(RHSA-2003:395) gnupg security update

GnuPG is a utility for encrypting data and creating digital signatures.

Phong Nguyen identified a severe bug in the way GnuPG creates and uses
ElGamal keys, when those keys are used both to sign and encrypt data. This
vulnerability can be used to trivially recover the private key. While the
default behavior of GnuPG when generating keys does not lead to the
creation of unsafe keys, by overriding the default settings an unsafe key
could have been created.

If you are using ElGamal keys, you should revoke those keys immediately.

The packages included in this update do not make ElGamal keys safe to use;
they merely include a patch by David Shaw that disables functions that
would generate or use ElGamal keys.

To determine if your key is affected, run the following command to obtain a
list of secret keys that you have on your secret keyring:

gpg --list-secret-keys

The output of this command includes both the size and type of the keys
found, and will look similar to this example:

/home/example/.gnupg/secring.gpg

sec 1024D/01234567 2000-10-17 Example User <[email protected]>
uid Example User <[email protected]>

The key length, type, and ID are listed together, separated by a forward
slash. In the example output above, the key’s type is “D” (DSA, sign
and encrypt). Your key is unsafe if and only if the key type is “G”
(ElGamal, sign and encrypt). In the above example, the secret key is safe
to use, while the secret key in the following example is not:

/home/example/.gnupg/secring.gpg

sec 1024G/01234567 2000-10-17 Example User <[email protected]>
uid Example User <[email protected]>

For more details regarding this issue, as well as instructions on how to
revoke any keys that are unsafe, refer to the advisory available from the
GnuPG web site:

http://www.gnupg.org/