Nonetheless, McPherson has granted conditional certification for the Diebold machines in California's elections -- with the proviso that supervisors adhere to new security guidelines when using the gear.

The guidelines require that administrators reset the cryptographic keys on every AccuVote-TSx machine from the factory-installed default before every election. Additionally, each memory card must be programmed securely under the supervision of the registrar of voters.

Over an unspecified long term, Diebold must fix the security vulnerabilities to retain the California certification.

In a statement, Diebold said it 'wholeheartedly agrees' with the proposed security procedures and said it plans to improve the security of the optical-scan firmware in its machines and create digital signatures to detect tampering.