Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD FOR AUTHENTICATING OBJECTS IDENTIFIED BY
IMAGES OR OTHER IDENTIFYING INFORMATION
TECHNICAL FIELD
The present invention relates generally to
techniques for preventing counterfeitir.ig or otherwise
illegal use of documents (e.g., titles, licenses, proofs
of insurance, etc.), especially documer.tts relating to
personal property such as a vehicle.
BACKGROUND OF THE INVENTION
Vehicle theft is a major crime problem, especially
in urban areas. One contributing factor to this problem
is the ease with which stolen vehicles or their parts can
be recycled in the marketplace. As is well known,
manufacturers place or engrave a so-called vehicle
identification number (VIN), which is unique to the
particular vehicle, on the engine and all major parts to
facilitate identification. The VIN is sometimes
identified on the vehicle title, which is normally a
conventional paper document issued by the particular
governmental authority having the appropriate
jurisdiction over the vehicle. The other standard
vehicle identifier is the vehicle's license plates.
Currently, titles, VIN's and license plates are quite
unrelated to each other, thereby contributing to the ease
with which an unauthorized party can recycle a stolen
car.
There has therefore been a long-felt need to
overcome these and other problems associated with
securing documentation associated with personal or real
property.
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BRIEF StJNIlMARY OF THE INVENTION
The present invention provides a niethod and system
for creating secure "titles" for persor.ial and real
property.
In accordance with exemplary embocliments of the
present invention there is provided a ntethod for enabling
a given authority to secure valuable documents (such as
titles, licenses, passports, registrations, etc.) from
alteration and fraudulent use.
In addition, enhanced techniques to prevent legal
titles or other documentation from beir.ig counterfeited or
otherwise illegally altered are provided.
The present invention also provides for the use of
public-key cryptography methods and systems to secure
title documentation of any personal or real property
wherein such property is identifiable by a unique
identifier and for digitally-secure physical or virtual
titles to thus facilitate the transfer of personal or
real property.
In an exemplary embodiment, a title according to the
present invention includes an identifier uniquely
associated with the personal or real property to be
identified (e.g., a vehicle identification number), and
information directly or indirectly identifying the legal
owner of the property. The identifier and the
information are preferably concatenated. into a data
string which is then digitally signed using a secret key
of a public-key cryptosystem pair. To verify the title,
a transaction terminal uses a corresponding public-key to
decrypt the data string.
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The method and system of the present invention thus
utilizes public-key cryptography to create "secure"
titles for personal and real property such as vehicles
and the like. The title preferably comprises a card in
which is stored a digital signature of one or more
identifiers such as a vehicle identification number, the
vehicle license plate and the owner's name. To effect a
transfer of the property, the digital signature on the
title must first be shown to have been generated from the
one or more identifiers.
Certain exemplary embodiments can provide a method
for authenticating an object identified by a data string,
the data string including a digitized image of the
object, comprising the steps of: generating a signature
of the data string using a private key of a public-key
cryptosystem pair, the public-key cryptosystem pair also
having a public key M; decrypting the signature using the
public key M of the public-key cryptosystem pair; and
comparing the decrypted signature with the digitized
image to thereby authenticate the object.
Certain exemplary embodiments can provided a method
for authenticating an object identified by a data string,
the data string being stored on a storage media and
including at least a digitized image of the object,
comprising the steps of: receiving the storage media and
generating a signature of the data string using a first
key of a cryptosystem pair, the cryptosystem pair also
having a second key; decrypting the signature using the
second key of the cryptosystem pair; and comparing the
decrypted signature with the digitized image to thereby
authenticate the object.
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BRIEF DESCRIPTION OF THE DRAWINGS
For a more complete understanding of the present
invention and the advantages thereof, reference should be
made to the following Detailed Description taken in
connection with the accompanying drawings in which:
FIGURE 1 is a schematic representation of one type
card "title" according to the invention; and
FIGURE 2 is a block diagram of a representative
multi-issuer system according to the present invention.
