Tracking Entities by Means of Hash Values

• US 20130197859A1
• Filed: 01/14/2013
• Published: 08/01/2013
• Est. Priority Date: 01/30/2012
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Albano, Gherardo, De Judicibus, Dario
• Granted Patent: US 9,600,443 B2
• Time in Patent Office: Days
• US Class Current: 702/150
• CPC Class Codes: G06F 17/11 for solving equations , e.g. nonlinear equations, general mathematical optimization problems optimization specially adapted for a specific administrative, business or logistic context G06Q10/04
• CPC Class Codes: G06F 17/13 Differential equations using digital differential analysers G06F7/64
• CPC Class Codes: G06V 20/52 Surveillance or monitoring of activities, e.g. for recognising suspicious objects recognising microscopic objects G06V20/69
• CPC Class Codes: G06V 20/625 License plates
• CPC Class Codes: G06V 40/103 Static body considered as a whole, e.g. static pedestrian or occupant recognition
• CPC Class Codes: G06V 40/166 using acquisition arrangements
• CPC Class Codes: G07C 1/10 together with the recording, indicating or registering of other data, e.g. of signs of identity
• CPC Class Codes: G10L 17/00 Speaker identification or verification techniques

Abstract

Mechanisms for tracking an entity are provided. A time is determined by a sensor having a clock, the time being within a time slot in a series of time slots. First data of the time slot is provided and shared between a plurality of sensors. The sensor receives data from the movable entity. The sensor calculates identifying data from the received data for identifying the entity. Derivative identifying data is calculated by applying a modifying function using the provided first data for modifying the identifying data. The sensor calculates a hash value by taking the derivative identifying data as input. The sensor sends a message to a central server for determining the position of the entity, the message comprising the hash value and an identifier of the sensor.

Claims

1. A computer-implemented method for tracking at least one movable entity, the method comprising:

a) determining a current time by a first one of one or more sensor devices, each of said sensor devices having a clock for determining the current time, the current time lying within a first time slot, the first time slot being one of a series of time slots, the clocks of all sensor devices being synchronized, the series of time slots being shared by all the sensor devices;

h) providing first data, the first data being particular to the first time slot and being shared between all first time slots of the sensor devices;

c) receiving by the first sensor device a set of data, the set of data being received from the at least one movable entity;

d) calculating by said first sensor device identifying data from the received set of data for identifying the at least one entity by means of said identifying data;

e) calculating derivative identifying data by applying a modifying function on the identifying data, the modifying function using the identifying data as first input value and using the provided first data as a second input value for modifying the identifying data;

f) calculating by said first sensor device a first hash value by taking the derivative identifying data as input, the first hash value being calculated by applying a hash function; and

g) sending a message from the first sensor device to a central server for determining the position of the at least one movable entity, the message comprising the hash value and an identifier of the first sensor device.

2. The computer-implemented method according to claim 1, the method further comprising encrypting the message before sending the message to the central server.

3. The computer-implemented method according to claim 1, wherein the hash function is operable to calculate, for any pair of two similar input values, a pair of similar output values, whereby a degree of similarity of said pair of input values correlates with a degree of similarity of said pair of output values.

4. The computer-implemented method according to claim 1, the method further comprising, for k second time slots preceding the first time slot in the series of time slots, k being an integer larger than 1, the following:

determining one of the k second time slots, the determined second time slot directly preceding a current time slot;

providing other first data, the other first data being particular to the determined second time slot and being shared between the sensor devices;

calculating a second derivative identifying data by applying a modifying function on the identifying data, the modifying function using the identifying data as first input value and using the provided other first data as a second input value for modifying the identifying data;

calculating by said first sensor device a second hash value by taking the second derivative identifying data as input, the second hash value being calculated by applying the hash function; and

storing the first and each of the k second hash values on a storage medium being integral part of the first sensor device.

5. The computer-implemented method according to claim 1, wherein:

the first data is first random data and wherein the step of providing the first data comprises the steps of executing a random function on the first sensor device;

the second data is a second random data and wherein the step of providing the second data comprises the steps of executing the random function on the first sensor device; and

the provided first and the second data are unique within all pieces of data respectively being particular for one of the time slots.

6. The computer-implemented method according to claim 1, the method further comprising:

h) repeating the steps c) to f) n times, n being an integer larger than 2 during the first time slot, thereby receiving n sets of data from the movable entity and calculating for each of said n received sets of data and for the first time slot a respective first hash value, wherein for the calculation of each of said n first hash values the respectively received set of data was used as input;

i) storing each of the n first hash values on a storage medium of the first sensor device;

j) determining by said first sensor device that the first time slot has expired; and

k) upon said determination, executing step g), wherein the message comprises said n first hash values.

