Solid state key for controlling access to computer systems and to computer software and/or for secure communications

What is claimed is:

1. Apparatus for affording access by a user to a computer and/or information residing in a computer, and/or for affording secure communications and comprising an access key capable of generating a password and of being transported independently of the computer, and an access key for verification means adapted to be resident in the computer, for allowing access and use of the software program wherein:

said access key includes:

(a) first clock means for generating a signal;

(b) means for storing a root;

(c) forward algorithm means coupled to said clock means and root storing means for encrypting the root, responsive to the signal from said clock means, into a password;

said access key verification means includes:

(a) second clock means for generating a signal;

(b) means for receiving the password;

(c) inverse algorithm means coupled to said second clock means for decrypting the password and for calculating the root;

(d) means for generating a stimulus and for communication said stimulus to said inverse algorithm means and said access key;

(e) said inverse algorithm means including means for using the stimulus to calculate the root from the password;

said access key includes:

(a) means for receiving the stimulus and communicating the stimulus to said forward algorithm means;

(b) wherein said forward algorithm means includes means for combining the stimulus with the root to produce the password;

(c) means for saving at least a portion of stimulus member;

(d) means for comparing the saved portion of the stimulus number with the next available stimulus number;

(e) means for inverting at least part of the root before the root is communicated to the forward algorithm module responsive to the comparing means if the saved portion does not have a predescribed relationship with the next available stimulus number; and

said access key verification means includes:

(a) second means for saving at least a portion of the stimulus number;

(b) means for merging the saved portion of the stimulus number with the next stimulus number;

(c) second means for storing at least a portion of the root;

(d) means for comparing the portion of the root number saved in the second storing means with the calculated root;

(e) means for generating a suspicion signal depending on whether there is a predetermined relationship between the calculated root and the saved portion of the root.

2. Apparatus for affording access by a user to a computer and/or information residing in a computer, and/or for affording secure communications and comprising an access key capable of generating a password and of being transported independently of the computer, and an access key verification means adapted to be resident in or function with the computer, for allowing access and use of the software program wherein:

said access key includes:

(a) first clock means for generating a signal;

(b) means for storing a root;

(c) forward algorithm means coupled to said clock means and root storing means for encrypting the root, responsive to the signal from said clock means, into a password;

said access key verification means includes:

(a) second clock means for generating a signal;

(b) means for receiving the password;

(c) inverse algorithm means coupled to said second clock means for decrypting the password and for calculating the root; and

wherein the computer has a video display, which can display another signal from the access key verification means, and wherein said apparatus further comprising:

said access key verification means including:

(a) a stimulus number generating means for generating a stimulus number;

(b) means for generating said another signal on the video display that is representative of said stimulus number; and

said access key further including:

(a) at least one sensor accessible from the exterior of said access key so that juxtaposition of the access key and the display efforts excitation of the sensor by the another signal;

(b) means coupled to said sensor for using the another signal to produce the stimulus number;

(c) said forward algorithm means including a means for combining the stimulus number with the signal from the clock means to produce the password; and

wherein the signal on the display is comprised of two optical differential pairs; and

wherein each optical pair is comprised of a first field and a second field, one of which fields can be illuminated more than the other field to communicate selectively a logical one or a logical zero signal.

3. The apparatus of claim 2 wherein one of said optical differential pairs represent a data signal and the other represents a clock signal.

4. The apparatus of claim 3 wherein the pairs alternate being the data signal and the clock signal.

5. A system for transmitting information in a secure fashion comprising:

a first access key capable of generating a password and adapted to be transported independently of a computer;

wherein said first access key includes:

(a) first means for storing a root;

(b) first forward algorithm means coupled to said first root storing means for encrypting the root into a password;

a first access key verification means adapted to reside in or function with a computer for receiving a password generated by the first access key and for encrypting the information to be transmitted based on the root calculated from the password;

wherein said first access key verification means includes:

(a) first inverse algorithm means for receiving and decrypting the password for calculating the root in order to encrypt the information;

(b) encrypt module means for using the root to encrypt the information;

a second access key capable of generating another password and adapted to be transported independently of another computer;

wherein said second access key includes:

(a) second means for storing the root;

(b) second forward algorithm means coupled to said second root storing means for encrypting the root into another password;

a second access key verification means adapted to reside in or function with the another computer for receiving the another password generated by the second access key and for decrypting the encrypted information based on a value calculated from the password; and

wherein said second access key verification means includes:

(a) second inverse algorithm means for receiving and decrypting the another password for calculating the root in order to decrypt the information;

(b) decrypt module means for using the root to decrypt the information.

