CN102117476B - Signature watermark system used for CAD (Computer-Aided Design) documents - Google Patents
Signature watermark system used for CAD (Computer-Aided Design) documents Download PDFInfo
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- CN102117476B CN102117476B CN2011100949499A CN201110094949A CN102117476B CN 102117476 B CN102117476 B CN 102117476B CN 2011100949499 A CN2011100949499 A CN 2011100949499A CN 201110094949 A CN201110094949 A CN 201110094949A CN 102117476 B CN102117476 B CN 102117476B
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Abstract
The invention discloses a signature watermark system used for CAD (Computer-Aided Design) documents, belonging to the field of mechanical drafting. The signature watermark system solves the problems that the existing CAD signature system is hard to restore the documents, and an issuer cannot be determined even the document is protected through the joint hands of encrypting and the system. The signature watermark system comprises a signature module, a check module and a restore module, wherein the signature module is used for decomposing the set shape of a signature for embedding the set shape to the original CAD document, then embedding a signature information watermark and a tamper location information watermark for signature, and finally publishing a CAD graph signed; the check module is used for conducting complete checking on the CAD graph received, extracting the signature information of the CAD document for verifying whether the signature of the CAD document is forged nor not, restoring the watermark graph of the CAD document for verifying whether the CAD document is tampered or not, and giving tamper location information when the graph is tampered; and the restore module is used for restoring the CAD document verified by the check process.
Description
Technical field
The present invention relates to a kind of stamped signature watermaking system of the CAD of being used for document, belong to the mechanical drawing field.
Background technology
Current, the CAD engineering drawing software is high because of its pattern precision, and render speed is fast, and advantages such as convenient are preserved in transmission, has progressively replaced hand-drawing and becomes architectural design, the first-selection of departments such as part manufacturing and guided missile, vehicle design.But it has brought severe challenge also for the safety of the intellecture property of electronic drawing and carrying thereof when offering convenience for slip-stick artist and designers.In the communication process of electronic drawing, people can make things convenient for, intactly duplicate, revise former figure, so very likely cause the leakage of confidential information, problems such as intellecture property dispute.
The CAD drawing can not directly be used traditional safety of image technology based on scalar with the storage of polar plot form, the polar plot software security design aspect of now, and still neither one can all have the software of considering to each secure context.In addition, the form of the DWG file of CAD drawing is unexposed always, and this has increased difficulty for again the Secure Application design for scheme to the AutoCAD drawing.
Existing security solution to electronic drawing mainly comprises the protection based on the format document, the softdog to the CAD drawing that embeds seal and occur recently.But how many these modes all exist hidden danger or shortcoming on the safeguard protection means.The structured message in the document (for example PDF document) has been deleted in the format protection fully, makes it be difficult to editor, and the difficulty that reverts to former document from the format document is very big, and on the format document, directly element is edited hardly and possibly realized; Stamped signature (for example the Electronic Seal System of excellent safe scientific & technical corporation adopts the COM technology that the stamped signature image of scalar is associated with electronic drawing) is scalar figure often, can not be compatible fully with the vector drawing, and make the stamped signature operation be very limited; Although the softdog security is higher, (i.e. drawing finishes and the intermediate link of encrypting) can't be confirmed its person of signing and issuing before softdog uses.
Summary of the invention
The present invention seeks in order to solve existing CAD sealing system reduction document difficulty big; Even jointly protect document also to have the problem that to confirm the person of signing and issuing with encrypting.A kind of stamped signature watermaking system of the CAD of being used for document is provided.
A kind of stamped signature watermaking system that is used for the CAD document according to the invention, it comprises the stamped signature module, tests chapter module and recovery module,
The stamped signature module is embedded into original CAD document after being used for the chapter shape of setting decomposed, and embeds the signing messages watermark and stamped signature is carried out in the watermark of tampering location information, then the CAD figure behind the stamped signature is issued;
Test the chapter module and be used for the CAD document behind the stamped signature that receives is carried out the checking of integrality: extract the signing messages of this CAD document, be used to verify whether the signature of this CAD document is forged; Reduce the watermark figure of this CAD document, be used to verify whether this CAD document is distorted, and the situation of being distorted when figure can provide tampering location information;
Recovery module is used to reduce tests the CAD document that chapter passes through.
