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Key production here depends on the mode. One mode fixes a private key size and derives the public value from the base, and the other uses a different construction. Mixing the two produces keys that look valid and fail only at verification, which is why the record has to name the mode.

What it asks

Record the mode, the private key size and the derivation for each key, and show that the key was generated under the same mode the verifier expects. Keep a negative test for a key from the other mode, and review the key size against the guidance rather than the library default.

What the revision does

The fourth edition will restate key production. The revised rules are not public. The 2009 wording is therefore superseded at publication.

Who it binds

The key management owner and the verifier operator.

Evidence an auditor samples

• The key record with mode, size and derivation (key management)
• The key size review against the guidance (design note)
• The negative test with a key from the other mode (test suite)

The test you can run

Generate a key in the other mode and present it. If the verifier accepts it, the mode check is absent.

Common failures

• The key size is inherited from a library default with no review.
• A key from the other mode is accepted because the verifier does not check the mode.

How to close it

Put the mode in the key identifier and check it on every verification. The identifier is the cheapest place to stop a cross-mode key, and it makes the record self describing. Start with the key record with mode, size and derivation 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 7.2, 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 key record with mode, size and derivation exists with a date, a named holder and a pointer, and when the test above has been run and recorded. The key management owner and the verifier operator. owns that answer for 7.2.