CN115828311B - Block chain-based crowd sensing privacy protection incentive mechanism method - Google Patents

Block chain-based crowd sensing privacy protection incentive mechanism method Download PDF

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CN115828311B
CN115828311B CN202310114476.7A CN202310114476A CN115828311B CN 115828311 B CN115828311 B CN 115828311B CN 202310114476 A CN202310114476 A CN 202310114476A CN 115828311 B CN115828311 B CN 115828311B
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worker
workers
task
bidding
data
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CN115828311A (en
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童飞
周远航
王凯明
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Southeast University
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Southeast University
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Abstract

The invention discloses a block chain-based crowd sensing privacy protection excitation mechanism method, which can effectively stimulate workers to participate in crowd sensing tasks under given cost constraint, maximize coverage functions and ensure the privacy of users; the block chain-based crowd sensing system provided by the invention can realize decentralization and ensure privacy and safety; the excitation mechanism method provided by the invention can maximize the coverage function under the given budget, and carry out the user recruitment process and the reward calculation process; the invention designs a specific protocol based on the intelligent contract of the block chain, and can be suitable for most block chain systems; the incentive mechanism provided by the invention has the advantages of calculation effectiveness, individuality, authenticity, approximation degree and privacy protection, and can obtain higher coverage, lower payment and more complete security than the similar algorithm, including authorization authentication, user anonymity and user data privacy.

Description

Block chain-based crowd sensing privacy protection incentive mechanism method
Technical Field
The invention relates to the field of Internet of things application, approximation algorithm and distributed systems, in particular to a block chain-based crowd sensing privacy protection incentive mechanism method.
Background
Crowd sensing is a data collection mode combining sensing capability and crowd sourcing of mobile equipment, and can collect large-scale sensing data by means of the strength of a general user; crowd sensing is now widely used in a number of fields including traffic monitoring, environmental detection, medical protection, location-based services, etc.; crowd sensing has the characteristics of high extensibility and low professional requirements.
The traditional crowd sensing system is too dependent on a centralized server and has the problem of single-point failure, so that the robustness of the crowd sensing system is lost; therefore, the block chain technology is introduced to replace the traditional server, so that a decentralised crowd sensing system is realized, and the safety of the crowd sensing system is improved; at present, most of block chains support intelligent contract technology, and intelligent contracts can realize the protocol functions set by a system, automatically and reliably execute given tasks, and are suitable for realizing specific interactions in a crowd sensing flow.
The main problem of limiting crowd sensing is insufficient participation and unstable data quality, so that it is important to design an effective excitation mechanism for the crowd sensing system to improve the participation; the goal of the incentive mechanism is to select the appropriate crowd-sourced participants and pay rewards in the form of rewards based on their contributions; the mainstream design concept is to set an optimization target, for example, to maximize the profit of the crowd sensing platform, and accordingly select the appropriate crowd sensing participants and decide to pay them.
The current blockchain-based incentive scheme design has the following problems: part of the work designs various incentive mechanisms, but omits how to realize the mechanisms in the blockchain through intelligent contracts, so that the work has no universality; some works are mainly optimizing the income of entities when designing the optimization scene, but neglecting the importance of the data quality factors in crowd sensing; most of the work considers that the blockchain and the intelligent contract have high security, but in practice, due to the openness of the blockchain and the transparency of the intelligent contract, privacy leakage is easily caused by the operation of an incentive mechanism, and the participation enthusiasm of users is restrained.
Disclosure of Invention
Aiming at the problems, the invention designs a block chain-based crowd sensing privacy protection excitation mechanism method, which can effectively stimulate workers to participate in crowd sensing tasks under given cost constraint, maximize coverage functions and ensure the privacy of users; the block chain-based crowd sensing system provided by the invention can realize decentralization and ensure privacy and safety; the incentive mechanism method provided by the invention comprises a user recruitment process and a reward calculation process; the invention designs a specific protocol based on intelligent contracts of the block chain according to the steps of crowd sensing, and can be suitable for most block chain systems; the incentive mechanism method provided by the invention has the advantages of calculation effectiveness, individuality, authenticity, approximation degree and privacy protection, and can obtain higher coverage, lower payment and more complete security than the similar algorithm, including authorization authentication, user anonymity and user data privacy.
The technical scheme of the invention is as follows:
the block chain-based crowd sensing privacy protection incentive mechanism method is characterized by comprising the following steps of:
step 1: designing and mathematical modeling is carried out on a block chain-based crowd sensing system, a crowd sensing system structure comprising a requester, workers, block chains and an excitation mechanism is built based on reverse auction, and mathematical models of the requester, workers, crowd sensing tasks, rewards and benefits of the workers are built;
step 2: based on the characteristics of the position-related crowd sensing system, designing a coverage function as an optimization target, and constructing an optimization problem of maximizing the coverage function under budget constraint;
step 3: the intelligent contract technology based on the block chain designs a group intelligent perception privacy protection incentive mechanism framework, which comprises six stages: a registration phase, a task delivery phase, a bidding phase, a worker recruitment phase, a data submission phase, and a payment phase;
step 4: in the registration stage, workers and requesters register on the blockchain to acquire identity certificates for authentication in subsequent operation, and elliptic curve cryptography is used as a public and private key system;
step 5: in the task delivery stage, the registered requester issues the crowd sensing task to the blockchain by calling a task delivery contract;
Step 6: in the bidding stage, the registered workers perform bidding operations by calling bidding contracts, in order to ensure the privacy of bidding books, the bidding books are uploaded to a blockchain in the form of Pedersen promise, and in order to ensure the anonymity of the workers, a ring signature method is adopted as an authentication mode;
step 7: in the recruitment stage of workers, all workers participating in bidding need to disclose own real bidding books, the bidding books disclose that the bidding information of the workers is verified by the closing date, all workers with illegal information are eliminated, the information of the rest workers is input into an incentive mechanism contract, the incentive mechanism contract is automatically executed at preset time, and the obtained result is published;
step 8: in the data submitting stage, all winners need to encrypt the data of the winners and submit the encrypted data to an interstellar file system, and the abstract and the storage address of the data are uploaded to a blockchain through a data submitting contract;
step 9: during the payoff phase, the requester gives each winner a consideration that is calculated by the incentive mechanism.
