Transformations An enciphering transformation (also called an enciphering function)is a bijective function Ee:M→e, where the key eE K uniquely determines Ee acting upon plaintert message units m E M to get ciphertert message units Ee(m)=c∈C. A deciphering transformation (or deciphering function)is a bijective function Da:CM, which is uniquely determined by a given key d E K,acting upon ciphertert message units c Ee to get plaintert message units Da(c）=m. The application of Ee to m,namely the operation Ee(m),is called enciphering, encoding,or encrypting m EM,whereas the application of Da to c is called deciphering,decoding,or decrypting ceC.Transformations