Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Title: METHOD AND SYSTEM FOR CONTROLLING ENCODED IMAGE
PRODUCTION USING IMAGE SIGNATURES
Field of the invention
The invention relates generally to counterfeit protection for
printed and digital documents, packaging and other printed materials, and
more particularly to the secure production of encoded images for use in
counterfeit protection measures.
Background of the invention
Counterfeiting and alteration of valuable documents and black
market sales of counterfeit goods are significant problems faced with
increasing regularity in today's world. Each year many millions of dollars are
lost through the fraudulent use of non-authentic documents and branded
goods. The increasing sophistication of optical scanners, copy machines and
other devices used for replicating items continues to enhance the
counterfeiter's ability to produce fraudulent documents and other imitations
which are of sufficient quality to often go undetected.
One method of providing increased security against
unauthorized copying, alteration or counterfeiting is to apply an encoded
image to the item to be protected. This image may include a visually apparent
image (visible image) along with a non-visible or hidden image incorporated
into the visible image in such a way as to be difficult or impossible to view
without an optical or digital decoder configured specifically for viewing the
hidden image. Application of such encoded images to documents and other
items subject to counterfeiting allows the authenticity of such items to be
readily verified by anyone having an appropriate decoder.
The content of encoded images can be widely variable and may
be changed on a regular basis. The content may even be tied specifically to
the individual item to which it is applied, in which case it must be generated
very quickly in order to be considered a practical security measure.
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Accordingly, methods of producing encoded images should be flexible and
preferably available to users on short notice.
It is therefore advantageous to make encoded image production
readily available to individual users. Doing so, however, raises the concern
that the encoded images themselves may be tampered with or produced by
unauthorized users for application to counterfeit articles or altered
documents.
Another concern is that the authorized user can use the encoding software for
non-authorized purposes, such as to protect printed material he is not allowed
to encode. Accordingly, sophisticated control measures are required to assure
that encoded images are produced only by authorized users and to assure
that such authorized users produce only authorized encoded images.
Summary of the invention
Embodiments of the present invention fulfill a need for additional
control over the production, transfer and use of encoded images used to
protect documents and other materials from unauthorized reproduction,
counterfeiting or other misuse.
An illustrative aspect of the invention provides an automated
method for authorizing and controlling the production of optically encoded
images. The method comprises receiving from a user data processor a
request for authorization to produce an encoded image. The authorization
request includes user-supplied data comprising at least one authentication
image file. The method further comprises determining whether the user is
authorized to produce an encoded image using the user-supplied data.
Responsive to a determination that the user is authorized to produce an
encoded image using the user-supplied data, an authentication image
signature is generated from the at least one authentication image file using
an
image signature algorithm and a positive authorization response is returned to
the user data processor. The positive authorization response includes the
authentication image signature.
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Brief descriution of the drawings
The invention can be more fully understood by reading the
following detailed description together with the accompanying drawings, in
which like reference indicators are used to designate like elements, and in
which:
Figure 1 illustrates an exemplary encoded image formed from
primary and secondary authentication images;
Figure 2 illustrates the use of a lenticular lens decoder to
decode the encoded image of Figure 1;
Figure 3 is a schematic representation of an automated encoded
image validation system according to an embodiment of the invention;
Figure 4 is a schematic representation of another automated
encoded image validation system according to an embodiment of the
invention;
Figure 5 is a flow chart of a method of controlling an encoded
image production process according to an embodiment of the invention;
Figure 6 is a schematic representation of an automated encoded
image validation system according to an embodiment of the invention;
Figure 7 is a flow chart of a method of controlling an encoded
image production process according to an embodiment of the invention;
Figure 8 is a flow chart of a method of controlling encoded
image production process according to an embodiment of the invention; and
Figure 9 is a flow chart of a method of controlling an encoded
image production process according to an embodiment of the invention.
Detailed descriation of the invention
Embodiments of the present invention provide methods for
controlling the production, transfer and use of encoded images. As discussed
above, such encoded images are used to discourage or prevent counterfeiting
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and misuse of documents and other materials to which the encoded images
are applied.
As used herein, the term "encoded image" (or "optically encoded
image") refers to a rasterized, scrambled or otherwise manipulated variation
of one or more authentication images that, when embedded in a document, or
in another printed background or source image, cannot be discerned from the
base document material or other background or source image without the use
of a decoding device. An encoded image may be generated from an
authentication image using a particular set of characteristics that include
encoding parameters corresponding to certain characteristics of the decoding
device. When the encoded image is printed, placement of the decoding
device over the printed encoded image in a predetermined orientation reveals
the authentication image. Without the decoding device, some or all of the
encoded image may be visible, but indecipherable or indistinguishable from
the background by the naked eye.
