Further Cryptanalysis of a CRT-RSA Algorithm at CCS 2003

At CCS 2003, Blomer, Otto, and Seifert proposed a new CRT-RSA signature algorithm, which was claimed to be secure against hardware fault attack. Unfortunately, one year later, Wagner presented a simple and practical fault attack on the so-called BOS algorithm. In this paper, we give a further cryptanalysis of the BOS algorithm and can completely break the security of it with a probability at least 25%. Compared to Wagner´s attack, the new attack is much simpler and requires fewer faulty signatures. We further conclude that the BOS algorithm is not safe for use in its present form.