old pgp2.6x keys imported in gpg (compile pgp 2.6)

[David Shaw]

On Jan 28, 2014, at 9:37 AM, Uwe Brauer <oub at mat.ucm.es> wrote:

> Hello
> 
> I have a problem to import my secret key into a iOS app called iPGmail.
> 
> The problem is that of course the key is password protected and the app
> seem to have difficulties with the password. 
> 
> So I just deleted the password and then can import the secret key, but I
> don't like this possibility and so I deleted my key.
> 
> The cipher for the key protection is CAST5
> 
> However the key was originally generated with pgp 2.6.2 more than 10
> years ago (yes I know it is only 1024 bit long and should not be used
> anymore), but could it be that such a key has some incompatibilities
> with RFC 4880??

Yes and no.  PGP 2.6.2 keys (version 3 keys) are compatible with RFC-4880, but that does not necessarily mean that every implementation supports them.  Version 3 key support is optional in the standard, so it is possible that the iPGmail app only supports OpenPGP (version 4) keys.

(Frankly, if I was writing a OpenPGP program today, I'd probably leave out version 3 support as well).

David