FR2607953A1 - Methods for marking and recognising a software support, in order to protect it from illegal copying, and combination of software and such a support - Google Patents

Abstract

A first location 10 on the support 1 is corrupted in a way which prevents the subsequent writing of information at this first location 10. Execution of an application program is enabled only in the presence of a support corrupted at the first location. After the corruption has been carried out, the coordinates C of the corruption 2 on the support 1 are determined and information indicative of these coordinates C is written to the support at a second predetermined location 20 different from the first 10. During verification, the coordinates in the second location are searched for, then, according to these coordinates, a search is made as to whether the first location is corrupted. Use for rendering marking more economical, by eliminating the need for physical precision.

Description

 The present invention relates to a method for marking in a manner which is difficult to imitate, a logical information medium, such as a flexible magnetic disk for a computer, in order to not allow the execution of a computer program, said program or software. application, only in the presence of a suitably marked medium, in which a first location of the support is altered, in a manner which prevents the subsequent writing of information at the first location.

 The invention also relates to a method for protecting an application program against an illegitimate duplication by means of a marking which may result from a method cited at the start.

 The present invention also relates to the combination of an application program and a magnetic medium such as a flexible disk, obtained in particular by the aforementioned method.

 Finally, the invention relates to a method for determining whether a magnetic medium such as a flexible disk is a suitably marked original, in particular according to a method of the aforementioned genre, or a copy.

 Methods are known for protecting computer programs against illegitimate duplication. These duplications which are carried out by means of other specific programs, for which the term "copier software" will be used, represent a significant shortfall for companies which design, produce and market application programs, for which will use the names of "software to protect" or "application" here.

 The manufacturers and producers of application software are therefore led to design processes prohibiting these duplications, processes in which any specific and specific information is defined, the presence and conformity of which are verified by a particular software, included in the software to be protected, and for which the term “test or verification software” will be used below.

 Purely software protections are known which do not require any other hardware device than the conventional peripheral devices of a computer or microcomputer. Software protections are currently becoming ineffective. Indeed, high performance copier software, capable of fully reproducing the logical content of a magnetic medium such as a flexible disk on another, are now available to the general public.

Mixed protections are also known which associate a hardware device with the test software, in which there is unequivocally associated a copyable application software, containing a copyable test software, an external hardware element which is not not reproducible, or very difficult to reproduce The application software is therefore not protected against illegitimate copying but against illegitimate use, since it imperatively requires the presence of a specific device which itself cannot be copied This additional external material element can be:
An electronic circuit, preferably integrated, commonly called "plug", whose particular characteristics are recognized by the test software included in the application software to be protected before authorizing the execution of the latter.

 A special flexible disk, which may be the support of the application software, or which may be another flexible disk, and the material itself has been altered, or partially destroyed, physically, mechanically or chemically, such as this is indicated at the beginning. Generally, using a laser beam, a partial burn of the magnetic support, or a tiny hole in this support, is practiced. Due to this physical alteration, the flexible disk thus treated cannot be duplicated by copying software which can only reproduce electrical quantities. In the same way as described above, the test software compares the conformity of this alteration to determined characteristics and authorizes or not the execution of the application software.

 Mixed protections are effective against copier software, but "plugs" are expensive. The same is true for the operation # which consists of burning or laser-drilling a flexible disc with precision. The disadvantage of these protections is therefore not the lack of reliability, but rather, for some, the lack of flexibility of implementation, and especially the relatively high manufacturing price, which can be disproportionate compared to that of the software. to protect.

 The protection that uses a physically altered flexible disk associated with test or verification software is the one that offers the greatest flexibility for the end user. However, it requires the use of an apparatus with a precise and sophisticated laser beam, therefore expensive, specially studied to allow pointing and altering a defined zone of magnetic support associated with the software to be protected from coordinates of this support. chosen a priori.

 The object of the present invention is to propose a method of marking of the type indicated at the start, the implementation of which is clearly simplified, and which also confers a very high degree of reliability.

