[ale] encryption/obfuscation (Was: No, wait- Leonard ...)

[Kevin Krumwiede]

On Tue, 2002-07-09 at 15:09, Sean Kilpatrick wrote:
 
> I _think_ steganography is the technique of hiding a simple text message
> within a standard graphics format, such as .JPG.  That is, the attachment
> <foopix.jpg> can be opened within a graphics viewer and, indeed, foopix is
> displayed, but when opened with different software, the encrypted message
> is revealed.

That's right, though I don't know if it's been done with JPEG files.  I
know it can be done with lossless image formats and even sound or video
files.  And you can encode not just text, but any type of data.

The concept is simple.  The least significant bit of each pixel is
replaced with a bit from the data to be encoded.  If the LSBs were
fairly random to begin with, as in a photograph, the image will not be
visibly altered.  If the data is plaintext or some well-known file
format, in theory it would be easily identified.  But if the data were
encrypted it might be impossible to detect.

Krum


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