Paper 2025/1888
HCTR2-FP and HCTR3-FP: Format-Preserving Encryption from Wide-Block Ciphers
, Fastly Inc.Abstract
Format-preserving encryption (FPE) enables encryption while maintaining syntactic properties such as character sets. The current NIST standard FF1 uses multi-round Feistel networks that sacrifice performance for flexibility, while FF3-1 was withdrawn in 2025 following successful cryptanalytic attacks. FAST, proposed as a faster alternative, has not been widely implemented due to its complexity, leaving limited practical alternatives. We present HCTR2-FP and HCTR3-FP, format-preserving adaptations of the HCTR2 and HCTR3 wide-block tweakable ciphers. These variants preserve the single-pass Hash-Encrypt-Hash structure while operating on arbitrary radix domains through base-radix encoding and modular arithmetic. The constructions are simple to implement and analyze, and benchmarks demonstrate significant speedup over FF1.
Note: Added references to the Vistrutah and the Samvadini-AEAD papers.
Metadata
- Available format(s)
-
PDF
- Category
- Secret-key cryptography
- Publication info
- Preprint.
- Keywords
- fpeformat preservingff1ff3ffxhctr2hctr3hctr2-fphctr3-fpencryption
- Contact author(s)
- fde @ 00f net
- History
- 2025-11-19: revised
- 2025-10-09: received
- See all versions
- Short URL
- https://ia.cr/2025/1888
- License
-
CC0
BibTeX
@misc{cryptoeprint:2025/1888,
author = {Frank Denis},
title = {{HCTR2}-{FP} and {HCTR3}-{FP}: Format-Preserving Encryption from Wide-Block Ciphers},
howpublished = {Cryptology {ePrint} Archive, Paper 2025/1888},
year = {2025},
url = {https://eprint.iacr.org/2025/1888}
}