6. The system of claim 5 wherein:

at lease one of said first and second access key verification means includes:

(a) means for generating a stimulus and for communicating said stimulus to at least one of said first and second inverse algorithm means respectively, and to at least one of said first and second access keys respectively;

at least one of first and second access keys includes:

(a) means for receiving the stimulus and communicating the stimulus to at least one of said first and second forward algorithm means respectively.

7. A system for protecting information residing in a computer and/or for affording secure communication comprising:

means separate from the computer for encrypting information in accordance with a root;

an access key capable of generating a password in accordance with the root and of being transported independently of a computer;

wherein said access key includes:

(a) first clock means for generating a signal that is dependent on the elapse of time;

(b) means for storing the root;

(c) forward algorithm means coupled to said clock means and root storing means for encrypting the root into a password responsive to the signal from said clock means;

an access key verification means, adapted to reside in or function with the computer, for using the password to calculate the root and to decrypt the encrypted information with the root;

wherein said access key verification means includes:

(a) second clock means for generating a signal that is dependent on the elapse of time;

(b) means for receiving the password;

(c) inverse algorithm means coupled to said second clock means for decrypting the password for calculating the root.

8. The apparatus of claim 7 wherein:

said access key verification means includes:

(a) means for generating a stimulus and for communication said stimulus to said inverse algorithm and said access key;

said access key includes:

(a) means for receiving the stimulus and communicating the stimulus to said forward algorithm means;

(b) wherein said forward algorithm means includes the means for combining the stimulus with the root to produce the password; and

said access key verification means includes:

(a) said inverse algorithm means including means for using the stimulus to calculate the root from the password.

9. Apparatus for affording access by a user to a computer and/or information residing in a computer, and/or for affording secure communications and comprising an access key capable of generating a password and of being transported independently of the. computer, and an access key verification means adapted to be resident in or function with the computer, for allowing access and use of the software program wherein:

said access key includes:

(a) first clock means for generating a signal;

(b) means for storing a root;

(c) forward algorithm means coupled to said clock means and root storing means for encrypting the root, responsive to the signal from said clock means, into a password;

said access key verification means includes:

(a) second clock means for generating a signal;

(b) means for receiving the password;

(c) inverse algorithm means coupled to said second clock means for decrypting the password and for calculating the root; and

wherein said signal of said first clock means includes a first signal having shorter time intervals and a second signal having longer time intervals comprised of more than one of the shorter time intervals and with:

said forward algorithm means including means for selecting among a plurality of algorithms;

said first signal for encrypting the root for any selected algorithm;

said second signal for selecting among the plurality of algorithms for encrypting the root.

10. The apparatus of claim 9 wherein said access key includes:

means for displaying the password for a predetermined time frame and for preventing the generation of another password for said predetermined time period.

11. A system for communicating secure information including:

an information sender having

(a) a first clock means for generating a signal that is dependent on the elapse of time;

(b) means for storing a root;

(c) forward algorithm means coupled to said clock means and root storing means for encrypting the root, responsive to the signal from said first clock, into a password and for sending said password;

(d) encryption means coupled to said root storing means for encrypting information input to the sender in accordance with the root and for sending encrypted information;

an information receiver having:

(a) a second clock means for generating a signal that is dependent on the elapse of time;

(b) inverse algorithm means coupled to said second clock means for receiving the password and for calculating said root in accordance with the signal from the second clock means and said password;

(c) decryption module means for receiving said encrypted data and coupled to said inverse algorithm means for receiving said calculated root and for decrypting the encrypted data.

