Function to prompt the user for a password to read a protected private key.
pinentry(prompt = "Enter your GPG passphrase:")
the string printed when prompting the user for input.
If available, this function calls the GnuPG pinentry
program. However this
only works in a terminal. Therefore the IDE can provide a custom password entry
widget by setting the askpass
option. If no such option is specified
we default to readline
.