Steganofy

DEPRECATED: this project is inactive and will be deleted in the future.

A simple, fast and open source image steganography app for Android.

Features

• Hide data into images
• Reveal data from of images
• Plain text and files support
• AES-256 encryption (optional)
• Light and dark mode

     

     

Byte Layout

The data to be hidden is written per bit in the pixels of the image. The two least significant bits of an image byte are replaced with the bits of the data to be hidden. This way the image is not noticeably changed. To hide one byte of data, 4 bytes of image data is required:

Data format

The hidden data has the following format:

<Version><Type><Encryption algorithm><Payload length><Payload>

Field	Field length	Description
Version	1 Byte	The file format version identifier
Type	4 Bits	Type of the payload
Encryption algorithm	4 Bits	Identifier of the encryption algorithm used for payload encryption
Payload length	4 Bytes	Length of the payload in bytes
Payload	n Bytes	Payload depending on type

Data Types

Type	Description
1	Plaintext
2	File

Encryption algorithms

Identifier	Description
0	No encryption
1	AES-256

AES-256

Payload encryption using AES/GCM/NoPadding with PBKDF2WithHmacSHA256. A random salt and IV is generated upon encryption and added as prefix to the ciphertext. Using this type of payload encryption will increase the size of the payload:

<IV><Salt><Ciphertext>

Field	Field length	Description
IV	12 Bytes	The initialization vector used for GCM
Salt	16 Bytes	Salt used for PBKDF2
Cipher text	n Bytes	Encrypted ciphertext

Payload

Plaintext

The bytes of the plaintext are used as payload.

File

File payloads have the following format:

<File mime type length><File mime type><File content>

Field	Field length	Description
File mime type length	4 Bytes	Length of the file mimie type in bytes
File mime type	n Bytes	File mime type (i.e. "image/jpeg")
File content	File extension length - payload length	Remaining bytes of payload

Contact

If you want to get in contact, contribute to the project or have any questions, feel free to contact me at:

[email protected]

-Markus Staudt

License

Apache License
Version 2.0, January 2004
http://www.apache.org/licenses/