Further, in the step 1, the crowd sensing system has the following structure:
the crowd sensing system comprises four roles of a requester, a worker, a blockchain and an incentive mechanism; requester (E)
Figure SMS_3
Is the initiator of the perception task, the requestor is gathered with +.>
Figure SMS_6
Indicating (I)>
Figure SMS_8
Task set usefulness->
Figure SMS_2
Indicating (I)>
Figure SMS_5
Comprises->
Figure SMS_7
A plurality of perception tasks; worker->
Figure SMS_9
Is the executor of the perception task, and the worker is integrated with +.>
Figure SMS_1
Indicating that it contains->
Figure SMS_4
A worker; the block chain provides a security platform for crowd sensing; the incentive mechanism is a program deployed on the blockchain with the goal of selecting workers and deciding to pay the workers;
each worker
Figure SMS_11
Submitting a triplet tagbook +.>
Figure SMS_14
Wherein->
Figure SMS_17
Is worker->
Figure SMS_12
Is (are) located>
Figure SMS_13
Is the task set of the worker, including all tasks that he is willing to perform, < >>
Figure SMS_16
Is worker->
Figure SMS_19
For quotations of>
Figure SMS_10
Indicating worker->
Figure SMS_15
Is>
Figure SMS_18
Is private and known only by the inventor;
given bidding document
Figure SMS_20
The goal of the incentive mechanism is to select a set of winners +.>
Figure SMS_21
And decides to give each winner a reward whose size depends on its contribution to the task, with +.>
Figure SMS_22
Representing files, wherein->
Figure SMS_23
Is to give workers +.>
Figure SMS_24
If the worker is ++>
Figure SMS_25
Is a delivery house, then->
Figure SMS_26
；
Worker's work
Figure SMS_27
Is->
Figure SMS_28
Can be calculated by subtracting the true cost from the reward, i.e
Figure SMS_29
。
Further, in the step 2, an overlay function is defined in consideration of the location-dependent crowd sensing system
Figure SMS_30
The following are provided: / >
Figure SMS_31
,
Wherein the method comprises the steps of
Figure SMS_33
Is task->
Figure SMS_37
Is determined by the importance and value of the task's position, +.>
Figure SMS_40
Is task->
Figure SMS_34
Is assembled->
Figure SMS_36
The number of times of worker's execution, +.>
Figure SMS_39
Is a system parameter controlling the decreasing gradient of benefit, by +.>
Figure SMS_41
And->
Figure SMS_32
Respectively represent task->
Figure SMS_35
Position importance and value of (2), weight +.>
Figure SMS_38
The calculation formula is that
Figure SMS_42
,
Wherein the method comprises the steps of
Figure SMS_43
Is a balance parameter; the goal of the incentive mechanism is to have a fixed budget +.>
Figure SMS_44
Under maximizing coverage function, a problem called maximizing coverage function under budget constraint, formalized as
Figure SMS_45
。
Further, in the step 3, the crowd sensing privacy protection incentive mechanism framework includes six stages: a registration phase, a task delivery phase, a bidding phase, a worker recruitment phase, a data submission phase, and a payment phase; the operation of the client side realizes the interaction between a requester and a worker and the intelligent contract, the intelligent contract realizes the request processing, the function realization and the data uplink, the intelligent contract interacts with the blockchain to complete the data uplink process, and the process forms a group intelligent perception privacy protection incentive mechanism framework.
Further, in the step 4, the registration stage is as follows:
all requesters and workers need to register when joining the crowd sensing system for the first time, and acquire a pair of public key and private key, the system adopts elliptic curve cryptography as a key management scheme, and the system sets the adopted elliptic curve in advance
Figure SMS_48
Prime order->
Figure SMS_49
And a common datum point on the curve->
Figure SMS_52
And discloses these information, workman +.>
Figure SMS_47
Randomly selecting private key +.>
Figure SMS_51
Satisfy->
Figure SMS_53
The corresponding public key is +.>
Figure SMS_54
The private key is stored by the worker himself, the public key is disclosed, and the worker can acquire an identity mark during registration>
Figure SMS_46
Requester->
Figure SMS_50
The registration procedure is the same.
Further, in the step 5, the task delivery stage is as follows:
the registered requester can issue own tasks by calling task delivery contracts, the requester needs to attach a digital signature generated by using own private keys and verify the digital signature by using intelligent contracts, and after the tasks are issued, workers can check task information on a blockchain and select interested tasks;
each perception task comprises a task name, a task position and a task description, the task position is divided according to a pre-determined area and is represented by a number, and the perception task information is attached with a abstract so as to ensure that the perception task is not tampered with and a task requester
Figure SMS_55
It will also be disclosed that the worker can find the public key of the requester later, and after delivering all the tasks, the requester will also submit a budget
Figure SMS_56
Indicating the payability it can offer to recruit workers.
Further, in the step 6, the bidding phase is as follows:
The registered worker can select the task set according to his own will, bid by calling a bidding contract, the information in the bidding including position information, task set and quotation are all present in a numerical mode, and hidden by using Pedersen promise, giving an elliptic curve in advance
Figure SMS_57
And two datum points->
Figure SMS_58
And->
Figure SMS_59
And->
Figure SMS_60
Unknown, true value for the need to be hidden +.>
Figure SMS_61
The Pedersen promise calculation formula is +.>
Figure SMS_62
Wherein->
Figure SMS_63
Blind factors selected randomly; />
In addition to submitting the petersen commitment, the worker needs to attach a ring signature to anonymously verify his identity, giving an elliptic curve, during the bidding step
Figure SMS_65
And datum point->
Figure SMS_68
，/>
Figure SMS_71
The public key of the individual worker is denoted +.>
Figure SMS_67
，/>
Figure SMS_69
It is assumed that the order parameter of the real signer is +.>
Figure SMS_72
，/>
Figure SMS_74
The private key of the signer is denoted +.>
Figure SMS_64
Use->
Figure SMS_70
A key image representing a signer, wherein +.>
Figure SMS_73
Is the public key of the signer,/->
Figure SMS_75
Is a hash function satisfying cryptographic security, its return value is +.>
Figure SMS_66
At the last point, the signature process is as follows:
by using
Figure SMS_79
Representing a message to be signed, the signer being all workers +.>
Figure SMS_80
Generating a randomization factor->
Figure SMS_84
And random variable->
Figure SMS_76
Wherein->
Figure SMS_82
Is->
Figure SMS_86
Prime order of->
Figure SMS_88
Is an integer modulo +.>
Figure SMS_78
The remaining set of >
Figure SMS_83
Indicating worker->
Figure SMS_87
Corresponding to the public key with +.>
Figure SMS_89
Indicating worker->
Figure SMS_77
Corresponding to the key image with +.>
Figure SMS_81
Indicating worker->
Figure SMS_85
The signer performs the following calculation on the hash value after the random factors of the random factors are combined;
Figure SMS_90
,
wherein the method comprises the steps of
Figure SMS_91
Is a return +.>
Figure SMS_92
The signer then continues to perform the following calculations as a hash function of a certain value in (a)
Figure SMS_93
，
Wherein the method comprises the steps of
Figure SMS_94
Let->
Figure SMS_95
Thus->
Figure SMS_96
Thus(s)
Figure SMS_97
，
The final ring signature is denoted as
Figure SMS_98
The signer attaches the generated ring signature to complete the bidding process, in which all bidding information is hidden, and the bidding worker identity is anonymous, the intelligent contract needs to verify the ring signature, and the verification process is as follows:
the intelligent contract end performs the following calculation
Figure SMS_99
，/>
Figure SMS_100
，
If it is
Figure SMS_101
Then the ring signature +.>
Figure SMS_102
Is legal, in particular if two ring signatures have duplicate key images +.>
Figure SMS_103
Then the two ring signatures are said to be linked and their signers are the same worker, for convenience of identification, a new +.>
Figure SMS_104
After the intelligent contract is verified, the bidding phase is ended.
