Paper 2023/253

XOCB: Beyond-Birthday-Bound Secure Authenticated Encryption Mode with Rate-One Computation (Full Version)

Zhenzhen Bao, Institute for Network Sciences and Cyberspace, BNRist, Tsinghua University, Beijing, China, Zhongguancun Laboratory, Beijing, China
Seongha Hwang, KAIST, Daejeon, Korea
Akiko Inoue, NEC, Kawasaki, Japan
Byeonghak Lee, KAIST, Daejeon, Korea
Jooyoung Lee, KAIST, Daejeon, Korea
Kazuhiko Minematsu, NEC, Kawasaki, Japan

We present a new block cipher mode of operation for authenticated encryption (AE), dubbed XOCB, that has the following features: (1) beyond-birthday-bound (BBB) security based on the standard pseudorandom assumption of the internal block cipher if the maximum block length is sufficiently smaller than the birthday bound, (2) rate-1 computation, and (3) supporting any block cipher with any key length. Namely, XOCB has effectively the same efficiency as the seminal OCB while having stronger quantitative security without any change in the security model or the required primitive in OCB. Although numerous studies have been conducted in the past, our XOCB is the first mode of operation to achieve these multiple goals simultaneously.

Available format(s)
Secret-key cryptography
Publication info
A minor revision of an IACR publication in EUROCRYPT 2023
Authenticated encryptionBlock cipherOCBBeyond-birthday- bound security
Contact author(s)
zzbao @ tsinghua edu cn
mathience98 @ kaist ac kr
a_inoue @ nec com
lbh0307 @ kaist ac kr
hicalf @ kaist ac kr
k-minematsu @ nec com
2023-02-22: approved
2023-02-22: received
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Creative Commons Attribution


      author = {Zhenzhen Bao and Seongha Hwang and Akiko Inoue and Byeonghak Lee and Jooyoung Lee and Kazuhiko Minematsu},
      title = {XOCB: Beyond-Birthday-Bound Secure Authenticated Encryption Mode with Rate-One Computation (Full Version)},
      howpublished = {Cryptology ePrint Archive, Paper 2023/253},
      year = {2023},
      note = {\url{}},
      url = {}
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