Thursday, April 14, 2011

Online AES-256 file and text crypter, at client side in javascript

Direct URL

A simple file and text encrypter using AES-256 implemented in javascript. The cypher implementation is from HERE.

If your browser supports HTML5 file-api you can encrypt/decrypt local files without uploading to a server.

The upper Encrypt/Decrypt buttons are for file encryption. The file size is limited to a few megabytes because of the data-URL saving. The file is read directly with the FileAPI. The encrypted file is padded up to a multiple of 16 bytes, but the original file size is saved in the first 4 bytes, so at decryption will be truncated to the original size.

The lower buttons are for text encryption/decryption. The action is applied to the upper text box. The encrypted text is displayed in hexadecimal. The same format must be used for decryption. The text is padded with spaces up to a multiple of 16 characters.

The password (key) is padded with zeros up to 32 bytes.

Direct URL


  1. hi!
    good job on the application. :)
    im doing my final year project for university and still learning about the AES.

    can you explain more about encryption with a file like you has there in your application. i mean what type of file it can be encrypt with?

    thank :)

    sorry, my english is weak :P

  2. Hi Amiriz,

    Any file can be encoded, the size limit is because the saving of the file. In order to save data directly from JavaScript I used Data URI.

  3. thanks for the information :)

  4. Lazer Laszlo please contact me on , i really need your help to open password protected .docx file .

  5. hi Lazar

    i am sorry to disturbe you but i have a little problem and your solution above there is exactle what i am looking for. if it would be no inconvinienc for you could you share your source with me

    would be a great help thx in advance. you can conntact me under

    thx man