Further, in the step 7, the worker recruiting stage is as follows:
all the workers participating in bidding need to reveal the true value of their own bidding by calling the bidding disclosure contract, and the intelligent closing date is compared and verified with the previously submitted Pedersen promise according to the true value, and for promise
Figure SMS_106
And received true value->
Figure SMS_109
Calculate->
Figure SMS_111
If->
Figure SMS_107
Then the promise is legal, the intelligent contract excludes all promise illegal workers, and the information of the rest workers is integrated, and the intelligent contract is used for +.>
Figure SMS_108
Representing the final anonymous set of workers with +.>
Figure SMS_110
Representing the final tagbook document,/->
Figure SMS_112
And->
Figure SMS_105
Will be sent to the incentive mechanism contract as input;
the incentive mechanism is realized through intelligent contracts, can be triggered at a given time, and aims to solve the problem of maximizing coverage functions under budget constraint, select workers and decide to give a return to winners, and the specific steps are as follows:
s1: initializing a set of winners
Figure SMS_113
Initializing the reward set +.>
Figure SMS_114
Initializing a set of screening workers
Figure SMS_115
；
S2: from a collection
Figure SMS_116
A value to be given to the random variable +.>
Figure SMS_117
；
S3: if it is
Figure SMS_118
Executing S4, otherwise, jumping to S6;
s4: finding a set of screening workers
Figure SMS_119
Can make->
Figure SMS_120
Anonymous worker with the greatest value->
Figure SMS_121
；
S5: will anonymize workers
Figure SMS_122
Add to the winner set->
Figure SMS_123
And give anonymity workers +.>
Figure SMS_124
The reward of (2) is->
Figure SMS_125
Wherein->
Figure SMS_126
For budget, jump to S17;
s6: finding a set of screening workers
Figure SMS_127
Can make->
Figure SMS_128
Anonymous worker with the greatest value->
Figure SMS_129
Wherein
Figure SMS_130
；
S7: if it is
Figure SMS_131
Executing S8, otherwise jumping to S10;
S8: will anonymize workers
Figure SMS_132
Add to the winner set->
Figure SMS_133
；
S9: finding collections
Figure SMS_134
Can make->
Figure SMS_135
Anonymous worker with the greatest value->
Figure SMS_136
，/>
Figure SMS_137
Is indicated at->
Figure SMS_138
Middle exclusion set +.>
Figure SMS_139
The rest set after the middle element jumps to S7;
s10: for a set of winners
Figure SMS_140
Each anonymous worker in->
Figure SMS_141
These workers, also called winners, perform steps S11-S16;
s11: initializing a temporary winner set
Figure SMS_142
；
S12: finding collections
Figure SMS_143
Can make->
Figure SMS_144
Second anonymous worker with maximum value +.>
Figure SMS_145
，/>
Figure SMS_146
Representing exclusion element anonymity worker +>
Figure SMS_147
Posterior Collection->
Figure SMS_148
；
S13: if it is
Figure SMS_149
Executing S14, otherwise jumping to S17;
s14: finding collections
Figure SMS_150
Can make->
Figure SMS_151
Second anonymous worker with maximum value +.>
Figure SMS_152
；
S15: updating anonymous workers
Figure SMS_153
Is the reward of (2)
Figure SMS_154
；
S16: second anonymizing worker
Figure SMS_155
Join to temporary winner set->
Figure SMS_156
Jump to S13;
s17: returning a set of winners
Figure SMS_157
And reward set->
Figure SMS_158
；
After the result is obtained by the contract calculation of the incentive mechanism, the result is published on the blockchain, and workers can anonymize through themselves
Figure SMS_159
Confirm whether itself is selected as the winner.
Further, in the step 8, the data submitting stage is as follows:
the winner needs to go through the carryingThe collected perceived data is submitted to a task using the interstellar file system as a distributed storage system to ease the storage burden on the blockchain, the winner first needs to share a secure key with the requester, and the winner generates a one-time private key
Figure SMS_160
The corresponding disposable public key is +.>
Figure SMS_161
The one-time public key needs to be uplink, the one-time private key is owned by the winner, and the shared secure key calculation formula is +.>
Figure SMS_162
The key has only the winner himself and has the private key +.>
Figure SMS_163
The requester of the (E) can be obtained through calculation, so that the safety is ensured;
the winner hashes the shared secure key to obtain a final encryption key
Figure SMS_164
Encrypting the submitted data by using the key, transferring the encrypted content to an interstellar file system to finish uploading the data, and then uploading the hash value and the storage address of the submitted data to a blockchain by a winner through a data submitting contract after encrypting the hash value and the storage address of the submitted data by using the encryption key, wherein a requester calculates the encryption key->
Figure SMS_165
Decrypting the encrypted hash value and the storage address, and obtaining data information submitted by a winner in an interstellar file system, wherein the hash value of the data ensures the integrity and the non-tamper property of the data.
Further, in the step 9, the payment phase is as follows:
after confirming the receiving of the perception data submitted by the winner, the requester gives a certain amount of payment to the winner according to the reward result calculated by the previous incentive mechanism, and the whole crowd sensing process is completed.
The beneficial effects of the invention are as follows:
the block chain-based crowd sensing privacy protection excitation mechanism method provided by the invention can effectively stimulate workers to participate in crowd sensing tasks, and solves the problem of insufficient crowd sensing participation; the block chain-based crowd sensing system provided by the invention does not need a centralized server, and can realize decentralization, privacy and safety; the excitation mechanism method provided by the invention can maximize the coverage function under a given budget and acquire the calculation effectiveness, individuality, authenticity and approximation degree; the excitation mechanism method provided by the invention is designed based on the intelligent contract of the blockchain, has completeness and feasibility, can be suitable for most blockchain systems, and ensures the privacy of users; compared with the similar algorithm, the incentive mechanism provided by the invention can achieve higher coverage, lower payment and more complete security, including authorization authentication, user anonymity and user data privacy.
Drawings
FIG. 1 is a flow chart of a block chain-based crowd sensing privacy protection incentive mechanism method;
FIG. 2 is a flow diagram of an incentive mechanism algorithm;
FIG. 3 (a) is a graph of test results of time consumption of registration, task delivery, incentive, and chain execution of payment steps in the privacy preserving incentive scheme method;
FIG. 3 (b) is a graph of test results of time consumption of execution on a chain of bidding, bidding disclosure, data submission steps in the privacy preserving incentive mechanism method;
FIG. 4 (a) is a graph of test results of execution time of registration, task delivery, payment steps in the privacy preserving incentive mechanism method;
FIG. 4 (b) is a graph of test results of execution time of bidding, worker recruitment, data submission steps in the privacy preserving incentive mechanism method;
FIG. 5 (a) is a graph of comparison of the optimized target values obtained by the privacy preserving incentive scheme method with the number of workers;
FIG. 5 (b) is a graph of the comparison of payments required by the privacy preserving incentive mechanism method as a function of the number of workers;
FIG. 6 (a) is a graph of comparison of the variation of the optimization target value with the budget obtained by the privacy preserving incentive mechanism method;
fig. 6 (b) is a graph of the comparison of the payment required by the privacy preserving incentive mechanism method as a function of budget.
Detailed Description
The technical scheme and effect of the present invention will be described in detail below with reference to the accompanying drawings. A simulation result compared with the similar excitation mechanism method is also provided as an example, but this example is only for the purpose of explaining the present invention and is not to be construed as a limitation of the present invention.
