asks to add an ...
16
votes
5answers
6k views

Why can SSL certificates not be free of charge?

I am a newbie in this field. I am confused with why SSL certificates cannot be free of charge. In my understanding the certificate is just a text file consisting of cryptic numbers installed on a ...
16
votes
2answers
1k views

Encryption and the “security time decay” of prior encrypted data

This question is on the assumption that any data once encrypted, may (eventually) be decrypted through Brute force (compute power/time) Exploits in the cryptography used Theft of private keys ...
16
votes
1answer
4k views

REST specific security weaknesses

I need to start working with RESTfull Web Services. SOAP based web services have already so many standards to secure communication, establish trust etc. I am not aware of any for REST. What I would ...
16
votes
2answers
2k views

SSL fingerprint inconsistency: what does it mean?

I apologize if this is not the best place to ask my question on the stackexchange network, I couldn't figure out where to get enough attention and be relevant. Facebook provides a SSL host, it can be ...
15
votes
2answers
785 views

Why does rfc6797 say “An HSTS Host MUST NOT include the STS header field in HTTP responses over non-secure transport.”

Why does the RFC prohibit the server from sending HSTS to the client over HTTP? I can see that if a HTTP client responds to that unsecure HTTP response it might cause that site to be inaccessible ...
15
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.
15
votes
2answers
4k views

Secure communication between applications using SSL Certificates

I am looking for a way how to secure communication between our applications. There is a "server" application listening on some TCP port and "client" application which is communicating with the ...
15
votes
3answers
3k views

Anything to do about old gpg keys?

Quite A few years ago (in middle school) I created some gpg keys, published them to a keyserver, etc. because I was l33test kid on the block. Now I have gone through a few new computers and OS's, ...
15
votes
1answer
15k views

Firebug reports SHA-1 certificate error

For the script at the bottom of this post, Firebug reports the following error: This site makes use of a SHA-1 Certificate; it's recommended you use certificates with signature algorithms that ...
15
votes
2answers
263 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
2k views

Is my Company Tracking Me?

Every time I try to connect to a site through HTTPS from my office computer, there is a Certificate Error thrown 2-3 times before showing the login screen. Till now I use to ignore this and click ...
14
votes
4answers
12k views

Provide subjectAltName to openssl directly on command line

Is it possible to provide a subjectAltName-Extension to the openssl req module directly on the command line? I know it's possible via a openssl.cnf file but that's not really elegant for ...
14
votes
1answer
3k views

PayPal encrypted with obsolete cryptography

My Chrome just complained from PayPal's security, similarly to this issue: Google Chrome "Your connection to website is encrypted with obsolete cryptography" The identity is verified, but ...
14
votes
3answers
20k views

Is it possible to use wildcard certificates on multiple devices?

I have a server that I want to use a wildcard cert on. It runs multiple services. I purchase a wildcard cert so that I can protect mail.something.dom, www.something.dom, im.something.dom, ...
14
votes
1answer
12k views

Which key usages are required by each key exchange method?

I'm only really concerned with RSA keys, so the exchange methods are RSA (generate a key, encrypt it, and send it over) and [EC]DHE_RSA (generate an ephemeral [EC]DH key, sign it, and use it for key ...
14
votes
4answers
26k views

Recommendations for a Certificate Management tool for Linux [closed]

A client is looking to roll out OpenVPN to all its mobile employees and will use certificates on both the server and all clients. This creates a new challenge to manage all these certificates and ...
14
votes
3answers
269 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
2answers
6k views

Is Apple's push notification service implementation vulnerable to a MitM attack

Recently(more info) I've spotted a strange message in the logs on my quite recent, fresh installation of OS X Mavericks 10.9.2 Apr 27 15:26:47 Ivans-MacBook-Pro.local apsd[194]: Unrecognized leaf ...
13
votes
2answers
2k views

Are SHA-2 certificates considered obsolete, or current?

I read here that I should be using SHA-2 certificates to secure a HTTPS webserver. Are SHA-2 certificates considered obsolete, or current for TLS/SSL website certificates? (as of 11/20/2015). If ...
13
votes
3answers
1k views

Trying to understand why signatures in root certs “are not used”?

Taken from here: Don't worry if the root certificate uses SHA1; signatures on roots are not used (and Chrome won't warn about them. Why are the signatures not used? Are not root certificates ...
13
votes
2answers
20k views

What's the difference between X.509 and PKCS#7 Certificate?

Am I correct calling file with .p7b file extension saved as 'Cryptographic Message Syntax Standard - PKCS#7 Certificates (.P7B)' in Windows - a 'PKCS#7 certificate'? Or is it better called 'X.509 ...
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
1answer
8k views

What is the difference between a “Thumbprint Algorithm” “Signature Algorithm” and “Signature Hash Algorithm” for a certificates?

I'm a bit confused on the differences between Signature Algorithm, Signature Hash Algorithm, and Thumbprint Algorithm that are present in SSL/TLS certificates. Can someone please elaborate?
13
votes
1answer
3k views

Renewing Microsoft Certificate Services Root Certificate

We currently have Microsoft Enterprise Certificate Server installed on a domain member machine which issues 1 year certificates to users for authenticating to VPN. We'd like to start issuing web ...
13
votes
4answers
2k views

Can real end-to-end SSL encryption be made?

I've read the various questions tagged [ssl] and [mitm] and [proxy] and I couldn't find a duplicate. I've got a very precise question but first I need to give some background. Basically I'm very ...
12
votes
3answers
602 views

Incorrect use of HTTPS?

When I open https://java.com my browser says “untrusted connection” but when I open https://www.java.com my browser says it’s ok. But it's the same site. So my question is: Is this a security bug? ...
12
votes
5answers
2k views

Why are certificates limited in time?

If a certificate has a limited duration of, say 5 years, but it gets somehow compromised after 2 years, waiting the 3 remaining years for it to get invalid is not a real solution to the breach ...
12
votes
5answers
5k views

Does HTTPS Everywhere defend me against sslsniff-like attacks?

http://www.thoughtcrime.org/software/sslsniff/ If I have a domain on my HTTPS Everywhere list, so that theoretically it could be only visited via an HTTPS connection in my Firefox, then could an ...
12
votes
5answers
2k views

Why is this certificate valid for so many domains?

If you look at the (invalid) certificate for https://i.imgur.com/ it says only valid for the following names: The certificate is only valid for the following names and then a list of about 100 names. ...
12
votes
4answers
1k views

Why isn't OCSP required by default in browsers?

According to the following screenshot, taken from firefox-3.6.17-1.fc14.i686, Firefox has an option to fail closed when unable to connect to OCSP servers. Can someone please explain why this isn't ...
12
votes
3answers
7k 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 ...
12
votes
2answers
2k views

Are there really functioning quantum computers?

I saw this video on youtube on quantum computing. It says that a company called dwavesys has already made commercially available quantum computer. I checked on the website and it exists. I thought ...