/png-decoder-rs

Primary LanguageRust

png-decoder-rs

A PNG image encoder/decoder used to hide messages in PNG images.

  1. Usage Instructions
  2. Example Usage
  3. Build Instructions

Usage Instructions

The executable this project produces has the capability to...

  • encode a secret message within a PNG image using a secret chunk type code
  • decode all secret messages within a PNG image using a secret chunk type code
  • remove all secret messages within a PNG image that use some secret chunk type code
  • print each chunk within a PNG image

These functionalities correspond to the encode, decode, remove, and print subcommands, respectively. The following blocks indicate how to use each subcommand.

Encode:

USAGE:
    ./png encode <PATH> <CHUNK_TYPE> <MESSAGE>

ARGS:
    <PATH>          The path to the PNG image to encode a message within
    <CHUNK_TYPE>    The 4-byte chunk type code to use to add messages under
    <MESSAGE>       The message to encode

OPTIONS:
    -h, --help    Print help information

Decode:

USAGE:
    ./png decode <PATH> <CHUNK_TYPE>

ARGS:
    <PATH>          The path to the PNG image to decode messages from
    <CHUNK_TYPE>    The 4-byte chunk type code to use to search for messages to decode

OPTIONS:
    -h, --help    Print help information

Remove:

USAGE:
    ./png remove <PATH> <CHUNK_TYPE>

ARGS:
    <PATH>          The path to the PNG image to remove encoded messages from
    <CHUNK_TYPE>    The 4-byte chunk type code to use to search for messages to remove

OPTIONS:
    -h, --help    Print help information

Print:

USAGE:
    ./png print <PATH>

ARGS:
    <PATH>    The path to the PNG image to print chunks for

OPTIONS:
    -h, --help    Print help information

Example Usage

$ ./png decode images/dice.png ruSt
$ ./png encode images/dice.png ruSt 'This is a secret message.'
$ ./png decode images/dice.png ruSt                            
This is a secret message.
$ ./png print images/dice.png                                  
Chunk {
  Length: 13
  Type: IHDR
  Data: 13 bytes
  Crc: 804134823
}

...

Chunk {
  Length: 25
  Type: ruSt
  Data: 25 bytes
  Crc: 3261152786
}

Chunk {
  Length: 0
  Type: IEND
  Data: 0 bytes
  Crc: 2923585666
}

$ ./png remove images/dice.png ruSt                            
$ ./png decode images/dice.png ruSt
$

Build Instructions

  1. Clone this repository
  2. Ensure Rust (and Cargo) are installed in your environment
  3. Build the executable. A Makefile has been provided for your convenience.
git clone https://github.com/nkaush/png-decoder-rs.git
make

The following instructions will generate an executable called ./png which you can use as shown in the sections above.