Method and system for the capture, storage, transport and authentication of handwritten signatures

• US 5,544,255 A
• Filed: 08/31/1994
• Issued: 08/06/1996
• Est. Priority Date: 08/31/1994
• Status: Expired due to Term

• Current Assignee: CIC Acquisition Corporation
• Original Assignee: Peripheral Vision Limited
• Inventors: Smithies, Christopher P. K., Newman, Jeremy M.
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Johns, Andrew W.
• Application Number:
  US08/298,991
• Time in Patent Office: 706 Days
• Field of Search: 382/119, 382/120, 382/121, 382/122, 382/123, 382/232, 178/18, 340/825.3, 340/825.33, 340/825.34, 283/70, 283/75, 395/155, 395/161, 380/23
• US Class Current: 382/119
• CPC Class Codes: G06Q 20/3821 Electronic credentials
• CPC Class Codes: G06Q 20/401 Transaction verification
• CPC Class Codes: G06V 10/94 Hardware or software architectures specially adapted for image or video understanding
• CPC Class Codes: G06V 40/30 Writer recognition; Reading and verifying signatures
• CPC Class Codes: G07C 9/35 by means of a handwritten signature

Abstract

A computer-based method and system for capturing and verifying a handwritten signature. The handwritten signature may relate to a document, such as an electronically stored document. An image of the document is displayed. A user signs the document electronically, and the handwritten signature is electronically captured. A set of measurements relating to the handwritten signature is determined and stored in a signature envelope. Optionally, a checksum of a checksum of the document can be determined and stored in the signature envelope. The claimed identity of the signatory can also be stored in the signature envelope. The signature envelope is encrypted. The signature envelope can be communicated to another application or computer platform, or stored for later verification. The signature envelope is decrypted, and the set of measurements stored in the signature envelope are compared against a known set of handwritten signature measurements to verify the identity of the signatory. The system includes a database of signature templates storing verified signature information. The verified set of signature measurements are compared with the set of measurements stored in the signature envelope to obtain a similarity score. The present invention includes a gravity prompt feature to alter the signatory as to the nature, seriousness and/or contents of what is being signed. The gravity prompt can be stored in the signature envelope as part of the record of the signing event.

Claims

1. A computer-based method for creating an electronic representation of a handwritten signature that relates to an electronic document, and thereafter verifying the handwritten signature, comprising the steps of:

at a first computer processor, electronically displaying an image of a document;

at the first computer processor, signing the document by electronically capturing a handwritten signature of a signatory;

statistically analyzing the handwritten signature to obtain a set of statistical measurements relating to the handwritten signature;

at the first computer processor, storing in a signature envelope the set of statistical measurements relating to the handwritten signature;

at the first computer processor, creating a checksum of the document;

at the first computer processor, storing the checksum in the signature envelope;

at the first computer processor, storing in the signature envelope a claimed identity of the signatory;

at the first computer processor, encrypting the signature envelope to create an encrypted signature envelope;

transmitting the encrypted signature envelope to a second computer processor;

at the second computer processor, decrypting the encrypted signature envelope;

at the second computer processor, retrieving a verified set of statistical measurements of a handwritten signature of a person having the claimed identity as stored in the signature envelope; and

at the second computer processor, comparing the verified set of statistical measurements with the set of statistical measurements stored in the signature envelope to obtain a similarity score.

2. The method of claim 1 further comprising the step of storing the encrypted signature envelope in a memory device.

3. The method of claim 1 wherein the set of statistical measurements include average stroke length.

4. The method of claim 1 wherein the set of statistical measurements include average pen-down time.

5. The method of claim 1 wherein the set of statistical measurements include number of acceleration and deceleration maxima.

6. The method of claim 1 wherein the set of statistical measurements include sum of position of slowest points in each stroke.

7. The method of claim 1 further comprising the step of, at the first processor, storing in the signature envelope a time and date of signing.

8. The method of claim 1 further comprising the step of, at the first processor, storing in the signature envelope an indicator representing the first processor'"'"'s identity.

9. The method of claim 1 further comprising the step of, at the first processor, storing in the signature envelope a compressed representation of an image of the handwritten signature.

10. The method of claim 1 further comprising the step of transmitting the similarity score to the first computer processor.

11. The method of claim 1 further comprising the step of transmitting the similarity score to a third computer processor.

