US5315658A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fair cryptosystems and methods of use
Assignee: Certco Inc
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Filing: 1993-04-19
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Granted: 1994-05-24
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Expires: 2013-04-19
Abstract
Abstract A method, using a public-key cryptosystem, for enabling a predetermined entity to monitor communications of users suspected of unlawful activities while protecting the privacy of law-abiding users, wherein each user is assigned a pair of matching secret and public keys. According to the method, each user's secret key is broken into shares. Then, each user provides a plurality of "trustees" pieces of information. The pieces of information provided to each trustee enable that trustee to verify that such information includes a "share" of a secret key of some given public key. Each trustee can verify that the pieces of information provided include a share of the secret key without interaction with any other trustee or by sending messages to the user. Upon a predetermined request or condition, e.g., a court order authorizing the entity to monitor the communications of a user suspected of unlawful activity, the trustees reveal to the entity the shares of the secret key of such user. This enables the entity to reconstruct the secret key and monitor the suspect user's communications.
Inventors
- 👤 Silvio Micali
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 10:26
CPC Classifications
G; G06; G06Q; G06Q20/00; G06Q20/02; G06Q20/38; G06Q20/382; G06Q20/3829; G06Q20/389; G06Q20/40; G06Q20/403; G07; G07F; G07F17/00; G07F17/32; G07F17/3241; G07F7/00; G07F7/08; G07F7/10; G07F7/1016; H; H04; H04K; H04K1/00; H04L; H04L9/00; H04L9/08; H04L9/0816; H04L9/085; H04L9/32; H04L9/321
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
126 words
A method, using a public-key cryptosystem, for enabling a predetermined entity to monitor communications of users suspected of unlawful activities while protecting the privacy of law-abiding users, wherein each user is assigned a pair of matching secret and public keys, comprising the steps of: breaking each user's secret key into shares; providing trustees pieces of information enabling the trustees to verify that the pieces of information include shares of a secret key of some given public key; and upon a predetermined request, having the trustees reveal the shares of the secret key of a user suspected of unlawful activity to enable the entity to attempt reconstruction of the secret key; and monitoring communications to the suspect user during a time period specified in the predetermined request.
Claim 2
Independent Claim
126 words
A method, using a public-key cryptosystem, for enabling a predetermined entity to monitor communications of users suspected of unlawful activities while protecting the privacy of law-abiding users, wherein each user is assigned a pair of matching secret and public keys, comprising the steps of: breaking each user's secret key into shares; providing trustees pieces of information enabling the trustees to verify that the pieces of information include shares of a secret key of some given public key; and upon a predetermined request, having the trustees reveal the shares of the secret key of a user suspected of unlawful activity to enable the entity to attempt reconstruction of the secret key; and monitoring communications to the suspect user during a time period specified in the predetermined request.
Claim 3
Dependent Claim
23 words
The method as described in claim 1 wherein the predetermined entity is a government agency and the predetermined request is a court order.
Claim 4
Independent Claim
86 words
A method, using a cryptosystem, for enabling a predetermined entity to monitor communications of users suspected of unlawful activities while protecting the privacy of law-abiding users, comprising the steps of: providing trustees pieces of information that are guaranteed to include shares of at least a secret decryption key; and upon a predetermined request, having the trustees reveal the shares of the secret decryption key to enable the entity to attempt to monitor communications to the suspected user during a time period specified in the predetermined request.
Claim 5
Independent Claim
86 words
A method, using a cryptosystem, for enabling a predetermined entity to monitor communications of users suspected of unlawful activities while protecting the privacy of law-abiding users, comprising the steps of: providing trustees pieces of information that are guaranteed to include shares of at least a secret decryption key; and upon a predetermined request, having the trustees reveal the shares of the secret decryption key to enable the entity to attempt to monitor communications to the suspected user during a time period specified in the predetermined request.
Claim 6
Independent Claim
90 words
A method, using a cryptosystem, for enabling a predetermined entity to monitor communications of users suspected of unlawful activities while protecting the privacy of law-abiding users, comprising the steps of: having trustees hold pieces of information, wherein a piece of information is guaranteed to include a share of secret decryption key; and upon a predetermined request, having a given number of trustees each reveal the piece of information that includes the share of at least one secret decryption key to enable the entity to monitor communications to the suspected user.
Claim 7
Independent Claim
90 words
A method, using a cryptosystem, for enabling a predetermined entity to monitor communications of users suspected of unlawful activities while protecting the privacy of law-abiding users, comprising the steps of: having trustees hold pieces of information, wherein a piece of information is guaranteed to include a share of secret decryption key; and upon a predetermined request, having a given number of trustees each reveal the piece of information that includes the share of at least one secret decryption key to enable the entity to monitor communications to the suspected user.
Claim 8
Dependent Claim
28 words
The method as described in claim 4 further including the step of: characterizing the user's activities as unlawful if the entity is unable to monitor the user's communications.
Claim 9
Dependent Claim
20 words
The method as described in claim 4 wherein a given minority of trustees are unable to reconstruct the secret key.
