A Formal Treatment of Envelope Encryption

Shoichi Hirose; Kazuhiko Minematsu

Paper 2023/1727

A Formal Treatment of Envelope Encryption

Shoichi Hirose

, University of Fukui

Kazuhiko Minematsu

, NEC (Japan), Yokohama National University

Abstract

Envelope encryption is a method to encrypt data with two distinct keys in its basic form. Data is first encrypted with a data-encryption key, and then the data-encryption key is encrypted with a key-encryption key. Despite its deployment in major cloud services, as far as we know, envelope encryption has not received any formal treatment. To address this issue, we first formalize the syntax and security requirements of envelope encryption in the symmetric-key setting. Then, we show that it can be constructed by combining encryptment and authenticated encryption with associated data (AEAD). Encryptment is one-time AEAD satisfying that a small part of a ciphertext works as a commitment to the corresponding secret key, message, and associated data. Finally, we show that the security of the generic construction is reduced to the security of the underlying encryptment and AEAD.

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: Preprint.
Keywords: Authenticated encryption Key wrap Key-committing Encryptment
Contact author(s): hrs_shch @ u-fukui ac jp
k-minematsu @ nec com
History: 2023-11-13: approved; 2023-11-08: received; See all versions
Short URL: https://ia.cr/2023/1727
License: CC BY

BibTeX

@misc{cryptoeprint:2023/1727,
      author = {Shoichi Hirose and Kazuhiko Minematsu},
      title = {A Formal Treatment of Envelope Encryption},
      howpublished = {Cryptology {ePrint} Archive, Paper 2023/1727},
      year = {2023},
      url = {https://eprint.iacr.org/2023/1727}
}