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Claims  |
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We claim:
1. A system for limiting reproduction of an electrically representable
process comprising:
process means for storing symbols U representative of a series of
operations performable by a plurality of electrical signals U';
symbol generating and storage means for generating and storing a plurality
of test symbols V representative of a go/no-go test and performable by a
plurality of signals V';
storage means responsive to said process means and said symbol generating
and storage means for storing a composite W of symbols U and V;
first translation and memory means for translating said symbols W, stored
by said storage means into digitally encoded electrical signals W',
including signals U' and V', representative of symbols U and V,
respectively, and storing these signals;
key generating means comprising means responsive to symbols having, in
part, a common derivative to that of said test symbols V for generating
key symbols K;
second translation and memory means for translating symbols K, from said
key generating means, into electrical signals K' and storing same;
signal processing means responsive to the receipt of said signals U' for
the performance of said series of operations;
coupling means responsive to a selected input signal for coupling said
signals U' from said first translation and memory means to said signal
processing means; and
a process limiting means comprising:
correlation means including means for effecting a selected correlation
between aspects of said signals V', from said first translation and memory
means, and signals K', from said second translation and memory means, and
for providing a correlation output signal which is a function of said
correlation;
and
signal means responsive to a selected output of said correlation means for
providing an input signal to said coupling means;
whereby, upon said selected output of said correlation means, the
performance of said series of operations is enabled.
2. A system as set forth in claim 1 wherein:
said system includes lock identity code generating means for generating a
selected class of electrical identification signals C' representative of
identification symbols C;
said symbols to which said key generating means is responsive have a common
derivative to that of said identification symbols C;
said process limiting means includes electronic locking means in turn
including memory means responsive to said lock identity code generating
means for storing said signals C';
said correlation means comprises a portion of said electronic locking
means, and includes means further responsive to a selected correlation
between signals C' and K' for providing said correlation output signal.
3. A system as set forth in claim 2 wherein:
said key generating means includes means for generating symbols A and B,
representative of a selected real time period, and includable in said
symbols K;
signals A' and B", representative of said symbols A and B and said selected
real time period, are stored via said second translation and memory means;
said electronic locking means includes time generating means for generating
signals T" indicative of current time; and
said correlation means comprises means responsive to a correlation between
the said T" signal, output of said time generating means, and said A" and
B" signals, aspects of said signals K', for enabling said correlation
output signal of said correlation means.
4. A system as set forth in claim 3 wherein:
said symbol generating and storage means comprises means for generating
said storing, as test symbols V, identity symbols S, algorithm symbols R
directive of the generation of a random number X, represented by signals
X', and algorithm symbols M directive of a selected combination of said
symbols S and random number X;
said first translation and memory means comprises means having stored
therein, as signals V', electrical signals S', R', and M', representative
of symbols S, R, and M, respectively;
said key generating means is responsive to said symbols S, and signals S",
representative of said signals S, are includable in said signals K' stored
in said second translation and memory means;
said electronic locking means comprises:
discrete, independent signal generating means for generating signals M",
representative of said symbols M, and
said means for effecting a selected correlation between aspects of said
signals V' of said correlation means is responsive to said signals X' as
an aspect of said signals R' from said first translation and memory means
and signals S" as aspects of said signals K' from said second translation
and memory means and said signals M" from said signal generating means for
generating a first correlatable output signal F"; and
said signal means comprises:
signal combining means responsive to said signals X', S', and M' from said
first translation and memory means for providing an intermediate signal
output representative of a like response to that effected by said
correlation means with respect to signals X', S", and M" for generating a
second correlatable output signal F'; and
comparator means means responsive to a selected relationship between said
correlatable output signals F' and F" for providing said input signal to
said coupling means.