12. The method of claim 1 further comprising the steps of:

at the second processor, creating a second checksum of an electronic document; and

comparing the second checksum to the checksum stored in the signature envelope to determine if the electronic document is a true representation of the document that was signed at the first computer processor.

13. A computer-based method for creating an electronic representation of a handwritten signature for an electronic document, comprising the steps of:

at a first computer processor, electronically displaying an image of a first document;

at the first computer processor, signing the first document by electronically capturing a handwritten signature of a signatory;

statistically analyzing the handwritten signature to obtain a set of measurements relating to the handwritten signature;

at the first computer processor, storing in a signature envelope the set of measurements relating to the handwritten signature;

at the first computer processor, creating a first checksum of the first document;

at the first computer processor, storing the first checksum in the signature envelope;

at the first computer processor, encrypting the signature envelope to create an encrypted signature envelope;

transmitting the encrypted signature envelope to a second computer processor;

at the second computer processor, decrypting the encrypted signature envelope;

at the second computer processor, creating a second checksum of a second document; and

comparing the second checksum to the first checksum stored in the signature envelope to determine if the second document is a true representation of the first document.

14. A computer-based method for creating an electronic representation of a handwritten signature for an electronic document, comprising the steps of:

at a first computer processor, electronically displaying an image of a first document;

at the first computer processor, signing the first document by electronically capturing a handwritten signature of a signatory;

statistically analyzing the handwritten signature to obtain a set of measurements relating to the handwritten signature;

at the first computer processor, storing in a signature envelope the set of measurements relating to the handwritten signature;

at the first computer processor, creating a first checksum of the first document;

at the first computer processor, storing the first checksum in the signature envelope;

at the first computer processor, storing in the signature envelope an indication of the signatory;

at the first computer processor, encrypting the signature envelope to create an encrypted signature envelope;

transmitting the encrypted signature envelope to a second computer processor;

at the second computer processor, decrypting the encrypted signature envelope;

at the second computer processor, verifying that the handwritten signature is that of the signatory by examining the set of measurements stored in the signature envelope;

at the second computer processor, creating a second checksum of a second document; and

at the second computer processor, comparing the second checksum to the first checksum stored in the signature envelope to determine if the second document is a true representation of the first document.

15. A computer-based method for creating an electronic representation of a handwritten signature for a document, comprising the steps of:

electronically displaying an image of a first document;

signing the first document by electronically capturing a handwritten signature of a signatory;

statistically analyzing the handwritten signature to obtain a set of measurements relating to the handwritten signature;

storing in a signature envelope the set of measurements relating to the handwritten signature;

creating a first checksum of the first document;

storing the first checksum in the signature envelope;

storing in the signature envelope an indication of the signatory;

encrypting the signature envelope to create an encrypted signature envelope;

storing the encrypted signature envelope in a memory;

decrypting the encrypted signature envelope;

verifying that the handwritten signature is that of the signatory by examining the set of measurements stored in the signature envelope;

creating a second checksum of a second document; and

comparing the second checksum to the first checksum stored in the signature envelope to determine if the second document is a true representation of the first document.

16. A computer-based method for capturing an electronic representation of a handwritten signature that relates to a document, and thereafter verifying the handwritten signature, comprising the steps of:

signing a document by electronically capturing a handwritten signature of a signatory;

storing in a signature envelope a set of measurements relating to the handwritten signature;

creating a checksum of the document;

storing the checksum in the signature envelope;

storing in the signature envelope a claimed identity of the signatory;

encrypting the signature envelope to create an encrypted signature envelope;

storing the encrypted signature envelope in a memory;

decrypting the encrypted signature envelope;

retrieving from the memory a signature template of a person having the claimed identity as stored in the signature envelope, the signature template comprising a verified set of measurements of a verified handwritten signature of said person; and

comparing the verified set of measurements stored in the signature template with the set of measurements stored in the signature envelope to obtain a similarity score representative of a degree of similarity between the handwritten signature captured upon signing the document and the verified handwritten signature.

17. The method of claim 16 further comprising the steps of:

creating a second checksum of an electronic document; and

comparing the second checksum to the checksum stored in the signature envelope to determine if the electronic document is a true representation of the document that was signed.