It will be understood that optically encoded images may be
digital images that are decodable by an optical decoding device if printed but
that also may be decoded in their digital form using a digital decoding device
such as a software-based decoder. Digital encoded images include encoded
images that have yet to be printed or applied in physical form, as well as
digital images that have been scanned or reproduced from printed encoded
images. It will also be understood that optically encoded images may be
printed or applied in such a way that they can be decoded only through the
use of incident light in the non-visible spectrum or through the use of
scanning
devices operable to view light in the non-visible spectrum. Such encoded
images includes those printed with a medium that emits or reflects light in
non-visible wavelengths (e.g., infrared) or that emits or reflects when
illuminated by light in non-visible wavelengths (e.g., ultraviolet).
As used herein, "authentication images" includes any image
used in the production of an encoded image. An authentication image may
therefore be an image provided for use as a visible background image or a
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secondary image provided for uses as a hidden image incorporated into a
visible image.
Encoded images of particular interest to the present invention
are those that are configured to be optically decoded using a lenticular lens.
Such images are described in Alasia, U.S. Pat. No. 5,708,717 ("'717 Patent"),
which is hereby incorporated by reference in its entirety. Such images take
advantage of the ability of the lenticular lens to screen image content based
on the lenticule frequency of the lens. These images are typically encoded by
one of several methods that involve establishing a regularized periodic
pattern
having a frequency corresponding to that of the lenticular lens to be used as
a
decoder, then introducing distortions of the pattern that render the image
difficult to discern with the naked eye.
Figures 1 and 2 illustrate the use of a lenticular lens to decode
an encoded image. Figure 1 shows an enlarged view of an optically encoded
image 10. The encoded image 10 was constructed from a primary image of a
human face and a secondary image of the letters "SI." The primary image
was rasterized at a particular screen frequency and angle. The secondary
image was embedded into the primary image by introducing variations in the
raster lines at locations corresponding to the content of the secondary image.
The result, as shown in Figure 1 is an encoded image 10 in which the primary
image is readily viewed but the secondary image cannot be discerned. As
shown in Figure 2, when a lenticular lens 20 having a line frequency
corresponding to the screen frequency is placed over the encoded image 10
at the correct orientation a, the secondary image (SI) may be viewed. As
discussed above, if the encoded image 10 is stored as a digital image or
embedded in a digital document, a digital decoder with a similar functionality
to the lenticular lens 20 can be used to decode the encoded image. If the
encoded image 10 has been printed, an image acquisition device, such as a
scanner or camera, can be used to create a digital version of the encoded
image 10. The digital encoded image can then be decoded using software
configured to extract the authentication image from the digital encoded image.
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Encoded images of this and other types are constructed from
digitized authentication images using a set of encoding parameters. These
parameters may determine the configuration and orientation of the decoding
device used to decode the encoded image. For images intended to be
decoded by an optical decoding device, some or all of the encoding
parameters may correspond to certain optical characteristics of the decoding
device. For example, for images intended to be decoded by a lenticular lens,
the encoding parameters may include a screen frequency, which corresponds
to the number and spacing of regular screen segments into which an image is
divided and the number and spacing of the lenticules of the lens. The
encoding parameters may also include an angular orientation of the screen
segments which determines the orientation at which the decoding device must
be positioned relative to the image in order to decode the image.
In the discussions that follow, encoded images that may be
decoded by lenticular optical decoding devices are used to illustrate the
embodiments of the invention. It will be understood by those of ordinary skill
in the art, however, that any image encoding method having a set of definable
image characteristics and encoding parameters may be used in conjunction
with the methods of the present invention.
As is discussed in co-pending applications U.S. Application No.
10/847,943 and U.S. Application No. 10/847,962 (collectively, "Copending
Alasia Applications"), both of which were filed May 18, 2004 and are
incorporated herein by reference in their entirety, some or all of the
encoding
parameters and authentication images used to construct an encoded image
may be supplied by a user and some or all may be supplied by a separate
party that actually carries out the encode image construction or that acts as
a
controller of encoded image production. Also, some of the image content or
encoding parameters may be determined from the content of a document to
which an encoded image is to be applied or in which an encoded image is to
be embedded. As is also discussed in the Copending Alasia Applications,
encoded images may be constructed using multiple sets of authentication
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images and encoding parameter sets. Each of these sets may be formed
from different combinations of user-supplied and controller-supplied
information (i.e., images and/or encoding parameters). For example, a first
encoded image or portion of an encoded image may be constructed based on
a user-supplied authentication image and user-supplied encoding parameters.
A second encoded image or portion of the same encoded image may be
constructed based on a controller supplied authentication image and
controller-supplied encoding parameters.