DETAILED DESCRIPTION
The techniques described below are useful
to provide titles or other documentation that are
"secure", i.e., titles that cannot be counterfeited
or illegally changed in any feasible way. Although
the technology is described in the context of
securing vehicle titles, the present invention is not
intended to be limited to such particular
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application. It should readily be appreciated by
those of skill in the art that the present invention
has direct applicability to secure any and all kinds
of titles and documentation (e.g., registrations,
licenses, proof of insurance or inspection, proof of
identity, etc.) and the invention should be and is
intended to cover any and all such types of
documentations, whatever their particular purpose or
association may be. Thus, for example, the
invention is useful to secure titles of all types of
property including, without limitation, precious or
semiprecious gems or stones, paintings, antiques,
artifacts, art objects, firearms or guns, or any
other object whose particular authenticity needs to
be verifiable for whatever purpose the owner or
transferor desires. Of course, the techniques are
also useful in connection with real property such as
deeds, surveys, and the like.
According to the present invention, so-called
"digital signatures" are used to bind in an
untamperable way certain quantities associated with
a piece of personal or real property to thereby
realize a "secure title" for the property. Digital
signatures provide high security for the system at
generally low cost. In the preferred embodiment of
the invention, a digital signature is derived from a
data stream (which will be described below) using a
private or secret key of a "public-key cryptosystem"
key pair. A "public-key cryptosystem" is a
well-known security scheme which includes two
"keys," one key which is public (or at least the key
pair owner does not really care if it becomes
public) and one key which is private or non-public.
All such public-key cryptosystem pairs include a
common feature -- the private key cannot be
determined from the public key. One such scheme is
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described mathematically in U.S. Patent: No. 4,995,081.
By way of further background and with reference to
FIGURE 1, a "title" card 10 is provided for maintaining
the digital signature as well as perhaps other
identifying information as will be described. The card
is conventional in the physical sense that it includes a
body portion 12 and a memory 16. A display 14 may also
be provided. Although not meant to be limited, the
memory 16 is preferably a magnetic strip or similar
media, or an electronic memory such as a PROM, affixed to
or embedded in the card in a known manner. The card 10
may or may not include a programmable microprocessor
embedded in the body portion. Some portion of the memory
may be "protected" against access such as described in
the prior art. Such "protected memory" or similar data
carrier products are available in the marketplace from
such manufacturers as Innovatron. The card 10 may
alternatively be any type of smart, magnetic, laser or
other type of data carrier.
With reference to FIGURE 2, in the preferred
embodiment, an issuing terminal 76 includes a
microcomputer 80 and associated memory devices 82 for
storing operating programs and application programs for
carrying out the invention. Input/output devices, such
as a keyboard 84 and display 86, are provided for
interfacing the terminal to the card issuer. One or more
transaction or "verification" terminals 78 may also be
provided for the purposes to be described. Such
terminals preferably include a microprocessor 88,
associated memory 90 and appropriate input/output devices
such as a cardreader 92, keyboard 94 and display 96.
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Now assume that it is desired to secure a
vehicle title and that such security is desired by
an Insurance Company. According to the invention,
the Insurance Company or other suitable authority is
provided with an issuing terminal to produce a
digital signature of a bit stream on a card 10.
That is, the Insurance Company has a public
(verification) key and a matching private (signing)
key, and the public and privatekeys form a key set
of a public-key cryptosystem. To digitally sign a
bit stream X, the Insurance Company (using its
secret key) computes a second bit stream X' and
writes it along with X on a card. X' mathematically
vouches that the Insurance Company has "approved"
the string X because:
1. everyone, given X and the Insurance
Company's public key, can verify (e.g.,
using a transaction terminal) that X' is
the Insurance Company's digital signature
of X, and
2. no one, without the right key, can forge
the Insurance Company's digital signature,
Y', of a new string Y.
The use of public-key cryptography for this
application is particularly advantageous because
different bit streams have different digital
signatures and because changing a single bit in an
already signed bit stream causes the new,
corresponding signature to change in a dramatic and
unpredictable way. Thus a digital signature can be
thought of as a very special sequence of "control
bits."
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According to the invention, the title of a car
whose VIN number is X, will preferably comprise a
card 10 containing the Insurance Company's digital
signature, X', of X (and possibly also X itself).