 Thus, the method of the kind indicated at the beginning for marking in a hardly imitable manner a logical information medium, is characterized in that after having practiced the alteration, one determines the coordinates of the alteration on the support, and one writes on the support, at a second predetermined location, different from the first location, information indicative of these coordinates.

 Thus, it is no longer necessary to carry out the marking in a precise position of the support. On the contrary, the first location, at which the marking is carried out, can be chosen randomly.

In other words, the marking can be carried out randomly on the disc, using rudimentary tools such as a punch. It is then that the position of the marking on the support is determined, so as to bear on the latter, in a second location, indications of this position. The cost of producing such a support is much lower than that of a laser-marked support in a predetermined precise position. In addition, the protection security is increased because the verification software will have to note on the support no longer simply the presence of an alteration in a determined position but also, before that, in a predetermined location of the support, existence of information. consistent with the position where the alteration should be sought on the support.

 The logical information presented on the flexible disk, whether or not it is hidden, can generally be duplicated using copier software, but the physical alteration of the flexible disk is difficult to reproduce. In addition, reproducing an identical alteration on a flexible disk copied, by hand or using any device, and at the same coordinates as those indicated in the second location, presents a character of difficulty almost completely dissuasive.

Preferably, at a third predetermined location different from the first and from the second location, information relating to the coordinates of the second location is written on the support,
More preferably, before writing the coordinates of the alteration at the second location, an arbitrary item of information is chosen from a predetermined list, and the coordinates of the second location are computed by the computer by means of a software using said arbitrary information as data.

The task of the verification program which protects access to the application will then be to determine, from easily accessible arbitrary information, and from a decoding algorithm, what is the hidden address where it can find the coordinates of the alteration on the alteration zone and finally to verify that it cannot write logical or binary information there
According to a second aspect of the invention, the method for protecting an application program against an illegitimate duplication, in which said program is associated on the one hand with a magnetic medium, such as a flexible disk which has been marked , in particular according to the first aspect, by an alteration at a first location, and and on the other hand to a verification software adapted to verify that the medium has an alteration at the first location and to authorize the execution of the application program that in case of a positive result of this verification, is characterized in that one determines the coordinates of the alteration on the support, and, only at this stage, one writes on the support, in a second location, predetermined, different of the location of the alteration, and / or the verification software incorporates information indicative of these coordinates, the verification software being designed to determine the location of the alteration based on the aforementioned information s.

 According to a third aspect of the invention, the combination of an application program and a magnetic medium such as a flexible disk, a combination obtained in particular by the aforementioned method, in which the flexible disk comprises in a first location, an alteration which prevents the writing of information at said first location, and the application program is associated with a verification program suitable for verifying the presence of an alteration at said first location and for not authorizing the execution of the program application that in the event of a positive result of this verification, is characterized in that the magnetic support also carries in a second location, distinct from the first, information relating to coordinates of the first location on the support, and in that the verification program is adapted to take this information into account to determine the coordinates of the first location to then verify the presence of an alteration.

 According to a fourth aspect of the invention, the method for determining whether a magnetic medium such as a flexible disk is a suitably marked original, in particular according to the method according to the first aspect, or a copy, method in which the execution of an application program if one has detected, in a first location, the presence of an alteration that cannot be modified by writing logical information, is characterized in that one searches first in at least a second location predetermined medium for the information from which the coordinates of the first location are determined after which, if said information is collected and if it is consistent, it is referred to the first location according to the coordinates thus determined and the presence of there is searched for. an alteration.

 Other features and advantages of the invention will emerge from the description below.

In the appended drawings, given by way of nonlimiting examples:
Figure 1 is a schematic view of computer equipment necessary for the implementation of the methods according to the invention;
Figure 2 is a schematic view of a flexible disk according to the invention;
Figure 3 is a simplified flowchart illustrating the mode of execution of a protected application program according to the invention;
FIG. 4 is a flowchart illustrating the various steps of the method according to the invention for protecting an application program against illegitimate duplication, this program being associated with the flexible disk of FIG. 2; and
FIG. 5 is a flowchart illustrating the various steps of the method according to the invention for determining whether a flexible disk is a suitably marked original or a copy.

