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Questions tagged [tls]

SSL (Secure Sockets Layer) and/or TLS (Transport Layer Security)

1086
votes
3answers
580k views

How does SSL/TLS 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. ...
513
votes
3answers
468k views

What's the difference between SSL, TLS, and HTTPS?

I get confused with the terms in this area. What is SSL, TLS, and HTTPS? What are the differences between them?
377
votes
14answers
54k views

How is it possible that people observing an HTTPS connection being established wouldn't know how to decrypt it?

I've often heard it said that if you're logging in to a website - a bank, GMail, whatever - via HTTPS, that the information you transmit is safe from snooping by 3rd parties. I've always been a little ...
283
votes
3answers
66k views

CRIME - How to beat the BEAST successor?

With the advent of CRIME, BEAST's successor, what possible protection is available for an individual and/or system owner in order to protect themselves and their users against this new attack on TLS?
268
votes
8answers
151k views

Is BASIC-Auth secure if done over HTTPS?

I'm making a REST-API and it's straight forward to do BASIC auth login. Then let HTTPS secure the connection so the password is protected when the api is used. Can this be considered secure?
261
votes
6answers
203k views

What is certificate pinning?

I'm superficially familiar with SSL and what certs do. Recently I saw some discussion on cert pinning but there wasn't a definition. A DDG search didn't turn up anything useful. What is certificate ...
238
votes
4answers
107k views

SSL3 “POODLE” Vulnerability

Canonical question regarding the recently disclosed padding oracle vulnerability in SSL v3. Other identical or significantly similar questions should be closed as a duplicate of this one. What is the ...
227
votes
5answers
139k views

What is the difference between https://google.com and https://encrypted.google.com?

Is it there any difference between the encrypted Google search (at https://encrypted.google.com) and the ordinary HTTPS Google search (at https://google.com)? In terms of security what were the ...
217
votes
14answers
37k views

My college is forcing me to install their SSL certificate. How to protect my privacy?

My college administration is forcing us to install Cyberoam Firewall SSL certificate so that they can view all the encrypted traffic to "improve our security". If I don't install the certificate than ...
194
votes
8answers
174k views

What is the difference between SSL vs SSH? Which is more secure?

What is the difference between SSH and SSL? Which one is more secure, if you can compare them together? Which has more potential vulnerabilities?
189
votes
7answers
23k views

How do mobile carriers know video resolution over HTTPS connections?

Verizon is modifying their "unlimited" data plans. Customers in the USA can stream video at 480p -or- pay to unlock higher resolutions (both 720p and +1080p). They are not the only mobile carrier to ...
165
votes
7answers
141k 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 ...
164
votes
2answers
22k views

What is DROWN and how does it work?

There is a new recent attack "on TLS" named "DROWN". I understand that it appears to use bad SSLv2 requests to recover static (certificate) keys. My question is: How? How can you recover static ...
147
votes
4answers
21k views

Which security measures make sense for a static web site?

I have a static web site. Users cannot log in or perform any other actions. Which of the common HTTP security measures make sense for my site? Do I need any of these? HTTPS Strict transport security ...
137
votes
14answers
45k 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 ...
126
votes
11answers
75k views

Is visiting HTTPS websites on a public hotspot secure?

It's often said that HTTPS SSL/TLS connections are encrypted and said to be secure because the communication between the server and me is encrypted (also provides server authentication) so if someone ...
122
votes
2answers
17k views

How is the Heartbleed exploit even possible?

I have read about the Heartbleed OpenSSL vulnerability and understand the concept. However what I don't understand is the part where we pass 64k as the length and the server returns 64kb of random ...
116
votes
8answers
8k views

Attacking an office printer?

I did an nmap scan on an advanced office printer that has a domain name and is accessible from outside the corporate network. Surprisingly I found many open ports like http:80, https:443, and svrloc:...
114
votes
6answers
30k views

I can't access websites that use HTTPS, instead getting the message “your connection is not private”!

I found myself suddenly unable to access websites that use HTTPS, so I contacted my service provider, and they asked me to install a certificate in the Trusted Root Certificate Authorities store. But ...
112
votes
18answers
18k views

Does an established HTTPS connection mean a line is really secure?

From the view of somebody offering a web application, when somebody connects with TLS (https) to our service and submits the correct authentication data, is it safe to transmit all sensitive data over ...
111
votes
4answers
102k views

What certificates are needed for multi-level subdomains?

I'm working on a web site with a several levels of subdomains. I need to secure all of them with SSL, and I'm trying to determine the correct certificate strategy. Here's what I need to secure: foo....
110
votes
7answers
22k views

Why should I offer HTTP in addition to HTTPS?

I am setting up a new webserver. In addition to TLS/HTTPS, I'm considering implementing Strict-Transport-Security and other HTTPS-enforcement mechanisms. These all seem to be based on the assumption ...
110
votes
4answers
17k views

A secret in a URL

Lately I've seen plenty of APIs designed like this: curl "https://api.somewebsite.com/v1/something&key=YOUR-API-KEY" Isn't it elementary that passing an API key in a query string as a part of ...
108
votes
2answers
224k views

Difference between .pfx and .cert certificates

What is the difference between .pfx and .cert certificate files? Do we distribute .pfx or .cert for client authentication?
107
votes
5answers
433k views

How do I use “openssl s_client” to test for (absence of) SSLv3 support?