The use of controller-supplied images and/or encoding
parameters allows a central controller to control some or all of the encoded
image. The encoded image itself may be constructed by a central image
encoding processor (which may be co-located with the central controller) and
transmitted to the user's processor or may be constructed on the user's
processor after authorization from a central control processor. Figures 3 and
4 illustrate systems for controlling the production of encoded images by
requiring a user to obtain validation/authorization before an encoded image is
produced.
With reference to Figure 3, an automated encoded image
validation system 100 comprises a user data processor connected to a
validation server 140 through a network 160. The network 160 may, by way
of example, be a local area network that connects a co-located validation
server 140 to a plurality of data processors 110. Alternatively, the
validation
server 140 may be remotely located relative to the data processor 110, the
two being connected or connectable via the Internet or other wide area
network. In either case, the user data processor 110 may be one of a plurality
of user data processors and may be connected to a user interface 120 and a
printer 130. The encoded image validation system 100 may also include an
authentication control device (not shown) attached to or in communication
with the user data processor 110. As is described in the Copending Alasia
Applications, such devices may include a separate processor or electronic
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security key that controls local processing of software on the user processor
110.
The automated document authentication system 100 may be
used to carry out any or all of the actions required to construct an encoded
image. It will be understood that these actions may be divided up so that
some or all of the actions are carried out as part of an interactive
transaction
conducted between the user data processor 110 and the validation server
140. It will also be understood that one or more of the actions of the methods
of the invention may be carried out by the user data processor 110 while one
or more additional actions are carried out by the validation server 140.
In an exemplary embodiment, an interactive session may be
established between the user data processor 110 and the validation server
140. As part of this transaction, the user may submit to the validation server
140 one or more authentication images and/or one or more user-supplied
encoding parameters. These may then be used by the validation server 140
to produce an encoded image that is returned to the user data processor 110,
where the encoded image is embedded into a document and stored or printed
to produce an authenticated printed document. Additional non-user-supplied
authentication images and/or encoding parameters may be incorporated into
the encoded image by the validation server 140.
In another exemplary embodiment, the user may submit an
entire document to the validation server 140, which creates and embeds an
encoded image into the document and returns it to the user data processor
110 for printing or storage. Along with the document, the user may submit
one or more authentication images and/or one or more user-supplied
encoding parameters for the validation server 140 to use in creating the
encoded image.
In some embodiments, some or all of the actions required to
produce an encoded image may produced by a second server. This provides
for separation of the validation and image encoding tasks and also allows for
multiple levels of authorization and control. With reference to Figure 4, an
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automated encoded image validation system 200 includes a first validation
server 240 connected to a user data processor 210 through a first network
260. The first network 260 may, for example, be a local area network and the
first validation server 240 may be co-located with the data processor 210.
Alternatively, the first validation server 240 may be remotely located
relative to
the data processor 210. In either case, the user data processor 210 may be
one of a plurality of user data processors and may be connected to a user
interface 220 and a printer 230. An authentication control device 250 may
also be attached to or in communication with the user data processor 210.
The user data processor 210 may be adapted to carry out one
or more of the actions associated with encoding an image. However, the user
data processor 210 may carry out these actions only upon receiving
authorization from one or both of the first validation server 240 and a second
validation server 270.
The first validation server 240 may be programmed to monitor
and control the processing of encoding actions on the user data processor
210. For example, the first validation server 240 may be configured to receive
from the user data processor 210 a request to encode an image using certain
user-supplied encoding parameters and/or authentication indicia. The first
validation server 240 may be further programmed to verify that the user and
the user data processor 210 are authorized to carry out the encoding process
using these encoding parameters and indicia. This verification is conducted
using a first set of authentication criteria that may be established, at least
in
part, by the management entity controlling the first validation server 240.
Upon concluding that the request meets the first authorization criteria, the
first
validation server 240 may return an authorization approval to the user data
processor 210. The user data processor 210 may then send the request or a
modified form of the request to the second validation server 270 via the
second network 280. Alternatively, the first data processor 240 may send the
request or a modified form of the request directly to the second validation
server 270.
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The second validation server 270 is in communication with or
selectively in communication with either or both of the user data processor
210 and the first validation server 240 via the second network 280. It will be
understood that the second network 280 may be the same network as the first
network 260 or may be a different network. In an illustrative embodiment, the
first network 260 is a local network while the second network 280 is the
Internet. In another embodiment, the user data processor 210, the first
validation server 240 and the second validation server 270 are all
interconnected via the Internet.
