GnuPG creates ElGamal keys for signing using insufficient entropy

ID VU:940388
Type cert
Reporter CERT
Modified 2003-12-29T15:52:00



Gnu Privacy Guard (GnuPG) is a cryptographic utility used to generate cryptographic keys and perform other cryptographic functions. A vulnerability in the way GnuPG generates ElGamal keys has been discovered. This vulnerability renders ElGamal signing key untrustworthy.


A vulnerability in the algorithm to generate ElGamal sign+encrypt keys can permit an attacker to generate valid signatures without access to the private key. This vulnerability does not affect encrypt-only (type 16) ElGamal keys, only the ElGamal sign+encrypt key (type 20) when used to make a signature with a GnuPG version 1.0.2 or later.


A remote attacker can generate a valid signature without access to the private key.


Revoke your ElGamal signing keys. GnuPG has released a patch for version 1.2.3 or you can upgrade to version 1.2.4 or later.

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GNU Privacy Guard __ Affected

Updated: December 29, 2003



Vendor Statement

We have not received a statement from the vendor.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.


Please see the GnuPG advisory at <>

If you have feedback, comments, or additional information about this vulnerability, please send us email.

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Thanks to Werner Koch for his advisory on this issue, and Phong Nguyen for reporting this vulnerability.

This document was written by Jason A Rafail.

Other Information

CVE IDs: | CVE-2003-0971
Severity Metric: | 6.33
Date Public: | 2003-11-27
Date First Published: | 2003-12-29
Date Last Updated: | 2003-12-29 15:52 UTC
Document Revision: | 7