7. The computer-implemented method according to claim 1, the method further comprising:

repeating the steps a) to g) for each of j time slots, j being an integer larger than 3, thereby receiving one or more sets of data for each of the j time slots and calculating one or more further hash values for each of said j time slots, wherein for the calculation of each further hash value of one of said j time slots the same first data is used, wherein the one or more further hash values are stored in a storage medium of the first sensor device; and

after having sent the message created for each one of the j time slots, deleting all hash values having been calculated for the m-last time slot and any time slot preceding said m-last time slot, wherein m is an integer larger than 0 and smaller than j.

8. The computer-implemented method according to claim 1, the method further comprising:

determining by said first sensor device one or more parameter values for the received set of data, the one or more parameter values being selected, in any combination, from a group of parameter values comprising;

a timestamp information being indicative of a moment in time when the set of data was received;

a parameter value of the movable entity, said parameter being automatically derived by the first sensor device by evaluating the received set of data; and

a property of the first sensor device, wherein the sent message in addition comprises the one or more determined parameter values.

9. The computer-implemented method according to claim 1, wherein providing the first and/or second data comprises:

generating by the central server the first or second random data; and

sending said first or second random data to each of the one or more sensor devices via a network.

10. The computer-implemented method according to claim 1, wherein:

the one or more movable entities are humans, the one or more sensor devices are cameras, the received set of data is an image taken from the at least one human by one of said cameras and wherein the identifying data is a face-print or thermal print of said at least one human;

or

wherein the one or more movable entities are humans, the one or more sensor devices are microphones, the received set of data is a voice record from one of the humans by one of said microphones and wherein the identifying data is a voice profile of said human;

or

wherein the one or more movable entities are vehicles, the one or more sensor devices are cameras or radar sensors, the received set of data is image data of the vehicle'"'"'s number plate and the number specified on said plate is said car'"'"'s identifying data.

11. A computer-implemented method for tracking one or more movable entities, the method comprising:

receiving by a central server a first message from a first one of one or more sensor devices, the first message comprising a first hash value, an identifier of said first sensor device and a first timestamp information;

evaluating the identifier of the first sensor device for determining a first location, the first location being the location of the first sensor device;

assigning the first location and the first timestamp information to a first data object, the first data object representing a first one of the one or more movable entities;

receiving by the central server at least one second message from the first or a second one of the one or more sensor devices, the at least one second message comprising a second hash value, a second identifier of said first or second sensor device and a second timestamp information;

evaluating the second identifier for determining a second location, the second location being the location of the first or second sensor device having sent the second message;

comparing the first hash value against the second hash value for determining a degree of similarity between the first and the second hash values;

in case the determined degree of similarity is below a threshold value, assigning the second location and the second timestamp information to a second data object representing a second one of the movable entities;

in case the determined degree of similarity is equal or above said threshold value, assigning the second location and the second timestamp information to the first data object; and

storing the first and/or second data object in a data storage of the central server, thereby tracking the movement of the movable entity represented by said first and/or second movable entity object.

12. The computer-implemented method according to claim 11, wherein the first message comprises one or more first ones of a plurality of parameter values and wherein each of the at least one second message comprises one or more second ones of said parameter values, the one or more first and second parameter values being selected, in any combination, from a group of parameter values comprising:

a timestamp information being indicative of a moment in time when a data set was received from one of the movable entities;

a parameter value of the movable entity; and

a property of the first sensor device, wherein executing the comparison further comprises;

evaluating the one or more first parameter values and the one or more second parameter values; and

in case the evaluation of the one or more first and second parameter values indicates that the parameters of the first message stem from another one of the movable entities than the parameter values of the at least one second message, creating the second data object and assigning the second location and the second timestamp information to the second data object even in case the determined degree of similarity is above the threshold value.

13. (canceled)

14. A sensor device for tracking at least one movable entity, the sensor device comprising:

a clock for determining a current time, the current time lying within a first time slot, the first time slot being one of a series of time slots, the clock being adapted for synchronizing the clock with clocks of one or more further sensor devices;

a controller module being adapted for;

sharing the series of time slots with all other sensor devices; and

providing first data, the first data being particular to the first time slot and being shared with all other first time slots of the sensor devices;

a first interface being adapted for receiving a set of data, the set of data being received from the at least one movable entity;

a calculation unit, the calculation unit being adapted for;

calculating identifying data from the received set of data for identifying the at least one entity by means of said identifying data;

calculating derivative identifying data by applying a modifying function on the identifying data, the modifying function using the identifying data as first input value and using the provided first data as a second input value for modifying the identifying data; and

calculating a first hash value by taking the derivative identifying data as input, the first hash value being calculated by applying a hash function; and

a second interface being adapted for sending a message from the first sensor device to a central server for indicating the position of the at least one movable entity, the message comprising the hash value and an identifier of the first sensor device.

