basic error? PHP and GPG

Tue Dec 17 14:40:10 2002

But if the group members, and only the group members, share the group sec=
ret
key, why should the server perform any additional encryption? A normal li=
st
server can be used, and no outsider will be able to read the messages.

Anyway, sharing secret keys among groups is also a bad idea: it puts the
security of all the members in the hands of the most careless one. I woul=
d
recommend, instead, a hybrid approach: anonymous posting though a web for=
m
over SSL (and a server setup where the passphrase for the server's key is
manually entered by the system operator when the HTTP daemon is restarted=
),
and distribution by mail PGP-encrypted to all the secret keys of each gro=
up
member. However, list expansions to large groups will tax the CPU quite a
bit. And if the attacker can get the same privilege as the httpd, or wors=
e
as root, all the messages will be readable.

Enzo

P.S. This thread should actually continue on gnupg-users .

----- Original Message -----
From: "Ken McCormack" <design@palmer21.com>
To: <Gnupg-devel@gnupg.org>
Sent: Tuesday, December 17, 2002 8:57 PM
Subject: Re: basic error? PHP and GPG

> Hi Enzo,
>
> You're right, storing a secret key anywhere near a server is a bad idea=
...
> just to note that I dont keep a secret key on the server at all - I'm
fully
> aware that once its on there anyone (including all the staff at the
hosting
> company) have free access to it!
>
> My understanding is fairly basic, that in general you don't need instal=
l a
> secret key unless the server is itself receiving encrypted e-mails... t=
his
> is unlikely... and certainly not a requirement in my application, as th=
e
> secure route to the server is via the browser and SSL.
>
> BUT it could happen, for example, if the server was needed to decrypt a=
n
> e-mail sent to it, and then convey this onward to several different
> recipients, encrypting for each with their own public key...
>
> I thought this was an interesting circumstance, and of course impossibl=
e
to
> do securely if the secret key is stored on the server, which it must.  =
One
> idea I had was that it could be possible to get round this by encryptin=
g
the
> data twice, using two different secret keys, only one of which would be
> stored on the server.
>
> If the encryption is 'transparent' mathematically, it should work:
>
> 1. The final recipients have their own secret key plus an additional
'group'
> secret key.
>
> 2. The initial sender uses the group public key to encrypt the message =
[->
> stage1].
>
> 3. The sender then further 'double encrypts' the message using the publ=
ic
> key of the server.
>
> 4. The message is sent to the server
>
> 5. On receipt, the server decrypts using its own secret key (which may =
be
> compromised), revealing the encrypted message [as at stage1].
>
> 6. This is then re-encrypted with the recipients' own public keys
>
> 7. This is sent on to each recipient.
>
> 8. On receipt the recipient first decrypts with their own secret key [a=
s
at
> stage 1]
>
> 9.  The recipient then decrypts with the group secret key.
>
>
> Do I have that right? (All these keys are confusing) Would that work?  =
Can
> we encrypt twice and then go in reverse?
>
> Ken
>
> ----- Original Message -----
> From: "Enzo Michelangeli" <em@who.net>
> To: "Ken McCormack" <design@palmer21.com>; <gnupg-devel@gnupg.org>
> Sent: Tuesday, December 17, 2002 11:07 PM
> Subject: Re: basic error? PHP and GPG
>
>
> > I don't think it's a good idea to keep a secret keyring on a shared
> server:
> > running a sniffer on the same LAN segment one can read your passphras=
e,
> and
> > then decrypt the secret key. The only exception would be if gpg could
make
> > use of tamperproof keystores, such as some types of smartcards: but t=
his
> is
> > not yet available.
> >
