File Encryptor

This app can be used for encrypting your files using Advanced Encryption Standard (AES) with 256 bit key. It can encrypt/ decrypt files using AES. This app ONLY REQUIRES PERMISSION to WRITE SD CARD and NOTHING MORE, so you can be sure ,that your DATA IS SAFE. It is COMPLETELY FREE OF ADVERTISEMENTS. You can be sure that the app does what it promises . The crack resistitvity of an AES depends on the password length and complexity. The app warns if the user does not selects a password with min 6 characters having atleast one uppercase letter, one lower case, one special character and one digit.

File Encryptor is a file Encryption application that allows you to protect your image,doc,xls etc data files. It allows you to encrypt/decrypt files using Advance Encryption Standard(AES) with a 256 bit (key length).

The system computes the 256 bit key from the password string using SHA-256. The system uses Cipher Block Chaining method (CBC) to encrypt the data in blocks of 128 bits. Block cipher modes for symmetric-key encryption algorithms require plain text input that is a multiple of the block size (ie 128 bits for AES), so messages may have to be padded to bring them to this length. The padding being used is PKCS5Padding. In CBC Explicit Initialization Vectors technique is being used wherein we prepend a single random block to the plaintext. Encryption is done as normal, except the IV does not need to be communicated to the decryption routine. Whatever IV decryption uses, only the random block is "corrupted". This block is discarded and the rest of the decryption is the original plaintext.

Electronic Codebook(ECB) block cipher method option has also been given to be compatible with legacy version of the app. In ECB the message is divided into blocks, and each block is encrypted separately.The disadvantage of this method is that identical plaintext blocks are encrypted into identical ciphertext blocks; thus, it must not be used with a non-random and repetitive data. The ECB mode is deterministic. ECB option is only for academic purpose and backward compatibility.

You can use it to encrypt files before putting them on online locations (cloud storage, Google Drive, Skydrive, Box, Dropbox, Gmail, etc.) or to store encrypted sensitive files on your Android phone so that they are unreadable to those who don't know your password.

Features
• AES encryption format.
• File encryption and decryption.
• Secure erase of original files after encryption or decryption ( will be build in future versions).
• Internal file browser for selecting.
• Send/share functionality for Google Drive, SkyDrive, Box, Dropbox, Gmail, Bluetooth etc.
• Encrypt your files before putting them in the cloud storage (Google Drive, SkyDrive, Box, Dropbox etc.)
• Password can be up to 40 characters (minimum 6 and recommended at least 12 characters or more)
• Encrypted files have .aes_ extension.
• Files after encryption/decryption go to the same folder.

Incase of any issues, feel free to write to me at
manindersinghgill@gmail.com

PS
Some good links to learn cryptography process being used in the app are as under
AES
https://www.youtube.com/watch?v=nL1ApwEXrz0
https://www.youtube.com/watch?v=ayiOhApI6SM

Block Ciphers, Why not use ECB?
https://www.youtube.com/watch?v=t0pREiDO7_g
https://en.wikipedia.org/wiki/Block_cipher

UTF-8
https://www.youtube.com/watch?v=vLBtrd9Ar28