The main goal of this project is to provide a method of correct design of digital circuit. It combines the advantages of VHDL, the well-known language of circuit design, with the power of B method that guarantees the correct design (w.r.t. a formal specification). This allows avoiding the design test since it is "correct by proven construction". Furthermore, this project provides a tool, called BHDL, with a graphical interface for creating, editing, viewing and proving modular hardware architectures.