Security of Streaming Encryption in Google's Tink Library

Viet Tung Hoang; Yaobin Shen

Paper 2020/1019

Security of Streaming Encryption in Google's Tink Library

Viet Tung Hoang and Yaobin Shen

Abstract

We analyze the multi-user security of the streaming encryption in Google's Tink library via an extended version of the framework of nonce-based online authenticated encryption of Hoang et al. (CRYPTO'15) to support random-access decryption. We show that Tink's design choice of using random nonces and a nonce-based key-derivation function indeed improves the concrete security bound. We then give two better alternatives that are more robust against randomness failure. In addition, we show how to efficiently instantiate the key-derivation function via AES, instead of relying on HMAC-SHA256 like the current design in Tink. To accomplish this we give a multi-user analysis of the XOR-of-permutation construction of Bellare, Krovetz, and Rogaway (EUROCRYPT'98).

Metadata

Available format(s): PDF
Category: Secret-key cryptography
Publication info: Published elsewhere. MINOR revision.ACM CCS 2020
Keywords: Online AE streaming encryption Google's Tink library
Contact author(s): tvhoang @ cs fsu edu
History: 2020-08-27: received
Short URL: https://ia.cr/2020/1019
License: CC BY

BibTeX

@misc{cryptoeprint:2020/1019,
      author = {Viet Tung Hoang and Yaobin Shen},
      title = {Security of Streaming Encryption in Google's Tink Library},
      howpublished = {Cryptology ePrint Archive, Paper 2020/1019},
      year = {2020},
      note = {\url{https://eprint.iacr.org/2020/1019}},
      url = {https://eprint.iacr.org/2020/1019}
}