This research is intended to help protect the contents of messages or data and confidential information. RSA (Rivest Shamir Adleman) is one of the cryptographic algorithm is good enough, because of the difficulty of factoring large numbers into prime factors. RSA applications are developed in accordance with the needs of today's simple and efficient. This application involves development platform in VB 6.0. Analysis and application requirements for users will be developed by the Water Fall method with the modeling language UML (Unified Modeling Language) so that this application may provide features encryption, and decryption. The results of this research is to protect a message by changing the original message into a secret code in the form of numbers and can change back into the original message