12. The system for claim 11 wherein:

said information receiver includes:

(a) means for generating a stimulus and for communicating said stimulus to said inverse algorithm means and to said sender;

said sender include:

(a) said forward algorithm means for additionally receiving the stimulus and for combining the stimulus with the root to produce the password;

said receiver includes:

(a) said inverse algorithm for additionally using said password and stimulus to calculate the root.

13. The system of claim 12 wherein:

said sender includes:

(a) first means for storing a seed and for communicating the stored seed to said forward algorithm means;

(b) said forward algorithm means includes means for selecting among a plurality of algorithms responsive to the stored seed.

14. The system of claim 13 wherein:

(a) said seed is a time-dependent algorithm; and

(b) the output from said seed storing means changes with time.

15. A system for transporting valuable data in a highly portable, secure fashion comprising a portable key in which the valuable data can be stored and data extraction means adapted resident in or function of a computer for extraction of the data from the key wherein:

said key includes:

(a) first clock means for generating a signal that is dependent on the elapse of time;

(b) means for storing the data;

(c) forward algorithm means coupled to said clock means and data storing means for encrypting the data into a password responsive to the signal from said clock means;

said data extraction means includes:

(a) second clock means for generating a signal that is dependent on the elapse of time;

(b) means for receiving the password;

(c) inverse algorithm means coupled to said second clock means for decrypting the password in order to calculate the data.

16. The system of claim 15 wherein: said data extraction means includes:

(a) means for generating a stimulus and for communicating said stimulus to said inverse algorithm means and said key;

said key includes:

(a) means for receiving the stimulus and communicating the stimulus to said forward algorithm means;

(b) wherein said forward algorithm means includes means for combining the stimulus with the data to produce the password; and

said access key verification means includes

(a) said inverse algorithm means including means for using the stimulus to calculate the data.

17. A system for affording access by a user to a computer and/or information residing in a computer with an output device, comprising access key verification means adapted to be resident in or function with the computer, for verfying an encrypted password and allowing access to the computer and/or use of the information, an access key capable of generating an encrypted password and of being transported independently of the computer, and a keypad for facilitating communication between the access key and the access key verification means, wherein:

said access key verification means includes:

(a) first clock means for generating a signal that is dependent on the elapse of time;

(b) a stimulus number generating means for generating a stimulus number;

(c) means for generating a signal on the display that is representative of said stimulus number; and

said access key includes:

(a) second clock means for generating another signal that is dependent on the elapse of time;

(b) means for storing a root;

(c) at least one sensor accessible from the exterior of said access key,

said keypad includes:

(a) means for entering the stimulus number

(b) excitation means communicating with the stimulus entering means for exciting the sensor of the access key when the excitation means of the keypad is adjacent the sensor of the access key for communicating the stimulus number to the access key;

said access key further includes:

(a) means coupled to said sensor for using the signal to produce the stimulus number;

(b) password generating means for encrypting said another signal produced by said second clock means and said stimulus number and said root for producing an encrypted password;

(c) displaying means communicating with the password generating means for display at least part of said encrypted password, so that the user can input the encrypted password into the computer;

wherein said access key verification means further includes:

(a) means for decrypting the encrypted password displayed on the access key to calculate said root.

Description Submit all comments and votes

FIELD OF THE INVENTION

This invention relates to apparatus for affording access to computer systems and/or computer software only by authorized persons and also for secure communications of data, and more particularly to apparatus physically independent of the computer but capable of executing an algorithm that can also be executed by the computer to afford access or secure communications of data.

BACKGROUND OF THE INVENTION

Numerous techniques for limiting access to computer systems (also known as access management) and software (also known as software protection), and for enabling secure communications of data are practiced. In multiuser systems it is typical for each user to have an identification code and/or a password which the user must enter before gaining access to the system. Security of the system can be compromised when an authorized user reveals his or her identification code and/or password to unauthorized persons or the access code is discovered by a systematic attack such as that used by hackers.

