CN101427242A - Secure signatures - Google Patents

Abstract

Systems and methods for secure signatures are described. In one aspect, a secure signature is generated. The secure signature strongly binds an image of an electronic signature (an ''electronic signature'') to content in either electronic or printed form. Responsive to receiving a request from a user, the systems and methods determine whether an electronic signature associated with a printed page represents a secure signature. If so, the systems and methods determine and notify the user of whether the secure signature was cryptographically bound by a signer of the electronic signature to the content being signed.

Description

Security signature

Background

The handwritten signature of obtaining a people is to set up this people's (signatory) identity and carry out document that (for example, record, contract, p.m.entry etc.) wish, and this people is by the tradition of the wish of the content of the document binding and useful technology.Even in this digital Age, handwritten signature also is the necessary part of the contract of legal agreements, bank and credit card trade and all kinds.When a personal electric ground handwritten signature document (for example, using such as the subsidiary pen of a pad equipment such as graphics pad, board PC), the document is added or logically be associated with to the digital picture of this signature (for example, JEPG, TIFF or other image type).The digital picture of handwritten signature is the electronic signature of the equivalent of binding legally as this individual handwritten signature.By using image processing software, a people's electronic signature can be sheared from document/duplicated and pastes usually/copy in the different documents to be used for undelegated use.This undelegated use comprises, for example, and forgery, duplicity promise etc.The identity theft problem that highlights rapidly demonstrates the easiness of the unauthorized use of electronic signature.

General introduction

The system and method that is used for security signature has been described.On the one hand, generate security signature.This security signature closely is tied to the image (" electronic signature ") of electronic signature or the content of electronic form or print form.In response to receiving request from the user, this system and method determines whether the electronic signature that is associated with the page of printing represents security signature.If then this system and method is determined and is notified this security signature of user whether to be tied to the content of being signed cryptographically by the signer of this electronic signature.

It is some notions that will further describe in the following detailed description for the form introduction of simplifying that this general introduction is provided.This general introduction is not intended to identify the key feature or the essential feature of theme required for protection, is not intended to be used to help to determine the scope of theme required for protection yet.

The accompanying drawing summary

Fig. 1 illustrates the example system that is used for security signature according to an embodiment.

Fig. 2 illustrates the example process that is used for security signature according to an embodiment.

Fig. 3 illustrates the further operation according to the example process that is used for security signature of Fig. 2 of an embodiment.

Describe in detail

General view

Referring to figs. 1 to Fig. 3, the system and method that is used for security signature is described below.This system and method bound or be tied to the optional network specific digit document of being signed by signing electronically certain content increases security to the digital picture (that is, " electronic signature ") of a people's handwritten signature.As described below, it also is tied to the printing edition (being ink/toner in this regard) of electronic signature image the printing edition of electronic document.For this reason, this system and method is from this people's electronic signature with generate first collision resistant Hash the combination of content of the document of signature electronically.By using this people/signer's private key, this system and method uses a kind of in the multiple possible public key cryptography technology that this collision resistant Hash is digitally signed.This creates public key digital signature.By using reversible technique (for example, least significant bit (LSB) mapping etc.), this system and method with this public key digital signature insertions/embeddings be associated with this electronic signature in, with generation " security signature ".This security signature comprises the fingerprint of digitally signing of electronic signature and the original document content of deciphering with the PKI that uses this right people of private/public key only.This security signature is tied to this content with this people's signature.At this moment, the document can be distributed to the final user for checking and printing.

Veritably whether bound/tied is to the content of electronics or printing (non-electronics) document for the signature of verifying a people, and this system and method determines at first whether this signature is " security signature ".As mentioned above, security signature comprises the public key digital signature of the hashed value that generates from the content of the document of this people's electronic signature and the actual signature of this people.(if the document that comprises this signature is paper spare/document printing, then scans the document to generate the electronic document of this document printing of expression).If this system and method does not detect the public key digital signature (that is, this signature is not security signature) of this embedding in the digital picture of this signature, then this system and method will not verify that this electronic signature binds the signer to the content of document veritably.Property illustrative purposes presented for purpose of illustration can comprise the document of the digital picture of security signature by printing, and depicts to generate " clean " signature on the version of the printing of this digital picture and forge a people's signature.In this scene, should " clean " signature will not be included in the public key digital signature that the signature with the signer that can detect and embed, the signer on the program is tied to the certain content of document.

