There are many Crypto-system are define in today’s world. There are some private key and public key Crypto-system. These Crypto-systems are all mathematical calculations So, each can be broken by computation machine. Computer can check all the possibilities of keys, a Crypto-system have in minutes or hours of time which depends on the speed of the computer and computation power. Computer applies keys to a cipher text and then checks the string matching with a dictionary. There are many techniques which are being used to increase the key space and secrecy of the Crypto-system but still the computer can find the solution by applying all possible combinations. Reverse String Cipher is a modification in all cipher techniques to increase the security. General Terms Reverse String, Modern Cipher.