Oblivious transfer (OT)

A functionality in which a sender provides 2 inputs {$m_0, m_1$} (typically strings or single bits), and a receiver provides an input {$b \in \{0,1\}$}. The sender receives no output (hence does not learn {$b$}), while the receiver learns {$m_b$} (hence does not learn {$m_{1-b}$}).