If this system and method can extract public key digital signature from this signature, then should signature expression security signature.The public key digital signature that uses this people/signer's PKI (private/public key is right) deciphering to extract subsequently.This system and method calculates document content second collision resistant Hash of (in this example, document content comprises that this people's handwritten signature (that is electronic signature) deducts the digital picture of the public key digital signature that is extracted).If first and second hash are complementary, then this system and method verifies that this people's signature represents that this people will carry out the intention of the document; Otherwise, do not verify this relation.

Now these and other aspect that is used for security signature will be described in more detail.

Example system

Although also nonessential, the system and method that is used for security signature will described by the general context of the computer executable instructions of carrying out such as computing equipments such as personal computers.Program module generally comprises the execution particular task or realizes the routine of particular abstract, program, object, assembly, data structure or the like.Though described this system and method in aforementioned context, action described below and operation also can realize with hardware.

Fig. 1 illustrates the example system that is used forsecurity signature 100 according to an embodiment.In this was realized,system 100 comprisedcomputing equipment 102, as universal computing device, server, laptop computer, mobile computing device, board PC etc.Board PC generally includes and allows the user to replace touch-screen or the digitizing figure input technology that keyboard or mouse come the operational computations machine with stylus or digital pen.In one realizes,computing equipment 102 be coupled to such as allow the user use stylus (a class plotting unit) provide/draw the mode of handwritten signature-be similar to usefulness pencil and paper drawing image-I/O equipment 104 such as figure board.

Computing equipment 102 comprises the one ormore processors 106 that are coupled to such as corresponding tangible computer-readable recording medium such assystem storage 108grades.Processor 106 can be microprocessor, microcomputer, microcontroller, digital signal processor etc.System storage 108 comprises, for example, the volatile random access memory that is used for the routine data that the computer program instructions that can be carried out byprocessor 106 and these computer program instructions generate and/or use (for example, RAM) and non-volatile ROM (read-only memory) (for example, ROM, flash memory etc.).Such computer program instructions is illustrated asprogram module 110 and routine data is illustrated as routine data 112.In this was realized, for example,program module 110 comprised secure hand-written signature module 114 and such asother program modules 116 such as the operating system that runtime environment is provided (OS), public key cryptography application program, device drivers.

Secure hand-written signature module 114 (hereinafter being commonly referred to " secure signature module 114 ") generates thesecurity signature 118 that a people's electronic signature is tied to cryptographically the content (for example, the one page or the pages content of expression record, contract, p.m.entry, official document) of document 120.The digital image version of electronic signature this people's of expression (being also referred to as " signer ") handwritten signature.This electronic signature is illustrated as the appropriate section of " other routine data " 124.In one realized, secure signature module 114 was from receiving electronic signature such as I/O equipment such as card reader, graphics pad.For example, in one realized, a people used the pen/stylus that is attached to digital pen pad equipment (for example, graphics pad, board PC etc.) to generate electronic signature.In this scene, electronic signature is affixed to or otherwise logically is associated with document 120.At this moment, electronic signature expression user carries out the wish (that is, the user is by the wish of the content ofdocument 120 binding) of the content of document 120.In view of this electronic signature, secure signature module 114 following establishments are cryptographically tied/bound to user's electronic signature thesecurity signature 118 of the content ofdocument 120.

