US5638447A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Compact digital signatures
Assignee: Individual
•
Filing: 1996-05-15
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Granted: 1997-06-10
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Expires: 2016-05-15
Abstract
Abstract Digitally signing data includes collecting a group of signers, each having a public key and a corresponding secret key, a subgroup of signers each producing a partial digital signature of the data, and obtaining a combined signature of the data by combining the partial digital signatures of the data, where the combined digital signature keeps the subgroup of signers accountable for the data for which the subgroup of signers each produce a partial digital signature. Verifying a digital signature of data includes ascertaining members of a subgroup of signers that contributed to provide the digital signature of the data, determining a combined public key corresponding to individual secret keys of a the subgroup of signers, and using the combined public key to verify that the subgroup of signers have each contributed to provide the digital signature of the data.
Inventors
- 👤 Silvio Micali
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:02
CPC Classifications
H; H04; H04L; H04L9/00; H04L9/32; H04L9/3247; H04L9/3255
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
148 words
A method of digitally signing data, comprising the steps of: (a) selecting a plurality of public keys and corresponding secret keys for a group of signers to provide each member of the group with at least one of the secret keys that is different from an other one of the secret keys provided to an other member of the group; (b) each signer of a first subgroup of signers producing an individual digital signature of the data relative to one of the public keys; (c) obtaining a combined digital signature of the data relative to one or more of the public keys by combining individual digital signatures of a second subgroup of signers that is less than the group of signers; and (d) keeping members of the second subgroup accountable by having the combined digital signature depend on the secret keys of the members of the second subgroup.
Claim 2
Independent Claim
148 words
A method of digitally signing data, comprising the steps of: (a) selecting a plurality of public keys and corresponding secret keys for a group of signers to provide each member of the group with at least one of the secret keys that is different from an other one of the secret keys provided to an other member of the group; (b) each signer of a first subgroup of signers producing an individual digital signature of the data relative to one of the public keys; (c) obtaining a combined digital signature of the data relative to one or more of the public keys by combining individual digital signatures of a second subgroup of signers that is less than the group of signers; and (d) keeping members of the second subgroup accountable by having the combined digital signature depend on the secret keys of the members of the second subgroup.
Claim 3
Dependent Claim
24 words
A method of digitally signing data, according to claim 1, wherein the first subgroup of signers is the entirety of the group of signers.
Claim 4
Dependent Claim
20 words
A method for digitally signing data, according to claim 1, wherein the second subgroup is identical to the first subgroup.
Claim 5
Dependent Claim
38 words
A method of digitally signing data, according to claim 1, wherein the step of keeping members of the second subgroup accountable includes having the combined digital signature contain information identifying the members of the second subgroup of signers.
Claim 6
Dependent Claim
51 words
A method of digitally signing data, according to claim 1, wherein the step of obtaining a combined digital signature includes having the combined digital signature of the data be relative to a verification key that is a combination of the public keys of the members of the second subgroup of signers.
Claim 7
Dependent Claim
38 words
A method of digitally signing data, according to claim 5, wherein the step of keeping members of the second subgroup accountable includes having the combined digital signature contain information identifying the members of the second subgroup of signers.
Claim 8
Dependent Claim
52 words
A method of digitally signing data, according to claim 1, further comprising the steps of: (e) predetermining the second subgroup of signers; and (f) using an individual signature of a member of the first subgroup of signers to obtain a digital signature of the data for the predetermined second subgroup of signers.
Claim 9
Dependent Claim
47 words
A method of digitally signing data, according to claim 1, wherein the step of keeping members of the second subgroup accountable includes using the combined digital signature to prove that all the members of the second subgroup of signers provided an individual digital signature of the data.
Claim 10
Dependent Claim
41 words
A method of digitally signing data, according to claim 8, further comprising the step of: (e) choosing the second subgroup to be any one of all possible subsets, of the group of signers, having greater than a predetermined number of members.
Claim 11
Dependent Claim
41 words
A method of digitally signing data, according to claim 1, further comprising the step of: (e) choosing the second subgroup to be any one of all possible subsets, of the group of signers, having greater than a predetermined number of members.