18. A computer-based method for capturing and verifying an electronic representation of a handwritten signature for a document, comprising the steps of:

at a first computer processor, electronically displaying an image of a first document;

at the first processor, electronically displaying a prompt summarizing the first document;

at the first computer processor, signing the first document by electronically capturing a handwritten signature of a signatory;

at the first computer processor, storing in a signature envelope a set of measurements relating to the handwritten signature;

at the first computer processor, storing in the signature envelope an indication of the signatory;

at the first processor, storing the prompt in the signature envelope;

at the first computer processor, encrypting the signature envelope to create an encrypted signature envelope;

transmitting the encrypted signature envelope to a second computer processor;

at the second computer processor, decrypting the encrypted signature envelope;

at the second computer processor, verifying that the handwritten signature is that of the signatory; and

at the second computer processor, retrieving the prompt from the signature envelope.

19. The method of claim 18 further comprising the step of displaying the prompt at the second computer processor.

20. The method of claim 18 further comprising the steps of:

at the first computer processor, creating a first checksum of the first document;

at the first computer processor, storing the first checksum in the signature envelope;

at the second computer processor, creating a second checksum of a second document; and

at the second computer processor, comparing the second checksum to the first checksum stored in the signature envelope to determine if the second document is a true representation of the first document.

21. A computer-based method for creating and verifying an electronic representation of a handwritten signature for a document, comprising the steps of:

electronically displaying an image of a first document;

electronically displaying a gravity prompt, the gravity prompt identifying the nature of the first document;

signing the first document by electronically capturing a handwritten signature of a signatory;

storing in a signature envelope a set of measurements relating to the handwritten signature;

storing in the signature envelope an indication of the signatory'"'"'s claimed identity;

storing the gravity prompt in the signature envelope;

encrypting the signature envelope to create an encrypted signature envelope;

thereafter, decrypting the encrypted signature envelope;

verifying that the handwritten signature is that of the signatory; and

retrieving the gravity prompt from the signature envelope to ascertain what the signatory was informed as to the nature of the first document.

22. The method of claim 21 further comprising the step of re-displaying the gravity prompt.

23. The method of claim 21 wherein the step of verifying that the handwritten signature is that of the signatory further comprises the steps of:

retrieving from a memory a signature template of a person having the claimed identity of the signatory as stored in the signature envelope, the signature template comprising a verified set of measurements of a verified handwritten signature of said person;

determining a similarity score representative of a degree of similarity between the handwritten signature captured upon signing the first document and the verified handwritten signature.

24. The method of claim 23 further comprising the step of transmitting the similarity score to a client application upon request of the client application.

25. The method of claim 23 further comprising the steps of:

transmitting the similarity score to a client application; and

transmitting the gravity prompt to the client application.

26. The method of claim 21 further comprising the steps of:

creating a first checksum of the first document;

storing the first checksum in the signature envelope;

storing the signature envelope in a memory;

creating a second checksum of a second document; and

comparing the second checksum to the first checksum stored in the signature envelope to determine if the second document is a true representation of the first document.

27. In a computer system having a client application, a signature capture application and a signature verification application, a computer-based method for capturing and verifying an electronic representation of a handwritten signature for a document, comprising the steps of:

under the control of the client application,

a. displaying an image of a first document,

b. requesting that the signature capture application capture a handwritten signature, and

c. passing a gravity prompt to the signature capture application, the gravity prompt being a message relating to the first document;

under the control of the signature capture application,

d. displaying a signature capture window,

e. displaying the gravity prompt,

f. enabling a user to sign the first document by electronically capturing a handwritten signature of the user,

g. storing in a signature envelope a set of measurements relating to the handwritten signature,

h. storing in the signature envelope an indication of the user'"'"'s claimed identity,

i. storing the gravity prompt in the signature envelope,

j. encrypting the signature envelope to create an encrypted signature envelope, and

k. passing the encrypted signature envelope to the client application;

under control of the client application,

l. passing the encrypted signature envelope to the signature verification application; and

under control of the signature verification application,

m. decrypting the encrypted signature envelope,

n. retrieving from a database a template comprising a verified set of measurements

corresponding to the verified handwritten signature of the user whose claimed identity is stored in the signature envelope,

o. comparing the set of measurements stored in the signature envelope with verified set of measurements in the template to obtain a similarity score,

p. retrieving the gravity prompt from the signature envelope, and

q. passing the gravity prompt and the similarity score to the client application.