5. A system as set forth in claim 4 wherein:
said symbol generating and storage means includes means for generating and
storing symbols N as elements of symbols V;
said system includes a digital computer, wjhich in turn includes said first
and second translation and memory means, and said first translation and
memory means having stored therein electrical signals S', R', N', and M',
representative of the symbols S, R, N, and M, respectively;
said key generating means is responsive to said symbols N and S, and
signals N" and S", representative of signals N and S, are included in said
signals K' stored in said second translation and memory means; and
said correlation means comprising a portion of said electronic locking
means is additionally responsive to a selected correlation of said signals
N', as aspects of said signals V' from said first translation and memory
means, and signals N" as aspects of said signals K' from said second
translation and memory means for enabling the generation of said
correlation output signal.
6. A system as set forth in claim 5 wherein:
said lock identity code generating means includes means responsive to
discrete symbols P and Q for generating signals C';
said key generating means comprises means responsive to signals
representative of said symbols P and Q for generating said symbols K and
thereby signals K';
said key generating means is further responsive to signals representative
of discrete symbols D for the generation of symbols K and thereby signals
K';
said electronic locking means includes discrete, independent means for
generating signals D' representative of symbols D; and
said correlation means comprising a portion of said electronic locking
means is futher responsive to a selected correlation between said signals
D' and said signals C' for providing said correlation output signal.
7. A system as set forth in claim 2 wherein:
said electronic locking means includes a container means for enclosing at
least said memory means, and
electrical control means coupled to said container means and said memory
means for altering said signal C' upon an entry into said container.
8. A system as set forth in claim 7 wherein said electrical control means
includes bias means for supplying an operating bias to said memory means,
and including means responsive to entry into said container means for
interrupting said bias and thereby altering said signal C'.
9. A system as set forth in claim 4 wherein:
said correlation means comprises:
first conversion means for complementing bits of a first group of selected
bytes of signals S", in instances where corresponding bits of signal X'
are set, to provide a signal Y",
first multiplication means responsive to said signals S" and Y" for
multiplying signal Y" by a second group of selected bytes of signal S" to
provide a signal Z", and
first division means responsive to said signals S" and Z" for dividing
signal Z" by a third group of selected bytes of signal S", and for
providing as an output a signal representative of the remainder from the
division, and being said first correlatable output signal F";
said signal means comprises:
second conversion means for complementing bits of a first group of selected
bytes of signals S', in instances where corresponding bits of X', as per
the selection of said first conversion means with respect to signals S",
are set, to provide a signal Y',
second multiplication means responsive to said signals S' and Y' for
multiplying signals Y' by a like second group of selected bytes of
selected signals S' to the order of selection of said second group with
respect to said signal S" by said first multiplication means to provide a
signal Z', and
second division means responsive to said signals S' and Z' for dividing
signals Z' by a like third group of selected bytes of signal S' to that
provided said first division means with respect to signal S", and for
providing a signal representative of the remainder of said last-named
division, and being said second correlatable output signal F'. |
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Claims |
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Description |
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FIELD OF INVENTION
This invention relates to devices and systems for preventing a digital
computer from executing a program unless means auxiliary to the computer
authorize it.
BACKGROUND OF INVENTION
The applicant has found, from a study of the field, basically three
suggested mechanisms for the protection of software products against
non-licensed use. The first one is simply a contract between the software
producer and user wherein misuse creates rights for the recovery of
damages or specific penalties for misuse. A second one is the display of
the licensee's name or other unique information on a CRT screen or
printout which publicizes the terms of the license and to some extent
provides a deterent against use by other than a licensee. The third one is
applicable to cases where a program is to be run on a computer into which
is incorporated an identification number. Thus, a software manufacturer
may incorporate into its software product instructions that the product
can only be employed with a computer bearing that identification number.
While the first two measures offer some protection against the illegal
resale of software products, they generally do not prevent the sharing of
licensed products among closedly related users. Furthermore, with respect
to the first one, it may not be effective at all in countries where
procedural or substantive law prevents the enforcement of a particular
contract (even in this country, little known enforcement has been
evidenced).