This card can be inserted in a transaction terminal,
which reads the information written on the card and
checks that X' is the Insurance Company's digital
signature of X. (Indeed, all such units will
possess the Insurance Company's public verification
key.) No one can, however, make a fake title for a
stolen car, since the thief will not know the
Insurance Company's secret signing key.
The above technique is enhanced by
incorporating the vehicle's license plate number.
For instance, if a car has a VIN number V and a
license plate number L, let X be the number obtained
by combining V and L (e.g., by concatenating V and
L). Then the title will comprise a card containing
the number X', the Insurance Company's digital
signature of X. This way it will be impossible for
an imposter to replace the license plate of a stolen
car, since for any new number L', X' will not be
the Insurance Company signature of XL'. The
technique of course also allows for "personalized"
license plates in lieu of or in addition to the
plate number L.
In this manner the license plate number or
other identifier is securely tied in the title. It
should be appreciated that once a secure title of
this form has been verified to be authentic, even if
it was stolen with the car, it allows someone, e.g.,
a policeman or other government authority, to
quickly verify that a car has been stolen by
verifying whether a given license number has
reported to be stolen. This solves the common
problem where, by taking away the license plate of a
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car not reported stolen (or not stolen or all) and
mounting it on a stolen car, a thief may have a
stolen car appear legitimate.
The system is yet further enhanced by
incorporating the name of the car's owner. For
instance, if a car has a VIN number V and a license
plate number L, and its owner's name is N, then the
title preferably comprises a card containing the
number X', the Insurance Company's digital signature
of the number X obtained by concatenating V, L, and
N (and possibly some of V, L, and N themselves).
This embodiment has many advantages. For instance,
the owner can prove ownership of the car by
providing the new title and a personal ID showing
that his/her name is N. By securely including the
name of the owner, an important advantage is
provided because when the car is legitimately sold
the owner must be present. Besides the owner's
name, the Insurance Company may include in the title
other information about the owner; e.g., the names
of other authorized drivers.
More generally, besides V (or L, or N), the new
title can contain an arbitrary information string,
I. This string is digitally signed by the Insurance
Company together with V (and/or L and N); that is,
the new title will contain the Insurance Company's
digital signature of the string VI. As described,
string I may consist of L or N, or both, but may
also be, for example, a description of the car or
even a digitized image of the car. This may be
useful, in case of accidents, to establish how the
car "looked like" before and after an accident or
other repair. The information string may include
other important information about the vehicle such
as an odometer reading or times and dates of service
visits.
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Several variations of the above techniques are also
envisioned by the present invention. For instance,
rather than the name of the owner, N, the new title may
incorporate a string f(P), where P is a password known to
the owner (and preferably only to the owner), and "f" is
a one-way function. One-way functions are functions that
are easy (for everyone) to compute but hard (for
everyone) to invert. That is, if "f" is such a function,
everyone can, given, say, a number A, if it is long
enough. Indeed, a brute-force search for A would require
astronomical time even with the most modern and
sophisticated computers if A consists of 100 digits or of
a long enough sentence.
Now assume that a new car has a VIN number V and
license plate number L. According to the invention, the
first legitimate owner of the car chooses a suitable
large alphanumeric string A (e.g., his/her mother's
maiden name) and sets f(A)=B. Then the number X is
obtained by concatenating V, L and B, and the title will
contain the Insurance Company's digital signature, X', of
X. In this manner, only the legitimate owner can prove
that he/she owns the car, since only he/she knows A. To
verify ownership, one may in fact check that X' is the
Insurance Company's digital signature of X=VLB, and then
ask the alleged owner for the value A, and verify that
indeed f(A)=B.
One advantage of this scheme is that the entire
ownership history of a car can be certified without
revealing the names of the owners. For instance, the
first entry on the title contains the Irisurance
Company's digital signature of X=VLB as above. When
the first owner wants to sell the car, he/she will
reveal to the Insurance Company the value of A (such
that f(A)=B), while the new owner will chose a value
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such that f(C)-D. Then a second entry is added to
C
the title containing the (possibly new) Insurance
Company's digital signature of the concatenation of
V, L (or possibly a new L', as when the second owner
wants a personalized license plate), A and D. That
is, the second entry certifies that the car has been
legitimately sold once. In fact, anyone can read A
from the second entry and verify that f(A)-B, the
value unalterably bound to V in the first entry.