Another technique employed, particularly with respect to application software that is provided on magnetic diskettes, is to encode on the diskette a protective routine that prevents the making of usable copies with standard copy methods. This technique has had only moderate success in preventing unauthorized use or unauthorized copying because programs for disabling such protective routines are widely available.

Further techniques for securing computers, software and communications include the use of seemingly random generated passwords affording the appropriate access. In some systems, these passwords are generated independently of where access is desired and in other systems the random passwords are generated in response to an inquiry or stimulus from the computer, software or communication source to which access is desired. For these types of systems, there are a number of approaches used by hackers and those intent on stealing valuable information in order to break into the system. One of the approaches is known as the "table attack" or "clear text attack." In the table attack, a table is built out of the relationship between the stimulus and the response or password generated therefrom. If the system for controlling access is relative static, a table can be built in a relatively short time so that given any particular stimulus, one intent on breaking into the system can determine the appropriate password from the table.

Another approach to break into such systems is known as the "cypher text attack." This approach is appropriate when the response or password results from a known or predictable stimulus. An analysis of the relationship between the stimulus and the response using standard cryptographic analysis techniques allows passwords appropriate to the future to be predicted.

Still a further approach or attack applicable to time dependent devices is time compression. This is accomplished by speeding up the clock to generate passwords appropriate to the future so as to more rapidly build a table for one of the other types of attack. Accordingly, when the future time arrives, the password is known and used to break into the system.

SUMMARY OF THE INVENTION

The present invention is embodied in a device that is analogous to a key in that it is a small portable device that can be conveniently carried by the user and that can be employed to obtain access to computers and software and for secure communications. The key contains solid state or semiconductor electronic elements that can execute a prescribed algorithm or one of a plurality of prescribed algorithms to produce a code which the computer receives and affords access to the computer, computer software, or provides secure communications if the code is correct.

A semiconductor key embodying the present invention includes a timer or clock which produces a series of pulses at a repetition rate corresponding to the elapse of real time. In the specific embodiments described hereinafter in more detail, the timer produces one pulse per day. The timer pulse changes the contents of a shift register, the output of the shift register being a predetermined function of the calendar date. The device includes a character output display of a password which is a function of the previously mentioned function. When the user inputs the displayed password to a computer, computer program or secure communications system to practice the invention, the computer affords access if the password is correct and/or has a prescribed relationship to a number generated within the computer.

In order for the software in the computer to be able to produce an internal password for comparison with the user input password, the user is first prompted by the computer to enter at least initially the current date. Most computers are presently configured with self-controlled battery operated clock cards which maintain the current date whether or not power to the system is maintained. The computer manipulates the current date by an algorithm corresponding to that in the key to produce the internal password.

An important aspect of the invention is that the shift register within the key is pre-loaded at manufacturing time with a unique number or numbers so that the likelihood of two keys being the same unique numbers is insignificant. For example, if the size of the shift register in the key is 32 bits, a size easily achievable under the present state of the art, there are almost five billion bit combinations that can be produced. Because the key is active, i.e., because a continuous supply of power is necessary to maintain the register state, disassembly of the key for the purposes of ascertaining the function is virtually impossible, because in disassembly it is highly likely that power to the shift register would be interrupted.

An enhanced version of a software access key embodying the invention, which is even more difficult for unauthorized persons to decode, involves an extra step to produce a password for input by the user. As in the version to which reference has been previously made, the key contains a shift register whose state changes with elapsed real time. The computer with which the key is adapted to cooperate is coded to generate a stimulus number which can be randomly generated and which is saved within the host computer. The stimulus number is transmitted to the key without direct connection. One technique for so transmitting the stimulus number involves excitation of one or more predetermined sites on the video display of the host computer and providing in the key one or more photo-sensors which respond to the pattern of excitation of the sites. The key includes circuitry for decoding the pattern of excitation at the display sites and generating a password from a combination of the decoded signal and the output of the above mentioned register that changes with real time. In practicing the invention employing the enhanced version, the association between the password displayed to the user and the current date as manifested by the output of the timer within the key is even more tenuous and therefore more difficult, if not impossible, to display by reverse engineering.