The second and third approach suffer from the requirement that software
distribution must be customized for each buyer, and while this may seem
simple, it has proved to be logistically difficult in practice.
The third approach is perhaps the most effective one, and for computers
which can read out identification numbers, it can be implemented in a
standardized fashion. However, most computers do not contain built-in
identifications which can be read by a program. In such cases, special
purpose identification devices must be supplied. Unfortunately, there are
no standards for such devices, and the use of a different identification
device for each product is unwieldy and generally leads to incompatibility
when more than one such product is to be used on the same computer. Also,
simple hardware identification readouts are easy to defeat.
Accordingly, it is the object of the invention to: (1) provide a software
protection system which effectively guarantees that a given software
product cannot be used on an unauthorized computer, (2) be both convenient
and simple to use with any computer system, and (3) be compatible with
usage by a computer of other software products, which may either be
adapted to be protected by the system, or may not be. In other words, no
limitations are placed upon a computer by virtue of the employment of the
present system.
SUMMARY OF THE INVENTION
This invention contemplates a digitally encoded program or process which is
electronically stored or storable in a memory associated with a computer
or process controller such as might control a proprietary industrial
process. As a matter of convenience of description, the present system
will be described in terms of the control of a computer, but it is to be
appreciated that both type devices are intended by such reference.
The signal makeup of the program or process stored, or to be stored, is
modified by the inclusion in it of procedures V to generate certain
signals V', which, by themselve, inherently interfere with the normal
performance, "running", of the program (or process) by the computer (or
process controller) and call for an external authorization to eliminate
the interference.
Separate from the computer, a "lock mechanism, equipped with a unique
identifying number C, (which defines signals C') is employed, and it is
uniquely equipped to facilitate the requests for and the provision of
"run" authorizations. Further, a set of "key" signals K', representing a
number K derived at least in part from bases common to signals V' and C',
are supplied to a memory accessible to the lock. As a first function, the
lock obtains the key signals K' and makes a comparison of them in terms of
the lock identity number C, and if signals K' bear a selected correlation
to signals C', at least a portion of the information in signals K' are
caused to be stored in a memory in the lock. These stored signals are thus
made available as, in effect, signals for the processing of subsequent
"run" authorization requests from the computer, which are in the form of
signals V' as described above.
When a "run" authorization request is generated, the lock causes a
correlation process to occur involving elements of signals V' and K', and
when the selected correlation is present, the "running" of the stored
program or process involved is enabled. In the absence of the selected
correlation between signals, V' and K', the stored program or process will
not be authorized to "run".
As an added feature of this invention, the key signals K' would include
signals representative of a selected time period, A to B, during which the
signals K' would be effective, and the lock would include a current time
generator for the generation of a current time signal T". A comparison
would be made by the lock between the authorization period signals, A' and
B', and current time signals, T", and thus, limit the time during which
the lock could enable "running" to the time period indicated by the time
expressed in signals K'.
A minor modification of this software protection system would be a system
in which many locks were assigned the same identity code C, and in which
the keys K were distributed in a form which was difficult to reproduce
(such as a magnetically encoded card). This "special case" implementation
of the invention would not provide as high a level of security, but its
simpler logistics might be desirable in certain applications.
It is to be appreciated that the alphabetical designation of signals and
symbols used herein is employed only for convenience of description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic illustration of a portion of the system of this
invention wherein the protected program, key, and lock identity are
developed.
FIG. 2 is a block diagram illustrating the computer and also the lock
mechanism which is a basic part of the system of the invention.
FIG. 3 is a pictorial view, partially cut away, of a structure of the
invention and illustrating a security feature of it.
DETAILED DESCRIPTION OF THE DRAWINGS
Referring to FIG. 1, the collection of elements labeled (1) is illustrative
of means for the generating of discrete data sets of terms identified as
N, S, R, M, A, B, D, P, Q, C, E and K, which are employed in the operation
of the system of this invention. Depending upon the complexity of the data
set, as will be further explained, the generators may vary from what
amounts to essentially no calculations, that is, the simple choice of a
number, to the determination of plurality of data sets indicative of
instructions for the performance of a selected algorithm by a general
purpose computer or other form of programmable computational device.
