[APP] StegDroid Alpha v 0.75

fredley · Jan 10, 2011

Hi guys/gals

I'm working on this app for my final year dissertation. It performs Echo Steganography on wave files. My app uses this to encode short text messages in an audio file, then share it. I've just got the Steg side of things working, so I wanted to get some early feedback on whether it works for other people (and if it's awfully slow - it uses a lot of Fourier Transforms etc...).

This is very early days, so the app isn't anything like ready for primetime yet, but the basics are in place. I'd really appreciate it if you could download it and:

* Have a go at embedding some text in a recording and seeing if it correctly extracts it again.
* Run the tests available in the menu
* Email me one of your recordings (tfmw2 [at] cam [dot] ac [dot] uk) to see if I can extract the data on my phone.
* Supports encryption with a shared key
* Transcodes audio files to ogg format for sharing

Updates (0.75)

* Added Multicasting of messages to contact groups

* Fixed bug with sharing files in paranoid mode
* Better memory management, should work more reliably with longer messages
* Reduced error rate (less garbled messages)
* Reduced file size by 33%
* Other bug fixes

Any problems let me know!

Cheers

tridge · Jan 11, 2011

I'm not sure what this does =\

fredley · Jan 11, 2011

The app records a file from the microphone and embeds a secret message into it. You can send that file to someone, and if they've got the same app they can extract the secret message from the audio file. Anyone listening to the audio file wouldn't be able to tell that it's got a message hidden in it, as the difference is hard to distinguish with the human ear.

fredley · Jan 11, 2011

I've uploaded a new version, it's a bit more stable and a bit easier to use!

00Ghz · Jan 11, 2011

Interesting, maybe we can team up this will be an interesting feature for my project

Meltus · Jan 11, 2011

Works pretty well, cool idea too!
I was able to make it fail though by using a long jumble of letters (I screenshotted before and after to compare) but it still only got about 5 wrong (little diamond with a ? In the middle).
Nice work!

Sent from my Nexus One using XDA App

fredley · Jan 11, 2011

Thanks Meltus

Could you let me know the length of the string. Were the wrong characters at the end or distributed throughout? What kind of audio input were you testing with (voice message, background noise, music etc.)?

fredley · Jan 11, 2011

Update

Now supports basic crypto. Run tests from the menu before you start to check the crypto test passes (if it doesn't, let me know!).

Meltus · Jan 12, 2011

fredley said:
Thanks Meltus

Could you let me know the length of the string. Were the wrong characters at the end or distributed throughout? What kind of audio input were you testing with (voice message, background noise, music etc.)?

Length of the string was about 30 characters, the wrong characters were distributed and were just regular letters.
As for the audio it was just me tapping on the mic for about 20 secs.

I've been doing more tests too and it only seems to occur when you have a few repeating characters. I typed out the keyboard lines and it got it correct, until i started repeating every other character a few times, then it started to get a few wrong.

fredley · Jan 12, 2011

Meltus said:
Length of the string was about 30 characters, the wrong characters were distributed and were just regular letters.
As for the audio it was just me tapping on the mic for about 20 secs.

I've been doing more tests too and it only seems to occur when you have a few repeating characters. I typed out the keyboard lines and it got it correct, until i started repeating every other character a few times, then it started to get a few wrong.

That's strange! The embedding works bit-by-bit, rather than byte-by-byte, so it's very strange that repeated chars should cause an issue. I'll look into it though. Did you try the same test with continuous sound, such as music? I'll see if I can replicate it here. What hardware/android version are you using?

kuelexx · Jan 14, 2011

Are you using a set algorithm to code messages and decode them? Or does it shift from how long the coded message is to the non-coded message? This is an interesting app that could serve a lot of uses, excellent idea! Hopefully this is seen all the way through to "perfection", its a keeper.

I will be watching this blog closely and will test the app. Cant wait until its totally complete.

--CueSA

Meltus · Jan 14, 2011

fredley said:
That's strange! The embedding works bit-by-bit, rather than byte-by-byte, so it's very strange that repeated chars should cause an issue. I'll look into it though. Did you try the same test with continuous sound, such as music? I'll see if I can replicate it here. What hardware/android version are you using?

I'm using a Nexus One with 2.3.
I didn't try it with other types of sound so it's not the most accurate of tests, but i'll have another go today.

fredley · Jan 18, 2011

I've had some issues with occasional chars being wrong, I may put in some kind of CRC, but I don't think it's that serious. It may have something to do with various microphones and their sensitivity.

In other news, now upgraded to version 0.4, which converts encoded files to ogg format, and can extract messages from ogg files too! (would be a bit silly if it didn't). Files are ~90% smaller as a result!

ledridge · Jan 19, 2011

I could see an RDS type implementation or advertising uses that would let you encode whatever data you wanted in the audio if the mobile app did something like SoundHound where you could have it listen for the message. If you could create a background app that listened for any messages and alerted when heard, without totally draining the battery, I could see implementations with nielsen ratings showing accurately what you saw and when.

fredley · Jan 19, 2011

ledridge said:
I could see an RDS type implementation or advertising uses that would let you encode whatever data you wanted in the audio if the mobile app did something like SoundHound where you could have it listen for the message. If you could create a background app that listened for any messages and alerted when heard, without totally draining the battery, I could see implementations with nielsen ratings showing accurately what you saw and when.

I believe this tech (or at least, steganography in general) is already used to watermark copyrighted material, in some cases uniquely. Authorities can then look at an illegally shared file and trace its origin or something like that. Certainly it's possible.

fredley · Jan 24, 2011

Just updated the version on the market, now integrates much better with email apps/file managers. Let me know if you can't launch StegDroid from your favourite app!

overclockxp · Jan 24, 2011

Make sure that your app stays your app. Many universities are after students' apps.

posted via the xda app with my Evo

fredley · Jan 24, 2011

Ha, it's ok, I signed away any rights I had to this app when I joined this course 3 years ago. It'll remain free and be properly open-sourced though.

d0ugie · Jan 30, 2011

you're famous OP

http://mobilitydigest.com/is-that-a-txt-in-your-ogg/

fredley · Jan 31, 2011

Thanks for finding that!

[APP] StegDroid Alpha v 0.75

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