Methods for Format-Preserving Encryption | Comment on the Second Public Draft of SP 800-38G Revision 1
February 03, 2025

NIST has released a second public draft (2PD) of Special Publication (SP) 800-38Gr1 (Revision 1), Recommendation for Block Cipher Modes of Operation: Methods for Format-Preserving Encryption, for public comment. The main technical changes to the original publication are the following:

• The domain size for the FF1 encryption method is increased.
• The encryption method FF3 is no longer specified.
• The inverse AES cipher function is no longer allowed to be CIPH.
• Floating point arithmetic is disallowed in implementations of FF1.

The public comment period for this draft is open through April 4, 2025. Submit comments to ciphermodes@nist.gov with the subject “Comments on SP 800-38Gr1 Second Public Draft.” Comments received in response to this request will be posted on this page under "Supplemental Material" after the due date. Submitters’ names and affiliations (when provided) will be included, while contact information will be removed.