Example 1: as shown in fig. 1, a block chain-based crowd-sourced privacy-preserving incentive mechanism method includes the following steps:
step 1: designing and mathematical modeling is carried out on a block chain-based crowd sensing system, a crowd sensing system structure comprising a requester, workers, block chains and an excitation mechanism is built based on reverse auction, and mathematical models of the requester, workers, crowd sensing tasks, rewards and benefits of the workers are built;
step 2: based on the characteristics of the position-related crowd sensing system, designing a coverage function as an optimization target, and constructing an optimization problem of maximizing the coverage function under budget constraint;
step 3: the intelligent contract technology based on the block chain designs a group intelligent perception privacy protection incentive mechanism framework, which comprises six stages: a registration phase, a task delivery phase, a bidding phase, a worker recruitment phase, a data submission phase, and a payment phase;
step 4: in the registration stage, workers and requesters register on the blockchain to acquire identity certificates for authentication in subsequent operation, and elliptic curve cryptography is used as a public and private key system;
step 5: in the task delivery stage, the registered requester issues the crowd sensing task to the blockchain by calling a task delivery contract;
Step 6: in the bidding stage, the registered workers perform bidding operations by calling bidding contracts, in order to ensure the privacy of bidding books, the bidding books are uploaded to a blockchain in the form of Pedersen promise, and in order to ensure the anonymity of the workers, a ring signature method is adopted as an authentication mode;
step 7: in the recruitment stage of workers, all workers participating in bidding need to disclose own real bidding books, the bidding books disclose that the bidding information of the workers is verified by the closing date, all workers with illegal information are eliminated, the information of the rest workers is input into an incentive mechanism contract, the incentive mechanism contract is automatically executed at preset time, and the obtained result is published;
step 8: in the data submitting stage, all winners need to encrypt the data of the winners and submit the encrypted data to an interstellar file system, and the abstract and the storage address of the data are uploaded to a blockchain through a data submitting contract;
step 9: during the payoff phase, the requester gives each winner a consideration that is calculated by the incentive mechanism.
Further, in the step 1, the crowd sensing system has the following structure:
the crowd sensing system comprises four roles of a requester, a worker, a blockchain and an incentive mechanism; requester (E)
Figure SMS_167
Is the initiator of the perception task, the requestor is gathered with +.>
Figure SMS_170
Indicating (I)>
Figure SMS_172
Task set usefulness->
Figure SMS_168
Indicating (I)>
Figure SMS_171
Comprises->
Figure SMS_173
A plurality of perception tasks; worker->
Figure SMS_174
Is the executor of the perception task, and the worker is integrated with +.>
Figure SMS_166
Indicating that it contains->
Figure SMS_169
A worker; the block chain provides a security platform for crowd sensing; the incentive mechanism is a program deployed on the blockchain with the goal of selecting workers and deciding to pay the workers;
each worker
Figure SMS_176
Submitting a triplet tagbook +.>
Figure SMS_180
Wherein->
Figure SMS_183
Is worker->
Figure SMS_175
Is (are) located>
Figure SMS_179
Is the task set of the worker, including all tasks that he is willing to perform, < >>
Figure SMS_182
Is worker->
Figure SMS_184
For quotations of>
Figure SMS_177
Indicating worker->
Figure SMS_178
Is>
Figure SMS_181
Is private and known only by the inventor;
given bidding document
Figure SMS_185
The goal of the incentive mechanism is to select a set of winners +.>
Figure SMS_186
And decides to give each winner a reward whose size depends on its contribution to the task, with +.>
Figure SMS_187
Representing files, wherein->
Figure SMS_188
Is to give workers +.>
Figure SMS_189
If the worker is ++>
Figure SMS_190
Is a delivery house, then->
Figure SMS_191
；
Worker's work
Figure SMS_192
Is->
Figure SMS_193
Can be calculated by subtracting the true cost from the reward, i.e
Figure SMS_194
。
Further, in the step 2, an overlay function is defined in consideration of the location-dependent crowd sensing system
Figure SMS_195
The following are provided:
Figure SMS_196
,
Wherein the method comprises the steps of
Figure SMS_198
Is task->
Figure SMS_200
Is determined by the importance and value of the task's position, +.>
Figure SMS_203
Is task->
Figure SMS_199
Is assembled->
Figure SMS_202
The number of times of worker's execution, +.>
Figure SMS_205
Is a system parameter controlling the decreasing gradient of benefit, by +.>
Figure SMS_206
And->
Figure SMS_197
Respectively represent task->
Figure SMS_201
Position importance and value of (2), weight +.>
Figure SMS_204
The calculation formula is that
Figure SMS_207
,
Wherein the method comprises the steps of
Figure SMS_208
Is a balance parameter; the goal of the incentive mechanism is to have a fixed budget +.>
Figure SMS_209
The lower maximizing coverage function, the problem called maximizing coverage function under budget constraint, is formalized as +.>
Figure SMS_210
。
Further, in the step 3, the crowd sensing privacy protection incentive mechanism framework includes six stages: a registration phase, a task delivery phase, a bidding phase, a worker recruitment phase, a data submission phase, and a payment phase; the operation of the client side realizes the interaction between a requester and a worker and the intelligent contract, the intelligent contract realizes the request processing, the function realization and the data uplink, the intelligent contract interacts with the blockchain to complete the data uplink process, and the process forms a group intelligent perception privacy protection incentive mechanism framework.
Further, in the step 4, the registration stage is as follows:
all requesters and workers need to register when joining the crowd sensing system for the first time, and acquire a pair of public key and private key, the system adopts elliptic curve cryptography as a key management scheme, and the system sets the adopted elliptic curve in advance
Figure SMS_212
Prime order->
Figure SMS_216
And a common datum point on the curve->
Figure SMS_218
And discloses these information, workman +.>
Figure SMS_213
Randomly selecting private key +.>
Figure SMS_215
Satisfy->
Figure SMS_217
Corresponding maleKey of +.>
Figure SMS_219
The private key is stored by the worker himself, the public key is disclosed, and the worker can acquire an identity mark during registration>
Figure SMS_211
Requester->
Figure SMS_214
The registration procedure is the same.
Further, in the step 5, the task delivery stage is as follows:
the registered requester can issue own tasks by calling task delivery contracts, the requester needs to attach a digital signature generated by using own private keys and verify the digital signature by using intelligent contracts, and after the tasks are issued, workers can check task information on a blockchain and select interested tasks;
each perceived task comprises a task name, a task position and a task description, in particular, the task position is divided according to a predetermined area and is represented by a number, and perceived task information is attached with a abstract to ensure that the perceived task information is not tampered with and a task requester
Figure SMS_220
It will also be disclosed that the worker can find the public key of the requester later, and after delivering all tasks, the requester will also submit a budget +.>
Figure SMS_221
Indicating the payability it can offer to recruit workers.