28. The method of claim 27 further comprising the steps of:

under the control of the signature capture application, creating a first checksum of the first document and storing the first checksum in the signature envelope; and

under the control of the signature verification application, creating a second checksum of a second document and comparing the second checksum to the first checksum stored in the signature envelope to determine if the second document is a true representation of the first document.

29. The method of claim 27 wherein the signature capture application is executed on a first computer processor and the signature verification application is executed on a second computer processor.

30. The method of claim 27 wherein the set of measurements include average stroke length.

31. The method of claim 27 wherein the set of measurements include average pen-down time

32. The method of claim 27 wherein the set of measurements include number of acceleration and deceleration maxima.

33. The method of claim 27 wherein the set of measurements include sum of position of slowest points in each stroke.

34. The method of claim 27 further comprising the step of, under the control of the signature capture application, storing in the signature envelope a time and date of signing.

35. The method of claim 27 further comprising the step of, under the control of the signature capture application, storing in the signature envelope an indicator representing an identity of a computer processor that is executing the client application.

36. The method of claim 27 further comprising the step of, under the control of the signature capture application, storing in the signature envelope a compressed representation of an image of the handwritten signature.

37. The method of claim 27 further comprising the step of, under the control of the signature capture application, storing in the signature envelope a compressed bitmap representation of an image of the handwritten signature.

38. In a computer system having a client application, a signature capture application and a signature verification application, a computer-based method for capturing and verifying an electronic representation of a handwritten signature, comprising the steps of:

under the control of the client application,

a. requesting that the signature capture application capture a handwritten signature;

under the control of the signature capture application,

b. enabling a user to electronically enter a handwritten signature;

c. electronically capturing the handwritten signature of the user,

d. calculating a set of measurements relating to the handwritten signature;

e. storing the set of measurements relating to the handwritten signature in a signature envelope,

f. storing in the signature envelope an indication of the user'"'"'s claimed identity, g. encrypting the signature envelope to create an encrypted signature envelope, and

h. passing the encrypted signature envelope to the client application;

under control of the client application,

i. passing the encrypted signature envelope to the signature verification application; and

under control of the signature verification application,

j. decrypting the encrypted signature envelope,

k. retrieving from a database a template comprising a verified set of measurements corresponding to the verified handwritten signature of the user whose claimed identity is stored in the signature envelope,

l. comparing the set of measurements stored in the signature envelope with verified set of measurements in the template to obtain a similarity score, and

m. passing the similarity score to the client application.

39. The method of claim 38 further comprising the step of, under the control of the client application, utilizing the similarity score to determine if the user can have access to one or more applications and data in a computer system.

40. The method of claim 38 further comprising the step of, under the control of the client application, utilizing the similarity score to determine if the user can purchase goods on credit.

41. The method of claim 38 wherein the signature capture application is executed on a first computer processor and the signature verification application is executed on a second computer processor.

42. The method of claim 38 wherein the set of measurements include average stroke length.

43. The method of claim 38 wherein the set of measurements include average pen-down time.

44. The method of claim 38 wherein the set of measurements include number of acceleration and deceleration maxima.

45. The method of claim 38 wherein the set of measurements include sum of position of slowest points in each stroke.

46. The method of claim 38 further comprising the step of, under the control of the signature capture application, storing in the signature envelope a time and date of signing.

47. The method of claim 38 further comprising the step of, under the control of the signature capture application, storing in the signature envelope an indicator representing an identity of a computer processor that is executing the client application.

48. The method of claim 38 further comprising the step of, under the control of the signature capture application, storing in the signature envelope a compressed representation of an image of the handwritten signature.

49. The method of claim 38 further comprising the step of, under the control of the signature capture application, storing in the signature envelope a compressed bitmap representation of an image of the handwritten signature.

