Red Hat Linux Advisory: gnupg

Red Hat Security Advisory

1. Topic:

Updated gnupg packages are now available for Red Hat 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.

2. Relevant releases/architectures:

Red Hat Linux 7.1 – i386
Red Hat Linux 7.2 – i386, ia64
Red Hat Linux 7.3 – i386
Red Hat Linux 8.0 – i386
Red Hat Linux 9 – i386

3. Problem 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/

4. 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

5. RPMs required:

Red Hat Linux 7.1:

SRPMS:
ftp://updates.redhat.com/7.1/en/os/SRPMS/gnupg-1.0.7-12.src.rpm

i386:
ftp://updates.redhat.com/7.1/en/os/i386/gnupg-1.0.7-12.i386.rpm

Red Hat Linux 7.2:

SRPMS:
ftp://updates.redhat.com/7.2/en/os/SRPMS/gnupg-1.0.7-13.src.rpm

i386:
ftp://updates.redhat.com/7.2/en/os/i386/gnupg-1.0.7-13.i386.rpm

ia64:
ftp://updates.redhat.com/7.2/en/os/ia64/gnupg-1.0.7-13.ia64.rpm

Red Hat Linux 7.3:

SRPMS:
ftp://updates.redhat.com/7.3/en/os/SRPMS/gnupg-1.0.7-13.src.rpm

i386:
ftp://updates.redhat.com/7.3/en/os/i386/gnupg-1.0.7-13.i386.rpm

Red Hat Linux 8.0:

SRPMS:
ftp://updates.redhat.com/8.0/en/os/SRPMS/gnupg-1.0.7-14.src.rpm

i386:
ftp://updates.redhat.com/8.0/en/os/i386/gnupg-1.0.7-14.i386.rpm

Red Hat Linux 9:

SRPMS:
ftp://updates.redhat.com/9/en/os/SRPMS/gnupg-1.2.1-9.src.rpm

i386:
ftp://updates.redhat.com/9/en/os/i386/gnupg-1.2.1-9.i386.rpm

6. Verification:

MD5 sum Package Name

4d62554490e85b7cc1f0cfef6518a979
7.1/en/os/SRPMS/gnupg-1.0.7-12.src.rpm
0591a2079aff5e7979b0225b568bceaa
7.1/en/os/i386/gnupg-1.0.7-12.i386.rpm
b619c30c293094d7dcd18487d8e62a43
7.2/en/os/SRPMS/gnupg-1.0.7-13.src.rpm
e7e3e75afd1ccd2267ccc7847c76ebb4
7.2/en/os/i386/gnupg-1.0.7-13.i386.rpm
6fb21011ca42ff395b8cfc7dce4c2936
7.2/en/os/ia64/gnupg-1.0.7-13.ia64.rpm
b619c30c293094d7dcd18487d8e62a43
7.3/en/os/SRPMS/gnupg-1.0.7-13.src.rpm
e7e3e75afd1ccd2267ccc7847c76ebb4
7.3/en/os/i386/gnupg-1.0.7-13.i386.rpm
bc375882f13e5c10eb29eb3615de911d
8.0/en/os/SRPMS/gnupg-1.0.7-14.src.rpm
a3de0844778cd994258f121330ff6d62
8.0/en/os/i386/gnupg-1.0.7-14.i386.rpm
e1f31f4a07ebb5b4040f8f6ca3816cc4
9/en/os/SRPMS/gnupg-1.2.1-9.src.rpm
604a2fb5b809ec99280871f46507f4a1
9/en/os/i386/gnupg-1.2.1-9.i386.rpm

These packages are GPG signed by Red Hat for security. Our key
is available from https://www.redhat.com/security/keys.html

You can verify each package with the following command:

rpm –checksig -v <filename>

If you only wish to verify that each package has not been
corrupted or tampered with, examine only the md5sum with the
following command:

md5sum <filename>

7. References:

http://lists.gnupg.org/pipermail/gnupg-announce/2003q4/000276.html

http://lists.gnupg.org/pipermail/gnupg-users/2003-November/020779.html

http://lists.gnupg.org/pipermail/gnupg-announce/2003q4/000277.html

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2003-0971

8. Contact:

The Red Hat security contact is <secalert@redhat.com>. More
contact details at https://www.redhat.com/solutions/security/news/contact.html

Copyright 2003 Red Hat, Inc.