Wherein, the workflow of stamped signature module is:
Step 1, judge whether this CAD document is affixed one's seal,
Judged result is for being to withdraw from this program; Judged result is for denying execution in step two;
Step 2, to the operation of affixing one's seal of CAD document, obtain to contain the CAD document of chapter shape;
Step 3, containing on the CAD document of chapter shape the signing messages watermark that embeds this CAD document;
Step 4, containing on the CAD document of chapter shape the information of the distorting watermark that embeds this CAD document, accomplishing the stamped signature of this CAD document, and the CAD figure behind the stamped signature is issued.
The workflow of testing the chapter module is:
Whether the CAD document that step 1, judgement receive is affixed one's seal,
Judged result is for being, execution in step 2, judged result be not for, and this CAD document can't be tested the chapter operation, quits a program;
Step 2, employing tampering location watermarking algorithm extract the fragile watermark in this CAD document,
Step 3, judge according to said fragile watermark information whether this CAD document is distorted,
Judged result identifies tampered position for being, tests the chapter failure; Judged result is for denying execution in step 4;
Step 4,8 DCT reversible water mark algorithms of employing extract reversible water marks, are the signing messages that this CAD document embeds,
Step 5, judge whether the signing messages of this CAD document is correct,
Judged result is for being to test Zhang Chenggong; Judged result is tested the chapter failure for not.
The workflow of recovery module is:
Steps A, judge whether the CAD document is reduced,
Judged result is for being to withdraw from this program; Judged result is for denying execution in step B;
Step B, judge this CAD document whether through testing chapter,
Judged result is for being execution in step C; Judged result is that testing Zhang Wei does not pass through, and withdraws from this program;
Step C, the information of the distorting watermark of this CAD document of reducing;
The reduction of this CAD document is accomplished in step D, the signing messages watermark of this CAD document of reducing.
Advantage of the present invention: system of the present invention at first carries out the embedding of reversible water mark and then carries out the embedding of fragile watermark.Owing to have based on the reversible water mark technology of integer transform and can accurately reduce the characteristic of original figure; And has bigger capacity; We can be embedded into signing messages in the original artwork; When extracting signing messages, figure also is reduced into the most initial state, has guaranteed the authenticity of graphical source intactly like this.And based on the Fragile Watermark Algorithm of grid dividing as the outermost protection scheme of system; The unchangeability of the susceptibility of distorting and graph topology structure has been guaranteed the integrality of figure with playing, and the polar plot electronic works has also just obtained excellent protection in the security of the process of completing and transmitting.
Description of drawings
Fig. 1 is stamped signature mercury of the present invention system carries out stamped signature to the CAD document a procedure chart;
Fig. 2 is the workflow diagram of embodiment two described stamped signature modules;
Fig. 3 is that embodiment four is described at the workflow diagram that is containing the signing messages watermark of this CAD document of embedding on the CAD document of chapter shape;
Fig. 4 is that embodiment five is described at the workflow diagram that is containing the information of the distorting watermark of this CAD document of embedding on the CAD document of chapter shape;
Fig. 5 is embodiment six described workflow diagrams of testing the chapter module;
Fig. 6 is embodiment seven described workflow diagrams of judging whether this CAD document is distorted;
Whether correct Fig. 7 be the described signing messages of judging this CAD document of embodiment eight workflow diagram;
Fig. 8 is the workflow diagram of embodiment nine described recovery module.
Embodiment
Embodiment one: below in conjunction with Fig. 1 to Fig. 8 this embodiment is described, the said a kind of stamped signature watermaking system that is used for the CAD document of this embodiment, it comprises the stamped signature module, tests chapter module and recovery module,
The stamped signature module is embedded into original CAD document after being used for the chapter shape of setting decomposed, and embeds the signing messages watermark and stamped signature is carried out in the watermark of tampering location information, then the CAD figure behind the stamped signature is issued;
Test the chapter module and be used for the CAD document behind the stamped signature that receives is carried out the checking of integrality: extract the signing messages of this CAD document, be used to verify whether the signature of this CAD document is forged; Reduce the watermark figure of this CAD document, be used to verify whether this CAD document is distorted, and the situation of being distorted when figure can provide tampering location information;
Recovery module is used to reduce tests the CAD document that chapter passes through.