Make that D is by the bitmap of theoriginal document 120 of user's electronic ground signature.Use in the multiple possible known collision resistant Cryptographic Hash Function (for example, SHA1 etc.), secure signature module 114 generates h (D), and it is the collision resistant cryptographic Hash ("hash 126 ") of D.Secure signature module 114 generates h (D) from the content of this signer's electronic signature and document 120.By (for example using public-key cryptographic application/infrastructure, RSA, DSA, ECDSA, BLS etc.) and this user/signer's private key, secure signature module 114 is calculated public key digital signature 122 (R) and (is noted from h (D), herein, system's foundation structure that uses public-key is verified the signer's who is stated identity).That is, secure signature module 114 is signed h (D) cryptographically to generate R.Secure signature module 114 is subsequently by generatingsecurity signature 118 with R (122) insertion/embedding or each position of logically being associated with electronic signature.In this way,security signature 118 is cryptographically tied/bound to electronic signature the content of document 120.In one realized, secure signature module 114 used least significant bit (LSB) (LSB) mapping techniques that R (122) insertion/embedding (or logically related) is arrived the image ofelectronic signature 118 to preserve the readability and the sharpness of security signature 118.In one realized, this LSB mapping techniques was created the fuzzy gray level image (Hash pattern) of the value of coding R.Unbred eyes are almost discovered less than this two-dimensional model.Yet, this two-dimensional model can program on sign and from screen capture or print image, extract can and contrast the mode that document content verifies by reconstruct.

In this is realized, security signature 114 be createdsecurity signature 118 by will R (122) embedding in signing electronically, so that R visually not eye-catching concerning the observer (for example, be hidden or invisible).In this was realized, if the user generatesdocument printing 128 fromdocument 120, the R that then is embedded in thesecurity signature 118 that is associated withdocument 120 still was embedded on one page ofdocument printing 128 and is illustrated in the ink/toner version of security signature.As describing in more detail at following joint, signature verification module 130 can detect and extraction R from the bitmap of the scanning input of document printing 128 (document D ').Thus, the operation of thegeneration security signature 118 of security signature 114 is tied to signer's electronic signature the page of printing.

The user is by confirming that with the security signature ofsystem 100 module 130 interfaces come certifying signature people's electronic signature (bysecurity signature 118 sealings) whether this signer to be tied to veritably the content (that is, electronic signature is not forged, shears and pastes and wait until that document is medium) of document.The user can or be coupled to remote computing device 136 interfaces ofcomputing equipment 102 withcomputing equipment 102 by network 132.(network 132 can comprise any combination of Local Area Network and general wide area network (WAN) communication environment, is common in the network of office, enterprise-wide. computer networks, Intranet and the Internet etc. as those).In one realized, security signature confirmed that module 130 conveys to the user with user interface (UI) and/or webpage.This UI and webpage allow user's specified documents D ' to comprise electronic signature and comprise the signer's that thesecurity signature 118 of this electronic signature is claimed PKI.(if the document that comprises this signature is paper spare/document printing 128, and then scanninginput document printing 128 is to generate electronic document D ').Property illustrative purposes presented for purpose of illustration, this PKI and D ' are by representing from therequest 140 of remote computing device 136 or specifying.

The bitmap of the handwritten signature part of signature verification 130 normal indication D '.In one realizes, the position that user/operator's Manual Logos are associated with signature (as, define the size of bitmap etc. with pointing device drafting rectangle).At this moment, do not understand unformatted, the conventional the digital picture whether signature bit that is identified comprises asecurity signature 118 or a people's handwritten signature.(for example, on the version of the printing ofsecurity signature 118, forge to depict to multipotency generate electronic signature).The signature of this forgery will not comprise public key digital signature detectable and that embed, the reality/actual signature people in the printing edition ofsecurity signature 118 on the program.Secure signature verification 130 attempts extracting public key digital signature R (122) from the position that is associated with electronic signature.In one realized, this least significant bit (LSB) by the pixel density value that the part correlation of writing down and being identified joins was finished.If public key digital signature R does not exist, then the electronic signature in the part that is identified is not that security signature 118 (that is, this electronic signature is not no cryptographic tie of the content of D ') and module 130 notify the user not verify about document D ' the authenticity of signature of content.