Claim 10
Independent Claim
99 words
A method, using a cryptosystem, for enabling a predetermined entity to monitor communications of users suspected of unlawful activities while protecting the privacy of law-abiding users, wherein one user has at least a secret decryption key, comprising the steps of: having trustees hold pieces of information that are guaranteed to include shares of a secret decryption key; and upon a predetermined request, having a given number of trustees each reveal the piece of information that includes the share of the secret decryption key to enable the entity to attempt to monitor communications to the user suspected of unlawful activities.
Claim 11
Independent Claim
99 words
A method, using a cryptosystem, for enabling a predetermined entity to monitor communications of users suspected of unlawful activities while protecting the privacy of law-abiding users, wherein one user has at least a secret decryption key, comprising the steps of: having trustees hold pieces of information that are guaranteed to include shares of a secret decryption key; and upon a predetermined request, having a given number of trustees each reveal the piece of information that includes the share of the secret decryption key to enable the entity to attempt to monitor communications to the user suspected of unlawful activities.
Claim 12
Dependent Claim
22 words
The method as described in claim 7 wherein upon the predetermined request all of the trustees each reveal the piece of information.
Claim 13
Independent Claim
72 words
A method for revealing a user's secret value, comprising the steps of: having trustees hold pieces of information, wherein a piece of information includes a share of secret value; and upon a predetermined request, having a given number of trustees each reveal the piece of information that includes the share of the secret value to enable the entity to reconstruct the secret value at a prescribed time specified in the predetermined request.
Claim 14
Independent Claim
72 words
A method for revealing a user's secret value, comprising the steps of: having trustees hold pieces of information, wherein a piece of information includes a share of secret value; and upon a predetermined request, having a given number of trustees each reveal the piece of information that includes the share of the secret value to enable the entity to reconstruct the secret value at a prescribed time specified in the predetermined request.
Claim 15
Independent Claim
92 words
A method, using a cryptosystem, for enabling a predetermined entity to monitor communications of users suspected of unlawful activities while protecting the privacy of law-abiding users, comprising the steps of: having trustees hold pieces of information that are guaranteed to include shares of a secret decryption key; upon a predetermined request, having the trustees send information to a secure device having its own internal clock; and using the secure device to enable the entity to monitor communications to a suspect user for an amount of time as specified in the predetermined request.
Claim 16
Independent Claim
92 words
A method, using a cryptosystem, for enabling a predetermined entity to monitor communications of users suspected of unlawful activities while protecting the privacy of law-abiding users, comprising the steps of: having trustees hold pieces of information that are guaranteed to include shares of a secret decryption key; upon a predetermined request, having the trustees send information to a secure device having its own internal clock; and using the secure device to enable the entity to monitor communications to a suspect user for an amount of time as specified in the predetermined request.
Claim 17
Independent Claim
95 words
A method, using a cryptosystem, for enabling a predetermined entity to verify that a user is sending messages encrypted by means of a secure device implementing the given cryptosystem, wherein the secure device contains a secret key known to the entity, comprising the steps of: having the secure device use the given cryptosystem to generate a first string, the first string being an encryption of a message; having the secure device use the secret key to generate a second string that guarantees to the entity that the first string was generated with the given cryptosystem.
Claim 18
Independent Claim
95 words
A method, using a cryptosystem, for enabling a predetermined entity to verify that a user is sending messages encrypted by means of a secure device implementing the given cryptosystem, wherein the secure device contains a secret key known to the entity, comprising the steps of: having the secure device use the given cryptosystem to generate a first string, the first string being an encryption of a message; having the secure device use the secret key to generate a second string that guarantees to the entity that the first string was generated with the given cryptosystem.
Claim 19
Independent Claim
101 words
A method, using a cryptosystem, for enabling a predetermined entity to confirm that users of a system exchange messages encrypted according to a predetermined algorithm, comprising the steps of: providing each user in the system with a secure chip containing at least one secret key unknown to the user; and having the user send encrypted messages using the secure chip; and with each encrypted message sent by a user, having the secure chip also send a data string, computed using the secret key, to guarantee the entity that the encrypted message was generated by the secure chip using the predetermined algorithm.
Claim 20
Independent Claim
101 words
A method, using a cryptosystem, for enabling a predetermined entity to confirm that users of a system exchange messages encrypted according to a predetermined algorithm, comprising the steps of: providing each user in the system with a secure chip containing at least one secret key unknown to the user; and having the user send encrypted messages using the secure chip; and with each encrypted message sent by a user, having the secure chip also send a data string, computed using the secret key, to guarantee the entity that the encrypted message was generated by the secure chip using the predetermined algorithm.
Claim 21
Dependent Claim
54 words
The method as described in claim 12 further including the steps of: providing trustees with pieces of information including shares of a secret key; and upon a predetermined request, having a given number of trustees send information including shares of the secret key to allow the entity to monitor communications to a suspect user.
References Cited (Backward Citations)
US4405829A
Cited
US4375579A
Cited
US5018196A
Cited
US4933970A
Cited
US5136643A
Cited
US5006200A
Cited
US5150411A
Cited
US5199070A
Cited
US5214698A
Cited
US5276737A
Cited
US5276737B1
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-05-23 | 1997-11-22 | 1998-05-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-05-23 | 2001-11-22 | 2002-05-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-05-23 | 2005-11-22 | 2006-05-24 | $7700.00 | Window Closed / Lapsed |