I had a customer this week that had an Apple Macbook Pro running Mac OS 10.10.5 (aka Yosemite) and certain websites wouldn’t work in Safari when they worked in Chrome. Also he couldn’t use his Mac Mail for his email account, it kept saying his password was incorrect, when it worked fine on the web based email.
Transport Layer Security is the way secure websites work. A secure website is merely a normal website that is encapsulated in an encryption.
TLS 1.3 is the latest version of the encryption, which helps to keep your data safe. Unfortunately, TLS 1.3 is not available for Safari prior to Mojave (10.14) It is also not supported in Mac Mail until Mojave either.
This explains why some websites the user wanted to see couldn’t be displayed because they don’t fall back to TLS 1.2 if TLS 1.3 is not usable.
What operating systems and browsers support TLS 1.3?
I had wondered why Microsoft wanted to ditch Internet Explorer, it turns out that none of the Internet Explorer versions support TLS 1.3, but Microsoft Edge does. Versions of Internet Explorer prior to 11 did not support TLS 1.1 nor TLS 1.2 unless manually enabled.
Mozilla Firefox has supported TLS 1.3 since version 63, it’s current version is 80. Google Chrome has supported TLS 1.3 from 69 and it’s current is 85.
iOS 12.2 and beyond supports TLS 1.3.
HTTP/2.0 was a breakthrough that enabled much faster and more efficient web surfing.
Instead of the browser asking the server for a page, then asking for all the images on that page in a separate connection for each image and in plain text, if the browser supports HTTP/2.0, then the browser asks the server for the web page in binary and the server gives the browser the page and all the images in one connection.
However, HTTP/2.0 requires TLS 1.3 support to work. This is the reason why Microsoft wanted to end support for Windows 7 and 8, because Internet Explorer can’t do TLS 1.3 and Microsoft wanted to push development for their new browser, Edge (which they have since abandoned for a Chrome based Edge browser)
Since the customer had a 2014 model Apple Macbook Pro, Mac OS Catalina is supported and actually works better on Macs with solid state drives.
Now every website can be opened without problems and the Mac Mail works as expected.