unable to use the public key

[David Shaw]

On Thu, Jul 03, 2008 at 02:36:07PM -0400, Seller, Scott wrote:
> Hello. I am using gpg v 1.4.7 on Windows.
> 
> I have successfully traded keys with a vendor I am working with. Gpg insists on using the subkey and will not use the primary  key.. here is what I am seeing:
> 
> gpg -seav -r 3DDD3ABE -u 6BEC8C4E --passphrase "passphrase"  "C:\Documents and Settings\user\Desktop\pgptest\test.txt"
> 
> You need a passphrase to unlock the secret key for
> user: "USA TODAY <xxxxx at usatoday.com>"
> 1024-bit DSA key, ID 6BEC8C4E, created 2008-07-02
> 
> gpg: using subkey C970A114 instead of primary key 3DDD3ABE
> gpg: using classic trust model
> gpg: This key belongs to us
> File `C:\\Documents and Settings\\xxx\\Desktop\\pgptest\\test.txt.asc' exists. Overwrite? (y/N) y
> gpg: writing to `C:\\Documents and Settings\\xxx\\Desktop\\pgptest\\test.txt.asc'
> gpg: ELG-E/AES256 encrypted for: "C970A114 BOAD072013 <DTS 24X7 support @ xxxxxx>"
> gpg: DSA/SHA1 signature from: "6BEC8C4E USA TODAY <xxxxx at usatoday.com>"
> 
> Is there any way around this. The vendor cannot decrypt the file unless I use the primary key.

There is confusion here.  Your key is a DSA primary.  You cannot
encrypt to it.  It's not a question of GPG disallowing it, it's a
question of the math simply not working that way.  DSA is not an
encryption algorithm.

Where is the origin of the belief that the vendor can only decrypt
from a primary key?  This is directly contrary to the behavior of all
known OpenPGP programs (GPG, PGP, etc).

David