# Why do we use addition and multiplication in GMW protocol

I don't understand why the protocol evaluates the addition and the multiplication ?

Why not just the multiplication ?

I didn't find any information about the OT used in this protocol. Is this a basic one like Rabin's or not ?

In GMW, a 1-out-of-4 OT is used to evaluate the AND gates (as I said above, XOR gates only require local computation - i.e., XORing the corresponding shares). This is the standard OT, i.e., not Rabin OT: the sender has 4 messages $$(m_i)_{i\leq 4}$$, and the receiver with input $$j \in \{1,2,3,4\}$$ learns $$m_j$$ without learning anything else; $$j$$ remains hidden to the sender.