This embodiment is taken all factors into consideration each secure context; Designed and Implemented polar plot stamped signature watermark based on the multi-watermarking technology; This system uses the reversible water mark technology to embed sender's digital signature information and use the softdog technology that graphic file is encrypted, and has fundamentally protected the security of polar plot.
The stamped signature module, the stamped signature part mainly comprises the embedding of chapter shape file, but the embedding of fragility tampering location watermark for the first time and the embedding of reversible water mark for the second time.Fig. 2 has described the main process of stamped signature.After whole figure of completing is carried out the embedding of chapter shape file, system will carry out watermark for the first time to the whole figure that comprises the chapter shape file and be about to the embedding of signing messages with the mode of reversible water mark.After obtaining embedding the figure of completion, the watermarking algorithm second time of use immediately is each branch block message that the mode of fragile watermark embeds figure.The works of accomplishing have so promptly been obtained embedding.
Test the chapter module, test the chapter module and mainly comprised the figure that receives is carried out the checking of integrality, the extraction of signing messages and the reduction of checking and watermark figure.Under the situation that figure is distorted, can provide tampering location information, can inform that under the situation that signing messages checking is not passed through user's signature forges.The flow process of testing chapter is referring to Fig. 5.
Recovery module; As shown in Figure 8; At first to whether existing watermark information to judge in the figure, only comprise the drawing that watermark information and preceding two steps card passes through and just can revert to original state before the reduction, and distorted or drawing that the source-verify of sign is failed can not be reduced.
Embodiment two: below in conjunction with Fig. 1 and Fig. 2 this embodiment is described, this embodiment is described further embodiment one, and the workflow of stamped signature module is:
Step 1, judge whether this CAD document is affixed one's seal,
Judged result is for being to withdraw from this program; Judged result is for denying execution in step two;
Step 2, to the operation of affixing one's seal of CAD document, obtain to contain the CAD document of chapter shape;
Step 3, containing on the CAD document of chapter shape the signing messages watermark that embeds this CAD document;
Step 4, containing on the CAD document of chapter shape the information of the distorting watermark that embeds this CAD document, accomplishing the stamped signature of this CAD document, and the CAD figure behind the stamped signature is issued.
At first be on the CAD document, to affix one's seal.The major function of this part is that chapter shape is inserted in the middle of the original figure, and the chapter piece is decomposed, for the embedding of watermark ready.
It in the step 3 embedding of signing messages watermark.Referring to Fig. 3, guarantee the authenticity of graphical source, best mode uses the mode of watermark to be embedded in the original figure this signing messages after just being to use the sender that its private key of Hash use of figure is encrypted.Use 8 integer DCT algorithms; All data messages in the figure are carried out after the Hash; Use sender's private key that it is signed, obtain 1024 signing messages, with this information as watermark information; Use 8 integer DCT algorithms to be embedded in the middle of the original figure, capacity that this algorithm is good and the purpose that changes very suitable this step of characteristics of figure visual characteristic hardly.
It in the step 4 embedding of tampering location information watermark.Referring to Fig. 4, after primary watermark embeds, but we use the watermark mode of tampering location to carry out the protection to pattern integrity.This algorithm need carry out once the initial work to original figure before embedding.The main thought of this algorithm is that watermark information is embedded in the middle of the straight line of graphic entity, and the coordinate size of straight line end points has then indicated this watermark information.
Embodiment three: this embodiment is described further embodiment two, step 2 said to the CAD document affix one's seal the operation process be: the chapter piece that configures is decomposed, is loaded into then in the CAD document.
Embodiment four: below in conjunction with Fig. 3 this embodiment is described, this embodiment is described further embodiment two, in the step 3 in the workflow that contains the signing messages watermark of this CAD document of embedding on the CAD document of chapter shape is:
Step 3 a, traversal contain chapter shape CAD document, obtain the coordinate data of all straight line entities;
Step 3 b, the coordinate data of obtaining according to step 3 a calculate the said cryptographic hash that contains chapter shape CAD document, and said cryptographic hash is 128;
Step 3 c, the cryptographic hash of obtaining according to the private key in the softdog and step 3 b are obtained 1024 signing messages;
Step 3 d, 1024 signing messages that adopt 8 DCT reversible water mark algorithms that step 3 c is obtained are embedded in the CAD document that contains chapter shape, accomplish the work that embeds the signing messages watermark of this CAD document on the CAD document of chapter shape containing.
