Smarty thinks that he can improve the security of affine cip

Smarty thinks that he can improve the security of affine ciphers by iteration. He performs one affine cipher and then feeds the result into another one. Is he correct? Justify your answer with clear reasoning.

Solution

An encipherment scheme (or algorithm) of the form E(x) = (ax + b) MOD 26 is called an affine cipher.

The function E(x) = (ax + b) MOD 26 defines a valid affine cipher if a is relatively prime to 26, and b is an integer between 0 and 25, inclusive.

Smarty is not correct if both the affine ciphers are modulo 26.