Home / The record / Discrete logarithm mechanisms

This family works in a group of prime order inside a prime modulus, and its best known member is the Schnorr scheme. It keeps the exchange short and makes the challenge size matter, so the parameter record has to carry the group, the generator and the challenge length together.

What it asks

Record the prime modulus, the subgroup order, the generator and the challenge length for each deployment, and show that the group was generated rather than copied. Test that a response outside the subgroup is rejected, because that check is where a shortcut implementation usually fails.

What the revision does

The fourth edition keeps the family and will restate the clause. The public record stops before the revised text. The 2009 wording is therefore superseded at publication.

Who it binds

The cryptography owner and the engineer who implements the verifier.

Evidence an auditor samples

• The group parameters per deployment, with their generation record (cryptography standard)
• The challenge length and the workload note behind it (capacity plan)
• The subgroup membership test in the verifier (test suite)

The test you can run

Send a response outside the subgroup. If the verifier accepts it, the membership check is missing.

Common failures

• The group is copied from a paper with no generation record.
• The subgroup check is present in the library but disabled by a configuration flag.

How to close it

Keep the group generation record with the deployment and test the membership check through the deployed configuration, not the library default. The gap between the two is the finding. Start with the group parameters per deployment, with their generation record and let the row close when it exists with a date and a named holder.

Where it sits against the 2009 edition

The 2009 edition carries Clause 6, and the fourth edition replaces it. The public record does not give the new wording, so this page records the obligation that stands today and the question the revision has to answer.

For the file, this row closes when the group parameters per deployment, with their generation record exists with a date, a named holder and a pointer, and when the test above has been run and recorded. The cryptography owner and the engineer who implements the verifier. owns that answer for Clause 6.