A decipher key based decipher with at least a portion of the decipher key dissolved into the decipher is disclosed. The decipher includes in-line instructions specifically designed to incrementally contribute to computation of M.sup.e Mod n, where e is a predetermined at least partially unique decipher key. In one embodiment, the decipher includes a first in-line instruction to set an output variable to equal to 1, and a second in-line instruction to set the output variable to equal to the square of the output variable modulus n. In another embodiment, the decipher includes in-line instructions that perform the incremental computation in accordance with an addition chain of e.