Steganography in Rust hiding secrets in images Sven Assmann @5422m4n /sassman 

I do lot of business application development with web technologies and big databases Sometimes I also write about learning rust Hi, I’m Sven @5422m4n /sassman 

tweeting coding writing @5422m4n /sassman twitter.com/@5422m4n github.com/sassman dev.to/sassman 

What is Steganography? in bloomy words: “the art of hiding information behind something” speaking more tech: “hiding data in image, audio or video data” @5422m4n /sassman 

Cryptography vs Steganography hiding information nobody should know Alice and Bob are communicating protects the sender and recipient inaccessible information anyone can know Alice and Bob are communicating protects the message Steganography can be combined with Cryptography @5422m4n /sassman 

About Images width height Pixel @5422m4n /sassman 

About Pixel Pixel Red Green Blue Transparency / Alpha @5422m4n /sassman 

About Colors R: 0xE7 G: 0xA6 B: 0x29 R: 0xE6 G: 0xA7 B: 0x28 Can you tell the difference? @5422m4n /sassman 

Least Significant Bit (LSB) R: 0xE7 G: 0xA6 B: 0x29 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 0xE6 G: 0xA7 B: 0x28 R: 1110 0110 G: 1010 0111 B: 0010 1000 1 bit 1 bit 1 bit - + - @5422m4n /sassman 

About Data R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 @5422m4n /sassman 

About Data R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 @5422m4n /sassman 

About Data R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 @5422m4n /sassman 

About Data R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 @5422m4n /sassman 

About Data R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 @5422m4n /sassman 

About Data R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1001 @5422m4n /sassman 

About Data R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0110 G: 1010 0111 B: 0010 1001 @5422m4n /sassman 

About Data R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0110 B: 0010 1001 R: 1110 0110 G: 1010 0111 B: 0010 1001 @5422m4n /sassman 

About Data R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0111 B: 0010 1001 @5422m4n /sassman 

R: 1110 0110 G: 1010 0110 B: 0010 1000 What about the end of data? How do we end the message? R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0111 B: 0010 1001 R: 1110 0110 G: 1010 0110 B: 0010 1000 @5422m4n /sassman 

R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0111 B: 0010 1000 What about the end of data? R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0110 G: 1010 0110 B: 0010 1000 “Zero out” the LSB for all Pixel Terminate the “Payload” with a marker byte sequence (like zip) Put the size of “Payload” at first (like UDP packages) R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0111 B: 0010 1001 R: 1110 0110 G: 1010 0110 B: 0010 1000 @5422m4n /sassman 

R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0111 B: 0010 1000 What about the end of data? R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0110 G: 1010 0110 B: 0010 1000 “Zero out” the LSB for all Pixel Terminate the “Payload” with a marker byte sequence (like zip) Put the size of “Payload” at first (like UDP packages) R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1000 R: 1110 0111 G: 1010 0110 B: 0010 1001 R: 1110 0110 G: 1010 0110 B: 0010 1000 R: 1110 0110 G: 1010 0111 B: 0010 1001 R: 1110 0110 G: 1010 0110 B: 0010 1000 @5422m4n /sassman 

Architecture @5422m4n /sassman 

Finally Code @5422m4n /sassman 

use stegano_core::{SteganoCore, SteganoEncoder, SteganoDecoder, Hide, Unveil}; #[test] fn should_hide_and_unveil_one_text_file() -> Result<()> { SteganoCore::encoder() .hide_file("Cargo.toml") .use_carrier_image("resources/plain/carrier-image.png") .write_to("/tmp/image-with-a-file-inside.png") .hide(); SteganoCore::decoder() .use_source_image("/tmp/image-with-a-file-inside.png") .write_to_folder("/tmp/") .unveil(); assert_eq_file_content( "/tmp/Cargo.toml".as_ref(), "Cargo.toml".as_ref(), "Unveiled data did not match the original content”, ); Ok(()) } @5422m4n /sassman 

use stegano_core::{SteganoCore, SteganoEncoder, SteganoDecoder, Hide, Unveil}; #[test] fn should_hide_and_unveil_one_text_file() -> Result<()> { SteganoCore::encoder() .hide_file("Cargo.toml") .use_carrier_image("resources/plain/carrier-image.png") .write_to("/tmp/image-with-a-file-inside.png") .hide(); SteganoCore::decoder() .use_source_image("/tmp/image-with-a-file-inside.png") .write_to_folder("/tmp/") .unveil(); assert_eq_file_content( "/tmp/Cargo.toml".as_ref(), "Cargo.toml".as_ref(), "Unveiled data did not match the original content”, ); Ok(()) } pub struct SteganoEncoder { target: Option, carrier: Option, message: Message, } @5422m4n /sassman 

use stegano_core::{SteganoCore, SteganoEncoder, SteganoDecoder, Hide, Unveil}; #[test] fn should_hide_and_unveil_one_text_file() -> Result<()> { SteganoCore::encoder() .hide_file("Cargo.toml") .use_carrier_image("resources/plain/carrier-image.png") .write_to("/tmp/image-with-a-file-inside.png") .hide(); SteganoCore::decoder() .use_source_image("/tmp/image-with-a-file-inside.png") .write_to_folder("/tmp/") .unveil(); assert_eq_file_content( "/tmp/Cargo.toml".as_ref(), "Cargo.toml".as_ref(), "Unveiled data did not match the original content”, ); Ok(()) } pub struct SteganoEncoder { target: Option, carrier: Option, message: Message, } pub struct SteganoDecoder { input: Option, output: Option, } @5422m4n /sassman 