15. A computer system comprising:

a central server, the central server comprising;

a data storage;

a first interface adapted for receiving a first message from a first one of one or more sensor devices, the first message comprising a first hash value and an identifier of said first sensor device, the first message comprising a first timestamp information;

a path assembly module, the path assembly module being adapted for;

evaluating the identifier of the first sensor device for determining a first location, the first location being the location of the first sensor device;

assigning the first location and the first timestamp information to a first data object, the first data object representing a first one of the one or more movable entities;

receiving by the central server at least one second message from the first or a second one of the one or more sensor devices, the at least one second message comprising a second hash value and a second identifier of said first or second sensor device, the at least one second message comprising a second timestamp information;

evaluating the second identifier of the at least one second sensor device for determining a second location, the second location being the location of the first or second sensor device having sent the second message;

comparing the first hash value against the second hash value for determining a degree of similarity between the first and the second hash values;

in case the determined degree of similarity is below a threshold value, creating a second data object representing a second one of the movable entities; and

assigning the second location and the second timestamp information to the second data object;

in case the determined degree of similarity is equal or above said threshold value, assigning the second location and the second timestamp information to the first data object; and

storing the first and/or second data object in the data storage of the central server, thereby tracking the movement of the movable entity represented by said first and/or second data object.

16. A computer program product comprising a computer readable storage medium having a computer readable program stored therein, wherein the computer readable program, when executed on a computing device, causes the computing device to:

a) determine a current time by a first one of one or more sensor devices, each of said sensor devices having a clock for determining the current time, the current time lying within a first time slot, the first time slot being one of a series of time slots, the clocks of all sensor devices being synchronized, the series of time slots being shared by all the sensor devices;

b) provide first data, the first data being particular to the first time slot and being shared between all first time slots of the sensor devices;

c) receive by the first sensor device a set of data, the set of data being received from the at least one movable entity;

d) calculate by said first sensor device identifying data from the received set of data for identifying the at least one entity by means of said identifying data;

e) calculate derivative identifying data by applying a modifying function on the identifying data, the modifying function using the identifying data as first input value and using the provided first data as a second input value for modifying the identifying data;

f) calculate by said first sensor device a first hash value by taking the derivative identifying data as input, the first hash value being calculated by applying a hash function; and

g) send a message from the first sensor device to a central server for determining the position of the at least one movable entity, the message comprising the hash value and an identifier of the first sensor device.

17. The computer program product according to claim 16, wherein the computer readable program further causes the computing device to encrypt the message before sending the message to the central server.

18. The computer program product according to claim 16, wherein the hash function is operable to calculate, for any pair of two similar input values, a pair of similar output values, whereby a degree of similarity of said pair of input values correlates with a degree of similarity of said pair of output values.

19. The computer program product according to claim 16, wherein the computer readable program further causes the computing device, for k second time slots preceding the first time slot in the series of time slots, k being an integer larger than 1, to perform the following:

determine one of the k second time slots, the determined second time slot directly preceding a current time slot;

provide other first data, the other first data being particular to the determined second time slot and being shared between the sensor devices;

calculate a second derivative identifying data by applying a modifying function on the identifying data, the modifying function using the identifying data as first input value and using the provided other first data as a second input value for modifying the identifying data;

calculate by said first sensor device a second hash value by taking the second derivative identifying data as input, the second hash value being calculated by applying the hash function; and

store the first and each of the k second hash values on a storage medium being integral part of the first sensor device.

20. The computer program product according to claim 16, wherein:

the first data is first random data and wherein the step of providing the first data comprises the steps of executing a random function on the first sensor device;

the second data is a second random data and wherein the step of providing the second data comprises the steps of executing the random function on the first sensor device; and

the provided first and the second data are unique within all pieces of data respectively being particular for one of the time slots.

21. The computer program product according to claim 16, wherein the computer readable program further causes the computing device to:

h) repeat the steps c) to f) n times, n being an integer larger than 2 during the first time slot, thereby receiving n sets of data from the movable entity and calculating for each of said n received sets of data and for the first time slot a respective first hash value, wherein for the calculation of each of said n first hash values the respectively received set of data was used as input;

i) store each of the n first hash values on a storage medium of the first sensor device;

j) determine by said first sensor device that the first time slot has expired; and

upon said determination, executing step g), wherein the message comprises said n first hash values.