GnuPG and PGP 5.0 compatibility problem

vedaal at vedaal at
Wed Jul 18 16:39:05 CEST 2007

>Message: 6
>Date: Fri, 13 Jul 2007 22:42:37 +0200
>From: Stefan Oltmanns <stefan-oltmanns at>
>Subject: GnuPG and PGP 5.0 compatibility problem

>I got a problem with GnuPG and PGP 5.0:
>Also PGP 5 accepts my key, it is not possible for PGP 5 to encrypt 
>my key. It?s not even displayed in the selection dialog when I try 
>encrypt something (it shows identities correct in key list (but 
>expiration not)).
>I read in the FAQ that PGP 5.0 does not accept ElGamal keys of 
>type 20, 
>but my key doesn?t seem to be of that type (--list-packets says 
>4, algo 16, created 1153340019, expires 0")

what is algo 16?

standard current open pgp algorithms go up to algo 10 (twofish)
for cipher algorithms, and algo 11 (sha224) for hash algorithms

>There seem to be another problem, do you have any idea how to 
>solve it?

just in case the algo '16' was a typo,
maybe consider the following:

am assuming the key was generated under the gnupg default settings,
which would mean it would use cast5 as the cipher algo, which 'is' 
compatible with pgp 5


the default setting for gnupg is to use the newer secret key 
which is not compatible with any (standard) pgp version before 8

[1] delete the key from pgp 5
[2] remove the passphrase from the key in gnupg
[3] re-import the key into pgp5, and set the passphrase in pgp5
[4] re-set the passphrase in gnupg

and see if that works

pgp5 accepts rsa keys only up to 2048
so if your key is a bigger rsa key, that is another reason why it 
won't work


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