The researcher has recently been working on the authenticity of information particularly with the use of cryptographic hash functions such as MD5 and Secure Hash Algorithm (SHA). After critically analyzing the Hash-based Message Authentication Code (HMAC) algorithm, the researcher finds out that it can still be improved and strengthened by adding the T9 conversion, which also adds more complexity and security to the system. T9 keypad-based conversion is used in converting the data and this pre-converted data would then pass through the process of encryption using HMAC encryption algorithm. This work focuses on following the cryptosystem design, and includes the study of the activity process and procedures, as well as the method of the proposed system. Cryptography key, plaintext, message security, cipher, message authentication code, and hash function are the major activities that go with the cryptosystems. The study uses the incremental model approach to generate and illustrate the system functions and architecture of this project. The resulting system is a new algorithm developed using hypertext preprocessor (PHP) in a form of Library PHP file by the researcher for securing the integrity and authenticity of the data. It provides high security of text data with the use of authentication process integrated with the new researcher-developed T9 encryption decryption process.