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CESA-2003:395: gnupg security update

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CESA-2003:395: gnupg security update

Severity
5
CVSS
(AV:N/AC:L/Au:N/C:P/I:N/A:N)
Published
12/15/2003
Created
07/25/2018
Added
03/12/2010
Modified
07/04/2017

Description

Updated gnupg packages are now available for CentOS 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.

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(s)

  • centos-upgrade-gnupg

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