Re: Encrypting incoming messages with GnuPG
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On 05/09/09 18:05, Harry Rickards wrote:
> On 05/09/09 17:42, Dave Patterson wrote:
>> * Harry Rickards <hrickards@l33tmyst.com> [2009-05-09 11:14:14 +0100]:
>
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>>> I was wondering if anyone knew of a way, perhaps using /etc/aliases, so
>>> that all incoming mail addressed to my username (hrickards) is encrypted
>>> with *my* public key, so that when I read it only I can read it using
>>> *my* private key. If the mail was signed or encrypted beforehand, it
>>> could then be decrypted with my private key as usual.
>>>
>> Hmm. So, we're looking at encrypting mails as they come in, prior to
>> disk write, in a format that you, and only you, can later decrypt them,
>> preferably using gpg. I don't care why, it's an intereUting problem.
>
>> Local storage remains secure. At least that's what I think is the
>> intention.
>
>> Outside of using some disk encryption system like this:
>
>> <http://www.debianhelp.org/node/15244>
>
>> I'd try to pipe the mail fetchmail, procmail (pipe to
>> encryptionscrypt,write-encrypted-email-to-disk)
>
>> Remembering procmail only functions as a gate, and does not write the
>> mail to disk until told to, and neither does fetchmail
>> (or getmail or retchmail).
>
>> script should be very simple:
>
>> gpg -e -r yourusergpgidhere themessage
>
>> Build from that command.
>
>> Trick is to not write to disk prior to encryption.
>
> Uh, huh. Thanks for the tips, I'll try to come up with something from that.
>
So far I've added the gpmail alias in /etc/aliases as a test using the
following line:
gpmail:|/usr/bin/gpmail
I then created the /usr/bin/gpmail script, and ran newaliases. In
/usr/bin/gpmail I've got:
gpg --encrypt --sign --armor -r hrickards@l33tmyst.com|mail -s Test
hrickards@l33tmyst.com
When piping stuff to it from the command line it works fine, but when
sending a test email to gpmail@l33tmyst.com I get a blank email in
response. I think this is because /usr/bin/gpmail is being executed as
the 'nobody' user (I setup a whoami script), and I've setup the GPG keys
for the 'mail' user. nobody can't use GPG, as it doesn't have a home
directory, so is there a way to change the user that Postfix pipes
things to with (to mail or any other user with a home directory)? Thanks
for all the help.
- --
Many thanks
Harry Rickards (a.k.a l33tmyst)
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