The development of technology in the field of telecommunications makes people more and more often send data files in the form of doc, pdf, xls, voice, image, video via the internet. because the internet is a public medium that is vulnerable to intrusion and theft of information on data or files by unauthorized parties. The problem is that there are frequent changes or manipulation of the contents of data files from bank notes processing, cash pickups, document pick-ups, clearing items, atm & cdm service, atm cash replenishment, atm first line maintenance and atm second line maintenance. The purpose of this study is to prevent irresponsible people from knowing the reports that will be sent from the branch to the center by made applying the twofish cryptographic algorithm application to secure file data. The results of the tests carried out were 15 encrypted files, the average encrypted file size was 0.11%, the encryption process time was 9.5352 milliseconds and the decryption process time was 9.3294 milliseconds. In the UAT test, a questionnaire with a Likert scale scale of 5. has been used. As a result, the respondents agree (above 91.23%) that the overall application of the twofish algorithm to secure data files can be kept confidential.