PixelKnot: Hidden Messages

1.19K reviews
Content rating
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About this app

Have a secret that you want to share? Why not hide it in a picture? With PixelKnot, only your friends with the secret password can unlock your special message. Everyone else just sees a pretty picture. It’s a fun and easy way to share hidden messages without anyone knowing. Take those pixels, twist them in a knot, and see for yourself!

★ DISGUISE YOUR MESSAGES: Pictures are public, the text is hidden inside. Even a trained eye will think the image is unedited. It’s security through obscurity!
★ FOR YOUR EYES ONLY: Put a password on the secret message to make sure that no one can read it except the person it’s meant for.
★ EASY IMAGE CHOOSER: You can use the camera to take photos, or just use photos you’ve already taken.
★ INVISIBLE CHANGES: Even a trained analyst analyst shouldn’t be able to detect any message. The image bytes should seem undistorted.
★ SHARE ACROSS PLATFORMS: Want to share the images over email, file sharing tools (like Dropbox & Sparkleshare), social media (like Google+ & Flickr) or directly through Bluetooth or NFC? Not a problem! The messages are still recoverable on the other side. We'll have even more tools (like Facebook) working soon, so stay tuned!
★ AD-FREE: We want your love, not your money.
★ MATHEMATICALLY SECURE: We use the newly developed steganography algorithm F5 which implements matrix encoding to improve the efficiency of embedding and employs permutative straddling to uniformly spread out the changes over the whole steganogram.
★ ATTACK RESISTANT: We’ve launched attacks on images with messages hidden in them using a specialized version of stegdetect, an automated tool for detecting steganographic content in images. In most cases, the pictures have been impervious to attack. We will be including detection in an upcoming version of the application so you can easily test it yourself!
Don’t see your language? Join us and help translate the app:

***Learn More***
★ ABOUT US: Guardian Project is a group of developers that make secure mobile apps and open-source code for a better tomorrow.
★ OUR WEBSITE: https://GuardianProject.info.
★ ON TWITTER: https://twitter.com/guardianproject
★ OPEN-SOURCE: PixelKnot is free software. You can take a look at our source code, or join the community to help make it even better: https://github.com/guardianproject/pixelknot
★ MESSAGE US: Are we missing your favorite feature? Found an annoying bug? Please tell us! We’d love to hear from you. Send us an email: support@guardianproject.info

The Guardian Project makes apps that are designed to protect your security and anonymity. The protocols that we use are widely regarded as the state of the art in security technology. While we are constantly upgrading our software to combat the latest threats and eliminate bugs, no technology is 100% foolproof. For maximum security and anonymity users must utilize best practices to keep themselves safe. PixelKnot is still an experimental application and should not be used in real world deployments. You can find a good introductory guide to these topics at https://securityinabox.org
Updated on
Jun 1, 2022

Data safety

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Ratings and reviews

1.13K reviews
A Google user
December 4, 2018
Be careful. I tested by choosing a photo, writing message and sending to myself. The email came with a different photo from my gallery. It was not next to or remotely similar to the photo I put the test message on. Imagine if a personal photo went to whomever you were sending the secret message to. Scary. Also, since first test and then second test the darn app won't work. Also tried retrieving messages from photos with no message or with wrong password and it just spins. Should give a message like no message detected or incorrect password.
75 people found this review helpful
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Shawn Brightman
August 3, 2020
Horrible doesn't work. Let's you type a message set a password and then it does to hide the message gets to 8% and closes. Ive tried it 20 times over the past two days and thats all it does
42 people found this review helpful
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September 15, 2021
Keeps crashing at 8% when loading message into picture i picked. Have uninstalled and reinstalled but still crashing at exactly same place everytime. I have had this app few yrs ago on different android phone. I want this app pls fix asap!
19 people found this review helpful
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What's new

- many translations added
- updated to Android 11 / SDK 30
- add support for Signal and Telegram as preferred sending channels
- update AES encryption code
- improve performance, stability
- make app movable to SD card