Follow Slashdot blog updates by subscribing to our blog RSS feed


Forgot your password?

New Optical Security Doesn't Require Embedment 30

An anonymous reader writes "Scientists are claiming to have a new type of optical security that doesn't require embedment. Optical security includes many different options but up until now they have all required that the secret image be embedded in a host image which left it vulnerable. From the article: 'To address this problem of finding the secret image in the watermark, scientists have developed a new optical security method that doesn't require embedment. Instead, the technique uses a phase retrieval algorithm to generate specific optical and phase keys that extract the secret information when applied. The optical keys contain information and are distributed to an individual through a personal identification number (PIN). The information contained in the phase keys (the main source for determining extraction) is distributed to the individual separately.'"
This discussion has been archived. No new comments can be posted.

New Optical Security Doesn't Require Embedment

Comments Filter:
  • I even RTFA'ed, and I still don't understand exactly how this technique is new, or even useful. Someone care to clarify?

    Oh, and Google says "embedment" doesn't mean quite what you think it means. :P


    • Re:Embedment? (Score:2, Informative)

      by DanQuixote ( 945427 )
      The difference is that the image and the message are transmitted separately. This means that you can publicly send a large data set (say a CD full of images) and then privately send information that will decode a message. The private part only has meaning when applied to the proper public image. Perhaps this means one could use an image as a password...
    • When the author says "doesn't require embedment" it means that the "host image" is not altered in any way. Since there is no information provided to potential hackers through discovery of an invisible watermark it is far more robust than traditiona stenographic techniques.

      I gather the way it works is that the "hidden image" is like the "secret key" you use when you generate SSL certificate requests--it is kept secure/inaccessible to the public. Through transforms and other mathematical wizardry they calcu
  • Embedment? (Score:5, Funny)

    by zenmojodaddy ( 754377 ) on Wednesday June 14, 2006 @04:37AM (#15530591)
    A fine cromulent word with which to embiggen your article.
  • Huh? (Score:5, Insightful)

    by Bjarke Roune ( 107212 ) on Wednesday June 14, 2006 @04:59AM (#15530643) Homepage
    I think I speak for most of us who has only read the summary when I say: huh?
  • embedment? (Score:3, Funny)

    by phreakv6 ( 760152 ) <phreakv6@gmail . c om> on Wednesday June 14, 2006 @05:24AM (#15530717) Homepage
    i want enlightenment on the article first.
    is the summary in greek or in latin?
    • It's in geek, in a dialect known as wannabe. This language is often characterized by technical sounding words that also sound familiar but are in fact nonsense words.
  • by TempeTerra ( 83076 ) on Wednesday June 14, 2006 @05:36AM (#15530741)
    Ok, so I read the article. Not much clue there. I thought to start with that they were talking about some kind of steganography [], but the article claims that the encoded message isn't embedded in the image. It's not a digital image either, (jpeg etc) it's a printed image. As far as I can tell they're using some optical properties of the image as a key to decode some other encrypted data. Hardly an earth shattering technique, but the linked article is just a brief, confusing write-up of an optical physics paper - perhaps there's actually something interesting in the paper that got dropped along the way.
    • by Aceticon ( 140883 ) on Wednesday June 14, 2006 @06:03AM (#15530812)
      The article is indeed about stenography.

      Scientists developed a new way of hidding images inside other images, in which, if understood it right, both images are treated as complex waves, and the image to be hidden is amplitude modulated into the waveform of the host (carrier) image. This is a bit similar to how sound waves are modulated into the carrier wave in radio transmission, only in this case the carrier wave is not a fixed frequency wave.

      The modulation of the image to hide into the host image is controlled via a phase key. The phase key used in the modulation of the hidden image into the host image is required to extract the hidden image from the encoded image.

      Also, this method allows adding multiple hidden images to the host image, as long as they have different phase keys.

      How exactly this is beter (in terms of avoiding that an attacker can get the hidden image) than encrypting the image to hide and then merging the resulting data stream into the host image in a straightforward way (for example, using the least significat digit of every RGB value) i don't know (the article doesn't cover it). I suspect this new method might be more rubust when transformations are applied to the encoded image, such as compression, cropping, etc...
  • by netpixie ( 155816 ) on Wednesday June 14, 2006 @05:55AM (#15530792) Homepage
    Storing information by modulating the Fourier (or Fresnel) modes of an image is not new.

    That being said, the actual underlying science of this post might be intersting, if only I could get to it through the torrent of drivel in the summary.

    e.g. "meaning that the secret image cannot be found in the watermarked image"

    Then how do you extract it then?

    Do you mean "the image cannot be extracted without the key"?

    "Since the watermarked image contains no secret information" Que?

    • Ahhh you missed the best bit, they have invented infinate compression.

      Finally, since the secret image is the same size as the host image, this method also satisfies the "capacity requirement."

      Another advantage of this optical technique is that one host image can hide several different secret images.

      I personally think the images are "compressed" using the 4 digit pin code passed through a different channel.

  • The optical keys contain information and are distributed to an individual through a personal identification number (PIN).
    The files are *in* the computer?!?
  • by POPE Mad Mitch ( 73632 ) on Wednesday June 14, 2006 @06:55AM (#15530935) Homepage
    If i understand this correctly, traditionally you use steganography to hide the secret (another image) inside an existing (host) image, with a key to decrypt it, the draw back being that someone might accidentally spot the steganography.

    This technique doesnt put any data in the host image at all, the keys contain all information required to distort the host image into the secret image, thus given the host image, you cant accidentally stumble across the secret, and likewise the keys are of no use unless you also have the host image.

    Its akin to having a text encryption system where the key is the offsets into a known document where the letters can be found, the known document can be public, but unless you know what both it and the key neither is of any use.
    • Maybe an interesting mod for this guy. I'd say informative, but after RTFA I still can't be certain he's got it right. It's a convincing summary though (he'd win my vote in a game of dictionary).

      Perhaps there's a lot more to this than I can reasonbly imagine, but wouldn't the keys need to be almost as large as the original image, unless the original is closely optically related? Why not just diff the images, encrypt it, and give the person who enters the PIN properly the diff and the key? There's no mention
    • From what I can tell, you've nailed what they're doing.
  • Once he was embedment he was enbiggened and she was...

To write good code is a worthy challenge, and a source of civilized delight. -- stolen and paraphrased from William Safire