Weakness of lightweight block ciphers mCrypton and LED against biclique cryptanalysis

In this paper, we evaluate the security of lightweight block ciphers mCrypton and LED against biclique cryptanalysis. In cases of mCryton-64/96/128, our attacks require computational complexities of $2^{63.18}, 2^{94.81}$ and $2^{126.56}$, respectively. These results are the first known biclique cryptanalytic results on mCrypton. The attack on a 29-round reduced LED-64 needs $2^{63.58}$ 29-round reduced LED-64 encryptions. In the cases of LED-80/96/128, we propose the attacks on two versions. First, to recover the secret key of 45-round reduced LED-80/96/128, our attacks require computational complexities of $2^{79.45}, 2^{95.45}$ and $2^{127.45}$, respectively. To attack the full version, we require computational complexities of $2^{79.37}, 2^{95.37}$ and $2^{127.37}$, respectively. However, in these cases, we need the full codebook. These results are superior to known biclique cryptanalytic results on LED.