Embodiment five: below in conjunction with Fig. 4 this embodiment is described, this embodiment is described further embodiment two, in the step 4 in the workflow that contains the information of the distorting watermark of this CAD document of embedding on the CAD document of chapter shape is:
Step 4 a, the CAD document that will contain chapter shape carry out the figure initialization;
Step 4 b, the CAD document after step 4 a handled carry out the self-adaptation piecemeal by the iteration division rule;
Step 4 c, obtain the cryptographic hash of the solid data of this each piecemeal of CAD document;
Step 4 d, basis are confirmed the precision position of cryptographic hash to the iteration division rule of CAD document;
Step 4 e, according to the precision position, adopt Fragile Watermark Algorithm that watermark is embedded in each piecemeal, accomplish the process that is embedding the information of the distorting watermark of this CAD document on the CAD document of chapter shape containing.
Embodiment six: below in conjunction with Fig. 5 this embodiment is described, this embodiment is described further embodiment one, and the workflow of testing the chapter module is:
Whether the CAD document that step 1, judgement receive is affixed one's seal,
Judged result is for being, execution in step 2, judged result be not for, and this CAD document can't be tested the chapter operation, quits a program;
Step 2, employing tampering location watermarking algorithm extract the fragile watermark in this CAD document,
Step 3, judge according to said fragile watermark information whether this CAD document is distorted,
Judged result identifies tampered position for being, and the chapter failure information is tested in output; Judged result is for denying execution in step 4;
Step 4,8 DCT reversible water mark algorithms of employing extract reversible water marks, are the signing messages that this CAD document embeds,
Step 5, judge whether the signing messages of this CAD document is correct,
Judged result is for being, the chapter successful information is tested in output; Judged result is exported and is tested the chapter failure information for not.
Test chapter and mainly comprise two major parts:
1, the checking of tampering location and fragile watermark thereof.The recipient takes figure in the hand and is one and had both comprised the stamped signature signing messages, has comprised the figure of tampering location information again.According to the order that multi-watermarking embeds, we must at first extract tampering location information and verify, under the situation that checking is passed through, just can carry out next step work.The checking process flow diagram of tampering location and fragile watermark thereof is referring to Fig. 6.
2, the checking of signature and reversible water mark thereof.After a last step tampering location checking was passed through, we can take a figure that only comprises the watermark of signing.At this moment, the recipient will verify whether the signing messages that comprises among this figure is real, at first will use the reversible water mark algorithm that watermark information is extracted, and this watermark information that extracts is the signing messages that needs checking.When extracting watermark information, owing to use the reversible water mark algorithm that figure is carried out the embedding of watermark, under the situation that figure is not distorted, we can access embed watermark is the figure before the signing messages.Because the verifier holds the PKI of signer, so can use this PKI that figure Hash after reducing is signed, compare with the signing messages that extracts thereby carry out this signing messages, confirm whether the source of figure is true.The proof procedure of signature and reversible water mark thereof is referring to Fig. 7.
Embodiment seven: below in conjunction with Fig. 6 this embodiment is described, this embodiment is described further embodiment six, judges in the step 3 that the process whether this CAD document is distorted is:
The watermark information that this CAD document that step 31, the fragile watermark that step 2 is extracted are divided is every;
Step 32, judge whether every watermark information is identical,
Judged result is for being that this CAD document is not distorted, and finishes the checking of this step; Judged result is not for, and then this CAD document was distorted, and will distort part with red block and identify.
