Reads
Identities
from the encrypted identities file. Each identity
is defined by one line that contains two to four tab-separated fields:
Email Identity key, Public Name, Description, and Email Address.
The first two are mandatory, the last two are optional.
Additionally, the file can set a default Email Identity by including a
line that starts with "Default ", followed by an Email Destination key.
The destination key must match one of the Email Identities defined in
the file.
An Email Identity key consists of two public keys and two private keys, whereas
an Email Destination consists only of two public keys.