Crate pnger 

PNGer - PNG Steganography Library

PNGer is a Rust library for embedding and extracting payloads within PNG images using steganography techniques. It provides both file-based and memory-based APIs for flexibility, with support for various embedding strategies and payload obfuscation methods.

Key Features

• Embedding Strategies: For now, only LSB (Least Significant Bit) strategy is supported with linear and random patterns
• Payload Obfuscation: XOR encryption for additional security
• Cross-platform: Compatible across different architectures
• Password Protection: Derive embedding patterns from passwords

Quick Start

Basic embedding and extraction from files

use pnger::{embed_payload_from_file, extract_payload_from_file};

// Embed a payload
let payload = b"this is a payload";
let png_with_payload = embed_payload_from_file("image.png", payload)?;
std::fs::write("output.png", png_with_payload)?;

// Extract the payload
let extracted_payload = extract_payload_from_file("output.png")?;
assert_eq!(extracted_payload, payload);

Basic embedding and extraction from bytes

use pnger::{embed_payload_from_bytes, extract_payload_from_bytes};

// Embed a payload
let payload = b"this is a payload";
let png_bytes = [137u8, 80u8, 78u8, 71u8, 13u8, 10u8, 26u8, 10u8, /* ... */];
let png_with_payload = embed_payload_from_bytes(&png_bytes, payload)?;

// Extract the payload
let extracted_payload = extract_payload_from_bytes(&png_with_payload)?;
assert_eq!(&extracted_payload, payload);

Advanced Usage with Options

use pnger::{embed_payload_from_file_with_options, EmbeddingOptions, Strategy};
use pnger::strategy::lsb::{LSBConfig, BitIndex};
use pnger::Obfuscation;

// Configure random pattern with password protection and XOR obfuscation
let strategy = Strategy::LSB(
    LSBConfig::random()
        .with_password("my_secret_password".to_string())
        .with_bit_index(BitIndex::Bit1)
);
let options = EmbeddingOptions::new_with_obfuscation(
    strategy,
    Obfuscation::Xor { key: b"encryption_key".to_vec() }
);

let payload = b"highly secure secret message";
let result = embed_payload_from_file_with_options("image.png", payload, options)?;

Fluent Builder API

The fluent builder API provides an ergonomic way to configure embedding options:

use pnger::{embed_payload_from_file_with_options, EmbeddingOptions};
use pnger::strategy::lsb::BitIndex;

// Simple linear embedding with XOR encryption
let options = EmbeddingOptions::linear()
    .with_xor_string("my_encryption_key");

// Random embedding with password and custom bit index
let options = EmbeddingOptions::random_with_password("secure_password")
    .with_bit_index(BitIndex::Bit2)
    .with_xor_key(b"additional_layer".to_vec());

// Conditional configuration
let password = Some("secret".to_string());
let options = EmbeddingOptions::random()
    .with_password_if_some(password)
    .with_xor_string("encryption_key");

let payload = b"fluent API example";
let result = embed_payload_from_file_with_options("image.png", payload, options)?;

Embedding Strategies

LSB (Least Significant Bit)

The primary embedding strategy modifies the least significant bits of image pixels:

• Linear Pattern: Sequential pixel modification (faster, less secure)
• Random Pattern: Pseudo-random pixel selection (slower, more secure)
• Password Protection: Derive random patterns from passwords
• Bit Index Selection: Choose which bit position to modify (0-7)

Considerations

• Capacity: 1 byte requires 8 pixels (1 bit per pixel for LSB)
• Random Patterns: Slightly slower due to PRNG operations

Error Handling

All functions return Result<T, PngerError> with comprehensive error types:

• Capacity Errors: Payload too large for image
• I/O Errors: File system or PNG format issues
• Crypto Errors: Random number generation or password derivation failures
• Format Errors: Invalid PNG structure or corrupted data

Re-exports

pub use crate::obfuscation::Obfuscation;

pub use crate::strategy::Strategy;

pub use error::PngerError;

Modules

error

Error types for PNGer Steganography Operations

obfuscation

Payload Obfuscation for Enhanced Security

strategy

Steganography strategy configuration for payload embedding.

Structs

EmbeddingOptions

Configuration options for payload embedding and extraction operations.

Functions

embed_payload_from_bytes

Embeds a payload into PNG data in memory using the default embedding strategy.

embed_payload_from_bytes_with_options

Embeds a payload into PNG data using custom embedding options.

embed_payload_from_file

Embeds a payload into a PNG file using the default embedding strategy.

embed_payload_from_file_with_options

Embeds a payload into a PNG file using custom embedding options.

extract_payload_from_bytes

Extracts a payload from PNG data in memory using the default embedding strategy.

extract_payload_from_bytes_with_options

Extracts a payload from PNG data using custom embedding options.

extract_payload_from_file

Extracts a payload from a PNG file using the default embedding strategy.

extract_payload_from_file_with_options

Extracts a payload from a PNG file using custom embedding options.