tss-lib leaks secret keys in response to incorrectly constructed Paillier moduli - The specification of the GG18 threshold ECDSA signature protocol contains a vulnerability allowing an attacker to recover the shared secret key. If a participant generates a Paillier modulus N containing small factors (less than 2^100) they can interact with other participants in the signing protocol to steal their secret key shares in as little as sixteen signing attempts. The master key can then be reconstructed from these shares.