Error using PGP 5 generated key

Werner Koch
Thu, 28 Oct 1999 09:00:22 +0200

Johan Wevers <> writes:

> 3072-bit ELG-E key, ID 1B240FEE, created 1999-10-26 (main key ID 624B3B3E)
> gpg: this is a PGP generated ElGamal key which is NOT secure for signatures!
You tried to use an encrypt only key for signatures. Keys of type 16 are not usable for signing (Bleichenbacher attack). There is one exception: Early versions of gpg created keys of type 16 which are secure for signature - however these keys are in v3 packets and gpg is the only version which ever used this packets vor ElGamal keys.
> What is going on? Is this key really insecure (and if so, why?), or are
ElGamal (aka DH) keys created by PGP >=5 are only intended for encryption. -- Werner Koch at keyid 621CC013