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

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375
votes
3answers
158k 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. ...
208
votes
13answers
20k 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 ...
193
votes
3answers
45k 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?
171
votes
4answers
37k 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 ...
99
votes
8answers
5k 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 ...
98
votes
3answers
68k 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?
88
votes
2answers
51k 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 ...
74
votes
7answers
29k 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?
73
votes
17answers
8k views

Does an established ssl connection mean a line is really secure

From the view of somebody offering a webapplication. When somebody connects with SSL (https) to our service and submits the correct authentication data, is it safe to transmit all sensitive data over ...
67
votes
4answers
32k 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 ...
67
votes
5answers
6k 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 ...
63
votes
12answers
21k 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? ...
58
votes
5answers
51k 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?
58
votes
10answers
12k 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 ...
58
votes
3answers
6k views

Heartbleed: Why does the client supply the length of the message at all?

"The fix for this bug is simple: check that the length of the message actually matches the length of the incoming request." Why do we even have the client report the length at all? If we can know ...
57
votes
4answers
25k views

Does Heartbleed mean new certificates for every SSL server?

If you haven't heard of the Heartbleed Bug, it's something to take a look at immediately. It essentially means that an attacker can exploit a vulnerability in many versions of OpenSSL to be able to ...
52
votes
4answers
34k 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 ...
51
votes
10answers
8k 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 ...
50
votes
13answers
11k 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?
49
votes
6answers
7k 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 ...
48
votes
4answers
13k 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 ...
46
votes
11answers
5k views

Is there ever a good reason _not_ to use TLS/SSL?

While writing an answer to this question on Server Fault, a thought that has been bouncing around my head for quite some time resurfaced again as a question: Is there ever a good reason to not use ...
46
votes
4answers
11k views

Is posting from HTTP to HTTPS a bad practice?

Working on the assumption that SSL serves both to encrypt data and to provide assurance as to the identity and legitimacy of the website, should the practice of providing a logon form on a page ...
44
votes
4answers
32k 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 ...
43
votes
5answers
4k views

How does a country block its citizens from accessing a site?

Following Turkey's recent social site blocks, I am wondering how can you efficiently accomplish that as a country. Similar for a big company. Blocking IPs → easy to circumvent, (proxys, tunnels, ...
41
votes
12answers
6k views

Why should I care if a site uses encryption or not if I'm not exchanging any sensitive data? [duplicate]

Lots of sites these days, that don't deal with sensitive data, enable encryption. I think it's mostly to make (paranoid?) users feel safer. In cases where there is a user's account being logged in, ...
39
votes
6answers
6k views

How does a country block/censor an encrypted website (HTTPS)?

Given that Site X uses HTTPS, how can it be blocked by a country? My browser reads: 128-bit encryption | ECDHE_RSA as key exchange. I say it's blocked since when I use Tor, it works fine. One ...
38
votes
9answers
14k 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 ...
36
votes
12answers
4k 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 ...
35
votes
7answers
3k views

Why is HTTPS not the default protocol?

Why is HTTP still commonly used, instead what I would believe much more secure HTTPS?
33
votes
5answers
4k views

HTTPS still NSA-safe? [closed]

There are exerpts, that say that using https can be broken by the NSA by now. So is https still a solution for secure web-browsing? source: ...
33
votes
5answers
4k views

Why do some websites enforce lack of SSL?

When trying to visit https://www.ebay.com, I noticed that I get redirected to HTTP immediately. Here's what cURL says about that: $ curl --max-redirs 0 -v -L https://www.ebay.com * Rebuilt URL to: ...
33
votes
5answers
22k 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 ...
33
votes
4answers
25k 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: ...
31
votes
6answers
16k views

Trying to make a Django-based site use HTTPS-only, not sure if it's secure?

The EFF recommends using HTTPS everywhere on your site, and I'm sure this site would agree. When I asked a question about using Django to implement HTTPS on my login page, that was certainly the ...
31
votes
3answers
14k 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 ...
30
votes
5answers
4k views

Is there any way for my ISP or LAN admin to learn my gmail address as a result of me logging into gmail's web interface through via their network?

The title says it all, really. I'm Alice, and I want to login to Gmail's web interface through my browser. Ike, the internet service provider, and Adam, the local network administrator, would like to ...
30
votes
8answers
7k views

If I visit a HTTPS website when using Tor, is my IP exposed?

HTTPS is an end-to-end encrypted connection. Given this, does the website I am visiting know my original IP? The website is only available over HTTPS (not unencrypted HTTP).
29
votes
5answers
15k views

Are there security issues with embedding an HTTPS iframe on an HTTP page?

I've seen websites placing HTTPS iframes on HTTP pages. Are there any security concerns with this? Is it secure to transmit private information like credit card details in such a scheme (where the ...
29
votes
3answers
1k views

Why do WordPress installations retrieve the crypto secrets remotely on installation?

It seems that WordPress retrieves all the crypto constants remotely (via HTTPS): // setup-config.php $secret_keys = wp_remote_get( 'https://api.wordpress.org/secret-key/1.1/salt/' ); Are there ...
29
votes
4answers
1k views

What is the impetus for major sites being HTTPS-exclusive now?

I've noticed that there are a good number of sites (Google, Twitter, Wikipedia) that are serving up every page over HTTPS. I can understand given that everyone is concerned over privacy now, but has ...
29
votes
2answers
17k views

Why is it possible to sniff an HTTPS / SSL request?

I'm new to the realm of HTTP requests and security and all that good stuff, but from what I've read, if you want your requests and responses encrypted, use HTTPS and SSL, and you'll be good. Someone ...
29
votes
4answers
24k views

What's an easy way to perform a man-in-the-middle attack on SSL?

I'd like to perform a man-in-the-middle attack on SSL connections between clients and a server. Assuming the following: I've got a certificate that the client will accept, via poor cert validation ...
28
votes
9answers
17k 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.logmein.com) they can't see what I'm doing on the site since all ...
28
votes
7answers
6k 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 ...
27
votes
10answers
942 views

Does hashing a file from an unsigned website give a false sense of security?

Consider this. Many websites with software downloads also make available MD5 or SHA1 hashes, for users to verify the integrity of the downloaded files. However, few of these sites actually use HTTPS ...
27
votes
4answers
23k 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 googling for a while, I feel ...
27
votes
2answers
6k views

I just send username and password over https. Is this ok?

When a user's logging in to my site, they send their username and password to me over https. Besides the ssl, there's no special obfuscation of the password - it lives in memory in the browser in the ...
27
votes
7answers
4k 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.
27
votes
2answers
1k views

Why aren't infinite-depth wildcard certificates allowed?

As far as I can tell, an SSL certificate for *.example.com is good for foo.example.com and bar.example.com, but not foo.bar.example.com. Wildcards certificates cannot have *.*.example.com as their ...