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.
173
votes
3answers
45k views
How does SSL work?
How does SSL work? I just realised we don't actually have a definitive answer here, and it's something worth covering.
I'd like to see details in terms of:
A high level description of the protocol.
...
19
votes
11answers
2k 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 ...
31
votes
3answers
3k 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 ...
11
votes
4answers
6k views
What ciphers should I use in my web server after I configure my SSL certificate?
There are many great questions that ask what is the best certificate to use for a website; but once the certificate is purchased, there is also the possibility to choose or edit the Cipher list.
...
8
votes
2answers
3k 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 ...
4
votes
2answers
536 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
votes
3answers
624 views
What is an SSL certificate intended to prove, and how does it do it?
If I get an SSL certificate from a well-known provider, what does that prove about my site and how?
Here's what I know:
Assume Alice and Bob both have public and private keys
If Alice encrypts ...
15
votes
4answers
569 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 ...
10
votes
3answers
6k views
Understanding 2048 bit SSL and 256 bit encryption
On DigiCert's page, they advertise a 2048 bit SSL with a 256 bit encryption: http://www.digicert.com/256-bit-ssl-certificates.htm
What exactly is the difference here and why are two encryption bits ...
5
votes
4answers
232 views
What fields in a suspicious certificate should I look at?
Looking at a certificate for a web-site (in Windows/Google Chrome) I see it lists the following fields
Version
Serial number
Signature algorithm
Issuer
Valid from
Valid to
Subject
Public Key
Basic ...
7
votes
4answers
1k views
Can Javascript/Flash verify the SSL connection to prevent “SSL Inspection”?
I'd like to determine if an SSL webpage is being debugged through Fiddler, or if it's going through an SSL Proxy.
So some people may ask
What is the point of re-validating SSL using javascript?
...
12
votes
2answers
393 views
Digital Certificate deployment: using two certs for each user?
At a large enterprise environment I have come across a deployment approach for Digital Certificates where each user is issued two (2) key pairs:
One for signing documents, emails, etc. that is ...
8
votes
4answers
387 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 ...
23
votes
9answers
1k 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 Certificat Authorities have an entry-level certificate (with less stringent validation of the purchaser's ...
11
votes
3answers
706 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
2answers
209 views
Extensions for SSL server certificate
I have some question about the X.509 v3 extensions. What extensions should appear in a proper certificate for a SSL server ?
1
vote
1answer
174 views
What are the benefits and drawbacks of the HTML5 Keygen element?
As of January 2013, what are the potential benefits and drawbacks of the HTML5 Keygen element?
41
votes
5answers
10k views
Certificate based authentication vs Username and Password authentication
What are the advantages and drawbacks of the certificate based authentication over username and password authentication?
I know some, but I would appreciate a structured and detailed answer.
UPDATE
...
28
votes
4answers
14k views
What is the difference between an x.509 “client certificate” and a normal SSL certificate?
I am setting up a web service through which my company will talk to a number of business customers' services. We will be exchanging information using SOAP. I would like to handle authentication with ...
7
votes
5answers
2k 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 ...
20
votes
8answers
2k views
Is anybody using client browser certificates?
Client browser certificates seem to be a nice way to protect sites from intruders - it is impossible to guess and should be harder to steal. Of course, they do not solve all the problems, but they add ...
6
votes
3answers
235 views
On-line cryptographically signed date/time?
I’m looking for a source of on-line cryptographically signed date/time. I do not need a full timestamp service, as I am happy with the information « date/time was that », without a link to a ...
12
votes
2answers
357 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
...
10
votes
4answers
649 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 ...
5
votes
3answers
844 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 ...
4
votes
5answers
436 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 ...
3
votes
1answer
151 views
What are the Netscape Cert Type attributes? Why/when are they needed?
What are the Netscape Cert Type attributes in a X.509 Certificate and how are they different with the X509v3 extensions?
