GPG is a multiplatform solution that can be used with Windows (Command Line) or Linux, this example is under a Linux platform.
There is an option --gen-key that can generate four kind of keys, for our purpose (1) RSA and RSA or (2) DSA and Elgamal are useful. In the next image (1) RSA and RSA was chosen.
The program asks for the key length (between 1024 and 4096 bits) and the expiration time, a year or two is a common caducity time.
In the example the keys have 2048 bits and 2 years of time before the key expires.
The program asks for a name, email address to identify the owner of the key and an optional comment. In the example the userid and the email address are the same (god@spam.com) after that the program shows the options to change the name (N), commen (C) or email (E) or Okay (O) for commit the changes or (Q) for quit the program.
After choosing the (O)kay the program asks for a passphrase to protect the private key, depending of the length of the key the program will need some time to generate the random numbers.
The keys and their signatures are created after the program find the randon numbers, finally it saves the keys in the private and the public rings of the gpg program.
The next entry shows how to list and manage the keys: http://davidalexandermejia.blogspot.com/2013/11/showing-managing-keys-using-gpg-to.html