A further improvement to the above enhanced version includes the use of a keypad into which the access key can be placed. The keypad can be used with a computer system that does not have a video display or has one which will not properly excite the sensors on the access key itself. The keypad includes key switches and excitation device such as light-emitting diodes which can be placed in juxtaposition to the sensors of the access key. The computer display or printer or other output device displays an appropriate alphanumeric code which is then entered into the keypad. The keypad in turn excites the sensors on the key in order to transfer the stimulus.

In a further aspect of the invention for access management, software protection and secured communications, the key can have what is known as a forward algorithm and the host computer can have what is known as an algorithm which is inverse to the forward algorithm. An inverse algorithm is sometimes referred to as a reverse algorithm. In such an arrangement each key can be provided with an individually personalized root which is encrypted into a password by the forward algorithm. The encrypted password is then provided to the inverse algorithm of the host computer where the original root is recalculated. This original root can be used for comparison with a root stored within a computer for allowing access to the computer or to the software. Alternatively, in the case where the root is not stored within the host computer, the calculated root can be used as part of the puzzle to decrypt previously encrypted software. The forward and inverse algorithm modules of the invention can in fact contain a plurality of algorithms which can be selected depending on the passage of time or depending on yet another algorithm. The another algorithm can be contained in a further module and is often times referred as a seed module. This seed algorithm can provide output which is also time dependent. Through the use of one or two time dependent algorithms, possibilities of the system becoming susceptible to any of the attacks previously described is minimal to non-existent. The reason for decreased susceptibility to attack is that there is not enough time to build an adequate table before the algorithm changes.

Yet another practical way to reduce drastically the odds that the system can be broken is to increase the minimum of possibilities for the stimulus number.

In yet another aspect of the invention, in a secured environment, a root is selected and the appropriate software is encrypted using the root as part of the encryption. The encrypted software is then stored in the computer. The root is placed in the appropriate personalized key. The key is then used to access the software in the computer by transferring the root from the key to a decryption module in the computer where the root is used as part of a puzzle to decrypt the software so that the software can be used.

This same approach is used for sending and receiving encrypted data, computer programs and the like. Further, the key itself can be used to transport valuable data. This is implemented by using the valuable data as the root itself. The host computer then uses the password obtained from the access key to recalculate the root and obtain the valuable data. As the root in the access key will be destroyed should any attempt be made to disassemble the key, the root is highly secure.

An object of the invention is to provide a hardware device that must be employed to gain access to computers and software and for secure communications. This object is achieved by producing and displaying a password which must be input by the user and by arranging the circuitry in the key so that it produces, each time the device is used, a different password in accordance with an algorithm that is virtually impossible to predict.

Another object of the invention is to provide a device of the type described above that is inexpensive, portable and longlasting. The advent of large scale integrated circuit technology, such as manifested in existent wristwatches and the like, permits a key in accordance with the invention to be produced at a moderate cost, particularly when compared to the cost of many software programs.

A feature and advantage of the invention is that it employs digital techniques which afford exponential expansion of the number of possible combinations by merely extending by one or more bits the size of the numbers that the apparatus employs in producing a password.

The foregoing, together with other objects, features and advantages, will be more apparent after referring to the following specification and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a computer access key embodying the invention with portions being broken away to reveal internal details.

FIG. 2 is a block diagram showing the interaction between a relatively uncomplex key in accordance with the invention and a computer containing code in accordance with the invention.

FIG. 3 is a block diagram similar to FIG. 2 but showing an enhanced key according to the invention.

FIG. 4 is a block diagram of exemplary circuitry within the key of FIG. 3.

FIG. 5 is a table showing logical states at various points in the circuit of FIG. 4 during a typical operating sequence.

FIG. 6 is a block diagram f a key showing various enhancements in accordance with the invention.

FIG. 7 is a block diagram of another embodiment of the access key and access verification system of the invention which uses forward and inverse algorithms.