The second validation server 270 may be programmed to
receive and evaluate encoding authorization requests from any of a plurality
of user data processors 210 and first validation servers 240. The second
validation server 270 may have a variety of user-associated or customer-
associated authorization criteria that may be compared to the data received in
an authorization request from a user data processor 210 or first validation
server. The second validation server 270 may be adapted to verify that the
user and the user data processor 210 are authorized to carry out the encoding
process using the encoding parameters and indicia submitted in the
authorization request. This verification may be conducted using a second set
of authentication criteria that may be based on the terms of any usage
agreement established with the using entity or organization. These criteria
may include limits on the encoding parameters that may be used, limits on the
number of times the encoding software may be used or how long it may be
used (base on an expiration date, for example), limits on the number of
encoded images that may be produced and limits on the content of user-
supplied authentication indicia. Upon concluding that the request meets the
second authorization criteria, the second validation server 270 may return an
authorization approval to the user data processor 210 and/or the first
validation server 240. At the same time, the second validation server 270
may provide certain non-user-supplied encoding parameters and/or
authentication indicia to be used by the user data processor in constructing
the requested encoded image.
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It will be understood that the various encoding actions of the
previously described authentication methods may be divided up so that some
or all of the actions are distributed between the user data processor 210 and
the first and second validation servers 240, 270. It will also be understood
that one or more of the actions of the methods of the invention may be carried
out by the user data processor 210 while one or more additional actions are
carried out by the validation servers 240, 270 as part of or in conjunction
with
the verification/authentication process.
Figure 5 illustrates a general method of controlling the
production of encoded image according to an embodiment of the invention.
The method begins at S105, and at S110, encoding parameters and variable
indicia are received by the data processor running the authentication
software. These may include any combination of user-supplied and non-user-
supplied authentication image indicia and/or encoding parameters. At S120
and S130, a verification is conducted to determine if the encoding parameters
requested by and/or provided by the user fall within previously established
authorization criteria. These criteria may, for example, include predetermined
limits on the encoding parameters that the user may submit. For example, a
user may be permitted to choose only a certain screen frequency or
orientation of an authentication image.
The verification criteria may be established based on terms of
use agreed to by the user. In addition to limits on encoding parameters or
authentication indicia, the verification criteria may include a limit on the
number of uses of the authentication software or the number of encoded
images that may be produced. In either case, an actual number of uses or
images may be incremented each time the software is used. Alternatively, a
time-based limit such as an expiration date may be included.
The authentication software may be configured so that an
attempt by a user to exceed usage limits or to use encoding parameters or
indicia that are outside the terms of use for that user will result in an
error
message being displayed at S135. The error message could be displayed, for
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example, if the user requests an encoded image having a screen frequency
outside the range assigned to the user, if the actual number of uses would
exceed the usage limit for the user, or if the authentication image does not
satisfy predetermined criteria related to its content or dots-per-inch
resolution.
Upon determining that the authorization criteria have not been met, the
method may be terminated. Alternatively, the user may be prompted to
provide input meeting the authorization criteria.
If the authorization criteria are met, the encoding procedure is
authorized at S140. The authentication indicia may then be used to establish
a digitized authentication image (or images) at 5150. If necessary, some or
all of the authentication indicia may be rendered to form a digitized image.
The authentication images may also include non-user-supplied authentication
indicia. At S160, the encoding parameters are assembled into an encoding
parameter set, which may be used to encode the authentication images) at
S170. The encoding parameter set may include non-user-supplied encoding
parameters in addition to any user-supplied encoding parameters. The
resulting encoded image may be stored or embedded into a document as
previously discussed. The method ends at S195.
As noted above the validation and encoding process steps may
be divided among multiple processors including a user data processor and
one or more validation servers. Figure 6 illustrates an exemplary encoded
image validation system 300 that is similar to the system 100 of Figure 3. The
validation system 300 has a user data processor 310 that may be selectively
connected to validation server 340 through a network 370. As illustrated in
Figure 6, the validation methods of the invention may be carried out using
three primary software modules: a client software module 312, a validation
module 342, and an encoding module 314. These modules may themselves
comprise one or more submodules to perform particular functions within a
module or interface with other modules. In the illustrated embodiment, the
client software module 312 and the encoding module 314 are resident on the
user data processor 310 and the validation module 342 is resident on the
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validation server 340. It will be understood that the encoding module 314 may
alternatively reside on a separate encoding processor in communication with
the user data processor 310 over the network 370 or over a different network.
The client software module 312 may be configured to receive
input from the user and is typically executed from the user data processor
310. The client software module 312 may be adapted to use a graphical user
interface through which the user may input data for transmission and
operation by the server software and encoding modules 314, 342. Input from
the user might include the authentication images that the user wants to use as
visible and/or hidden images in the creation of an encoded image. It may also
include user-specified encoding parameters such as the screen frequency or
resolution of the original images and the desired encoded image.
The client software module 312 may be adapted for accepting
the user input and formulating a request for authorization to produce an
encoded image based on that input. This request can be transmitted to the
validation server as described in the previously discussed validation methods.
