MPDX: An HTML Encryptor-Decryptor


Transferring data from one location to another is conveniently made possible by the Internet. However, the Internet’s overwhelming capabilities are accompanied by a questionable computer security. This study was conducted to address this problem by means of developing software that can protect transferred files over the Internet.

The development of software (coined MPDX) was based on the paradigm Fourth-Generation Technique. The first stage was devoted to gathering for computer specications that would support the development of the MPDX software. The second stage was developing the design, which involved the development of hierarchical input process output, flowcharts pseudocodes pertaining to the logic, and menu layout of the MPDX software. The third stage was the coding, wherein design was transferred to machine code using the programming language Visual Basic 6.0. The final stage was the testing, wherein MPDX software was exposed to possible beneficiaries for evaluation.

The results prove that MPDX software is effective and agreeable to the user based on the following criteria: user-friendliness, eficiency, and security.


Millions of ordinary citizens are using the electronic mail (email) to conduct business or send confidential letters. email, as its many users know, has been around for over two decades. The first email system simply consisted of file transfer protocols, with the convention that the first line of each message contains the recipient’s address. As time went by, the limitations of this approach became more obvious.

The present e-mail systems support two protocols for transferring messages from sender to recipient and vice versa. Within the Internet, email is delivered by having the source machine establish a TCP (transmission control protocol) connection to destination machine. Listening to this port is an e-mail daemon, a system program that speaks SMTP (simple mail transfer protocol). This daemon accepts incoming connections and copies messages from them into the appropriate mailboxes.

Materials & Equipment

Selected References:

Lapin, Lawrence L. 1990. Statistics for Modern Business Decisions. 5th ed. Florida, USA: Harcourt Brace Jovanovich, Publishers. Jamsa, Kris and Klander Lars. 1997. 1001 Visual Basic TIPS. Nevada, USA: Prentice-Hall, PTR, Inc. Davis, Alan M. 1995. 201 Principles of Software Development. New York, USA: McGraw-Hill, Inc. Alter mail, Jose Rhoniel P. Espiritu, AMACC Makati, 1999, unpublished. Cipher Lock, Frederick Vincent Tan, AMACC Makati, 1996, unpublished. Oliva, Erwin Lemuel. Computer firms say security is a necessary investment, Press Release,, March 20, 2002.

Further clarification of the procedures and results should be directed to the researchers and adviser.

Melvin P. De Guzman

Johnny E. de Leon
Juan R. Liwag Memorial High School
Gapan City

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