In the paper Biased Nonce Sense: Lattice Attacks against Weak ECDSA Signatures in Cryptocurrencies on section 5.2 Cryptanalytic tests for biased nonces, one of test is:
- Select two signatures at random and check for nonces of length less than 128 bits. We repeated this test ...
My question is how this can be done? Mean from one valid signature how can we check bits length of nonce used?