Red Hat Product Errata RHSA-2003:395 - Security Advisory
Issued:
2003-12-10
Updated:
2003-12-10

RHSA-2003:395 - Security Advisory

Synopsis

gnupg security update

Type/Severity

Security Advisory: Important

Topic

Updated gnupg packages are now available for Red Hat Enterprise Linux.
These updates disable the ability to generate ElGamal keys (used for both
signing and encrypting) and disable the ability to use ElGamal public keys
for encrypting data.

Description

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 <example@example.com>
uid Example User <example@example.com>

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 <example@example.com>
uid Example User <example@example.com>

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/

Solution

Before applying this update, make sure all previously released errata
relevant to your system have been applied.

To update all RPMs for your particular architecture, run:

rpm -Fvh [filenames]

where [filenames] is a list of the RPMs you wish to upgrade. Only those
RPMs which are currently installed will be updated. Those RPMs which are
not installed but included in the list will not be updated. Note that you
can also use wildcards (*.rpm) if your current directory *only* contains the
desired RPMs.

Please note that this update is also available via Red Hat Network. Many
people find this an easier way to apply updates. To use Red Hat Network,
launch the Red Hat Update Agent with the following command:

up2date

This will start an interactive process that will result in the appropriate
RPMs being upgraded on your system.

If up2date fails to connect to Red Hat Network due to SSL Certificate
Errors, you need to install a version of the up2date client with an updated
certificate. The latest version of up2date is available from the Red Hat
FTP site and may also be downloaded directly from the RHN website:

https://rhn.redhat.com/help/latest-up2date.pxt

Affected Products

  • Red Hat Enterprise Linux Server 3 x86_64
  • Red Hat Enterprise Linux Server 3 ia64
  • Red Hat Enterprise Linux Server 3 i386
  • Red Hat Enterprise Linux Server 2 ia64
  • Red Hat Enterprise Linux Server 2 i386
  • Red Hat Enterprise Linux Workstation 3 x86_64
  • Red Hat Enterprise Linux Workstation 3 ia64
  • Red Hat Enterprise Linux Workstation 3 i386
  • Red Hat Enterprise Linux Workstation 2 ia64
  • Red Hat Enterprise Linux Workstation 2 i386
  • Red Hat Enterprise Linux for IBM z Systems 3 s390x
  • Red Hat Enterprise Linux for IBM z Systems 3 s390
  • Red Hat Enterprise Linux for Power, big endian 3 ppc

Fixes

The Red Hat security contact is secalert@redhat.com. More contact details at https://access.redhat.com/security/team/contact/.