use stegano_core::{SteganoCore, SteganoEncoder, SteganoDecoder, Hide, Unveil}; #[test] fn should_hide_and_unveil_one_text_file() -> Result<()> { SteganoCore::encoder() .hide_file("Cargo.toml") .use_carrier_image("resources/plain/carrier-image.png") .write_to("/tmp/image-with-a-file-inside.png") .hide(); SteganoCore::decoder() .use_source_image("/tmp/image-with-a-file-inside.png") .write_to_folder("/tmp/") .unveil(); assert_eq_file_content( "/tmp/Cargo.toml".as_ref(), "Cargo.toml".as_ref(), "Unveiled data did not match the original content”, ); Ok(()) } @5422m4n /sassman 

impl Hide for SteganoEncoder { fn hide(&mut self) -> &Self { let mut img = self.carrier.as_mut().unwrap(); let mut dec = LSBCodec::new(&mut img); let buf: Vec = (&self.message).into(); dec.write_all(&buf[..]) .expect("Failed to hide data in carrier image."); // ... self.carrier .as_mut() .expect("Image was not there for saving.") .save(self.target.as_ref().unwrap()) .expect("Failed to save final image"); self } } @5422m4n /sassman 

impl Hide for SteganoEncoder { fn hide(&mut self) -> &Self { let mut img = self.carrier.as_mut().unwrap(); let mut dec = LSBCodec::new(&mut img); let buf: Vec = (&self.message).into(); dec.write_all(&buf[..]) .expect("Failed to hide data in carrier image."); // ... self.carrier .as_mut() .expect("Image was not there for saving.") .save(self.target.as_ref().unwrap()) .expect("Failed to save final image"); self } } pub struct Message { pub header: ContentVersion, pub files: Vec<(String, Vec)>, pub text: Option, } @5422m4n /sassman 

impl Hide for SteganoEncoder { fn hide(&mut self) -> &Self { let mut img = self.carrier.as_mut().unwrap(); let mut dec = LSBCodec::new(&mut img); let buf: Vec = (&self.message).into(); dec.write_all(&buf[..]) .expect("Failed to hide data in carrier image."); // ... self.carrier .as_mut() .expect("Image was not there for saving.") .save(self.target.as_ref().unwrap()) .expect("Failed to save final image"); self } } @5422m4n /sassman 

impl<'img> Write for LSBCodec<'img> { fn write(&mut self, buf: &[u8]) -> Result { let carrier = &mut self.subject; let (width, height) = carrier.dimensions(); let mut bit_iter = BitReader::endian( Cursor::new(buf), LittleEndian, ); let mut bits_written = 0; for x in 0..width { for y in 0..height { let image::Rgba(mut rgba) = carrier.get_pixel(x, y); for c in 0..3 as usize { rgba[c] = bit_wave(rgba[c], bit_iter.read_bit()); bits_written += 1; } carrier.put_pixel(x, y, Rgba(rgba)); } } Ok((bits_written / 8) as usize) } } @5422m4n /sassman 

impl<'img> Write for LSBCodec<'img> { fn write(&mut self, buf: &[u8]) -> Result { let carrier = &mut self.subject; let (width, height) = carrier.dimensions(); let mut bit_iter = BitReader::endian( Cursor::new(buf), LittleEndian, ); let mut bits_written = 0; for x in 0..width { for y in 0..height { let image::Rgba(mut rgba) = carrier.get_pixel(x, y); for c in 0..3 as usize { rgba[c] = bit_wave(rgba[c], bit_iter.read_bit()); bits_written += 1; } carrier.put_pixel(x, y, Rgba(rgba)); } } Ok((bits_written / 8) as usize) } } @5422m4n /sassman 

impl<'img> Write for LSBCodec<'img> { fn write(&mut self, buf: &[u8]) -> Result { let carrier = &mut self.subject; let (width, height) = carrier.dimensions(); let mut bit_iter = BitReader::endian( Cursor::new(buf), LittleEndian, ); let mut bits_written = 0; for x in 0..width { for y in 0..height { let image::Rgba(mut rgba) = carrier.get_pixel(x, y); for c in 0..3 as usize { rgba[c] = bit_wave(rgba[c], bit_iter.read_bit()); bits_written += 1; } carrier.put_pixel(x, y, Rgba(rgba)); } } Ok((bits_written / 8) as usize) } } #[inline] fn bit_wave(byte: u8, bit: Result) -> u8 { let byt = match bit { Err(_) => byte, Ok(byt) => if byt { 1 } else { 0 } }; (byte & 0xFE) | byt } @5422m4n /sassman 

impl<'img> Write for LSBCodec<'img> { fn write(&mut self, buf: &[u8]) -> Result { let carrier = &mut self.subject; let (width, height) = carrier.dimensions(); let mut bit_iter = BitReader::endian( Cursor::new(buf), LittleEndian, ); let mut bits_written = 0; for x in 0..width { for y in 0..height { let image::Rgba(mut rgba) = carrier.get_pixel(x, y); for c in 0..3 as usize { rgba[c] = bit_wave(rgba[c], bit_iter.read_bit()); bits_written += 1; } carrier.put_pixel(x, y, Rgba(rgba)); } } Ok((bits_written / 8) as usize) } } #[inline] fn bit_wave(byte: u8, bit: Result) -> u8 { let byt = match bit { Err(_) => byte, Ok(byt) => if byt { 1 } else { 0 } }; (byte & 0xFE) | byt } R: 1110 0111 G: 1010 0110 B: 0010 1000 @5422m4n /sassman 

Demo @5422m4n /sassman 

@5422m4n /sassman github.com/steganogram www.stegano.org/ 

Q & A @5422m4n /sassman