A state recovery attack on ACORN-v1 and ACORN-v2

Abstract

We propose a state recovery attack on full round of initial two versions of stream cipher ACORN with 2120 complexity. It is possible to recover the full state of the 39-th clocking of encryption phase of ACORN using our technique. In this method one needs to inject 326 faults and 10 known plaintext bits. To the best of our knowledge this is the first work which breaks ACORN-v1 and ACORN-v2 by using a practical attack model with a complexity lesser than the complexity of exhaustive search on secret key of 128 bits.