Introduction A $(t-n)$ threshold signature protocol allows distributed signing among $n$ participants such that any group of $t+1$ participants can produce a valid signature, while any group of fewer that $t$ participants cannot. A threshold signature consists of two protocols KeyGen, Sign and an algorithm Verify as follow: Keygen: This is an interactive protocol between $n$ participants $P_1,P_2,\dots,P_N$. If the interaction suceeds, each participant $P_i$ receives a secret key $sk_i$. In addition, all participants output a common public key $pk$. Gennaro's Protocol Introduction In this section we briefly describe the threshold ECDSA protocol of Gennaro etal in. This is the protocol that provide the best security and efficiency so far. As the title suggest, the protocol provide the following features: