Are there any standards or industry practices with respect to the implementation of DUKPT with AES (as opposed to DUKPT / TDEA which is covered by ANSI X9.24-1:2009)?

Understanding that DUKPT is a Key management scheme for deriving a double length TDES key, can that 128 bit derived key then be used as an AES key for Encryption / Decryption? Or is there any reason why this is insecure?

1 Answer 1


All DUKPT is defined by ANSI X9.24 part 3.

ANSI X9.24 specifies that working keys shall be the same strength or weaker than the key from which they are derived.

Whilst you can derive a TDES from an AES initial key, you wouldn't derive one for use with AES; You would derive an AES Key (either AES-128, AES-192 or AES-256). The size of this derived key is limited by the above rule (any derived working key would be the same strength or weaker than the initial key). If your base derivation key is AES-256, then you have no limitations on the size of your derived working keys).

If you want to stick with TDEA for your key usage, you can still derive 2TDES or 3TDES keys, but then you would be restricted to using TDES algorithms with those keys.

Any sensible crypto engine / HSM will be enforcing these rules, so attempting to use a TDES key with an AES algorithm will throw issues pretty quickly.

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