FIG. 8 depicts the invention of FIG. 7 with the enhancement of a stimulus number generator.

FIG. 9 depicts an enhanced version of the embodiment of FIG. 7 wherein a calculated root is compared with a stored root to allow access to a computer or software.

FIG. 10 depicts an enhanced version of the embodiment of FIG. 7 with the use of a seed or a second personality characteristic in addition to the root.

FIG. 11 depicts the block diagram of a system for encrypting and securing software including a software encrypter, the access key, and access key verification and decrypter system.

FIG. 12 depicts a block diagram of a secured communication system for communicating secure data between two computers at distant locations.

FIG. 13 depicts another embodiment of a secured communications system for communicating secure data between two computers.

FIG. 14 depicts an embodiment of the key pad of the invention.

FIG. 15 depicts a block diagram of the key pad of the invention.

FIG. 16 depicts patterns of optical signals of the invention.

FIG. 17 depicts a block diagram of an embodiment of the invention for detecting misuse of the access key.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring more particularly to the drawings, reference numeral 12 indicates a key embodying the present invention. The key includes a housing of plastic or like imperforate material which is hollow so as to define a central cavity 14. Within cavity 14 are elements, such as an integrated circuit device indicated fragmentarily at 16. Accessible from the exterior of the imperforate housing is a display 18 formed of conventional numeric or alphanumeric display elements, there being four numeric display elements in the embodiment shown in FIG. 1. Such elements are typically liquid crystal display or LCD elements. In the specific example seen in FIG. 1, display 18 displays the password or a displayed character representation "1854."

The top surface of key 12 is formed with a circular recess 20. The bottom surface of the recess contains one or more contact points 22, or openings in alignment with contact points within cavity 14, for establishing electrical contact with the circuitry 16 within the key. The contact points are employed when the key is set or initialized during manufacture to load a code or bit pattern that is unique to each user. After the key has been so set, a disk-shaped cover 24 is installed in recess 20 to insulate contacts 22. Disk-shaped cover 24 can be an adhesive-backed label having an outer surface containing trademark or product identifying information.

Key 12 has a front face 26. Mounted within face 26 and accessible from the exterior of key are sensors 28a, 28b, 28c and 28d. In the specific embodiment shown in the drawings, sensors 28a-28d are photoelectric diodes which respond to images formed on the video display screen D of the computer system containing software to which access is to be had. A fragment of video display screen D is shown at reduced scale in FIG. 1. As will be described subsequently, predetermined sites S on the screen are excited in an appropriate time-space pattern to produce a signal that is received by key 12 by way of sensors 28a-28d. The sensors and the sites on the computer video display exemplify an information transmission link that uses radiant energy and not direct connection between the key and the computer. Other useful forms of radiant energy are sonic energy or radio frequency energy.

As will be described hereinbelow with respect to FIGS. 14 and 15, in the situation where the computer system does not have a video screen, but has for example, a printer output or LCD or LED output, a keypad with sensors cannot be used in the way contemplated by the present embodiment. In that situation an access key can be inserted into the keypad with the appropriate stimulus from the computer entered into the keypad and simultaneously communicated through the light-emitting diodes of the keypad.

Referring to FIG. 2, there is a key 12' which is somewhat less complex than that shown in FIG. 1 in that key 12' is not equipped with sensors 28a-28d Key 12' includes a crystal-controlled pulse generator or clock 30 that produces a series of timing pulses that count real time. In one device designed in accordance with the invention, pulse generator 30 produces one pulse per day. The timing pulses supplied by pulse generator 30 are coupled to a password generator 32. The password generator produces a unique combination of binary digits depending on the number of date pulses that have been supplied to it by pulse generator 30 since initialization. Thus the binary bit pattern produced by password generator 32 is a function of the current date, referred to in this description and in FIG. 1 as f'(date).

As will be described in more detail hereinafter in connection with the embodiment of FIGS. 3 and 4, password generator 32 can be embodied in a shift register into which pulses from pulse generator 30 are introduced serially and which produces a bit pattern representing f'(dat