Unusual (unintended?) behavor upon decryption of a message

Peter Lebbing peter at digitalbrains.com
Tue Nov 19 12:07:00 CET 2013

On 19/11/13 10:15, Laurent Jumet wrote:
>     In my opinion, this is a symetric crypted message. You need the exact
> password (called passphrase as well) to decrypt it, but it's not a double key
> cipher.

You're only partly correct. Letting 'gpg2 --list-packets --list-only' inspect
the message, I see:

:pubkey enc packet: version 3, algo 1, keyid CB0669F10BD2393E
        data: [2048 bits]
:symkey enc packet: version 4, cipher 3, s2k 3, hash 2, seskey 256 bits
        salt 8813f6959e774f45, count 9437184 (210)
gpg: CAST5 encrypted session key
:encrypted data packet:
        length: unknown
        mdc_method: 2
gpg: encrypted with 1 passphrase
gpg: encrypted with RSA key, ID 0BD2393E

So it can be decrypted either with the mentioned RSA key, or by some passphrase.
There are two ways to get at the data. If you don't have that RSA key, programs
will likely query you for the passphrase. If you do have the secret key for that
RSA key, I suppose it will ask that first, although I'm not sure. It will ask
for the passphrase for the RSA key, but I'm unsure if it will be the first
passphrase it asks for.



I use the GNU Privacy Guard (GnuPG) in combination with Enigmail.
You can send me encrypted mail if you want some privacy.
My key is available at <http://digitalbrains.com/2012/openpgp-key-peter>

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