def signature_hash_unsafe(m, sk, pk)
        h = HH(sk)
        a = 2**(@@b - 2) + (3...@@b - 2).inject(0) { |sum, i| sum + 2**i * bit(h, i) }
        r = Hint_hash(
          intlist2bytes((@@b / 8...@@b / 4).map { |j| indexbytes(h, j) }) + m