Most people with color vision deficiency can see colors, but they have difficulty differentiating between the following colors: 1  particular shades of reds and greens (most common) 2  blues and yellows (less common)
This article describes how to update the expiration date of a key with PGP Command Line. The expiration date of your key can be updated if the key has a specified expiration date. You can update the expiration date, the number of days, or remove the expiration date for your PGP key. When specifying the date for the key to expire, the date format is yyyy-mm-dd. Note: < 1 user> is the user ID, portion of the user ID, or the key ID of the key whose expiration date is being removed. < 2 pass> is the passphrase of the key.  Use the following commands to update the expiration date of your PGP key.
Explanation of the web of trust of PGP. Everyone can generate a PGP key by himself. If you want to know if a given key belongs really to the person stated in the key, you have to verify that. This is very easy if you know the person who created the key. But is is difficult if you do not know that person at all.