The client software module 312 may also be adapted to compress the
authentication image files that have been identified for use in creating the
encoded image. Compression of an authentication image produces a
compressed or "thumbnail" authentication image. The original authentication
image (and the resulting compressed image) may be any type of image file,
such as bitmap, JPEG, TIFF or GIF images. Thumbnail authentication
images may be transmitted to the validation server 340 along with the
encoding validation request, and, as will be discussed in more detail
hereafter, can be used by the validation module 342 to generate an image
signature that can be used in a second level of verification.
In the validation system 300, the client software module 312
requests authorization from the validation module 342 and subsequently calls
upon the encoding module 314 to create an encoded image using the
authentication images and encoding parameters approved by the validation
module 342. It will be understood that while the client software module 312
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may be resident on and executed by the user data processor 310, it may
alternatively be resident on a remote server (which may be the validation
server 340) accessed by the user via a web browser or a dedicated client
software module. In this case, the software executed on the user data
processor 310 may be limited to a user interface used to submit information to
request validation and construction of an encoded image.
Figure 7 illustrates a flow diagram of a of a process of obtaining
an encoded image from the perspective of the user data processor and, in
particular, the client software module. The process begins at S205. At S210,
information relating to the desired image encoding is received from a user
through a user interface. The user may also provide user credentials, such as
a username and password, which may optionally be required in order to
obtain authorization of an encoded image. The information provided by the
user may identify one or more authentication images to be used for the
encoded image. These images may be stored in image files identified in any
typical manner of selecting a file from any data storage medium. The user
information may also include encoding parameters to be used in encoding the
authentication image(s).
At S220, the one or more authentication images are obtained by
the client software module. The images will typically be obtained by
retrieving
them from storage based on information provided by the user. Alternatively,
they can be rendered from the user-provided data. The authentication images
may then be compressed into thumbnail images at S230. The thumbnail
images, along with the user credentials (if required) and the encoding
parameters are then transmitted as an encoded image authorization request
to a validation server at a location that may be remote from the user
processor. It will be understood by those of ordinary skill in the art that
the
images sent with the encoded request could alternatively be sent in
uncompressed form. It has been found, however, that there are significant
processing and transmission speed advantages in using compressed image
files.
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As discussed in more detail below, the validation module on the
validation server verifies the user credentials and the encoding parameters
and returns an authorization response. If an encoded image is authorized,
the validation module may also return one or more image signatures
generated from the authentication image and encoding parameters received
in the request. In some embodiments, the validation module will also return
non-user-supplied encoding parameters for use in constructing the encoded
image. In some of these embodiments, the validation module may also
supply a non-user-supplied authentication image for use in encoding an
additional encoded image over which the user does not have control.
At S250 and S260, the client software module receives the
authorization response from the validation server. If the authorization
response is negative, an error message is generated at S265 and returned to
the user. This message may inform the user as to why the authorization was
negative an/or may indicate that the user is to be given another opportunity
to
request authorization for the image creation. If the authorization response is
positive, at S270, image signatures) may also be received from the validation
module. The client software module then calls the encoding module and
passes to it, at S280, the image signatures received from the validation
module along with the original, uncompressed authentication image files, the
encoding parameters designated by the client prior to requesting authorization
and, if appropriate, any encoding parameters or authentication images
received from the validation module. As will be discussed in more detail
below, the encoding module performs a final validation procedure and, if the
result is positive, constructs the requested encoded image. The process ends
at S295.
The validation module may be configured to receive and validate
encoded image requests. Validation may include verifying that the user is an
authorized user of encode images, generally and whether that user is
authorized to receive or produce the requested encoded image. It will be
understood that the functions of the validation module may be executed by a
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single validation server or may be spread across plurality of servers, any or
all
of which may be remote from the user data processor. The validation
servers) may be hosted by an application such as Internet Information Server
from Microsoft, for example.
Figure 8 illustrates a flow diagram of a of a process of validating
an encoded image request from the perspective of the validation server and,
in particular, from the perspective of the validation module. The method
begins at S300. At S310, an encoded image request is received from an
encoded image requestor via user data processor. The encoded image
request may include requestor identification information such as a username
and password as well as image information relating to the encoded image or
images requested. As discussed above, the image information may include
either or both user-supplied authentication images and user-supplied
encoding parameters. Using information from a user database, the requestor
identification information can be used to verify that the requestor is a valid
system user at S320 and S330. If the username and password are not valid,
a negative validation response is returned to the requestor at S345. If the
username and password are valid, a set of predetermined validation criteria
for the requestor are retrieved from data storage at S350. At S360, the
images and encoding parameters received from the requestor are compared
with the validation criteria. If the requested encoding parameters are not
within the ranges specified in the validation criteria, a negative validation
response is returned to the requestor at S345. If the requested encoding
parameters are within the ranges specified in the validation criteria, the
requested encoded image creation is authorized and a positive validation
response is returned to the requestor At S380. For future verification
purposes, the validation module may store a log of each user's activity in the
user database. As shown in the exemplary system 300 of Figure 6, a user
database 352 may be established on a separate database server 350 such as
an SQL server.