50. In a computer system having a client application, a signature capture application and a signature verification application, a computer-based method for capturing and verifying an electronic representation of a handwritten signature on an electronic document, comprising the steps of:

under the control of the client application,

a. displaying an image of a document,

b. requesting that the signature capture application capture a handwritten signature;

under the control of the signature capture application,

c. enabling a user to electronically enter a handwritten signature;

d. electronically capturing the handwritten signature of the user,

e. calculating a set of measurements relating to the handwritten signature;

f. storing the set of measurements relating to the handwritten signature in a signature envelope,

g. storing in the signature envelope an indication of the user'"'"'s claimed identity,

h. creating a checksum of the document,

i. storing the checksum in the signature envelope,

j. encrypting the signature envelope to create an encrypted signature envelope, and

k. passing the encrypted signature envelope to the client application;

under control of the client application,

l. passing the encrypted signature envelope to the signature verification application; and

under control of the signature verification application,

m. decrypting the encrypted signature envelope,

n. retrieving from a database a template comprising a verified set of measurements corresponding to the verified handwritten signature of the user whose claimed identity is stored in the signature envelope,

o. comparing the set of measurements stored in the signature envelope with verified set of measurements in the template to obtain a similarity score, and

p. passing the similarity score to the client application.

51. In a computer system having a client application, a signature capture application and a signature verification application, a computer-based method for capturing and verifying an electronic representation of a handwritten signature on an electronic document, comprising the steps of:

under the control of the client application,

a. displaying an image of a first document,

b. requesting that the signature capture application capture a handwritten signature;

under the control of the signature capture application,

c. enabling a user to electronically enter a handwritten signature;

d. electronically capturing the handwritten signature of the user,

e. calculating a set of measurements relating to the handwritten signature;

f. storing the set of measurements relating to the handwritten signature in a signature envelope,

g. creating a first checksum of the first document,

h. storing the first checksum in the signature envelope,

i. encrypting the signature envelope to create an encrypted signature envelope, and

j. passing the encrypted signature envelope to the client application;

under control of the client application,

k. passing the encrypted signature envelope to the signature verification application; and

under control of the signature verification application,

l. decrypting the encrypted signature envelope,

m. creating a second checksum of a second document,

n. comparing the first checksum stored in the signature envelope to the second checksum to ascertain if the first document is the same as the second document, and

o. informing the client application if the first document is the same as the second document.

52. The method of claim 51 wherein the signature capture application is executed on a first computer processor and the signature verification application is executed on a second computer processor.

53. The method of claim 51 wherein the set of measurements include average stroke length.

54. The method of claim 51 wherein the set of measurements include average pen-down time.

55. The method of claim 51 wherein the set of measurements include number of acceleration and deceleration maxima.

56. The method of claim 55 wherein the set of measurements include sum of position of slowest points in each stroke.

57. The method of claim 51 further comprising the step of, under the control of the signature capture application, storing in the signature envelope a time and date of signing.

58. The method of claim 51 further comprising the step of, under the control of the signature capture application, storing in the signature envelope an indicator representing an identity of a computer processor that is executing the client application.

59. The method of claim 58 further comprising the step of, under the control of the signature capture application, storing in the signature envelope a compressed representation of an image of the handwritten signature.

60. The method of claim 51 further comprising the step of, under the control of the signature capture application, storing in the signature envelope a compressed bitmap representation of an image of the handwritten signature.

61. In a computer system having a first client application, a second client application, a signature capture application and a signature verification application, a computer-based method for capturing and verifying an electronic representation of a handwritten signature, comprising the steps of:

under the control of the first client application,

a. requesting that the signature capture application capture a handwritten signature;

under the control of the signature capture application,

b. enabling a user to electronically enter a handwritten signature;

c. electronically capturing the handwritten signature of the user,

d. calculating a set of measurements relating to the handwritten signature;

e. storing the set of measurements relating to the handwritten signature in a signature envelope,

f. storing in the signature envelope an indication of the user'"'"'s claimed identity,

g. encrypting the signature envelope to create an encrypted signature envelope, and

h. passing the encrypted signature envelope to the first client application;

under control of the first client application,

i. passing the encrypted signature envelope to the second client application

under the control of the second client application,

j. passing the encrypted signature envelope to the signature verification application; and

under control of the signature verification application,

k. decrypting the encrypted signature envelope,

l. retrieving from a database a template comprising a verified set of measurements corresponding to the verified handwritten signature of the user whose claimed identity is stored in the signature envelope,

m. comparing the set of measurements stored in the signature envelope with verified set of measurements in the template to obtain a similarity score, and

n. passing the similarity score to the second client application.

62. The method of claim 61 further comprising the step of, under the control of the second client application, utilizing the similarity score to determine if the user can have access to one or more applications and data in a computer system.

63. The method of claim 61 further comprising the step of, under the control of the second client application, utilizing the similarity score to determine if the user can purchase goods on credit.

