What follows is a treatise on the use of block chain technology to authenticate
video and pictures to avoid the fake news problem that seems so pervasive of
late. I already published this on LinkedIn, but would like your thoughts on it
to flesh it out further. Who knows, even publish a full paper on it and really
become a published citizen researcher. :)
***
How to determine if a video or picture is real or fake?
The question seems simple enough, doesn't it? However, with today's
advancing computer technology in image manipulation, you can no longer be
absolutely sure that the photo you are viewing, or the video being broadcast is
the "real McCoy". There have already been examples, courtesy of the Russian
Internet Research Agency, of video that appears real, yet has been entirely
faked. This is called False Evidence Appearing real and it can be a real
problem when trying to sort out real documented events from those which have
been faked. So, how do you certify that a picture or video is real and
unaltered? The answer is a recent technological advancement called "Block
Chain".
What is Block Chain?
Block Chain technology is an outgrowth of cryptographic hashing in
combination with cryptocurrencies. It is a method by which you can certify and
reference a given event as real using the P.O.W. of the block chain itself.
P.O.W. refers to the Proof of Work crypt-graphic hash function used to certify
that a particular job was completed using a specific set of rules and other
criterian. This model is used in cryptocurrencies to certify, by consensus,
that a given chain of crypto hashes was done correctly and completed before
anyone else did the same function.
OK, So how does this relate to using block chain to certify video or picture
images as real?
Lately, there has been a number of incidents where the press (or some
third party) has tried to claim that a given video (or picture) has been
altered or is not as presented. This has created a situation where you cannot
always take the evidence of your eyes and ears at face value. This is the
problem of perception being reality, and as we all know, perception can be
altered in a myriad of ways to make reality appear different than it really is.
How do we overcome this conundrum? We use the concept of block chain to certify
that a picture or video has been unaltered by taking a digest of information
found in the picture, combined with external references (such as GPS, local
clock, etc) and create a cryptographic block that represents the picture (or
each frame of a video). With video, this would also include the sound track.
Once done, the block chain would then be embedded within the picture or video
in question as an integrated data stream that can be read by an external
program. This program would take the exif data from the picture (or video) and
use that to decrypt and certify the picture (or video or frame therein) by
comparing the decrypted output to the exif data along with the digest of the
image(s) involved. Of necessity, this would be both computationally complex and
intensive, but the result would be a certified image (or set of images).
How to implement this in a real world scenario.
implementation is rather simple from a layman's point of view. The
entire process would be hidden from the end user. The imaging device would have
2 additional components installed and running in background. The first is a gps
receiver that provides location index data as well as a certified time code.
The second device would be an ASIC (Application Specific integrated circuit
that would handle hashing the images and generating the block chain. The
second item in this case has yet to be incorporated into the latest smart
electronics, but given the need for certification of video or images as real,
the justification of it being installed is clear enough.
Implementation
Now, part of this has already been implemented. The use of GPS for
location services is built into just about every modern imaging device on the
market these days (except for the "low end cheap stuff"). This means that some
of the data is already setup to be used. Now, until ASIC's are actually
installed in hardware, a handoff to an external device can be implemented in
the cloud. That device would read the image and the exif data included (GPS
location, time, image size, color bit range, brightness, etc.) and generate a
block chain of that image based on those criteria. There are several methods
that can be used depending on the level of certification one chooses to use.
Level 1 certification would involve a simple direct sample of the image
(or video stream) reading the exif data and calculating a block chain based on
image size, number of pixels, color bit range, brightness and a random sample
of pixels in the entire image (or image frame of a video) combined with the
time code and GPS coordinates to create a simple block chain. This would
minimally certify the image as unaltered in any way and would also be the
fastest method.
The second level of certification would involve the fast method of
level 1, but would break the image (or image frame of a stream) into sectors
and create a block chain of each sector. This would be a sub chain to the
primary chain built for the image itself (level 1) It would, by necessity,
include more data (including line count, number of pixels per sector, etc.) and
could be used to compute the equivalent of a level 1 chain, but vastly more
detailed.
Level three would involve doing a line by line hashing of the pixels in
the image, using the number of pixels in each line, number of color or
brightness changes, bit rate of the image itself and then combine with the GPS
and timing info to create a block, each line would be it's own block and would
be used to compute a complete chain of the image (or audio/video streaming
frame). This method would be the most computationally intensive and complex,
but the level of certification would mean that it could be verified as
authentic under rules of evidence in a court of law or when used in a news item
to certify that the data stream was shot on location or is otherwise authentic
in content.
A nice additional feature of this set of methods, especially in a video stream,
it can be used to reference specific areas of the stream (much like a built in
time code was being used on old video formats for over the air transmission)
Also, because each "Frame" in the stream has it's own block chain, a single
frame or series of frames can be used independent of the others or as a single
stream/picture in multimedia content (such as presentations). Since the data,
itself would not be visible to the end user (unless a program designed to read
it were used, or that feature were included in the multimedia playback
program), the user wouldn't be concerned too much. As
Security and authenticity
a security model, there are benefits that become immediately apparent.
The first of these is determining if the stream or frame had been altered. This
could be done by computing a new block chain from the existing video/audio or
picture content and comparing it to the existing. Any differences would result
in a failure and even show where the alterations took place. For evidence
certification, this would be a definite requirement to insure authenticity in
chain of custody. This very same block chain could also be used to encrypt the
data stream (audio/video or picture frame) for secure storage, or also allow
recovery should the data be otherwise corrupted. Something like this is already
in use today in the guise of bittorrent. The function is similar in that the
original file is hashed, broken into chunks, transmitted and then reassembled
using a provided key. Only block chain would take this a step further and allow
certification of the data as well. I must point out that the differences
between torrent and block chain make a 1 to 1 comparison irrelevant and is only
used to show simple comparative use.
In conclusion
Block chain shows promise as a method to authenticate, in real time,
events being recorded in audio/video or as pictures at a given time and
location. It also shows promise as a method for preserving evidence and chain
of custody where multimedia content might be used in a court of law or during
an investigation leading up to a court proceeding. Block chain Also shows
promise as a protection and recovery mechanism that could be used concurrent to
other methods for data preservation and recovery. In short, this technology has
a wide range of uses that has not yet been explored and shows promise in being
used in everyday life. This technology would effectively remove the conundrum
of flawed perception being made reality and would effectively nullify some
elements of propaganda currently in use.
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