Information tapping can occur when there is a transfer process of information by e-mail. Encoding process is needed to prevent information tapping, because this process can improve information security. Cryptography provides some services that are supportive to increase information security, such as authentication, non-repudiation, and confidentiality. This research is focused on protecting the information (confidentiality) with encoding process and preventing negation by the information sender (non-repudiation) using digital signature process.