Claim 12
Independent Claim
150 words
A method of digitally signing data, comprising the steps of: (a) selecting a common public key; (b) selecting a plurality of individual secret keys for a group of signers to provide each member of the group with at least one of the secret keys that is different from an other one of the secret keys provided to an other member of the group; (c) each signer of a first subgroup of one or more signers using the corresponding individual secret key to produce a partial digital signature of the data; (d) combining the partial digital signatures of a second subgroup of signers, less than the group of signers, to provide a combined digital signature of the data relative to the common public key; and (e) keeping members of the second subgroup accountable by having the combined digital signature depend on the secret keys of the members of the second subgroup.
Claim 13
Independent Claim
150 words
A method of digitally signing data, comprising the steps of: (a) selecting a common public key; (b) selecting a plurality of individual secret keys for a group of signers to provide each member of the group with at least one of the secret keys that is different from an other one of the secret keys provided to an other member of the group; (c) each signer of a first subgroup of one or more signers using the corresponding individual secret key to produce a partial digital signature of the data; (d) combining the partial digital signatures of a second subgroup of signers, less than the group of signers, to provide a combined digital signature of the data relative to the common public key; and (e) keeping members of the second subgroup accountable by having the combined digital signature depend on the secret keys of the members of the second subgroup.
Claim 14
Dependent Claim
24 words
A method of digitally signing data, according to claim 11, wherein the first subgroup of signers is the entirety of the group of signers.
Claim 15
Dependent Claim
20 words
A method for digitally signing data, according to claim 11, wherein the second subgroup is identical to the first subgroup.
Claim 16
Dependent Claim
38 words
A method of digitally signing data, according to claim 11, wherein the step of keeping members of the second subgroup accountable includes having the combined digital signature contain information identifying the members of the second subgroup of signers.
Claim 17
Dependent Claim
51 words
A method of digitally signing data, according to claim 11, wherein the step of obtaining a combined digital signature includes having the combined digital signature of the data be relative to a verification key that is a combination of the public keys of the members of the second subgroup of signers.
Claim 18
Dependent Claim
38 words
A method of digitally signing data, according to claim 15, wherein the step of keeping members of the second subgroup accountable includes having the combine digital signature contain information identifying the members of the second subgroup of signers.
Claim 19
Dependent Claim
52 words
A method of digitally signing data, according to claim 11, further comprising the steps of: (e) predetermining the second subgroup of signers; and (f) using an individual signature of a member of the first subgroup of signers to obtain a digital signature of the data for the predetermined second subgroup of signers.
Claim 20
Dependent Claim
47 words
A method of digitally signing data, according to claim 11, wherein the step of keeping members of the second subgroup accountable includes using the combined digital signature to prove that all the members of the second subgroup of signers provided an individual digital signature of the data.
Claim 21
Dependent Claim
41 words
A method of digitally signing data, according to claim 18, further comprising the step of; (e) choosing the second subgroup to be any one of all possible subsets, of the group of signers, having greater than a predetermined number of members.
Claim 22
Dependent Claim
41 words
A method of digitally signing data, according to claim 11, further comprising the step of: (e) choosing the second subgroup to be any one of all possible subsets, of the group of signers, having greater than a predetermined number of members.
Claim 23
Independent Claim
88 words
A method of verifying a digital signature of data, comprising the steps of: (a) ascertaining members of a subgroup of signers containing a plurality, but not all, members of a group of all possible singers each having one or more secret keys assigned thereto; (b) determining a combined public key corresponding to the secret keys; (c) using the combined public key to verify the digital signature; and (d) keeping members of the subgroup accountable by verifying that the digital signature depends on the secret keys of the subgroup.
Claim 24
Independent Claim
88 words
A method of verifying a digital signature of data, comprising the steps of: (a) ascertaining members of a subgroup of signers containing a plurality, but not all, members of a group of all possible singers each having one or more secret keys assigned thereto; (b) determining a combined public key corresponding to the secret keys; (c) using the combined public key to verify the digital signature; and (d) keeping members of the subgroup accountable by verifying that the digital signature depends on the secret keys of the subgroup.
Claim 25
Dependent Claim
40 words
A method of verifying a digital signature of data, according to claim 21, wherein the step of determining a combined public key includes combining a sequence of individual public keys, each of which corresponds to one of the secret keys.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-06-09 | 2000-12-09 | 2001-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-06-09 | 2004-12-09 | 2005-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-06-09 | 2008-12-09 | 2009-06-10 | $7700.00 | Window Closed / Lapsed |