 FIG. 4 illustrates the different steps of the method according to the invention for protecting an application program or software against illegitimate duplication in accordance with the invention. This application program is associated on the one hand with a logical information medium 1, such as a conventional flexible magnetic disk for a computer (FIG. 2) which is marked by one or more physical alterations 2, for example at by means of a pointed object (not shown); such as a needle or the like, in one or more first location (s) 10 chosen (s) randomly, and on the other hand to test or verification software suitable for verifying that the support 1 has one or more alterations 2 to the first location (s) 10 and to authorize the execution of the application program only in the event of a positive result of this verification.

 The verification software is incorporated into the application program so that a request for access to this application program from a user automatically causes (FIG. 3), beforehand, the execution of the verification software.

 Furthermore, the altered support 1 is preferably distinct from that which contains the application program but or understands that it can also constitute the support for the application program.

 In the latter case, it will not be possible for the user to make backup copies of the application program but the protection remains intact.

The flexible disk 1 having been altered as indicated above, the following operations are carried out:
we have (Figure 1) the altered magnetic support 1 in a flexible disc player 3 connected to a computer or microcomputer 4;
a specific software or protective software is loaded into the central memory of the computer or of the microcomputer 4 which, when it starts executing it, performs the following operations:
it determines the coordinates C of the alteration or alterations 2 of the support 1. For this, it uses the conventional formatting control means of the computer 4 which make it possible to structure the flexible disk 1 in tracks and in logical sectors such as the "zero" track 5 and the "two" sector 6 of the "zero" track 5. The space for writing and reading logical information from the flexible disk 1 is thus arranged and logical indicators or benchmarks are placed , which can later be used to find the information sought by the user. It is a classic command of any floppy disk operating system or "disk operating system" (DOS) which writes the following meaning bits on each track of floppy disk 1: indicators for the start of sector (number of face, track, sector and sector length), synchronization or clock bits, checksum at the end of each sector which determines the state of the sector, whether it is altered or not.

These elements therefore provide information on the state of each sector, information which is used by the protective software to determine the coordinates (track number, sector number) of the alteration (s);
then, the protective software stores the coordinates C of the alteration or alterations, in binary form in a random access memory of the computer;
it requests from the operator a serial number S intended to be associated with the magnetic medium 1, this number S being stored in another random access memory of the computer 4; this serial number S is an arbitrary item of information chosen from a predetermined list held by the manufacturer of the protection so that to a determined serial number S corresponds a determined altered medium 1;
using a particular coding algorithm, it generates from the serial number S a number N so that to a given serial number S can only correspond to a determined number N;
he writes the coordinates of C of alteration 2 or alterations 2 in a second location 20 of the flexible disk 1 whose address (or "memory location") corresponds to the number N.

 If the second location turns out to coincide with the first location, the protective software asks the operator for another serial number, so as to recalculate a second location different from the first location.

 it writes in binary form the serial number S at a third predetermined location 30 of a particular track assumed to be unaltered of the flexible support 1, for example the "zero" track 5 of this flexible support 1.

 The third location is always the same on all flexible disks in a series, marked according to the process. Although the choice of the first location is essentially arbitrary, care has been taken to ensure that the marking does not affect the third location.

 FIG. 5 illustrates the various steps of the method according to the invention for determining whether a flexible disk 1 associated with an application program is an original which has been properly altered as this results in particular from the method described above, in which case the execution will be authorized of this application program, or a copy in which case the execution of said application program will be prohibited.

This process thus comprises the following stages:
there is (FIG. 1) the altered flexible disk 1 in a flexible disk reader 3 connected to a computer or a microcomputer 4;
the application program containing verification software suitable for determining whether the disk 1 is marked as stored in the central memory of the computer 4 is stored, in particular as a result of the marking process described above.