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As noted above, the positive validation response may also
include non-user-supplied authentication images and/or non-user-supplied
encoding parameters that will be incorporated into the requested encoded
image. As an additional security precaution to prevent later attempts by the
requestor to change the authentication images or the encoding parameters
after authorization, the positive validation response sent to the requestor at
S380 may include an image signature generated at S370 from the
authentication images passed to the validation module in the encoded image
request. As used herein, "image signature" means any unique numerical
calculation or graphical representation that is calculated or constructed from
an image using a predetermined signature algorithm and that can be used to
compare the content of one image to the content of another image.
In the method of the present invention, image signatures
generated by the validation module using a particular signature algorithm may
be passed to the requestor's user processor where they are received by the
client software module and forwarded to the encoding module. As will be
discussed, the encoding module uses the same signature algorithm to
generate comparison signatures from the authentication images it receives
from the client software module. It can then compare the comparison
signatures to the signatures received from the validation module to determine
if the authentication images and/or encoding parameters have been changed.
The encoding module is the portion of the system that is
executed to create an encoded image using the authentication images and
encoding parameters. The encoding module may execute locally with respect
to the client software module, such as via software installed on the user's
computer. Alternatively, the encoding module may execute remotely, such as
on the computer used to host the validation module. Determining whether the
encoding module should execute locally or remotely may depend on the size
of the encoded images created. The system is capable of creating encoded
images that are of both high and low resolution.
~
.
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A local execution of the encoding module may be preferable
when the encoded image is to be produced from high resolution
authentication images. In such instances, remote execution would require the
original and encoded images to be transmitted across a network, which could
result in the user experiencing long times to send original images and receive
encoded images. High resolution encoded images used in exemplary
embodiments of the invention may be up to 1 GB or larger in size. Thus,
remote encoding may involve prohibitively high processing times. If, however,
data transfer speed is not a concern or if bandwidth is sufficient to transfer
even large files quickly, then remote encoded image creation may be a
desirable alternative.
The client and validation modules are typically developed using
interpreted languages, such as Java, or managed code, such as Microsoft
.NET, that may not provide for sufficient data processing speed and security
against decompiling. Because of this, the encoding module preferably uses a
precompiled, highly optimized set of image processing functions from image
processing code, written in C, C++ or assembly language, and which might be
additionally wrapped in a security envelope, such as one provided by Aladdin
Systems. This may provide for increased processing speeds during the
encoded image creation process, as well as provide additional security from
attempts to decompile the image processing code.
An exemplary method of producing a validated encoded image
from the perspective of the encoding module is shown in Figure 9. The
method begins at S400 and at S410, the encoding module receives the image
signatures passed from the validation module, along with the actual, original
(i.e., non-compressed) images identified by the user as the authentication
images to be used for creating the encoded image. The encoding module
also receives the encoding parameters validated and/or provided by the
validation module when the encoded image creation was authorized.
Upon receiving the image and encoding parameter information,
the encoding module may optionally retrieve locally stored validation criteria
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that is not accessible to the user. In cases where the encoding module is
located in a user data processor, validation criteria may be stored, for
example, in a hardware key attached to the user data processor. The
hardware key may have a separate memory that is accessed by the computer
to verify that the encoding parameters are within the criteria stored on the
hardware key. This assures that the encoding parameters are not altered
after validation by the validation module. The hardware key may also include
limits on the use of the encoding module based on a predetermined number
of uses available to the user or based on an expiration date.
The encoding module retrieves the locally stored validation
criteria at S420 and validates the encoding parameters against these criteria
at S 430. If this validation step is not successful, an error message is
returned at S435. If validation is successful, the encoding module
independently calculates at S440 a comparison image signature (or
signatures) from the original images passed to the encoding module by the
client module. The comparison image signature is calculated using the same
algorithm used by the validation module to calculate the image signature for
the images sent to the validation module. The image signatures) created by
the encoding module are then compared at S450 against the ones) passed
to the encoding module from the validation module. If the signatures do not
match within a certain, pre-determined tolerance, an error message is
returned at S465. If the signatures match within the pre-determined
tolerance, then the final authorization for creating the encoded image is
granted and the encoded image is created at S470. At S480, the newly
created encoded image may then be saved to a data storage medium such as
a disk for later access in creating printing plates. Alternatively or in
addition,
the encoded image may immediately be displayed or printed. The method
ends at S495.