Further, in the step 6, the bidding phase is as follows: the registered worker can select the task set according to his own will, bid by calling a bidding contract, the information in the bidding including position information, task set and quotation are all present in a numerical mode, and hidden by using Pedersen promise, giving an elliptic curve in advance
Figure SMS_222
And two datum points->
Figure SMS_223
And->
Figure SMS_224
And->
Figure SMS_225
Unknown, true value for the need to be hidden +.>
Figure SMS_226
The Pedersen promise calculation formula is
Figure SMS_227
Wherein->
Figure SMS_228
Blind factors selected randomly;
in addition to submitting the petersen commitment, the worker needs to attach a ring signature to anonymously verify his identity, giving an elliptic curve, during the bidding step
Figure SMS_229
And datum point->
Figure SMS_233
，/>
Figure SMS_236
The public key of the individual worker is denoted +.>
Figure SMS_230
，/>
Figure SMS_235
It is assumed that the order parameter of the real signer is +.>
Figure SMS_238
，/>
Figure SMS_240
The private key of the signer is expressed as/>
Figure SMS_232
Use->
Figure SMS_234
A key image representing a signer, wherein +.>
Figure SMS_237
Is the public key of the signer,/->
Figure SMS_239
Is a hash function satisfying cryptographic security, its return value is +.>
Figure SMS_231
At the last point, the signature process is as follows:
by using
Figure SMS_243
Representing a message to be signed, the signer being all workers +.>
Figure SMS_246
Generating a randomization factor->
Figure SMS_250
And random variable->
Figure SMS_244
Wherein- >
Figure SMS_248
Is->
Figure SMS_252
Prime order of->
Figure SMS_254
Is an integer modulo +.>
Figure SMS_241
The remaining set of>
Figure SMS_247
Indicating worker->
Figure SMS_251
Corresponding to the public key with +.>
Figure SMS_253
Indicating worker->
Figure SMS_242
Corresponding to the key image with +.>
Figure SMS_245
Indicating worker->
Figure SMS_249
The signer performs the following calculation on the hash value after the random factors of the random factors are combined;
Figure SMS_255
,
wherein the method comprises the steps of
Figure SMS_256
Is a return +.>
Figure SMS_257
The signer then continues to perform the following calculations as a hash function of a certain value in (a)
Figure SMS_258
，
Wherein the method comprises the steps of
Figure SMS_259
Let->
Figure SMS_260
Thus->
Figure SMS_261
Thus(s)
Figure SMS_262
，
The final ring signature is denoted as
Figure SMS_263
The signer attaches the generated ring signature to complete the bidding process, in which all bidding information is hidden, and the bidding worker identity is anonymous, the intelligent contract needs to verify the ring signature, and the verification process is as follows:
the intelligent contract end performs the following calculation
Figure SMS_264
，
If it is
Figure SMS_265
Then the ring signature +.>
Figure SMS_266
Is legal, in particular if two ring signatures have duplicate key images +.>
Figure SMS_267
Then the two ring signatures are said to be linked and their signers are the same worker, for convenience of identification, a new +.>
Figure SMS_268
After the intelligent contract is verified, the bidding phase is ended.
Further, in the step 7, the worker recruiting stage is as follows:
All the workers participating in bidding need to reveal the true value of their own bidding by calling the bidding disclosure contract, and the intelligent closing date is compared and verified with the previously submitted Pedersen promise according to the true value, and for promise
Figure SMS_271
And received true value->
Figure SMS_272
Calculate->
Figure SMS_274
If->
Figure SMS_270
Then the promise is legal, the intelligent contract excludes all promise illegal workers, and the information of the rest workers is integrated, and the intelligent contract is used for +.>
Figure SMS_273
Representing the final anonymous set of workers with +.>
Figure SMS_275
Representing the final tagbook document,/->
Figure SMS_276
And->
Figure SMS_269
Will be sent to the incentive mechanism contract as input;
the incentive mechanism is implemented by intelligent contracts, can be triggered at a given time, and aims to solve the problem of maximizing coverage functions under budget constraints, select workers and decide to give a return to winners, as shown in fig. 2, the specific steps of the incentive mechanism are as follows:
s1: initializing a set of winners
Figure SMS_277
Initializing the reward set +.>
Figure SMS_278
Initializing a set of screening workers
Figure SMS_279
；
S2: from a collection
Figure SMS_280
A value to be given to the random variable +.>
Figure SMS_281
；
S3: if it is
Figure SMS_282
Executing S4, otherwise, jumping to S6;
s4: finding a set of screening workers
Figure SMS_283
Can make->
Figure SMS_284
Anonymous worker with the greatest value->
Figure SMS_285
；
S5: will anonymize workers
Figure SMS_286
Add to the winner set- >
Figure SMS_287
And give anonymity workers +.>
Figure SMS_288
The reward of (2) is->
Figure SMS_289
Wherein->
Figure SMS_290
For budget, jump to S17;
s6: finding a set of screening workers
Figure SMS_291
Can make->
Figure SMS_292
Anonymous worker with the greatest value->
Figure SMS_293
Wherein
Figure SMS_294
；
S7: if it is
Figure SMS_295
Executing S8, otherwise jumping to S10;
s8: will anonymize workers
Figure SMS_296
Add to the winner set->
Figure SMS_297
；
S9: finding collections
Figure SMS_298
Can make->
Figure SMS_299
Anonymous worker with the greatest value->
Figure SMS_300
，/>
Figure SMS_301
Is indicated at->
Figure SMS_302
Middle exclusion set +.>
Figure SMS_303
The rest set after the middle element jumps to S7;
s10: for a set of winners
Figure SMS_304
Each anonymous worker in->
Figure SMS_305
These workers, also called winners, perform steps S11-S16;
s11: initializing a temporary winner set
Figure SMS_306
；
S12: finding collections
Figure SMS_307
Can make->
Figure SMS_308
Second anonymous worker with maximum value +.>
Figure SMS_309
，/>
Figure SMS_310
Representing exclusion element anonymity worker +>
Figure SMS_311
Posterior Collection->
Figure SMS_312
；
S13: if it is
Figure SMS_313
Executing S14, otherwise jumping to S17;
s14: finding collections
Figure SMS_314
Can make->
Figure SMS_315
Second anonymous worker with maximum value +.>
Figure SMS_316
；
S15: updating anonymous workers
Figure SMS_317
The reward of (2) is->
Figure SMS_318
；
S16: second anonymizing worker
Figure SMS_319
Join to temporary winner set->
Figure SMS_320
Jump to S13;
s17: returning a set of winners
Figure SMS_321
And reward set->
Figure SMS_322
；
After the result is obtained by the contract calculation of the incentive mechanism, the result is published on the blockchain, and workers can anonymize through themselves
Figure SMS_323
Confirm whether itself is selected as the winner.
Further, in the step 8, the data submitting stage is as follows:
winners need to complete tasks by submitting collected perceived data, use the interstellar file system as a distributed storage system to ease storage burden on the blockchain, the winner first needs to share a secure key with the requester, and the winner generates a one-time private key
Figure SMS_324
The corresponding disposable public key is +.>
Figure SMS_325
The one-time public key needs to be uplink, the one-time private key is owned by the winner, and the shared secure key calculation formula is +.>
Figure SMS_326
The key has only the winner himself and has the private key +.>
Figure SMS_327
The requester of the (E) can be obtained through calculation, so that the safety is ensured;
the winner hashes the shared secure key to obtain a final encryption key
Figure SMS_328
And uses the key to pair the submitted numberEncrypting the data, transmitting the encrypted content to an interstellar file system to finish uploading the data, encrypting the hash value and the storage address of the submitted data by using an encryption key, uploading the encrypted hash value and the storage address to a blockchain through a data submitting contract, and calculating the encryption key by a requester>
Figure SMS_329
Decrypting the encrypted hash value and the storage address, and obtaining data information submitted by a winner in an interstellar file system, wherein the hash value of the data ensures the integrity and the non-tamper property of the data.
