What is the most usable software for email encryption that has manual key management?
In case some are unaware of its meaning, manual key management is where users (not programs) are left in charge of generating, exchanging and storing their cryptographic keys. This application should be easy to use, even for people without prior experience with cryptography (e.g. with PGP).
I'd like to recommend GPG4Win. It's an open source software that run's on Microsoft Windows. It contains a tool called Kleopatra which provides a really nice GUI interface for managing keys. It doesn't require any technical knowledge to use. It's also quite powerful as you dig deeper into the application.
Gpg4win enables users to securely transport emails and files with the help of encryption and digital signatures. Encryption protects the contents against an unwanted party reading it. Digital signatures make sure that it was not modified and comes from a specific sender.
Gpg4win supports both relevant cryptography standards, OpenPGP and S/MIME (X.509), and is the official GnuPG distribution for Windows. It is maintained by the developers of GnuPG. Gpg4win and the software included with Gpg4win are Free Software (Open Source; among other things free of charge for all commercial and non-commercial purposes).
*Note: This screenshot came from a German version, there are other translations including English
And if you have the Outlook desktop client, you can use the Outlook Privacy Plugin. It works directly with PGP4Win so you can manage your keys there and then encrypt/decrypt from this plugin. (This is what I use, highly recommend it:)
There is also GnuPGk, another application for Windows written in C#. It too is open source and very easy to use. It will provide another key management solution for you.
A GnuPG Frontend GUI made in C#. It is compatible with PGP as well so it can be a very useful tool for encryption/decryption. It also incorporates a shell extension so it can be easy to right click and decrypt or decrypt.
I would recommend gpg4o. It integrates perfectly with Outlook and comes with an integrated key management. IMHO gpg4o's keymanagement is easier to use than Kleopatra.
Since last year they offer also a free version for private use.