In order to mitigate the "Poodle" vulnerability, I'd like to disable SSLv3 support in my (in this case, TLS, rather than HTTPS) server. How can I use openssl s_client to verify that I've done this?
104
votes
4answers
131k views

Now that it is 2015, what SSL/TLS cipher suites should be used in a high security HTTPS environment?

It has become quite difficult to configure an HTTPS service that maintains "the ideal transport layer". How should an HTTPS service be configured to permit some reasonable level of compatibility while ...
94
votes
8answers
39k views

Is it safe to send clear usernames/passwords on a https connection to authenticate users?

I'm setting up a home HTTP server which can send and receive JSON data to/from different clients (Android and iPhone apps). I'd like to allow access only to certain users and I'm considering using a ...
92
votes
5answers
25k views

How can my employer be a man-in-the-middle when I connect to Gmail? [duplicate]

I'm trying to understand SSL/TLS. What follows are a description of a scenario and a few assumptions which I hope you can confirm or refute. Question How can my employer be a man-in-the-middle when ...
91
votes
4answers
95k 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 ...
89
votes
15answers
20k views

Why would someone “double encrypt”?

If I have a website or mobile app, that speaks to the server through a secured SSL/TLS connection (i.e. HTTPS), and also encrypt the messages sent and received in-between user and server on top of the ...
88
votes
10answers
33k 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 ...
88
votes
4answers
15k 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 ...
87
votes
5answers
48k views

Let's Encrypt for intranet websites?

Many companies have intranet websites that are not reachable via the internet. Usually they just use a self-signed certificate, which causes a bad habit for the users since they get used to just ...
86
votes
10answers
38k views

Should I change the private key when renewing a certificate?

My security department insists that I (the system administrator) make a new private key when I want a SSL certificate renewed for our web servers. They claim it's best practice, but my googling ...
86
votes
9answers
44k views

https security - should password be hashed server-side or client-side?

I am building a web application which requires users to login. All communication goes through https. I am using bcrypt to hash passwords. I am facing a dilemma - I used to think it is safer to make a ...
85
votes
5answers
36k 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 ...
82
votes
4answers
49k views

What is Logjam and how do I prevent it?

I heard there is a "new" TLS vulnerability named Logjam, what does it do and how do I prevent it?
82
votes
4answers
101k views

What is ECDHE-RSA?

What is the difference between ECDHE-RSA and DHE-RSA? I know that DHE-RSA is (in one sentence) Diffie Hellman signed using RSA keys. Where DH is used for forward secrecy and RSA guards against MITM, ...
82
votes
5answers
119k views

How does SSLstrip work?

I've been reading up on SSLstrip and I'm not 100% sure on my understanding of how it works. A lot of documentation seems to indicate that it simply replaces occurrences of "https" with "http" in ...
81
votes
2answers
45k views

ssltest: Chain issues - Contains anchor

I've run ssltest on web application and it found "Chain issues - Contains anchor" (section "Additional Certificates (if supplied)") What does it mean? Should it be fixed? Can it be exploited?
80
votes
13answers
25k views

What are the pros and cons of site wide SSL (https)?

What are the pros and cons of encrypting all HTTP traffic for the whole site through SSL, as opposed to SSL on just the login page?
80
votes
12answers
13k 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 ...
80
votes
6answers
89k views

How do I secure my REST API?

In detail here's the problem: I'm building an Android app, which consumes my REST API on the back-end. I need to build a Registration and Login API to begin with. After searching with Google for a ...
79
votes
5answers
84k views

Should SSL be terminated at a load balancer?

When hosting a cluster of web application servers it’s common to have a reverse proxy (HAProxy, Nginx, F5, etc.) in between the cluster and the public internet to load balance traffic among app ...
76
votes
9answers
78k views

Can my company see what HTTPS sites I went to?

At work my company uses internet monitoring software (Websense). I know if I visit a https ssl-encrypted site (such as https://secure.example.com) they can't see what I'm doing on the site since all ...
75
votes
6answers
10k views

Should I reject a CSR when the host emailed me the private key for SSL certificate request?

I just requested a CSR from my shared web hosting provider, to generate a certificate which I will send back to them to install. (The certificate itself is to be generated properly by an organisation ...
74
votes
12answers
24k views

Is Google overreaching by forcing me to use TLS?

Gmail was recently changed to require HTTPS for everyone, whether they want to use it or not. While I realize that HTTPS is more secure, what if one doesn't care about security for certain accounts? ...
74
votes
4answers
82k views

“Optimal” Web Server SSL Cipher Suite Configuration

Over the last couple of years there have been a number of changes in what would be considered an optimal SSL cipher suite configuration (e.g. the BEAST and CRIME attacks, the weaknesses in RC4) My ...
73
votes
4answers
34k views

What clients are proven to be vulnerable to Heartbleed?

On several pages, it is re-iterated that attackers can obtain up to 64K memory from the server or client that use an OpenSSL implementation vulnerable to Heartbleed (CVE-2014-0160). There are dozens ...
72
votes
8answers
45k views

Need to access old forgotten router that only supports SSLv3

I need to access the web interface of a router standing here in the office. The problem is that it only supports SSLv3 and I cannot find a browser that allows me to connect to it. In order to update ...