Further, in the step 9, the payment phase is as follows:
after confirming the receiving of the perception data submitted by the winner, the requester gives a certain amount of payment to the winner according to the reward result calculated by the previous incentive mechanism, and the whole crowd sensing process is completed.
The following is the simulation experiment result:
the crowd sensing privacy protection incentive mechanism method based on the blockchain is compared with an SPPIM method in Towards a smartprivacy-preserving incentive mechanism for vehicular crowd sensing published by Wang et al in Security and Communication Networks and a CrowdBC method in A blockchain-based decentralized framework for crowdsourcing published by Li et al in IEEE Transactions on Parallel and Distributed Systems in 2018 in performance.
All simulation experiments are carried out on one Ubuntu virtual machine, the memory is 50GB, the CPU of the host is i9-7900X 3.30GHz, and the memory is 128GB. Experiments were deployed on a Hyperledger Fabric v2.3 platform, with each test being an average of 5 results.
In the cryptography method, ed25519 is selected as a public key signature scheme, SHA-512 is selected as a hash function, AES-256 is selected as a symmetric encryption algorithm, and the same cryptography scheme is adopted in the comparison algorithm in order to ensure the fairness of comparison. For the excitation mechanism, the criteria are set as follows: number of workers
Figure SMS_330
100, task number->
Figure SMS_331
20, the size of the worker task set is from [5,10]Random selection of specific tasks, system parameters->
Figure SMS_332
Set to 0.8 and the budget set to 100,000. The offers are randomly selected from the dataset and are all in the range 100,500]Is a kind of medium.
As shown in fig. 3 (a) and 3 (b), the time consumption of the privacy-preserving incentive mechanism method on the chain is tested, it can be seen that the average time of each transaction increases with the number of transactions, and the amount of increase of other contracts except the incentive mechanism contract (IM) is small, and considering the computational complexity of the incentive mechanism algorithm, such increase is normal, and in practical application, there is generally no such number of concurrent requests, and thus no excessive processing time is caused. According to the result of time consumption, fig. 3 is divided into two sub-graphs according to different measurement sizes, it can be seen that the time consumption of registering contracts, task delivery contracts, incentive mechanism contracts and payment contracts is less, while the time consumption of bidding contracts, bidding exposing contracts and data submitting contracts is greater, because the verification process in the ring signature scheme is time consuming, but considering anonymity that can be brought by the ring signature, such time consumption is worth, and the time consumption of all contracts is not more than 330ms, which is suitable for practical application.
As shown in fig. 4 (a), 4 (b), the step execution time of the privacy preserving incentive mechanism method was tested, and the step execution included the client operation under the chain and the smart contract operation on the chain. It can be seen that the registration, task delivery and payment steps are accomplished in a short time, while the bidding, worker recruitment and data submission steps are time consuming. In practice, the time taken to generate the ring signature is about as much as the time taken to verify the ring signature, resulting in a larger time taken for the bidding and data submission steps. The worker recruitment step includes a tagbook exposure and incentive mechanism process, and thus time consumption is also large. As the number of requests increases, the average time cost increases slightly and the rate of increase of the worker recruitment step is greatest.
Figure SMS_333
As shown in table 1, the privacy-preserving incentive mechanism method was tested against the step execution time of the same class of algorithms in milliseconds, N/a indicating that the scheme did not involve the design of the step. It can be seen that the proposed solution of the present invention has a time advantage over the other two solutions in the registration step and the task delivery step. In the worker recruiting step and the data submitting step, the scheme of the invention consumes longer time due to the use of the ring signature, but the scheme also achieves anonymity. The payment step performs a few schemes quite different.
Defining an incentive scheme evaluation index overdrinking rate, the calculation of which is obtained by dividing the total cost by the total cost, i.e
Figure SMS_334
。
As shown in fig. 5 (a) and 5 (b), the performance of the privacy preserving incentive scheme method was tested to change with the number of workers, and it can be seen that the proposed scheme is much larger than the coverage function achieved by SPPIM, because the incentive scheme adopted in the scheme selects winners according to the contribution of workers, the coverage function achieved by the scheme is 35.8% higher than SPPIM under standard setting, and the number of users recruited by the scheme is also much higher than SPPIM, which is mainly related to payment strategy. The total payment spent by the scheme is also much smaller than SPPIM, and a lower overdry rate is achieved, indicating the high efficiency of the payment scheme. As the number of workers increases, both the coverage function and the number of workers available to the solution increases, as the mechanism is able to select more valuable workers as more workers become available. Thus, the total payment and overstock rate also decrease slightly as the number of workers increases.
As shown in fig. 6 (a) and 6 (b), the performance of privacy-preserving incentive mechanism methods was tested for changes with budget, and as the budget increases, the number of workers recruited by all mechanisms increases, and thus the coverage function achieved increases. As the budget increases, more users need to be recruited, and thus the overall rewards and overpayment rate increase at the same time.
It should be noted that any process or method descriptions in flow charts or otherwise described herein may be understood as representing modules, segments, or portions of code which include one or more executable instructions for implementing specific logical functions or steps of the process, and that scope of preferred embodiments of the present invention includes additional implementations in which functions may be executed out of order from that shown or discussed, including in substantially the same way or in reverse order from that shown or discussed, depending on the functionality involved, as would be understood by those skilled in the art of the embodiments of the patent.
In the description of the present specification, the descriptions of the terms "one embodiment," "some embodiments," "examples," "particular examples," or "some examples" and the like mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Although embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives, and variations may be made in the above embodiments by those skilled in the art without departing from the spirit and principles of the invention.