This application program residing beforehand for example (FIG. 1) on a hard disk or another flexible disk 7 disposed in a hard disk drive or another flexible disk reader 8 connected to the computer 4;
access to the application program is requested so as to launch the execution of the verification software it contains.

The verification software then performs the following operations:
it reads the serial number S of the disk 1 at the third predetermined location 30th the zero track 5 of this disk and stores this serial number S in a random access memory of the computer 4;
using a particular algorithm corresponding to the coding algorithm defined above, it determines from the serial number S a number N which corresponds to the address where the coordinates C of location 10 of disk 1 of l must appear 'disc alteration or alterations 2;
. fl reads the information present at this address N ;;
it checks the consistency of this information as coordinates C relative to the formatting of the disc 1, that is to say that it verifies that said coordinates C actually correspond to the expected track and sector coordinates of the disc 1.

If these coordinates are inconsistent, this means that the flexible disk 1 which has been placed in the reader 3 connected to the computer 4 is not an appropriately marked original and the verification software prohibits the execution of the application program. Otherwise, the verification software performs the following additional operations:
it stores said coordinates C in a random access memory of computer 4;
it commands the writing of random logical information or random or arbitrary bits at the location or locations 10 of the flexible disk 1 defined by these coordinates C. If the computer 4 authorizes the writing of said bits at said locations 10, this means that these places do not contain the expected alterations and that disk 1 is a copy so that the verification software refuses the execution of the application program. Otherwise, the altered flexible disk which has been placed in the reader 3 connected to the computer 4 is an original suitably marked so that the verification software authorizes the execution of the application program.

 To illegitimately duplicate a damaged flexible disc according to the method of the invention, it is therefore necessary, on the one hand, to produce and apply to a flexible disc which is damaged by hand (which is simple) protective software similar to that of the present method, therefore comprising a strictly equivalent coding algorithm (which is not simple), and on the other hand, that one takes the risk of assigning to the flexible disk thus worked a serial number.

Indeed, the numbers can be listed at the manufacturer of the protection, and they are listed there for each damaged flexible disk, in one-to-one relationship with the alteration coordinates specific to each flexible disk. it can therefore be easily determined whether the process itself has been stolen, provided that the manufacturer accidentally finds himself in possession of a copy of a fraudulent flexible disc.

 The implementation of the protection method according to the invention does not require any particular apparatus, except a simple computer or microcomputer, which is generally of the same type as that of the end user. The advantages of simplicity, manufacturing price and cost are obvious compared to known methods, and reliability is at least as good.

 Of course, the invention is not limited to the examples described and variations can be made without departing from its scope.

 Thus, the verification software could be coded in various ways in order to make its detection and analysis difficult and thereby dissuasive.

 Instead of appearing "in the clear", the serial number and the coordinates of the alteration could be coded in any desired manner, the verification software being of course adapted to a corresponding decoding.

 If the second location, calculated from the serial number, turns out to correspond to the first location, rather than changing the serial number, it can be foreseen that the protective software is capable, using "backup" logic, of calculate another second location. The verification software, calculating the second location according to the main logic and noting that it is an altered location, that is, if it is an original and not a copy, it the same backup logic should be used to check, if the coordinates of the alteration are indeed where they should be.

 Another solution to avoid that the second location does not correspond to the first, consists in first determining the second location using the serial number, then in carrying out the marking always in an essentially random manner, but avoiding that it affects the second location, calculated beforehand.

 A serial number could be assigned to both the corrupted floppy disk and the verification software so that a specific verification software corresponds to a single corrupted floppy disk. For example, verification software can each contain a logical element which is characteristic of them and which allows them to find the alteration only on a respective information medium (flexible disk) so that each software recognizes as original only a single flexible disk which is unequivocally associated with it.

 Such a logical element can for example consist of the address of one of the locations, for example that of the first location, in which case the writing of the coordinates of the first location in a second location of the support becomes unnecessary.