Example:
There is the Client/Server Extended Key Usage (X.509) but there is ...
11
votes
1answer
1k 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 ...
41
votes
10answers
2k 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 ...
9
votes
2answers
6k views
Does https prevent man in the middle attacks by proxy server?
There is a desktop client A connecting to website W in a https connection
A --> W
Somehow between A and W, there is a proxy G.
A --> G --> W
In this case, will G be able to get the ...
6
votes
1answer
1k views
How does adding a random serial number improve a certificates' security?
This article says:
"Finding collisions is a tricky process, since it requires you to muck
with the bits of the public key embedded in the certificate (see this
paper for more details). Also, ...
5
votes
4answers
4k views
Recommendations for a Certificate Management tool for Linux
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 ...
5
votes
2answers
1k views
Dealing with expired or revoked signing certificates with Infopath documents
Suppose I have an Infopath form that is digitally signed today by a valid, and active user.
When that user leaves the company, we disable the account and revoke the certificate. This causes a problem ...
11
votes
3answers
9k 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?
10
votes
2answers
647 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 ...
8
votes
3answers
24k views
How can I export my private key from a Java Keytool keystore?
I would like to export my private key from a Java Keytool keystore, so I can use it with openssl. How can I do that?
8
votes
2answers
2k views
SSL Certificate revocation check
In the SSL protocol I don't see where the certificate is checked for revocation status.
https://developer.mozilla.org/en/Introduction_to_SSL
Is the Certificate Revocation and Status Checking not ...
13
votes
4answers
945 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 ...
8
votes
2answers
602 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 ...
8
votes
1answer
215 views
Why can the validity of an SSL certificate exceed the registration period of a domain?
I can understand why one might desire to purchase a certificate for multiple years but I am left wondering why it appears to be possible to obtain a valid certificate for a domain that may have come ...
6
votes
2answers
372 views
security of PKI, Certificates, certificate authorities, forward secrecy
I want to understand how certificates add to the security of information exchange.
Suppose i have a encrypted bidirectional connection between Alice and Bob, using a public key/private key pair. As ...
5
votes
2answers
161 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/...).
...
5
votes
6answers
707 views
Should the bit-strength selection of a child certificate be influenced by the CA or the chain?
All things being equal; suppose I have a CA chain that has 1024 bits of RSA encryption. Does this mean that my selection of a child CA or WebServer certificate gains no benefit from a higher level of ...
4
votes
1answer
254 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 ...
3
votes
1answer
105 views
How can I use certificates to secure my webservices? What is available to javascript?
I have a few web services that are accessed over public wifi connections and I think it would be a good idea to issue certificates to encrypt data, prevent MITM, and invalid impersonation (beyond what ...
2
votes
1answer
149 views
Which extensions to use for a S/MIME certificate?
Analogously to the SSL server certificate question, which extensions should I use for S/MIME, and should the CA be restricted somehow as well?
(I'm using openssl, which at the moment creates CA and ...
1
vote
3answers
317 views
Do client certificates provide protection against MITM?
I'm looking for a way to protect clients from a MITM attack without using a VPN, and ToR. My thought is that client certificates might do the job, but I'm not entirely sure since not too much server ...
0
votes
1answer
246 views
How do I constrain Windows Smartcards for AD Authentication so that “anyExtendedKeyUsage” is not implied?
This document describes how there are 3 ways to constrain a SmartCard certificate
The Enhanced Key Usage field defines one or more purposes for which
the public key may be used. RFC 5280 states ...
8
votes
3answers
2k views
What are the risks of self signing a certificate for SSL
Let's say I sign a SSL certificate for myself, and I'm not using a certified CA. What are the risks and/or threats of doing it?
7
votes
2answers
282 views
X.509 certificate policies question
I asked another question about certificate policy mappings. This is a different issue. This is about Certificate Policies.
To quote from the X.509 RFC:
In an end entity certificate, these ...
