International Association
for Cryptologic Research

Grain-128AEAD is one of the second-round candidates of the NIST lightweight cryptography standardization process. There is an existing body of third-party analysis on the earlier versions of the Grain family that provide insights on the security of Grain-128AEAD. Different from the earlier versions, Grain-128AEAD reintroduces the key into the internal state during the initialization. The designers claim that internal state recovery no longer results in key recovery, due to this change. In this paper, we analyze this claim under different scenarios.