US6157719A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Conditional access system
Assignee: Tech 5 Sas
•
Filing: 1998-07-31
•
Granted: 2000-12-05
•
Expires: 2018-07-31
Abstract
Abstract A cable television system provides conditional access to services. The cable television system includes a headend from which service "instances", or programs, are broadcast and a plurality of set top units for receiving the instances and selectively decrypting the instances for display to system subscribers. The service instances are encrypted using public and/or private keys provided by service providers or central authorization agents. Keys used by the set tops for selective decryption may also be public or private in nature, and such keys may be reassigned at different times to provide a cable television system in which piracy concerns are minimized.
Inventors
- 👤 Anthony J. Wasilewski
- 👤 Howard G. Pinder
- 👤 Glendon L. Akins, III
- 👤 Michael S. Palgon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 18:54
CPC Classifications
H; H04; H04L; H04L63/00; H04L63/04; H04L63/0428; H04L63/0442; H04L63/045; H04L63/06; H04L63/062; H04L63/08; H04L63/0823; H04L63/12; H04L63/123; H04N; H04N21/00; H04N21/20; H04N21/23; H04N21/234; H04N21/2347; H04N21/23476; H04N21/40; H04N21/45; H04N21/4508; H04N21/4524; H04N7/00; H04N7/16; H04N7/162; H04N7/163; H04N7/167; H04N7/1675; H04J; H04J2203/00; H04J2203/0001; H04J2203/0073; H04J2203/008; H04L2463/00; H04L2463/101
Claims Analysis
Total Claims: 49
Claim 1
Independent Claim
124 words
A method of decrypting an instance of a service that has been encrypted with a short-term key, the method being carried out in a receiver that has a public key-private key pair and the method comprising the steps of: receiving a first message in the receiver whose contents include a long-term key, the contents having been encrypted using the public key for the receiver; using the private key to decrypt the contents; storing the long-term key; receiving a second message in the receiver together with the instance of the service, the second message including a key derivation value; using the key derivation value and the long-term key to obtain the short-term key; and using the short-term key to decrypt the instance of the service.
Claim 2
Independent Claim
124 words
A method of decrypting an instance of a service that has been encrypted with a short-term key, the method being carried out in a receiver that has a public key-private key pair and the method comprising the steps of: receiving a first message in the receiver whose contents include a long-term key, the contents having been encrypted using the public key for the receiver; using the private key to decrypt the contents; storing the long-term key; receiving a second message in the receiver together with the instance of the service, the second message including a key derivation value; using the key derivation value and the long-term key to obtain the short-term key; and using the short-term key to decrypt the instance of the service.
Claim 3
Dependent Claim
53 words
The method set forth in claim 1 wherein: the receiver includes a secure element in which the private key is stored; the steps of decrypting the contents, storing the long-term key, and using the longterm key and the key derivation value to obtain the short-term key are carried out in the secure element.
Claim 4
Dependent Claim
49 words
The method set forth in claim 1 wherein the first message further includes first authentication information; and the method further comprises the steps of: using the first authentication information to determine whether the first message is authentic; and disregarding the first message if the first message is not authentic.
Claim 5
Dependent Claim
99 words
The method set forth in claim 3 wherein: the receiver has a public key for an entitlement agent; the first authentication information is a digest of information in the first message, the digest being encrypted with a private key corresponding to the public key for the entitlement agent; and the step of using the first authentication information includes the steps of: making a new digest of the information in the first message; decrypting the first authentication information; and comparing the new digest with the decrypted first authentication information, the first message being authentic when the two are the same.
Claim 6
Dependent Claim
70 words
The method set forth in claim 4 wherein: the receiver includes a secure element in which the public key for the entitlement agent and the private key for the receiver are stored; and the steps of decrypting the contents, storing the long-term key, using the first authentication information, and using the long-term key and the key derivation value to obtain the short-term key arc carried out in the secure element.
Claim 7
Dependent Claim
75 words
The method set forth in claim 1, wherein: the first message and the second message each includes an indication of an entitlement agent; the step of storing the long-term key includes the step of associating the long-term key with the entitlement agent identified by the indication in the first message; and the method further comprises the step of using the indication of the entitlement agent in the second message to locate the stored long-term key.
Claim 8
Dependent Claim
70 words
The method set forth in claim 6, wherein: the first message and the second message each further includes a key identifier for the long-term key; the step of storing the long-term key further includes the step of associating the long-term key with the key identifier from the first message; and the method further comprises the step of using the key identifier from the second message to locate the long-term key.