While, as an aid to an appreciation of the different data sets, individual
generation elements are shown in FIG. 1, it is to be appreciated that the
function of all may be discretely performed by a single general purpose
computer. As shown, the data set or terms are produced by one of the
generating elements as follows:
User program identity number designator 2 generates a number N which is a
three-byte, randomly chosen, non-secret number destined for a particular
software protection program V, a part of a computer program to be supplied
to a software owner for incorporation into a particular software product
U, producing a protected program W. When incorporated, N is used as an
address for a content-addressable memory 35 in the lock 22 of FIG. 2, as
will be further discussed.
User program identity code designator 3 generates an identity code S, being
a 24-byte number, randomly chosen. It is utilized in two forms, in the
protection program V and in a software key K separately provided the
software owner for use with the protected program W. The number S is kept
secret from all but the owner of the program U to which it is to be
applied. It and its processing play a vital part in the security aspects
of this invention.
Random number algorithm designator 4 generates a series of program
instructions R for the performance by a digital computer of a selected
algorithm for the computation and generation of signal X', representative
of an eight-byte random number X. A typical example of this algorithm R
would be one which would instruct a computer to determine X' from any data
continuously varying in the computer, such as time of day in fractions of
a second. This random number is used with secret number S to enhance
security of the system. Signal R is embodied in protection program V.
Combiner algorithm designator 5 generates a term M which comprises a series
of computer program instructions for the performance of a second
algorithm, as an example, the instructions would be: (1) Separate the term
S into three 8-byte quantities: SA, SB, and SC, (2) For each bit which is
set in X, the corresponding bit in SA is complemented to provide Y, (3)
The 8-byte result is multiplied by SB to provide Z, (4) The 16-byte
product of step 3 is divided by SC yielding an 8-byte remainder of which
the fifth, sixth, and seventh bytes are taken as an answer. In this
example, it is to be seen how terms S and X are herein related. Actually,
any mathematical computation in which it would be difficult to deduce from
the answer the components being combined would be sufficient for M.
Term M is combined with terms N, S, and R to complete the protection
program V, and these terms as combined form the protection program listing
6. A logically identical signal M" is independently generated by combiner
algorithm designator or generator 33 in program lock 22 of FIG. 2.
Authorization period designator 7 is simply an encoder which would provide
a digital output designating by a term A the first date on which it is
permissible to run the program to be protected by the protection program V
of listing 6 and designating by a term B the last day on which it would be
permissible to run the same program. Each of these terms, A and B, are
expressed as three-byte quantities, the first byte representing a day, the
second byte representing a month, and the third byte representing a year.
Key deciphering code designator 8 is simply an encoder which provides as an
output a digital representation D of any selected odd number. This term,
which appears in software key K, is also replicated as signal D' by a like
key deciphering code designator 32 in program lock 22.
Prime number calculators 9 and 10 calculate, respectively, prime numbers P
and Q, each being different numbers 16-bytes long (with the most
significant byte non-zero), and each must be chosen so that the prime
number minus one is relatively prime to key deciphering code term D.
Lock identity code calculator 11 receives the outputs P and Q from prime
number calculators 9 and 10 and multiplies the first prime number P by the
second prime number Q to produce a 32-byte product C, which is effectively
a secret identity code which is assigned to a particular program lock 22.
Key enciphering code calculator 12 is responsive to the terms D, P, and Q
and functions to calculate a number E such that when E is multiplied by D
and subsequently divided by the product (P-1)(Q-1), the remainder is 1. E
is thus the modular inverse of D with respect to the product (P-1)(Q-1),
and there are well known mathematical procedures for its computation.
