A note on quantum related-key attacks

  • Martin Roetteler ,
  • Rainer Steinwandt

MSR-TR-2014-130 |

also posted as arxiv:1306.2301

Publication

In a basic related-key attack against a block cipher, the adversary has access to encryptions under keys that differ from the target key by bit-flips. In this short note we show that for a quantum adversary such attacks are quite powerful: if the secret key is (i) uniquely determined by a small number of plaintext-ciphertext pairs, (ii) the block cipher can be evaluated efficiently, and (iii) a superposition of related keys can be queried, then the key can be extracted efficiently.