Paper 2020/1019

Security of Streaming Encryption in Google's Tink Library

Viet Tung Hoang and Yaobin Shen


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).

Available format(s)
Secret-key cryptography
Publication info
Published elsewhere. Minor revision. ACM CCS 2020
Online AEstreaming encryptionGoogle's Tink library
Contact author(s)
tvhoang @ cs fsu edu
2020-08-27: received
Short URL
Creative Commons Attribution


      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{}},
      url = {}
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