Key calculator 13, responsive to key enciphering code E and lock identity
code C, enciphers the terms N, S, A and B to produce a program
authorization key K as follows: The bytes of information comprising N, S,
A, and B are separated into two groups, each of which is padded with
random bytes so that each group is 30 bytes long. For example, a first
group may be formed of 24 bytes of S plus six random bytes, and the second
group of N, A, and B padded with 21 random bytes. Each group is enciphered
separately so that the key K actually comprises two sets of information.
The enciphering process effectively multiplies the 30-byte quantity of
each by itself as many times as the value of key enciphering code E, and
then divides the result by C, and finally takes the 32-byte remainder of
the division process as the result of each enciphering procedure. The two
32-byte sets of information are concatenated (placed serially) to form key
K. The procedure followed in these calculations is actually implemented by
modular multiplication instead of ordinary arithmetic.
The protection listing 6 is given to the software owner. The software owner
would then combine the protection program V with a particular software
product U illustrated as software product listing 15. The combination
would be accomplished by a selected pattern of mixing of the owner's
program with the protection program. As an example of such a pattern, the
software owner may: (1) alter a critical program variable in his software
product U by adding to it random number X, (2) transiently decipher an
enciphered representation of S and, using X and algorithm M, calculate F,
the number to be represented by signal F', (3) recover the critical
program variable by subtracting from it random number X, (4) send N and X
to the program lock 22 and receive its reply, to be represented by signal
F", (5) make use of the critical variable transiently altered by
combination with X, and (6) abort or cause the program to malfunction if
signal F" does not equal signal F'. These discrete procedures would be
spaced as far apart as possible in the execution of the program so as to
make it difficult for someone to find and modify the procedures.
The resultant program, now a protected program, would then be processed by
an assembler 16 to translate it to its binary representation which would
then be recorded in a protected program memory 17 (e.g. some conventional
magnetic media). As many copies as might be required by potential users of
the software product could be made, only one of which is shown. This would
typically be accomplished by a general purpose digital computer.
Upon completion of the recording step, the program owner would then furnish
a copy of program memory 17, now comprising the protected program W, to a
purchaser of his program. A key printout 14 would also have to be provided
to that purchaser, but this could be done by any party privy to the
various information described in FIG. 1, typically an agency specializing
in that service. Alternately, instead of the key being in printed form, it
may be in a more secure form, as, for example, in the form of a magnetic
recording, either in plain form or in an encoded form. For example, the
recording may comprise a small card having a magnetic memory therein.
Prior to his purchase, the purchaser of a protected program W is informed
that the program can only be run on a computer which has a program lock
22, shown in FIG. 2, connected to it. Accordingly, the software purchaser
user would arrange (if such arrangement had not already been made) with a
supplier of a program lock for the installation of such a program lock on
the computer the program user intends to employ. It should be noted that
the prime numbers P and Q used to generate the lock identity code C,
incorporated into the lock acquired by the purchaser, must be known in
order to generate the key K required for use of the protected program W by
the particular user. Thus, the lock would typically be provided by the
same agency specializing in the service of issuing keys, as mentioned
above.
Assuming that this has been accomplished, the software user would then load
his protected program W, from program memory 17, and the related key K,
from key printout 14, into memory sections of his computer 21 as shown in
FIG. 2. As protected program memory 17 is in magnetic media form as
described, it would be loaded by means of a magnetic media input component
23 to the computer 21 into memory section 24 of the computer. Key K, where
in source or plain language, would be entered via keyboard input 25 into
memory section 26 of computer 21.
In the same manner described, other protected programs, and their discrete
related program keys, configured within the constraints described above,
may be loaded into the same computer and be discretely protected from
unauthorized usage. A program and related key would be matched by a common
program identity number N. Unprotected programs may also be loaded into
and run on computer 21, as the present system does not interfere with
their running.