64. The method of claim 61 wherein the signature capture application is executed on a first computer processor and the signature verification application is executed on a second computer processor.

65. The method of claim 61 wherein the first client application is executed on a first computer processor and the second client application is executed on a second computer processor.

66. The method of claim 65 wherein the first computer processor operates according to a first operating system and the second computer processor operates according to a second operating system.

67. The method of claim 65 wherein the signature capture application is executed on the first computer processor and the signature verification application is executed on the second computer processor.

68. The method of claim 65 wherein the signature capture application is executed on a third computer processor and the signature verification application is executed on a fourth computer processor.

69. A computer-based system for creating an electronic representation of a handwritten signature for an electronic document, comprising the steps of:

means for enabling a signatory to sign a first document by electronically capturing a handwritten signature of the signatory;

means for statistically analyzing the handwritten signature to obtain a set of measurements relating to the handwritten signature;

means for storing in a signature envelope the set of measurements relating to the handwritten signature;

means for creating a first checksum of the first document;

means for storing the first checksum in the signature envelope;

means for storing in the signature envelope an indication of the signatory; and

means for encrypting the signature envelope to create an encrypted signature envelope.

70. The system of claim 69 further comprising:

means for decrypting the encrypted signature envelope;

means for verifying that the handwritten signature stored in the signature envelope is that of the signatory;

means for creating a second checksum of a second document; and

means for comparing the second checksum to the first checksum stored in the signature envelope to determine if the second document is a true representation of the first document.

71. The system of claim 70 further comprising means for storing the encrypted signature envelope in a memory.

72. A signature verification bureau system comprising:

a plurality of first processors for capturing handwritten signatures, each one of the plurality of first processors including;

means for enabling a signatory to electronically enter a handwritten signature to the first processor,

means for electronically capturing the handwritten signature of the signatory,

means for storing a set of measurements relating to the handwritten signature in a signature envelope,

means for entering the signatory'"'"'s claimed identity,

means for storing the signatory'"'"'s claimed identity in the signature envelope,

means for encrypting the signature envelope to create an encrypted signature envelope, and

means for communicating the encrypted signature envelope to a remote signature verification bureau; and

a signature verification bureau for verifying handwritten signatures, remotely located with respect to each of the plurality of first processors but electronically coupled thereto, the signature verification bureau controlled by a second processor coupled to a database of signature templates, the second processor including;

means for receiving the encrypted signature envelope from one of the first processors,

means for decrypting the encrypted signature envelope,

means for accessing the database to retrieve a signature template corresponding to the signatory'"'"'s claimed identity, each signature template including a verified set of signature measurements,

means for verifying the handwritten signature by comparing the set of measurements stored in the signature envelope with the verified set of signature measurements,

means for determining a similarity score representing a similarity between the set of measurements stored in the signature envelope and the verified set of signature measurements, means for communicating the similarity score to the one of the first processors.

73. A signature verification bureau system comprising:

a plurality of first processors for capturing handwritten signatures, each one of the plurality of first processors including;

means for enabling a signatory to electronically enter a handwritten signature to the first processor,

means for electronically capturing the handwritten signature of the signatory,

means for storing a set of measurements relating to the handwritten signature in a signature envelope,

means for entering the signatory'"'"'s claimed identity,

means for storing the signatory'"'"'s claimed identity in the signature envelope,

means for encrypting the signature envelope to create an encrypted signature envelope, and means for communicating the encrypted signature envelope to a remote signature verification bureau;

a central database for storing verified handwritten signature data comprising a plurality of signature templates, each signature template indexed by identity of signatory and including a verified set of signature measurements for said signatory;

a signature verification bureau for verifying handwritten signatures, remotely located with respect to each of the plurality of first processors but electronically coupled thereto, the signature verification bureau controlled by a second processor coupled to the central database, the second processor including;

means for receiving the encrypted signature envelope from one of the first processors,

means for decrypting the encrypted signature envelope,

means for accessing the central database to retrieve a signature template corresponding to the signatory'"'"'s claimed identity,

means for verifying the handwritten signature by comparing the set of measurements stored in the signature envelope with the verified set of signature measurements,

means for determining a similarity score representing a similarity between the set of measurements stored in the signature envelope and the verified set of signature measurements,

means for communicating the similarity score to the one of the first processors.