Claims (11)

 1. Method for marking in a manner which is difficult to imitate, a logical information medium, such as a flexible magnetic disk (1) for a computer, in order to allow the execution of an application program only in the presence of a suitably marked support, method in which a first location (10) of the support (1) is altered in a manner which prevents subsequent writing of information at the first location (10), characterized in that after having practiced the alteration we determine the coordinates (C) of the alteration (2) on the support (1), and we write on the support (1), in a second location (20), predetermined, different from the first location (10) , information indicative of these coordinates (C)  2. Method according to claim 1, characterized in that in a third predetermined location (30) different from the first (10) and from the second location (20), information (S) relating to the coordinates (N) of the second location (20).  3. Method according to claim 1 or 2, characterized in that, before writing the coordinates (C) of the alteration (2) at the second location (20), information is supplied to a computer (4) ) chosen from a predetermined list, and the coordinates (N) of the second location (20) are calculated by the computer (4) by means of software using said arbitrary information (S) as data.  4. Method for marking a series of supports (1) according to claim 2, characterized in that the same third location (30) is chosen on each of the supports (1).  5. Method for protecting an application program against an illegitimate duplication, in which said program is associated on the one hand with a magnetic medium, such as a flexible disk (1) which has been marked, in particular according to one of claims 1 to 4, by an alteration (2) at a first location (10) and on the other hand to a verification software adapted to verify that the support (1) has an alteration (2) at the first location (10 ) and to authorize the execution of the application program only in the event of a positive result of this verification, characterized in that after the marking, the coordinates (C) of the alteration (2) are determined on the support (1), and, only at this stage, we write on the support (1), in a second location (20), predetermined, different from the location (10) of the alteration (2), and / or incorporates information indicative of these coordinates (C) into the verification software, the verification software being designed to determine the location (10) of e alteration (2) according to the above information.  6. Combination of an application program and a magnetic medium such as a flexible disk (1), combination obtained in particular by the method according to claim 5, in which the flexible disk (1) has in a first location (10) an alteration (2) which prevents the writing of information at said first location, and the application program is associated with a verification program adapted to verify the presence of an alteration (2) at said first location (10 ) and to authorize the execution of the application program only in the event of a positive result of this verification, characterized in that the magnetic support (1) further carries in a second location (20), distinct from the first ( 10), information relating to coordinates (C) of the first location (10) on the support (1), and in that the verification program is adapted to take account of this information to determine the coordinates (C) of the first location (10) to then check for the presence alteration (2).  7. Combination according to claim 6, characterized in that the support (1) comprises logical information (S) in a third location (30), distinct from the first (10) and from the second location (20), and in that the verification program is adapted to search for this logical information (S) in invariable coordinates of the support, corresponding to the third location (30), and to take account of this information to determine coordinates (N) of the second location (20) and read at this location the information relating to the coordinates (C) of the alteration (2).  8. A series of combinations according to one of claims 6 or 7, characterized in that the verification program for each combination comprises a specific logic element allowing it to recognize as authentic only a flexible disk forming part of the same combination.  9. Method for determining whether a magnetic medium such as a flexible disc (1) is a suitably marked original, in particular according to a method according to one of claims 1 to 5, or a copy, method in which the execution of an application program if one has detected, in a first location (10), the presence of an alteration (2) which cannot be modified by writing logical information, characterized in that one first searches for at least a second predetermined location (20) of the support (1) of information from which coordinates (C) of the first location (10) are determined after which, if said information is collected and if it is consistent, reference is made to the first location (10) according to the coordinates (C) thus determined and one searches there for the presence of an alteration (2).  10. Method according to claim 9, characterized in that in order to search for the presence of an alteration (2), the writing of logical information in a domain including the first location (10) is controlled, it is detected whether said logical information have been faithfully written, and otherwise the application program is authorized to run.  11. Method according to one of claims 9 or 10, characterized in that one searches in a third predetermined location (30) of the support (1), information (S) from which, if they exist and are consistent, coordinates (N) of the second location (20) are determined.