Affine Cipher is a kind of substitution cipher where in each letter in the plaintext is first mapped to its numeric equivalent, then encrypted using a mathematical function and is decrypted back. From analysis, it is found that Affine Cipher is restricted to messages containing only 26 English alphabets. It has a limitation that it cannot consider all ASCII (128 ASCII + 128 Extended ASCII) characters. As messages that we wish to communicate may contain any combinations of alphabets, numbers and special symbols, it is essential that the existing technique be enhanced. This paper proposes an enhanced Affine Cipher that considers all 256 ASCII characters. © Research India Publications.