If the images supplied to the validation module for validation are
provided in compressed format, the tolerance range for signature matching
should be established so as to account for differences between an image
~i ,
CA 02490565 2004-12-21
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signature created from an original image file versus one created from a
compressed image file, such as the image signatures created by the
validation module. Alternatively, the encoding module may include the
additional step of compressing the authentication images prior to calculating
the comparison signatures. Another alternative is to have the client software
provide compressed images to the encoding module along with the
uncompressed images. The encoding module would use the compressed
images to calculate comparison signatures and the uncompressed images to
produce the encoded image.
The system 300 of Figure 6 may also include a database
monitoring module 360. For enhanced security, the database monitoring
module 360 may be a standalone module outside of the call functions
connecting the client software, server software, and encoding modules 312,
314, 342. The database monitoring module 360 may be executed by a single
workstation or over a secure local network that in either case preferably has
access only to the server database to keep the database monitoring module
360 separate from the other portions of the system 300. The database
monitoring module 360 can be used by a party other than the user to access
and update information stored in the server database 352, such as adding or
expanding authorized encoding parameters for a particular user and other
managerial functions useful in servicing the database 352.
The system 300 may be established in any development
environment, such as Java or Microsoft .NET, for example. Likewise, the
programming model may use any available model, although three widely
available options include ASP.NET, .NET Remoting, and Web Services. For
example, a model built with ASP.NET or Web Services may be preferable if a
large number of encoding requests and many client access points on diverse
computing systems are anticipated. However, .NET Remoting may be
preferable for more controlled, lower volume, custom-built applications, which
are typically associated with high-resolution images for the protection of
packaging, currencies, stamps, tickets etc.
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Each module of the system may comprise one or more
submodules designed to perform certain functions within a particular module
of the system. For example, the client software module 312 may include a
user interface module 315, a client remoting module 316, and an encoding
interface module 317.
The user interface module 315 may be a graphical user
interface. This interface is the portion of the system that the client sees on
his
computer screen and that is used to collect encoding and communication
parameters. Encoding parameters may include the number or orientation of
the encoded images to be created, while communication parameters may
adjust how the client software module connects with the validation module
342 to authorize the creation of the encoded images.
The client remoting module 316 of the client software module
312 manages communications with the validation module 342. Similarly, the
encoding interface module 317 communicates with the encoding module 314
and is responsible for passing information to the encoding module 314
received by the client software module 312 from the validation module 342 as
well as the information from the client software module 312 itself. It can
also
send information from the encoding module 314 back to the client software
module 312, such as encoding progress information, or encoding error
messages.
The validation module 342 may include submodules such as a
server remoting module 344 that manages communications to and from the
client software module 312 and a database interface module 346 that
manages communications with the server database 352 to log client activity
on the validation server 340. The validation module 342 may also include a
data processing module 348 that processes information received by other
modules and submodules of the system 300.
If a database monitoring module 360 is used, it may also include
several submodules. Typical submodules may include a user interface
module 362 for use by the party accessing the monitoring application module
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to view database records, client reports, and other stored information. A
database interface module 364 manages communications with the database
352 to retrieve information provided to the user interface module 362. A
database administration module 366 may be used to handle administrative
functions, such as storing usernames and passwords, performing database
backups and other administrative type functions useful for the maintenance of
the database 352.
The functions of the primary software modules discussed above
may be executed in various combinations on different computers to create a
multi-furcated system that separates the software modules into client-side and
business-side applications. It will be understood that one or more users may
access the system through computers connected to the Internet. It should be
appreciated that although the Internet may be the most readily accessible
network over which the modules of the system communicate, any network of
computers may be used. As discussed previously, if the user computers
include the encoding module, the computers may also have a security key
attached, such as the HASP key available from Aladdin Systems.
User computers carrying out the methods of the invention may
connect to a web server across the Internet through a first firewall. The web
server can then access information in a database server through a second
firewall to obtain and/or record information. The database server may also be
connected to a monitoring module that may include one or more workstations
and an exchange server useful for accessing the database server to monitor
the status of incoming and outgoing communications from the database
server.
The systems and methods of the invention provide multiple
levels of security with respect to preventing unauthorized use by a
counterfeiter or keeping a user from creating encoded images outside of the
authorized encoding parameters may be accomplished in several ways.
Additional protection may be established through the use of a hashing
function to create the described image signatures for the images that the user
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intends to use to create the encoded image. A hashing function assigns a
compact digest or signature to transmitted data that may then be compared
against an independently created signature to analyze whether or not the data
was tampered with during transmission. Some examples of hashing functions
known in the art are MD2, MD4, MDS, SHA, and SHA-1.
As discussed above, in some embodiments of the invention, an
authentication image designated by the user is transmitted to the server
software module in thumbnail (i.e., compressed) form. During verification, the
server software module produces a signature for the transmitted image and
returns it to the user along with the verification. The encoding module
independently produces a signature for the same but uncompressed image,
which may then be compared against that returned by the server software
module. If the image the user attempts to use for creating an encoded image
is not the same as that authorized by the server, the signatures will not
correspond and the system will not process the request to create the encoded
image.
