Steganography Online

Steganography reference: hide and extract, explained

A quick, accurate reference for the whole round trip — embedding text in an image and reading it back out — and what each step really does.

Method

LSB (least-significant-bit) encoding — the lowest bit of each pixel's red, green and blue value is replaced with one bit of your message. The alpha (transparency) channel is left untouched.

Accepted input

PNG, JPEG or WebP as the cover image. JPEG and WebP are fine as the source — they are decoded to raw pixels first — but the saved result is always PNG.

Output format

Always a lossless PNG. JPG and WebP re-compress the pixels, which would wipe out the hidden bits, so the tool never exports those.

Password option

Optional. With a password the message is encrypted before embedding using a key stretched from your password with PBKDF2 (SHA-256, 150,000 iterations) plus a random salt; without one, the bits are hidden but not encrypted.

How extraction knows

On hide, a small 4-byte marker plus a length field is written ahead of your message. On extract, the tool reads those bits first; if the marker isn't there it reports that nothing is hidden, rather than showing random noise.

How much fits

Bigger images carry more: a 1920 × 1080 cover holds about 759 KB, while a 1080 × 1080 square holds about 427 KB. Because only the lowest bit of each colour is used, the file size barely changes after hiding — the image is the same dimensions, just re-saved as PNG.

Security: it hides, it doesn't lock

Concealment versus encryption — know the difference. Steganography hides that a message exists; it does not, on its own, scramble what the message says. Anyone who knows to run this kind of image through an LSB extractor can read an un-passworded message. For real secrecy, set a password so the text is encrypted as well as hidden — and remember that LSB is not designed to survive forensic statistical analysis. The strongest setup this tool offers is both at once: a password-encrypted message hidden inside a busy photo.

Tips that actually matter

• Keep and share the exact PNG the tool produces. Screenshotting it, re-saving it as JPG, or letting a chat app auto-compress it re-encodes the pixels and erases the hidden message.
• Extraction needs the original carrier file, not a copy that's been through a screenshot or a messaging app — those rewrite the pixels and the message is gone.
• If you set a password on hide, the same password is required on extract; a wrong password produces a clear error, not garbled text.