As stated above, the program lock 22 is a necessary and vital element of
the protection system of this invention. It functions to require that a
computer attempting to run a protected program interact with it in a
precise manner in order that the program perform in its advertised
fashion. The program lock 22 comprises an electronic system depicted by
the blocks illustrating it in FIG. 2. As is well known, electronic systems
may often be instrumented by either discrete circuit elements wherein each
performs a single function or may be instrumented by a single multipurpose
device, such as a microprocessor, wherein all, or a substantial portion
of, the required signal functions are performed by it. Typically, a
microprocessor is constructed in a manner which enables it to rapidly
switch from one functional configuration to another, and to thus serially,
in time, perform the several assigned functions. Here, either approach may
be used, and in referring to a functional element, such is contemplated.
In either event, typically a timing and control circuit 27 is employed to
route signals between electronic subsystems or units, and in the case of a
microprocessor, the timing and control circuit would effect the
configuration of the microprocessor to sequentially take the form of the
electronic subsystems shown. Timing and control circuit 27 typically
comprises a conventional clock driven logic circuit which controls program
circuit interconnections and routing of signals during precise intervals.
Its control function is illustrated by Tc labelled circuit
interconnections between functional elements. An equivalent timing and
control circuit 36 is shown for computer 21 and its output signal is also
labelled Tc. Typically, however, the timing and control functions of the
computer 21 would be distinct from those of the program lock 22.
In examining program lock 22, it is to be first noted that in addition to
its particular circuit arrangement as illustrated in FIG. 2, it must be
supplied certain references or reference signals. As shown in both FIGS. 1
and 2, signal combining device 18 is coupled to signal input 28 of program
lock 22 for this purpose. The first of these references is a signal
equivalent C' of term C. The second one is a signal T', representative of
current time. Referring to FIG. 1, signal C' is generated by lock identity
code encoder 19 responsive to a C input from lock identity code calculator
11. Alternately, the C' signal may be taken directly as a digital signal
output of calculator 11, assuming that calculator 11 is an electronic
calculator having a compatible signal output. The current time signal T'
is obtained from a conventional clock signal encoder or current time
encoder 20 which provides as an output a digitally encoded representation
of Greenwich standard time. The signals C' and T' are combined, by
parallel-to-serial converter or signal combining device 18, and as
combined, are fed from converter 18 to signal input 28 (FIG. 2) of program
lock 22.
Timing and control 27 (FIG. 2) controls signal input 28 to route signal C'
to lock identity code memory 30 where it is permanently stored as a
reference. Similarly, current time signal T' is routed to clock 31, a
resettable clock with a digitally encoded output. The result is that clock
31 is set to current time. In this manner, the time of the request for the
running of a program is always available as a reference. Both the lock
identity code memory 30 and the clock 31 are, thus, set by the same
operation which precludes the possibility of someone resetting the clock
31 without knowing (or inadvertantly destroying) the pre-existing lock
identity code C.
In order to mantain the data stored in memory 30 and the correct time in
clock 31, some circuitry of program lock 22 must be continuously powered,
as is facilitated by self-contained, rechargeable, battery power supply
29, which supplies operating power to critical circuit elements of the
program lock 22.
Program lock 22 provides by its circuitry two additional references. One of
these is signal D', a signal representative of the same odd number as D,
which is an element of the determination of K. Signal D' is generated by
key enciphering code designator 32, which may simply be a digital encoder
which provides as an output a digital signal representative of D. The
final one is a digital group M", which is a digitally encoded signal group
representative of the program algorithm or instructions M described above.
This signal group is generated by combiner algorithm designator 33, which
in one form may be a set of digitally encoded signals stored in a memory
and which are read out pursuant to a demand from timing and control 27.
