Questions tagged [certificates]

A piece of data used in public key cryptography (specifically public key infrastructures) 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. For questions specifically about [x509], [certificate-authority], or [public-key-infrastructure], please use those tags.

Filter by
Sorted by
Tagged with
42
votes
4answers
11k 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 ...
41
votes
2answers
35k 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 ...
40
votes
3answers
6k views

Why is the issuer certificate different at my workplace and at home?

I have viewed Gmail's certificate chain at my workplace, and I realised it's different. It looks like this: Root CA Operative CA1 ___________.net mail.google.com When I get the ...
38
votes
3answers
21k 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 ...
37
votes
6answers
28k 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 ...
37
votes
1answer
3k views

Why are some websites seemingly immune to self-signed certificate MitM attacks?

I recently did an experiment using MitM to gain account information (username and password) while accessing websites. I used two PCs in the scenario; one as the target, running Internet Explorer, and ...
37
votes
2answers
3k views

Is there any security risk when a certificate authority is used more than all others?

According to NetTrack, Let's Encrypt is now used on more than 50% of domains (51.21% as of April 2018). I know Let's Encrypt helped a lot of people to get free certificates for their websites, so I ...
37
votes
3answers
5k 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 ...
36
votes
2answers
39k views

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

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?
36
votes
3answers
42k views

Why is 'avast! Web/Mail Shield Root' listed as CA for google.com?

I just noticed something weird in my browser: the certificate for www.google.com has been issued by avast! Web/Mail Shield Root. Should I be worried? I am using avast! Antivirus so it's probably a ...
35
votes
5answers
6k views

Should I trust a website which uses a SHA-1 HTTPS certificate?

I am on a website where I need to pay for something. This website has the following warning in the top left: This site uses a weak security configuration (SHA-1 signatures) so your connection may ...
35
votes
7answers
7k views

Could governments and banks become CAs?

When you apply for a passport, driver's license, home mortgage, bank account, credit card, etc., the issuing organization must verify your identity. In the course of doing so, would it be feasible for ...
35
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 ...
35
votes
4answers
58k 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?
35
votes
2answers
5k views

Can a SSL certificate have longer validity period than its parent in X.509 chain?

When a X.509 certificate chain is composed of X1, X2 ... Xn and Xn is root CA, Can a certificate in lower level have longer validity period than its parents? I think that lower level should be proper ...
34
votes
3answers
8k views

Why are Let's Encrypt certificates accepted by default by browsers? [duplicate]

I recently almost got caught by a phishing attempt, due to the use of a relatively convincing domain name and valid SSL certificate (specifically this website). When checking the certificate it turns ...
34
votes
2answers
17k 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 ...
34
votes
4answers
5k 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 ...
34
votes
2answers
7k views

Can I restrict a Certification Authority to signing certain domains only?

Is it possible to create a CA certificate (even unsigned), which is only allowed to sign certificates for specific limited domain(s), so that it can't be misused for other domains?
34
votes
2answers
49k 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 ...
33
votes
3answers
20k 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 ...
33
votes
4answers
11k views

HTTPS but NOT encrypted?

I'm accessing Bing (https://www.bing.com) from within China. I got the following information: How could this happen? HTTPS but not encrypted, and with SSL certificate? Here is the packet capture ...
33
votes
1answer
69k 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 ...
33
votes
1answer
41k 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?
33
votes
4answers
78k views

how to import a private key in windows

Say I have an X.509 cert and a private key that corresponds to it. I can import X.509 certs easily enough into Windows but what about private keys? Is the only way I can do that by converting both ...
33
votes
5answers
7k 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 ...
32
votes
4answers
7k views

Why are SSL certificates an annual expense?

I understand SSL certificates cost money because of reputation: most/all web browsers have a limited list of companies that demonstrated they are trusted sources of SSL certificates and therefore don'...
32
votes
10answers
14k views

Can an HTTPS site be malicious or unsafe?

I know it's possible for a computer to be infected just by visiting a website. I also know that HTTPS websites are secure. To my understanding, "secure" here refers to "immune to MITM attacks", but ...
31
votes
5answers
6k views

How do you tell a website they have expired security certificates?

I often go to more obscure pages on NASA websites, and I have gotten used to running into an expired security certificate now and then. Over the last week, it started coming up a lot more, to the ...
31
votes
3answers
6k views

Is there a security issue in using the same certificate for all a company's services?

We are a small startup. One of our products is a B2B web service, accessible through its https://service.example.com canonical URL. For testing purposes, that service also runs on different testing/...
30
votes
6answers
3k views

Is there a risk to a business that is using a shared certificate?

I was looking at my bank website's certificate and discovered that it's issued to multiple websites, and the bank's domain name is only listed among many other domains in the 'alternative names' field....
30
votes
6answers
38k 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. ...
29
votes
2answers
4k views

Can you sign using a digital certificate itself?

Googling I saw several lectures saying that it is possible to sign using digital certificates. I am confused about that, because according to my knowledge it is possible to sign only using the private ...
29
votes
3answers
13k views

How does an end user differentiate between OV and DV certificates?

This is a very good link that explains the different types of SSL certificates and level of trust provided by them. An Extended Validation (EV) certificate it is easily identified by the green color ...
28
votes
7answers
9k views

How can I be sure that I am using the real Facebook?

I type www.facebook.com into my browser's address bar and press enter, then use Facebook. Could I actually be visiting a fake Facebook even if I see a URL of https://www.facebook.com and a lock icon ...
28
votes
3answers
2k views

Does any technology prevent a CA unilaterally revoking a certificate?

As far as I can tell, a CA is in a position to unilaterally revoke a certificate via the standard mechanisms (CRL, OCSP). In an increasingly TLS world, what current technology stops a CA shutting ...
28
votes
6answers
10k 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 ...
28
votes
3answers
6k 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.
27
votes
3answers
9k views

Why is it more secure to use intermediate CA certificates?

I've read that using Intermediate CA certificates is more secure because this way the Root CA is offline. So, if the Intermediate is compromised it does not impact the Root CA. What I understand is ...
27
votes
1answer
3k views

Why does Firefox not trust this US government SSL certificate?

Shouldn't this be a trusted certificate considering it's a wildcard SSL certificate? That is, shouldn't *.delaware.gov cover www.corp.delaware.gov?
26
votes
1answer
28k 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 ...
26
votes
5answers
43k 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?
25
votes
5answers
8k views

What does “signing” a file really mean?

I'm a bit new to security and trying to get the concepts properly. I'm wondering what exactly "signing" a file (a certificate, an apk file, or something else) means? Do we sign the whole file so ...
25
votes
6answers
5k views

Is it secure to consume services over HTTPS which is not signed by a trusted CA?

I am building a client application that will consume a web-service application provided by a third party service provider. The service is exposed with a HTTPS URL that is not signed by a trusted ...
25
votes
3answers
12k 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 ...
25
votes
4answers
3k 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 ...
25
votes
4answers
22k 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 ...
25
votes
1answer
48k views

OpenVPN Tap vs Tun Mode [closed]

I would like to know practical difference between TAP and TUN mode when use with OpenVPN. When to use TAP and When to use TUN ? What types of traffic will pass with both mode ?
24
votes
5answers
3k views

What prevents a man in the middle from requesting a certificate for your server?

Let's say you have a server at shop.example.com and you are requesting a certificate from some trusted CA like Comodo (they say they'll issue it within few minutes online). First of all, how can they ...
24
votes
5answers
5k 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 ...