K4 TR-31 key blocks

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Lesson K4: The header, the key usage and mode of use, versions A to D, wrapping, unwrapping and the MAC.

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The opening of the lesson

Why it matters

When a key leaves an HSM it must travel encrypted. Its purpose must travel with it and must not be changeable. TR-31 key blocks (published by ASC X9, now ANSI X9.143; ISO 20038 is close) do exactly that. They are the format PCI PIN requires for exchanging keys, and the format of almost every modern HSM import and export command.

In the full lesson

The concept
Step by step: reading and unwrapping a block
In the real world
Common mistakes
What to test

What module K4 covers →

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