This means that the first legitimate owner has
consented to the sale, since he/she has willingly
revealed the correct and unpredictable value A. The
second entry may actually replace the first one (or
the old title is destroyed and a new one is issued
only containing the second entry). Successive sales
are handled in a similar manner. The new buyer is
thus always informed of the number of previous
owners. It is thus possible to count the number of
values B, D, etc. that are added to the title at
each sale. Such a title can be conveniently left in
the automobile, since stealing it will not enable a
thief to sell the vehicle in a legitimate way; he
will not be able to reconstruct the value A from B
(if the car had only one owner when stolen), or the
value C from D (if the car had two owners), etc.
An alternative method for obtaining similar
benefits may be used if the digital signature
adopted is such that a signature X' for a string X
does not betray X, that is, if X cannot be
reconstructed from X'. In this case, the new title
may consist of, say VI (where I is the information
string) and the Insurance Company digital signature,
X', of VIA (where A is a string known to the
owner). Thus, if the owner willingly provides A,
anyone can verify that X' is the Insurance Company's
digital signature of VIA, thereby verifying that
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both V and I have been certified, while: without the
cooperation of owner X' is quite useless.
As for another variant, if the title comprises a
smart card, rather than sending or otherwise exhibiting
or making available to the transaction terminal the
digital signature of the relevant information, the card
may simply "convince" such apparatus that it contains
(e.g., in a protected area of the chip) the relevant
signature, without explicitly giving it. One such
technique for establishing such proof of legitimacy is
described in U.S. Patent No. 4,995,081.
Alternatively, rather than using a digital signature
that can be universally verified (e.g., by means of a
public verification key), the title may contain a private
digital signature, that is a string that can be verified
by a selected group of people (e.g., those who know, or
whose verifying apparatuses know, a given secret key).
This is a so-called private-key cryptosystem.
According to another embodiment of the invention, it
is not required that the titles be specific physical
objects (e.g., a magnetic, laser, or smart card). The
advantages of the present invention can also be realized
in a virtual manner, for instance, by means of an
accessible database. As in the previous examples, the
database preferably contains VINs digitally signed by a
proper authority (and possibly by different authorities,
each having a different signing scheme and different key,
both public and secret). To verify the legitimacy of a
title, an inquiring party (e.g., an insurance agent,
policemen, a bank officer wishing to verify the
information concerning collateral, departments of motor
vehicles, etc.) can query the database with,
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say, a given VIN V, and receive in return a pair
(V,S), where S is the digital signature of V by a
specified authority. The querying party can then
verify that S is a correct digital signature of V
for the specified authority, whose verification key
is publicly known. Thus, while the database can be
made widely queriable, preferably only the proper
authority can insert data therein. In fact, even
assuming that a malicious party were able to
illegally insert a given VIN V into the database, he
would not be able to forge the digital signature of
V (by the proper authority) that should be stored
together with V and should be retrieved in case of a
query. Without this signature, inserting V into the
database is essentially useless, since V alone will
not be accepted or believed by the querying
parties. This security aspect is particularly
attractive in that it protects a large and
distributed database so as to make sure that no one
can illegally write his own data in such database.
While described in the context of a vehicle
title, it should be appreciated that the method
extends to all other kinds of titles, when the
object(s) of interest possess a string that, like
the VIN, acts as a unique identifier of the object.
Sometimes this unique identifier can be constructed
ad hoc. For instance, in the case of a land title
the string in question can be obtaining by writing
down a sufficiently detailed English description of
a given lot. This English string can then be
digitized if desired.
It should be appreciated by those skilled in
the art that the specific embodiments disclosed
above may be readily utilized as a basis for
modifying or designed other structures for carrying
out the same purposes of the present invention. It
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should also be realized by those skilled in the art
that such equivalent constructions do not depart
from the spirit and scope of the invention as set
forth in the appended claims.
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