Embodiment eight: below in conjunction with Fig. 7 this embodiment is described, this embodiment is described further embodiment six, judges in the step 5 whether correct process is for the signing messages of this CAD document:
Step 51, traversal contain chapter shape CAD document, obtain the coordinate data of all straight line entities;
Step 52, the coordinate data of obtaining according to step 51 calculate the said cryptographic hash that contains chapter shape CAD document, and said cryptographic hash is 128;
Step 53, the cryptographic hash of obtaining according to private key from softdog and step 52 are obtained 1024 signing messages;
The signing messages that step 54, the signing messages that step 53 is obtained and step 4 are obtained compares,
If comparative result is consistent, then the signature verification of this CAD document is correct; Comparative result is inconsistent, the then signature verification of this CAD document failure.
Embodiment nine: below in conjunction with Fig. 8 this embodiment is described, this embodiment is described further embodiment one, and the workflow of recovery module is:
Steps A, judge whether the CAD document is reduced,
Judged result is for being to withdraw from this program; Judged result is for denying execution in step B;
Step B, judge this CAD document whether through testing chapter,
Judged result is for being execution in step C; Judged result is that testing Zhang Wei does not pass through, and withdraws from this program;
Step C, the information of the distorting watermark of this CAD document of reducing;
The reduction of this CAD document is accomplished in step D, the signing messages watermark of this CAD document of reducing.
Claims (6)
1. a stamped signature watermaking system that is used for the CAD document is characterized in that, it comprises the stamped signature module, tests chapter module and recovery module,
The stamped signature module is embedded into original CAD document after being used for the chapter shape of setting decomposed, and embeds the signing messages watermark and stamped signature is carried out in the watermark of tampering location information, then the CAD figure behind the stamped signature is issued;
Test the chapter module and be used for the CAD document behind the stamped signature that receives is carried out the checking of integrality: extract the signing messages of this CAD document, be used to verify whether the signature of this CAD document is forged; Reduce the watermark figure of this CAD document, be used to verify whether this CAD document is distorted, and the situation of being distorted when figure can provide tampering location information;
Recovery module is used to reduce tests the CAD document that chapter passes through,
The workflow of stamped signature module is:
Step 1, judge whether this CAD document is affixed one's seal,
Judged result is for being to withdraw from this program; Judged result is for denying execution in step two;
Step 2, to the operation of affixing one's seal of CAD document, obtain to contain the CAD document of chapter shape;
Step 3, containing on the CAD document of chapter shape the signing messages watermark that embeds this CAD document;
Step 4, contain on the CAD document of chapter shape the information of the distorting watermark that embeds this CAD document, accomplishing the stamped signature of this CAD document, and with the issue of the CAD figure behind the stamped signature,
In the step 3 be in the workflow that contains the signing messages watermark of this CAD document of embedding on the CAD document of chapter shape:
Step 3 a, traversal contain chapter shape CAD document, obtain the coordinate data of all straight line entities;
Step 3 b, the coordinate data of obtaining according to step 3 a calculate the said cryptographic hash that contains chapter shape CAD document, and said cryptographic hash is 128;
Step 3 c, the cryptographic hash of obtaining according to the private key in the softdog and step 3 b are obtained 1024 signing messages;
Step 3 d, 1024 signing messages that adopt 8 DCT reversible water mark algorithms that step 3 c is obtained are embedded in the CAD document that contains chapter shape, accomplish the work that embeds the signing messages watermark of this CAD document on the CAD document of chapter shape containing,
In the step 4 be in the workflow that contains the information of the distorting watermark of this CAD document of embedding on the CAD document of chapter shape:
Step 4 a, the CAD document that will contain chapter shape carry out the figure initialization;
Step 4 b, the CAD document after step 4 a handled carry out the self-adaptation piecemeal by the iteration division rule;
Step 4 c, obtain the cryptographic hash of the solid data of this each piecemeal of CAD document;
Step 4 d, basis are confirmed the precision position of cryptographic hash to the iteration division rule of CAD document;
Step 4 e, according to the precision position, adopt Fragile Watermark Algorithm that watermark is embedded in each piecemeal, accomplish the process that is embedding the information of the distorting watermark of this CAD document on the CAD document of chapter shape containing.
2. a kind of stamped signature watermaking system that is used for the CAD document according to claim 1 is characterized in that, step 2 said to the CAD document affix one's seal the operation process be: the chapter piece that configures is decomposed, is loaded into then in the CAD document.