If extracted digital signature R from the electronic signature of the part that identified, then this electronic signature is security signature 118.Extract operation with the pixel density value removing/zero clearing (zero-out) in thesecurity signature 118 that is identified, thereby cause unformatted electronic signature.In case this electronic signature is extracted out, then signature verification is followed and is the selected digital signature protocol of this scheme.In more detail, Signature Confirmation 130 uses digital signature R that received PKI deciphering extracted to identify the first collision resistant cryptographic Hash value h (D) 126.In one realized, under the situation of RSA digital signature R, this PKI that will be referred to use the signer carried out exponentiation and verification and assessment to R and checks that whether the result is complementary with signer's disclosed certificates/keys.The second collision resistant Hash h (D ') of the D ' that comprises content and electronic signature is calculated in signature verification 130 subsequently.(when calculating h (D '), D ' still compriseselectronic signature 118, but this electronic signature no longer issecurity signature 118, because it no longer comprises the digital signature R that is embedded into).

Signature Confirmation logical one 30 is first andsecond hashed values 126 relatively.If first andsecond hashed values 126 are identical, then Signature Confirmation 130 electronic signature of notifying the user to be sealed in thesecurity signature 118 represents that author/signer is bound to the wish of the content of D '.Otherwise Signature Confirmation 130 notice user's electronic signatures do not represent that author/signer is bound to the wish of the content of D '.

Example process

Fig. 2 illustrates the example process that is used forsecurity signature 200 according to an embodiment.The property purpose of description will be come the operation ofdescription process 200 with reference to some assembly of figure 1 presented for purpose of illustration.In this was described, the certain figures of this assembly was wherein introduced in the leftmost numeral indication of Reference numeral first.In one realizes, the operation of the correspondingmodule implementation procedure 200 in secure signature module 114 and the secure verification module 130.The operation atframe 202 places receives the electronic signature thatdocument 120 is carried out in indication from signatory/signer.The operation offrame 204 is expanded this electronic signature to generate thesecurity signature 118 of the content that is tied to document 120 cryptographically of will signing electronically.In one realized, this finished by generate collision resistant Hash from the content ofdocument 120 and electronic signature.The password foundation structure that uses public-key is subsequently signed this collision resistant Hash cryptographically to generate public key digital signature 122.In this was realized, the operation offrame 204 was inserted in theelectronic signature 118 public keydigital signature 122 to generate security signature 118.In this way,security signature 118 is cryptographically tied/bound to signer's electronic signature the certain content of document 120.For example, thesecurity signature 118 of shearing and pasting the different document from original document will not be cryptographically tied to the content of this different document.

Whether the operation Receipt Validation signer's atframe 208 places electronic signature is tied/bound to document D safely ' requests for content.This request comprises the document D that (or otherwise sign) will be verified ' and the document signature people's that claimed the right PKI of private/public key.The operation offrame 210 attempt from embed or with electronic signature that received document logically is associated extract public key digital signature R (122).If this public key digital signature R is present in the electronic signature, then this electronic signature is security signature 118.Extract operation and from this electronic signature, delete/remove (for example, zero clearing) any indication R.The operation offrame 212 determines whether find public key digital signature R in this electronic signature.If this electronic signature is not digitally signed, then the page or leaf that operates in Fig. 3 ofprocess 200 is gone up with reference to " A " and is located to continue, and can not be verified as the expression signer in this electronic signature of notifying the user to be associated with D ' and carry out document D ' the wish of content.Otherwise, the public key digital signature R (122) that the PKI of manipulating the signer of frame 214 (this PKI receives in the request that the operation withframe 202 is associated) deciphering is extracted.These decryption oprerationss cause the first hashed value h (D) 126.The operation offrame 216 is from document D ' content and the electronic signature of having removed the public key digital signature that is extracted (seeing also the operation of frame 210) calculate second hashed value 126 (that is collision resistant Hash value).At this moment, the page or leaf that operates in Fig. 3 ofprocess 200 is gone up with reference to " B " and is located to continue.

