Unable to decrypt the data from encrypted pdf file

Hi, I have a requirement to store data in encrypted format in pdf. I am using utils bas 64 encode. I am able to do it. When I try to get the data from the pdf unable to get it in nadir phones.

To write into Pdf I am using the below code

var f = Ti.Filesystem.getFile(Ti.Filesystem.tempDirectory, '.data.pdf'); var encodeData = Ti.Utils.base64encode(this.responseData); f.write(encodeData);

To get Data from the PDF

var f = Ti.Filesystem.getFile(Ti.Filesystem.tempDirectory, '.data.pdf'); var decodedData = Ti.Utils.base64decode(f.read().text);

decodedData is returning NULL.