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.
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.
|Date First Published:||2003-12-29|
|Date Last Updated:||2003-12-29 15:52 UTC|