Fig. 3 illustrates the further operation according to the example process that is used forsecurity signature 200 of Fig. 2 of an embodiment.The operation offrame 302 is first and second hashed values 126 (please refer to the operation of theframe 216 of previously described Fig. 2) relatively.As implied above, first hashedvalue 126 be deciphering with embedding or logically be associated with document D ' result of the public keydigital signature 122 that is associated of thesecurity signature 118 of (120).Second hashed value 126 is used the collision resistant Hash functions from document D ' content and corresponding electronic signature (having removed thesecurity signature 118 of digital signature) calculate.Iffirst hashed value 126 is identical withsecond hashed value 126, thenframe 306 places that operate in offrame 304 continue.The wish of operational notification user's of frame 306 (that is the requestor of theframe 202 of Fig. 2) and document D ' be associated electronic signature represent that the signatory carries out document D ' content.If first hashedvalue 126 is different withsecond hashed value 126, thenframe 308 places that operate in offrame 304 continue.The operational notification user and the document D of frame 308 ' electronic signature that is associated can not be verified as the wish that the expression signatory carries out the content of (for example, being bound to) document.At this moment, the operation ofprocess 200 stops.

Conclusion

Although with to the special-purpose language description of the operation of architectural feature and/or method or action security signature, be appreciated that the realization that presents in the appended claims not necessarily will be limited to above-mentioned concrete feature or action.For example, though the operation that is associated with secure hand-written signature module 114 (Fig. 1) is to illustrate and describe as the seal operation to secure verification module/logical one 30, the operation of these corresponding program modules can be independently of one another.In one realized, for example, the operation of the operation blow-by module 130 of secure hand-written signature module 114 was operated and is realized but be totally independent of these.In one realized, for example, operating on the computing equipment different with the operation of module 130 of module 114 realized.Therefore, above-mentioned concrete feature and operation are as the exemplary form that realizes theme required for protection and disclosed.

Claims (20)

1. computing equipment comprises:

Processor; And

Be coupled to the storer of described processor, described storer comprises the executable computer program instructions of described processor, and described computer program instructions is used to carry out following operation when being carried out by described processor, comprising:

Receive electronic signature; And

Generation is tied to the security signature of the content of printer page safely with described electronic signature, and described binding makes can verify on program that based on the verification operation of password the author of described electronic signature has expressed the wish of the content that is bound to described printer page.

2. computing equipment as claimed in claim 1 is characterized in that, described security signature merges in the described electronic signature in the mode of visually hiding concerning the observer of described printer page.

3. computing equipment as claimed in claim 1 is characterized in that, the described computer program instructions that is used to generate described security signature also comprises the instruction that is used to carry out following operation:

Calculate the collision resistant Hash value from the content of document and described electronic signature, described document with storer that described computing equipment is associated in, described printer page is represented the printing edition of described document;

The described collision resistant Hash value of signing cryptographically is to generate secure digital signature; And

Described secure digital signature is embedded in the position that is associated with described electronic signature.

4. computing equipment as claimed in claim 3, it is characterized in that, the described collision resistant Hash value of signing cryptographically comprises that also the cryptographic application that uses public-key signs cryptographically, described collision resistant Hash value is used described author's private key, and described private key is described author's of the private/public key centering that is used to use described public key cryptography application program to come signature contents digitally.

5. computing equipment as claimed in claim 3 is characterized in that, embeds described secure digital signature and comprises that also use least significant bit (LSB) algorithm is inserted into described secure digital signature in the described electronic signature.

6. computing equipment as claimed in claim 1 is characterized in that, described computer program instructions also comprises the instruction that is used to carry out following operation:

The signatory of the described electronic signature of the actual expression of the electronic signature that is associated with described printer page from user's Receipt Validation carries out the request of wish of the content of described printer page, and described request identifies the electronic version of described content and described author's PKI;

Determine whether described electronic signature comprises secure digital signature;

If described electronic signature does not comprise described secure digital signature, then notify the described electronic signature of described user can not be verified as the wish that the described author of expression carries out described content; And

If described electronic signature comprises described digital signature, then use described PKI to verify whether described electronic signature represents that described author carries out the wish of described content.