Signal C', now stored in memory 30, and signal D' are employed to decipher
the contents of the signal K', representative of key K for a given
program. There would be a signal K' stored in memory 26 of computer 21 for
each protected program to be run by computer 21. Timing and control
circuit 27 of program lock 22 would be operated to accept discrete signals
K' and separately supply the same to key decipherer 34. The latter would,
responsive to signals C' and D', decipher the key K' into its constituents
N", S", A", and B", representative of the like lettered constituents of
the term K as described above. Key decipherer 34 comprises a discrete
computer or microprocessor which performs a multiplication function
followed by a division function, the multiplication function being
directed by D', and the division function directed by C', these functions
being performed on the input signal K'. More specifically, each of the two
parts of K are multiplied by itself as many times as the value represented
by signal D', and each result is divided by the value represented by
signal C'. The remainder of this process on the first part of K is
representative of S as described above, and the remainder of the process
on the second part of K is representative of terms N, A, and B. They take
the related forms of signals S", N", A", and B", and a discrete set of
these signals (for a given K') is stored in a discrete address in
content-addressable memory 35, employing the signal N" for subsequent
memory addressing.
In the manner described, sets of signal values for each key K of each
protected program to be used in computer 21 are uniquely stored in program
lock 22 for use when called upon to determine an authorization for the
running a program.
A demand for the running of a selected program is effected by a prearranged
selected keyboard entry which identifies the selected program. Such
occurrence would typically be directed through timing and control circuit
36 of computer 21, which would then cause the N' term of the particular
program requested to be applied to the interrogating input of memory 35 of
program lock 22. When this occurs, the S", A", and B" signals for the
program key for that program are read out of memory 35.
The S" term is used if, and only if, the present time, as represented by
signal T" from clock 31, is within the permissible time frame between the
times indicated by time signals A" and B". Time comparison is made by
comparator 37. Typically, comparator 37 would be a digital comparator
which simply compares digitally encoded signal T" with digitally encoded
time values A" and B". It provides an enabling output signal H' to gate 38
when the value of signal T" is between the values of signals A" and B".
Comparator 37, like other active elements of program lock 21, may be
instrumented by a discrete electronic comparator or by a microprocessor
which, for a discrete period of time, is configured by timing and control
27 to accomplish the function at hand, in this case, the comparison of
sets of bytes to determine relations among them. In either form, the
presence of the proper relationship is indicated by signal H' causing a
gating function represented by gate 38 to gate or pass signal S" to
computational element 39. Gate 38 may, alternately, be either a discrete
electronic gate which passes a signal S" upon the presence of gating
signal H', or may be a like functional configuration of a microprocessor
during a programmed time to effect the gating function. Upon being gated
through, signal S" is supplied to computational element 39.
Computational element 39 provides the system of this invention with one of
two final signals, in this instance, a signal F", necessary for the
authorization of the running of the protected program U' portion of
program W'. It operates on two signals, the S" signal and a random number
signal X', from computer 21 and in accordance with instructions M" from
algorithm generator 33. Computational element 39 performs the steps 1-4 as
described above for term M, and as a result provides as an output a signal
F". Computational element 39 may be comprised of discrete devices or be a
configured program state, on a time shared basis, of a microprocessor as
illustrated as comprising exclusive-OR circuit 39a, multiplier 39b, and
divider 39c. In terms of the computational steps outlined for the
instruction of term M, exclusive-OR circuit 39a would provide a signal Y",
and multiplier 39b would provide a signal Z", counterparts of the terms Y
and Z as discussed above. Divider 39c would then provide, as illustrated,
the signal F".
The generation of signal X' will be discussed below in the description of
computer 21.
In summary, there has been described up to this point the generation and
encoding of a protected program W' and program key K' into computer 21 and
the makeup and functioning of program lock 22 up to the point where it
would provide its decoding signal F" to computer 21. In order to effect a
final determination of authorization to run the portion U' of protected
program W' in computer 21, computer 21 must operate to generate a like
signal to signal F", a signal F'.
Computer 21 is typically a general purpose computer, but in the present
system, it would be sequentially configured, or programmed, particularly
as illustrated. It would function under the control of its timing and
control 36 to perform the functions illustrated by the labelled blocks of
computer 21 as shown in FIG. 2. Alternately, these blocks would be
representative of a hardwired device under the control of a timing and
control 36, again to function as will be described.