3. a kind of stamped signature watermaking system that is used for the CAD document according to claim 1 is characterized in that the workflow of testing the chapter module is:
Whether the CAD document that step 1, judgement receive is affixed one's seal,
Judged result is for being, execution in step 2, judged result be not for, and this CAD document can't be tested the chapter operation, quits a program;
Step 2, employing tampering location watermarking algorithm extract the fragile watermark in this CAD document,
Step 3, judge according to said fragile watermark information whether this CAD document is distorted,
Judged result identifies tampered position for being, and the chapter failure information is tested in output; Judged result is for denying execution in step 4;
Step 4,8 DCT reversible water mark algorithms of employing extract reversible water marks, are the signing messages that this CAD document embeds,
Step 5, judge whether the signing messages of this CAD document is correct,
Judged result is for being, the chapter successful information is tested in output; Judged result is exported and is tested the chapter failure information for not.
4. a kind of stamped signature watermaking system that is used for the CAD document according to claim 3 is characterized in that, judges in the step 3 that the process whether this CAD document is distorted is:
Step 31, the fragile watermark that step 2 is extracted are divided into the watermark information of every of this CAD document;
Step 32, judge whether every watermark information is identical,
Judged result is for being that this CAD document is not distorted, and finishes the checking of this step; Judged result is not for, and then this CAD document was distorted, and will distort part with red block and identify.
5. a kind of stamped signature watermaking system that is used for the CAD document according to claim 3 is characterized in that, judges in the step 5 whether correct process is for the signing messages of this CAD document:
Step 51, traversal contain chapter shape CAD document, obtain the coordinate data of all straight line entities;
Step 52, the coordinate data of obtaining according to step 51 calculate the said cryptographic hash that contains chapter shape CAD document, and said cryptographic hash is 128;
Step 53, the cryptographic hash of obtaining according to the private key in the softdog and step 52 are obtained 1024 signing messages;
The signing messages that step 54, the signing messages that step 53 is obtained and step 4 are obtained compares,
If comparative result is consistent, then the signature verification of this CAD document is correct; Comparative result is inconsistent, the then signature verification of this CAD document failure.
6. a kind of stamped signature watermaking system that is used for the CAD document according to claim 1 is characterized in that the workflow of recovery module is:
Steps A, judge whether the CAD document is reduced,
Judged result is for being to withdraw from this program; Judged result is for denying execution in step B;
Step B, judge this CAD document whether through testing chapter,
Judged result is for being execution in step C; Judged result is that testing Zhang Wei does not pass through, and withdraws from this program;
Step C, the information of the distorting watermark of this CAD document of reducing;
The reduction of this CAD document is accomplished in step D, the signing messages watermark of this CAD document of reducing.
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| CN2011100949499A CN102117476B (en) | 2011-04-15 | 2011-04-15 | Signature watermark system used for CAD (Computer-Aided Design) documents |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102495833B (en) * | 2011-11-30 | 2014-03-12 | 哈尔滨工业大学 | Document watermark copyright information protection device based on Opentype vector outline fonts |
| CN102867135A (en) * | 2012-08-01 | 2013-01-09 | 广东南方数码科技有限公司 | Right control system and control method for computer-aided design (CAD) graph entity |
| CN104952029B (en) * | 2015-05-22 | 2017-12-22 | 湖北大学 | The plug-in unit of AutoCAD suspension physical watermarks realizes system and method |
| CN107347007B (en) * | 2017-08-02 | 2023-08-18 | 泰州市抗震办公室（泰州市建设工程施工图设计审查中心） | CAD signature authentication system and CAD signature authentication method for construction drawing examination |
| CN108280371A (en) * | 2018-01-28 | 2018-07-13 | 丁超 | Generate method, computer readable storage medium and the computing device of electronic document |
| CN109255591A (en) * | 2018-09-11 | 2019-01-22 | 河南省建筑设计研究院有限公司 | A kind of method of construction drawing drawing Electronic Signature, storage medium |
| CN112084516A (en) * | 2020-09-14 | 2020-12-15 | 洛阳众智软件科技股份有限公司 | Method and equipment for safely protecting CAD drawing information |
| CN112052435B (en) * | 2020-09-30 | 2023-11-28 | 杭州尚尚签网络科技有限公司 | CAD drawing multiuser electronic signature method |
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