Steganography application to private journal writing



Many people are writing private journals everyday. Some are hoping for publishing them in the future, but the majority are hoping for keeping it in secret forever.

You can keep your journal secret by using some cryptography. However, encryption sounds a bit bothersome. And once you start encrypting your journal, your nearby people may think you are writing bad thing everyday.

Under windows OS you can easily encrypt your folders including your private files just by setting, and you can secure your secret writing. However, such encryption is canceled when you move such files from one PC to another. All PCs inevitably cause fatal errors in time, and you may lose all your encrypted data in a second. So, cryptography may not be the almighty for you. 

Here comes Steganography, especially, BPCS-Steganography that has a large embedding capacity.

Let's see a sample photo shown below. (A) is a PNG formatted color photo having 3,000x1,800 pixels. The file size is 8,694,810 Byte. This is your "new diary book", but it's a vessel image from our point of view. According to our Qtech-HV program, the maximum embedding capacity of this image is 7,700KB (or more) with a complexity setting as 40. So, if you are writing a 3KB journal everyday as a text file, you'll see that you can hide your writing for more than 2,500 days long. The fact is more than that. Because Qtech-HV compresses the text files into 1/2 size (in average) before embedding, you can continue embedding for more than 5,000 days, that is 14 years long in this single photo image.

Actual scenario of your secret writing goes like this. You first extract all the previous journals (from the first day to yesterday) which was packed under one folder yesterday, then you write and add today's journal to that folder again, and embed it back to the yesterday's stego. The embedding capacity today is exactly the same as yesterday only if you keep the complexity value unchanged. You can continue this routine until the system says "it's overloaded."

(B) is a text-file-embedded stego image of (A) in PNG format having the file size of 9,576,387 Byte. The total size of the embedded files (not actual journal files, but are English-Japanese mixed barf-mail texts including headers) is 16,000,004 Byte. You can extract everything from (B) by using Qtech-HV011/02 without any access key.

(FYI) The text size in this page (starting from "Many ...", ending in "... access key.") is 2.31 KB.


 (A) Vessel Image   (B) Stego Image
(Download this image)   (Download this image)


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(Updated Jan. 26, 2015 by Eiji Kawaguchi)