If you place the application in the public domain, you can decode it and understand the algorithm of operation. But the result of the application (an array of numbers) very much depends on the input source text. However, you can add some algorithms and input data to the generator, which will further change the resulting array. How spices change the taste of soup.
Because the sender will have to enter additional data, this will increase the complexity of use and increase labor intensity. But it will also improve data protection. There are so many to choose from.
If your application copies (for the sender and recipient) are made under an individual contract (custom), then data protection will be significantly higher.