Real Time Related Key Attack on Hummingbird-2
Kai Zhang · KSII Transactions on Internet and Information Systems · 2012
Hummingbird is a lightweight encryption and message authentication primitive published in RISC'09 and WLC'10.In FSE'11, Markku-Juhani O.Saarinen presented a differential divide-and-conquer method which has complexity upper bounded by 2 64 operations and requires processing of few megabytes of chosen messages under two related nonces (IVs).The improved version, Hummingbird-2, was presented in RFIDSec 2011.Based on the idea of differential collision, this paper discovers some weaknesses of the round function WD16.Combining with the simple key loading algorithm, a related-key chosen-IV attack which can recover the full secret key is proposed.Under 15 pairs of related keys, the 128 bit initial key can be recovered, requiring 2 27 chosen IV and the computational complexity is O(2 27 ).In average, the attack needs several minutes to recover the full 128-bit secret key on a PC.The experimental result corroborates our attack.The result shows that the Hummingbird-2 cipher can't resist related key attack.