7. computing equipment as claimed in claim 6 is characterized in that, the public key digital signature that described secure digital signature is to use public key cryptography application program and described signatory's private key to generate.

8. computing equipment as claimed in claim 6 is characterized in that, the described computer program instructions that is used to verify also comprises the instruction that is used to carry out following operation:

Decipher described secure digital signature to identify first hashed value with described PKI;

Calculate second hashed value from described content and the described electronic signature that is independent of described secure digital signature;

If described first hashed value and described second hashed value are complementary, then notify the described electronic signature of described user to be bound to described content; And

If described first hashed value and described second hashed value do not match, then notify the described electronic signature of described user not to be bound to described content.

9. tangible computer-readable data storage medium that comprises the executable computer program instructions of processor, described computer program instructions is used to carry out following operation when being carried out by described processor, and described operation comprises:

By following operation a people's electronic signature is no cryptographic tie of the content of document, described operation comprises:

Content of described document of digitally signing and described electronic signature are to create digital signature;

Described digital signature is embedded in the position that is associated with described electronic signature to generate security signature;

The document distribution that will comprise described security signature gives the final user for checking and authenticating.

10. computer-readable data storage medium as claimed in claim 9 is characterized in that described electronic signature obtains from document printing.

11. computer-readable data storage medium as claimed in claim 9 is characterized in that, digitally signature also comprises:

Generate collision resistant Hash from described content and described electronic signature;

Use described individual's private key digitally to sign described collision resistant Hash to generate described digital signature, described private key is a right key of private/public key that is used for the public key cryptography operation; And

Wherein said digital signature can only be deciphered with the right PKI of described private/public key.

12. computer-readable data storage medium as claimed in claim 9 is characterized in that, institute's rheme comprises the least significant bit (LSB) that is associated with described electronic signature.

13. a computer implemented method comprises:

The electronic signature that is associated with a document from user's Receipt Validation is tied to the requests for content of described document cryptographically by the signer of described electronic signature;

Each that assess described electronic signature is to determine whether institute's rheme represents the digital signature that embeds;

If institute's rheme is not represented the digital signature of described embedding, then notify the described electronic signature of described user not to be tied to the content of described document cryptographically; And

If institute's rheme is the digital signature of the described embedding of expression really, verify then whether described electronic signature is tied to described content cryptographically by described signer.

14. method as claimed in claim 13 is characterized in that, described document is the electronic document that generates from non-electronic document.

15. method as claimed in claim 13 is characterized in that, described request identifies described document, described electronic signature be described document a part, append to described document or logically be associated with described document.

16. method as claimed in claim 13 is characterized in that, institute's rheme is a least significant bit (LSB).

17. method as claimed in claim 13, it is characterized in that, verify that whether described electronic signature is tied to described content cryptographically by described signer and comprises that also the cryptographic technique that uses public-key determines whether described electronic signature is tied to described content by described signer.

18. method as claimed in claim 13 is characterized in that, verifies whether described electronic signature is tied to described content cryptographically by described signer and also comprises:

The digital signature of deciphering described embedding with the right PKI of described signer's private/public key is to obtain first hashed value;

The digital signature of the described embedding of deletion from described electronic signature;

Calculate second hashed value from described content and described electronic signature; And

If described first hashed value and described second hashed value are complementary, then indicate described electronic signature to be tied to described content cryptographically by described signer to described user.

19. method as claimed in claim 18 is characterized in that, described first and second hashed values are anti-collision.

20. method as claimed in claim 18 is characterized in that, described method also comprises, if described first hashed value and described second hashed value do not match, then notifies the described electronic signature of described user not to be tied to described content by described signer.

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