Claims (3)

1. The block chain-based crowd sensing privacy protection incentive mechanism method is characterized by comprising the following steps of:
step 1: designing and mathematical modeling is carried out on a block chain-based crowd sensing system, a crowd sensing system structure comprising a requester, workers, block chains and an excitation mechanism is built based on reverse auction, and mathematical models of the requester, workers, crowd sensing tasks, rewards and benefits of the workers are built;
step 2: based on the characteristics of the position-related crowd sensing system, designing a coverage function as an optimization target, and constructing an optimization problem of maximizing the coverage function under budget constraint;
step 3: the intelligent contract technology based on the block chain designs a group intelligent perception privacy protection incentive mechanism framework, which comprises six stages: a registration phase, a task delivery phase, a bidding phase, a worker recruitment phase, a data submission phase, and a payment phase;
Step 4: in the registration stage, workers and requesters register on the blockchain to acquire identity certificates for authentication in subsequent operation, and elliptic curve cryptography is used as a public and private key system;
step 5: in the task delivery stage, the registered requester issues the crowd sensing task to the blockchain by calling a task delivery contract;
step 6: in the bidding stage, the registered workers perform bidding operations by calling bidding contracts, in order to ensure the privacy of bidding books, the bidding books are uploaded to a blockchain in the form of Pedersen promise, and in order to ensure the anonymity of the workers, a ring signature method is adopted as an authentication mode;
step 7: in the recruitment stage of workers, all workers participating in bidding need to disclose own real bidding books, the bidding books disclose that the bidding information of the workers is verified by the closing date, all workers with illegal information are eliminated, the information of the rest workers is input into an incentive mechanism contract, the incentive mechanism contract is automatically executed at preset time, and the obtained result is published;
step 8: in the data submitting stage, all winners need to encrypt the data of the winners and submit the encrypted data to an interstellar file system, and the abstract and the storage address of the data are uploaded to a blockchain through a data submitting contract;
Step 9: in the payment phase, the requester gives each winner a certain consideration, and the consideration is calculated by an incentive mechanism;
in the step 1, the crowd sensing system has the following structure:
the crowd sensing system comprises four roles of a requester, a worker, a blockchain and an incentive mechanism; requester (E)
Figure QLYQS_2
Is the initiator of the perception task, the requestor is gathered with +.>
Figure QLYQS_6
Indicating (I)>
Figure QLYQS_8
Task set usefulness->
Figure QLYQS_3
Indicating (I)>
Figure QLYQS_5
Comprises->
Figure QLYQS_7
A plurality of perception tasks; worker->
Figure QLYQS_9
Is the executor of the perception task, and the worker is integrated with +.>
Figure QLYQS_1
Indicating that it contains->
Figure QLYQS_4
A worker; the block chain provides a security platform for crowd sensing; the incentive mechanism is a program deployed on the blockchain with the goal of selecting workers and deciding to pay the workers;
each worker
Figure QLYQS_11
Submitting a triplet tagbook +.>
Figure QLYQS_15
Wherein->
Figure QLYQS_18
Is worker->
Figure QLYQS_12
Is (are) located>
Figure QLYQS_14
Is the task set of the worker, including all tasks that he is willing to perform, < >>
Figure QLYQS_17
Is worker->
Figure QLYQS_19
For quotations of>
Figure QLYQS_10
Indicating worker->
Figure QLYQS_13
Is>
Figure QLYQS_16
Is private and known only by the inventor;
given bidding document
Figure QLYQS_20
The goal of the incentive mechanism is to select a set of winners +.>
Figure QLYQS_21
And decides to give each winner a reward whose size depends on its contribution to the task, with +. >
Figure QLYQS_22
The file is represented by a set of data,wherein->
Figure QLYQS_23
Is to give workers +.>
Figure QLYQS_24
If the worker is ++>
Figure QLYQS_25
Is a delivery house, then->
Figure QLYQS_26
；
Worker's work
Figure QLYQS_27
Is->
Figure QLYQS_28
Can be calculated by subtracting the true cost from the reward, i.e
Figure QLYQS_29
；
In the step 2, an overlay function is defined in consideration of a location-dependent crowd sensing system
Figure QLYQS_30
The following are provided: />
Figure QLYQS_31
,
Wherein the method comprises the steps of
Figure QLYQS_33
Is task->
Figure QLYQS_35
Is determined by the importance and value of the task's position, +.>
Figure QLYQS_38
Is task->
Figure QLYQS_34
Is assembled->
Figure QLYQS_37
The number of times of worker's execution, +.>
Figure QLYQS_40
Is a system parameter controlling the decreasing gradient of benefit, by +.>
Figure QLYQS_41
And->
Figure QLYQS_32
Respectively represent task->
Figure QLYQS_36
Position importance and value of (2), weight +.>
Figure QLYQS_39
The calculation formula is that
Figure QLYQS_42
,
Wherein the method comprises the steps of
Figure QLYQS_43
Is a balance parameter; the goal of the incentive mechanism is to have a fixed budget +.>
Figure QLYQS_44
Under maximizing coverage function, a problem called maximizing coverage function under budget constraint, formalized as
Figure QLYQS_45
；
In the step 3, the crowd sensing privacy protection incentive mechanism framework comprises six stages: a registration phase, a task delivery phase, a bidding phase, a worker recruitment phase, a data submission phase, and a payment phase; the operation of the client side realizes the interaction between a requester and a worker and the intelligent contract, the intelligent contract realizes the request processing, the function realization and the data uplink, and the intelligent contract interacts with the blockchain to complete the data uplink process;
In the step 4, the registration stage is as follows:
all requesters and workers need to register when joining the crowd sensing system for the first time, and acquire a pair of public key and private key, the system adopts elliptic curve cryptography as a key management scheme, and the system sets the adopted elliptic curve in advance
Figure QLYQS_47
Prime order->
Figure QLYQS_50
And a common datum point on the curve->
Figure QLYQS_53
And disclose->
Figure QLYQS_49
、/>
Figure QLYQS_52
、/>
Figure QLYQS_55
Worker->
Figure QLYQS_57
Randomly selecting private key +.>
Figure QLYQS_46
Satisfy->
Figure QLYQS_51
The corresponding public key is +.>
Figure QLYQS_54
The private key is stored by the worker himself, the public key is disclosed, and the worker can acquire an identity mark during registration>
Figure QLYQS_56
Requester->
Figure QLYQS_48
The registration process is the same;
in the step 5, the task delivery stage is as follows:
the registered requester can issue own tasks by calling task delivery contracts, the requester needs to attach a digital signature generated by using own private keys and verify the digital signature by using intelligent contracts, and after the tasks are issued, workers can check task information on a blockchain and select interested tasks;
each perception task comprises a task name, a task position and a task description, the task position is divided according to a pre-determined area and is represented by a number, and the perception task information is attached with a abstract so as to ensure that the perception task is not tampered with and a task requester
Figure QLYQS_58
It will also be disclosed that the worker can find the public key of the requester later, and after delivering all tasks, the requester will also submit a budget +.>
Figure QLYQS_59
Representing its ability to pay for recruiter to offer;
in the step 6, the bidding stage is as follows:
the registered worker can select the task set according to his own will, bid by calling a bidding contract, the information in the bidding including position information, task set and quotation are all present in a numerical mode, and hidden by using Pedersen promise, giving an elliptic curve in advance
Figure QLYQS_60
And two datum points->
Figure QLYQS_61
And->
Figure QLYQS_62
And->
Figure QLYQS_63
Unknown, true value for the need to be hidden +.>
Figure QLYQS_64