In terms of a general purpose computer, and under the control of timing and
control 36, and coordinate with its directions to memory 24 to provide an
interrogating signal N' to content addressable memory 35 of program lock
22 as described above and leading to the development of signal F", memory
24 would have been directed to output a signal R' counterpart of term R,
which would direct computer 21 to function for a discrete period as a
random number generator, depicted by random number generator block 40, and
thereby generate the term X'. In addition to supplying this signal X' to
computational element 39 of program lock 22, as described above, this
signal is employed in a time shared configured state of computer 21
wherein computer 21 functions as a second computational element 41, which
functions to perform the same computational steps as computational element
39, and thus illustrated to comprise exclusive-OR circuit 41a, multiplier
41b, and divider 41c. The intermediate outputs of computational element 41
are labelled as counterparts to computational element 39, and thus the
output of exclusive-OR circuit 41a is labelled as Y', and the output of
multiplier 41b is labelled as Z'. It is significant as a further feature
of the present invention that the immediate sources of signals stemming
from terms S and M are different for computational element 41 than for
computational element 39, and thus signals S' and M' supplied to
computational element 41 are obtained from the program W' stored in memory
24 rather than being obtained via the process described for program lock
22. Assuming that there is identity of terms S' and M' in memory 24 with
the counterpart M" internally generated by program lock 22, and S" from
key K', then the computation from these terms will be, as illustrated, a
signal F', which is identical to signal F" from program lock 22.
The next role of computer 21, and as would be directed by timing and
control 36, would be to function as a digital comparator, represented by
block 42, to compare the signals F" and F', and, provided they are
identical, to provide an enabling or authorization signal, represented by
signal G'. Finally, computer 21 would function under the direction of
timing and control 36 as a gating circuit represented by gate 43 and,
responsive to the signal G', pass the program U' to a "run" state of
computer 21 as represented by user program processor element 44, and by
this state, execute program U', adhering completely to its advertised
specifications. On the other hand, if signal G' was not asserted, the
execution of program U could be aborted or conducted in a manner not
advantageous to the user.
As a final feature of this invention, program lock 22 includes means for
particularly protecting from discovery the makeup of signal C', which is
representative of the lock identity code C, the security of which is very
significant. As stated, signal C' is obtained through signal input 28 and
stored in lock identity code memory 30. The operation and retention of the
signal in memory 30 is dependent upon power being continuously supplied by
battery power supply 29 of program lock 22 which supplies power to some of
the circuit elements of program lock 22 by conventional circuitry not
shown. Any attempt to access memory 30 to read out lock identity code C is
prevented by the system shown in FIG. 3. As shown, circuit board 45, upon
which circuit components of program lock 22 are mounted, are enclosed by
top and bottom protective plates 46 and 47. Battery power lead 48 is
mounted on circuit board 45 and it supplies power through a power lead 49
to circuit component terminal 50, and thus to components by means not
shown. Power lead 49 is attached by glue 53 to an inner surface of
protective plates 46 and 47. As an aid to the positioning of power lead
49, spacers to which glue will not adhere 51 and 52 are positioned on
either side of circuit board 45 and are pressed against conductor 49.
Thus, if one attempts to get to any one of the components mounted on
printed circuit board 45, including, of course, lock identity code memory
30, at least one of plates 46 and 47 would be significantly moved, and the
effect would be to break power lead 49. This would then remove power from
some components on circuit board 45, including memory 30. When this
occurs, memory 30 would be altered, destroying lock identity code C. In
this manner, the system is protected against discovery of the lock
identity code C.
From the foregoing, it will be appreciated that in accordance with the
system of this invention, an otherwise unprotected software product which
may essentially be copied at will is very effectively protected against
unauthorized use. As an essential feature, the invention enables a single
program lock to effectively protect software products emanating from
different owners. At the same time, the invention enables the
incorporation of a program lock with a computer in such a manner tha | | |