> > Enzo
> >
> > ----- Original Message -----
> > From: "Ken McCormack" <design@palmer21.com>
> > To: <gnupg-devel@gnupg.org>
> > Cc: "Noel D. Torres Ta=F1o" <ndtt@ll.iac.es>
> > Sent: Tuesday, December 17, 2002 7:38 PM
> > Subject: Re: basic error? PHP and GPG
> >
> >
> > > Thanks Noel, will try that. I was aware of the difference, but not
what
> to
> > > do about it.
> > >
> > > On the recent post regarding the secring.pgp:file open error - ( I
> haven't
> > > seen the full thread, sorry... please forgive me if I'm 'barking up
the
> > > wrong tree' with this),  this error looks quite similar to the one =
I
was
> > > getting.
> > >
> > > Just to give a basic explanation about what happened (in case any
other
> > poor
> > > designers are having the same trouble), I was getting an error beca=
use
I
> > had
> > > imported keys as the wrong user -- I was importing key files into m=
y
> site
> > > login username or as root, rather than the web server user 'apache'=
 or
> > > 'httpd'.  The keys weren't found because they had been installed fo=
r
> > another
> > > user.
> > >
> > > Its pretty obvious when you think about it, as neither root nor the
site
> > > user actually call the gpg script. But it fooled me for a few days.
> When
> > > using PHP for example, this is done on behalf of the web server
user...
> so
> > > the keys need to be added from apache or httpd or 'nobody'... what =
I
did
> > was
> > > log in as root and su to apache.
> > >
> > > I also found that 'apache' also needed to have full write permissio=
ns
on
> > the
> > > /home/apache/.gnupg/ directory, so it could create the keyring etc.
> > >
> > > I recently tried to set this up on a shared hosting account for a
design
> > > client, my host charged me $75 to set up the keyrings, apparently i=
t
was
> > the
> > > first time they had this requested...!
> > >
> > > Perhaps a good subject for a FAQ for the site would be 'setting up =
GPG
> on
> > a
> > > shared server'?
> > >
> > > Best regards
> > >
> > > Ken
> > >
> > >
> > > ----- Original Message -----
> > > From: "Noel D. Torres Ta=F1o" <ndtt@ll.iac.es>
> > > To: <gnupg-devel@gnupg.org>
> > > Cc: "Ken McCormack" <design@palmer21.com>
> > > Sent: Tuesday, December 17, 2002 10:04 PM
> > > Subject: Re: basic error? PHP and GPG
> > >
> > >
> > > > > Ken McCormack wrote:
> > > > >
> > > > > Hi All...
> > > > >
> > > > > I've just recently got into GPG for the first time, its a
wonderful
> > > > > tool, but there are so many mysteries!
> > > > > Having finally sussed that for use with PHP I need to set keyri=
ngs
> > > > > from the web user - apache - rather than root or my own account=
, I
> am
> > > > > now up and running....
> > > > >
> > > > > Only one small problem, after encrypting an e-mail which
> > > > > contains standard carriage returns ( \n or (for html) <br>), th=
e
> > > > > output in Outlook Express comes out as having black squares whe=
re
> the
> > > > > line feeds should be....
> > > > >
> > > > > Does anyone have any ideas as to why this is, and if there are =
any
> > > > > ways to counteract this?
> > > > > I'm using PGP 7.0.3 on my PC... using 1024 bit DSA cipher...
> > > > >
> > > > > Regards
> > > > >
> > > > > Ken
> > > > >
> > > > Keep in mind the diference between the UNIX way of line brakes an=
d
the
> > > > DOS way. For DOS, you need the pair CR LF. Try using -text in you=
r
> gpg.
> > > >
> > > > Noel
> > > >
> > > > _______________________________________________
> > > > Gnupg-devel mailing list
> > > > Gnupg-devel@gnupg.org
> > > > http://lists.gnupg.org/mailman/listinfo/gnupg-devel
> > > >
> > >
> > >
> > > _______________________________________________
> > > Gnupg-devel mailing list
> > > Gnupg-devel@gnupg.org
> > > http://lists.gnupg.org/mailman/listinfo/gnupg-devel
> >
>
>
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