The Pedersen promise calculation formula is +.>
Figure QLYQS_65
Wherein->
Figure QLYQS_66
Blind factors selected randomly;
in addition to submitting the petersen commitment, the worker needs to attach a ring signature to anonymously verify his identity, giving an elliptic curve, during the bidding step
Figure QLYQS_69
And datum point->
Figure QLYQS_73
，/>
Figure QLYQS_76
The public key of the individual worker is denoted +.>
Figure QLYQS_70
，/>
Figure QLYQS_72
It is assumed that the order parameter of the real signer is +.>
Figure QLYQS_75
，/>
Figure QLYQS_78
The private key of the signer is denoted +.>
Figure QLYQS_67
Use->
Figure QLYQS_71
A key image representing a signer, wherein +.>
Figure QLYQS_74
Is the public key of the signer,/->
Figure QLYQS_77
Is a hash function satisfying cryptographic security, its return value is +. >
Figure QLYQS_68
At the last point, the signature process is as follows:
by using
Figure QLYQS_80
Representing a message to be signed, the signer being all workers +.>
Figure QLYQS_83
Generating a randomization factor->
Figure QLYQS_87
And random variable->
Figure QLYQS_82
Wherein->
Figure QLYQS_84
Is->
Figure QLYQS_88
Prime order of->
Figure QLYQS_91
Is an integer modulo +.>
Figure QLYQS_79
The remaining set of>
Figure QLYQS_86
Indicating worker->
Figure QLYQS_90
Corresponding to the public key with +.>
Figure QLYQS_92
Indicating worker->
Figure QLYQS_81
Corresponding to the key image with +.>
Figure QLYQS_85
Indicating worker->
Figure QLYQS_89
The signer performs the following calculation on the hash value combined by the random factors:
Figure QLYQS_93
,
wherein the method comprises the steps of
Figure QLYQS_94
Is a return +.>
Figure QLYQS_95
The signer then continues to perform the following calculations:
Figure QLYQS_96
，
wherein the method comprises the steps of
Figure QLYQS_97
Let->
Figure QLYQS_98
Thus->
Figure QLYQS_99
Thus(s)
Figure QLYQS_100
Figure QLYQS_101
The final ring signature is denoted as
Figure QLYQS_102
The signer attaches the generated ring signature to complete the bidding process, in which all bidding information is hidden, and the bidding worker identity is anonymous, the intelligent contract needs to verify the ring signature, and the verification process is as follows:
the intelligent contract end performs the following calculation:
Figure QLYQS_103
，/>
Figure QLYQS_104
，
if it is
Figure QLYQS_105
Then the ring signature +.>
Figure QLYQS_106
Is legal, in particular if two ring signatures have duplicate keysImage->
Figure QLYQS_107
Then the two ring signatures are said to be linked and their signers are the same worker, for convenience of identification, a new +. >
Figure QLYQS_108
After the intelligent contract is verified, the bidding phase is ended;
in the step 7, the worker recruitment stage is as follows:
all the workers participating in bidding need to reveal the true value of their own bidding by calling the bidding disclosure contract, and the intelligent closing date is compared and verified with the previously submitted Pedersen promise according to the true value, and for promise
Figure QLYQS_110
And received true value->
Figure QLYQS_112
Calculation of
Figure QLYQS_114
If->
Figure QLYQS_111
Then the promise is legal, the intelligent contract excludes all promise illegal workers, and the information of the rest workers is integrated, and the intelligent contract is used for +.>
Figure QLYQS_113
Representing the final anonymous set of workers with +.>
Figure QLYQS_115
Representing the final tagbook document,/->
Figure QLYQS_116
And->
Figure QLYQS_109
Will be sent to the incentive mechanism contract as input;
the incentive mechanism is realized through intelligent contracts, can be triggered at a given time, and aims to solve the problem of maximizing coverage functions under budget constraint, select workers and decide to give a return to winners, and the specific steps are as follows:
s1: initializing a set of winners
Figure QLYQS_117
Initializing the reward set +.>
Figure QLYQS_118
Initializing a set of screening workers
Figure QLYQS_119
；
S2: from a collection
Figure QLYQS_120
A value to be given to the random variable +.>
Figure QLYQS_121
；
S3: if it is
Figure QLYQS_122
Executing S4, otherwise, jumping to S6;
s4: finding a set of screening workers
Figure QLYQS_123
Can make- >
Figure QLYQS_124
Anonymous worker with the greatest value->
Figure QLYQS_125
；
S5: will anonymize workers
Figure QLYQS_126
Add to the winner set->
Figure QLYQS_127
And give anonymity workers +.>
Figure QLYQS_128
The reward of (2) is->
Figure QLYQS_129
Wherein->
Figure QLYQS_130
For budget, jump to S17;
s6: finding a set of screening workers
Figure QLYQS_131
Can make->
Figure QLYQS_132
Anonymous worker with the greatest value->
Figure QLYQS_133
Wherein
Figure QLYQS_134
；
S7: if it is
Figure QLYQS_135
Executing S8, otherwise jumping to S10;
s8: will anonymize workers
Figure QLYQS_136
Add to the winner set->
Figure QLYQS_137
；
S9: finding collections
Figure QLYQS_138
Can make->
Figure QLYQS_139
Anonymous worker with the greatest value->
Figure QLYQS_140
，/>
Figure QLYQS_141
Is indicated at->
Figure QLYQS_142
Middle exclusion set +.>
Figure QLYQS_143
The rest set after the middle element jumps to S7;
s10: for a set of winners
Figure QLYQS_144
Each anonymous worker in->
Figure QLYQS_145
These workers, also called winners, perform steps S11-S16; />
S11: initializing a temporary winner set
Figure QLYQS_146
；
S12: finding collections
Figure QLYQS_147
Can make->
Figure QLYQS_148
Second anonymous worker with maximum value +.>
Figure QLYQS_149
，/>
Figure QLYQS_150
Representing exclusion element anonymity worker +>
Figure QLYQS_151
Posterior Collection->
Figure QLYQS_152
；
S13: if it is
Figure QLYQS_153
Executing S14, otherwise jumping to S17;
s14: finding collections
Figure QLYQS_154
Can make->
Figure QLYQS_155
Second anonymous worker with maximum value +.>
Figure QLYQS_156
；
S15: updating anonymous workers
Figure QLYQS_157
Is the reward of (2)
Figure QLYQS_158
；
S16: second anonymizing worker
Figure QLYQS_159
Join to temporary winner set->
Figure QLYQS_160
Jump to S13;
s17: returning a set of winners
Figure QLYQS_161
And reward set->
Figure QLYQS_162
；
After the result is obtained by the contract calculation of the incentive mechanism, the result is published on the blockchain, and workers can anonymize through themselves
Figure QLYQS_163
Confirm whether itself is selected as the winner.
2. The blockchain-based crowd-aware privacy-preserving incentive scheme method of claim 1, wherein in step 8, the data submission stage is as follows:
winners need to complete tasks by submitting collected perceived data, use the interstellar file system as a distributed storage system to ease storage burden on the blockchain, the winner first needs to share a secure key with the requester, and the winner generates a one-time private key
Figure QLYQS_164
The corresponding disposable public key is +.>
Figure QLYQS_165
The one-time public key needs to be uplink, the one-time private key is owned by the winner, and the shared secure key calculation formula is +.>
Figure QLYQS_166
The key has only the winner himself and has the private key +.>
Figure QLYQS_167
Is->
Figure QLYQS_168
Can be calculated, and ensures the safety;
the winner hashes the shared secure key to obtain a final encryption key
Figure QLYQS_169
Encrypting the submitted data by using the key, transferring the encrypted content to an interstellar file system to finish uploading the data, and then uploading the hash value and the storage address of the submitted data to a blockchain by a winner through a data submitting contract after encrypting the hash value and the storage address of the submitted data by using the encryption key, wherein a requester calculates the encryption key- >
Figure QLYQS_170
Decrypting the encrypted hash value and the storage address, and obtaining data information submitted by a winner in an interstellar file system, wherein the hash value of the data ensures the integrity and the non-tamper property of the data.
3. The blockchain-based crowd-aware privacy-preserving incentive scheme method of claim 2, wherein in step 9, the payment phase is as follows:
after confirming the receiving of the perception data submitted by the winner, the requester gives a certain amount of payment to the winner according to the reward result calculated by the previous incentive mechanism, and the whole crowd sensing process is completed.
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