Any signature algorithm may be used in the methods of the
present invention. There are, however, certain signature characteristics that
enhance the security performance and processing speed of the invention.
When dealing with high-resolution images, for example, an image signature is
preferred that does not change significantly when the image is subjected to
strong and/or poor fidelity image compression. Such compression is often
desirable in order to reduce the amount of information that must be
exchanged over a network during the remote verification process. The
signature calculation also preferably has a high execution speed to avoid
unnecessary delays in receiving the server response, delays in the pre-
encoding signature calculation or in the comparison of the signature created
in the server software module. Notwithstanding the desirability of the above
characteristics, the signature algorithm should also be sensitive enough to
allow detection of significant modifications to the images. The hashing
functions mentioned above may be extremely sensitive to any modification of
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the protected image, but also have low tolerance to poor compression
algorithms. Signatures based on the image content descriptors, including, but
not limited to morphological features, color and brightness histograms etc.
can
be constructed to withstand significant levels of compression, and still be
sensitive enough to detect even a small modification of the image. Signatures
may be constructed as either reversible or irreversible transformations,
though
the use of the latter tends to enhance the speed of the overall process.
The above-stated signature goals may be achieved by
constructing the image signatures using image projection on the specified
axis. The image is thresholded first and the number of foreground pixels is
calculated for every point on the given axis, thus creating a signature. To
make the signature more robust relative to compression losses, the image
can be divided into a predefined number of stripes and the number of
foreground pixels is then calculated for each stripe, instead of for each
point
on the axis. The calculated values are normalized to keep the signature
shape independent of the image size. To improve the sensitivity to image
modification, projections on several different axes can be used.
The image signature calculated by the server software module
may be based on compressed images received from the client software
module, which in some embodiments of the invention may be compressed
JPEG images. The image signature calculated by the encoding module uses
original, uncompressed files. This may result in reduced processing time and
simplified communication between the user interface, remoting code, and
image processing code that creates the encoded image. This may further
result in a small difference in values between client and server generated
signatures that has to be accounted for during the signature comparison. The
absolute value of the error is calculated for every value of the signature.
These error values are then normalized and the mean is calculated. If the
mean error is bigger than the predefined tolerance level, the images are
considered to be corrupted or swapped. This results in the validation step
failing and an error message returned.
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In some embodiments of the invention, the thumbnail images
being sent to the software server module may be packed together into a
single data structure before being sent by the client software module. This
assures that the digital information is all received by the server at the same
time. Similarly, the signatures created by the validation module for all
images
may be packed together into one data structure before being sent back to the
user computer.
In some embodiments, when the server software determines
that a request is not valid, the validation module may assign a default
signature, such as zero, that will not match any signature created by the
encoding module. This results in the encoding module denying any
processing of the encoded image.
The use of a security key in some embodiments may allow the
use of symmetric key encryption in the transfer of information across the
network. This may be advantageous in providing faster communications while
still keeping the data encrypted.
Yet another level of protection that may be instituted individually
or in combination with the other discussed security features is a secure
Internet connection, such as a Secure Sockets Layer, to provide secure
communications between the client software module and the validation
module.
Additional security features may be implemented, such as using
two separate servers to perform the functions of the validation module. For
example, a first server may be a web server, separated from all client-side
modules (the client software module and in some cases, the encoding
module) by a firewall. The web server is the initial server with which the
client
software module communicates when sending a request for remote
verification. The web server may also be used to add new records to the
database. The web server may then be connected to a second server
through another firewall. The second server is the database server that
provides the primary data storage used to verify and authorize the creation of
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encoded images by the client. Although the use of two servers may be
advantageous in some circumstances, it will be understood that this is not
required and the database server and the web server could in fact be a single
computer with no firewall protection between them.
It will be understood that communications channel and data
formatting for remote transmission of data may vary depending on the desired
functionality of the system. Typical protocols for the transmission of data
include HTTP and TCP. The use of TCP may result in significantly faster
transmission, although third party or client firewalls and proxy servers may
hinder or block TCP communications, such that HTTP may be an acceptable
or even preferable alternative in Internet environments. Data formatters may
include SOAP, binary or custom formatters.
It will be readily understood by those persons skilled in the art
that the present invention is susceptible to broad utility and application.
Many
embodiments and adaptations of the present invention other than those
herein described, as well as many variations, modifications and equivalent
arrangements, will be apparent from or reasonably suggested by the present
invention and foregoing description thereof, without departing from the
substance or scope of the invention.
While the foregoing illustrates and describes exemplary
embodiments of this invention, it is to be understood that the invention is
not
limited to the construction disclosed herein. The invention can be embodied
in other specific forms without departing from the spirit or essential
attributes.
