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4. Passphrase Cache

Mailcrypt can remember your passphrase so that you need not type it repeatedly. It will also "forget" your passphrase if it has not been used in a while, thus trading some security for some convenience. You can tune this tradeoff with the variable mc-passwd-timeout, which is a duration in seconds from the last time the passphrase was used until Mailcrypt will forget it. The default value is 60 seconds.

So, for example, to make Mailcrypt remember your passphrase for 10 minutes after each use, you would use the following line in your `.emacs' file:

(setq mc-passwd-timeout 600)

A value of nil or 0 will disable passphrase caching completely. This provides some increase in security, but be aware that you are already playing a dangerous game by typing your passphrase at a Lisp interpreter.

Mailcrypt understands multiple secret keys with distinct passphrases.

To manually force Mailcrypt to forget your passphrase(s), use the function mc-deactivate-passwd. Both mc-read-mode and mc-write-mode bind this function to C-c / f by default.

Warning: Although Mailcrypt takes pains to overwrite your passphrase when "forgetting", it cannot prevent the Emacs garbage collector from possibly leaving copies elsewhere in memory. Also, your last 100 keystrokes can always be viewed with the function view-lossage, normally bound to C-h l. So be sure to type at least 100 characters after typing your passphrase if you plan to leave your terminal unattended.