Re: O.J. ObCrypto: Fuhrman's Folly Fans Fakery Fears...

At 23:50 8/30/95, MONTY HARDER wrote:
>I recommend that anyone who will be using escrowed keys generate two
>pairs: First, the signature key, including in the userid some kind of
>[sig use] identifier (we should settle on a standard abbreviation for
>this) follower by the encryption key. This way, when a person gets your
>pubkeys, they get the encryption key =last=, which gets it searched
>first whenever they PGP -e... something.
>
>  Whatever arrangements are made for escrowing my encryption key,
>=nobody= gets my signature key. If I am fired, quit, become brain
>damaged or dead, my key can never be used by anyone to implicate me in
>any criminal activity.
>
>
>
>  Please don't mention to anyone the fact that my signature key can be
>used to send me something that even the escrow agents can't read....

I do not think that PGP 2.x can easily (ie: Automatically) use one key for
Signing and another for Encrypting a Message (it does both at the same time
if you ask). If I "Clear Sign" a message and then Encrypt it, then I get
the result but I'm not sure if doing the decrypt on such a message will
automatically spot the signature and verify it (as would occur with a E+S
pass).

PGP3 is supposed to have the ability to have keysets that contain two keys
for this purpose (ie: When you generate a key set you can ask it to
generate separate Sign and Encrypt keys so that separate keys get used for
each function).

> I do not think that PGP 2.x can easily (ie: Automatically) use one key for
> Signing and another for Encrypting a Message (it does both at the same time
> if you ask). If I "Clear Sign" a message and then Encrypt it, then I get
> the result but I'm not sure if doing the decrypt on such a message will
> automatically spot the signature and verify it (as would occur with a E+S
> pass).

Sure it can, and I know people who do.  Here is what you do:

1) Generate two keys.  First generate your encryption key, then
generate your signature key.  This way, your signature key will be
placed first in your secret keyring, and it will be used by default.
Alternatively, you could use two (slightly) different userIDs on the
keys and put something in your config.txt

2) Extract the keys in reverse order into a single keyfile and then
distribute that keyfile to people.  This way, when it gets added to
other people's keyrings, the encryption key will be placed first, and
that will be used by default.

3) Proceed to use PGP normally.  When you sign a message, it will find
the signature key first and use that.  When someone wants to encrypt
to you, they will find the encryption key first.  When verifying the
signature or trying to decrypt the message, it uses the keyID to
determine which key was used, so order does not matter.

The only problem is that if someone re-orders their keyring then this
will no longer work.  E.g., if the keys are added in the wrong order.

-derek