Claim 9
Dependent Claim
144 words
The method set forth in claim 7 wherein: the second message further includes an entitlement specifier specifying an entitlement; and the method further comprises the steps of: receiving a third message in the receiver, the contents of the third message including an entitlement agent specifier and an entitlement specifier and the contents of the third message having been encrypted using the public key for the receiver; using the private key to decrypt the contents of the third message; storing the entitlement specifier in association with the entitlement agent specified by the entitlement agent specifier; and determining whether the entitlement specifier in the second message matches a stored entitlement specifier associated with the entitlement agent specified in the second message, and performing the step of using the key derivation value and the long-term key to obtain the short-term key only if a match is found.
Claim 10
Dependent Claim
39 words
The method set forth in claim 8 wherein: there is a plurality of entitlement agents; a plurality of long-term keys are associated with a given entitlement agent; and a plurality of entitlements are associated with a given entitlement agent.
Claim 11
Dependent Claim
110 words
The method set forth in claim 8 wherein: the receiver includes a secure element in which the private key for the receiver is stored; and the secure element performs the steps of decrypting the contents of the first message; decrypting the contents of the third message; storing the long-term key; storing the entitlement specifier in association with the entitlement agent; using the indication of the entitlement agent; determining whether the entitlement specifier in the second message matches a stored entitlement specifier; using the key identifier from the second message to locate the long-term key; and using the key derivation value and the long-term key to obtain the short term key.
Claim 12
Dependent Claim
138 words
The method set forth in claim 6 wherein: the second message further includes an entitlement specifier; and the method further comprises the steps of: receiving a third message in the receiver, the contents of the third message including an entitlement agent specifier and an entitlement specifier and the third message having been encrypted using the public key for the receiver; using the private key to decrypt the contents of the third message; storing the entitlement specifier in association with the entitlement agent specified by the entitlement agent specifier; and determining whether the entitlement specifier in the second message matches a stored entitlement specifier associated with the entitlement agent specified in the second message, and performing the step of using the key derivation value and the long-term key to obtain the short-term key only if a match is found.
Claim 13
Dependent Claim
27 words
The method set forth in claim 11 wherein: there is a plurality of entitlement agents; and a plurality of entitlements are associated with a given entitlement agent.
Claim 14
Dependent Claim
97 words
The method set forth in claim 11 wherein: the receiver includes a secure element in which the private key for the receiver is stored; and the secure element performs the steps of decrypting the contents of the first message, decrypting the contents of the second message, storing the long-term key, storing the entitlement specifier in association with the entitlement agent, using the indication of the entitlement agent, determining whether the entitlement specifier in the second message matches a stored entitlement specifier; and using the key derivation value and the long-term key to obtain the short term key.
Claim 15
Dependent Claim
51 words
The method set forth in claim 9 wherein: the third message further includes authentication information; and the method further comprises the steps of: using the authentication information to determine whether the third message is authentic; and disregarding the third message if it is determined that the third message is not authentic.
Claim 16
Dependent Claim
96 words
The method set forth in claim 14 wherein: the receiver has a public key for an entitlement agent; the authentication information is a digest of information in the third message which has been encrypted with a private key corresponding to the public key for the entitlement agent; and the step of using the first authentication information includes the steps of: making a new digest of the information in the third message; decrypting the authentication information; and comparing the new digest with the decrypted authentication information, the third message being authentic if the two are the same.
Claim 17
Independent Claim
129 words
A method of enabling a receiver that has a public key to decrypt an instance of a service that has been encrypted with a short-term key, the method comprising the steps of: using the public key to encrypt contents of a first message, the contents including a long-term key; sending the first message to the receiver; sending a second message to the receiver together with the encrypted instance of the service, the second message including a key derivation value; and the receiver responding to the first message by decrypting the contents and storing the long-term key and responding to the second message by using the key derivation value and the long-term key to obtain the short-term key and using the short-term key to decrypt the instance of the service.
Claim 18
Independent Claim
129 words
A method of enabling a receiver that has a public key to decrypt an instance of a service that has been encrypted with a short-term key, the method comprising the steps of: using the public key to encrypt contents of a first message, the contents including a long-term key; sending the first message to the receiver; sending a second message to the receiver together with the encrypted instance of the service, the second message including a key derivation value; and the receiver responding to the first message by decrypting the contents and storing the long-term key and responding to the second message by using the key derivation value and the long-term key to obtain the short-term key and using the short-term key to decrypt the instance of the service.
Claim 19
Dependent Claim
20 words
The method set forth in claim 16 wherein the public key for the receiver is stored in a certified form.
Claim 20
Dependent Claim
35 words
The method set forth in claim 16 further comprising the steps of: obtaining the long-term key from a secure element in which it is stored; and using the long-term key to produce the short-term key.
Claim 21
Dependent Claim
57 words
The method set forth in claim 16 further comprising the step of: adding first authentication information to the first message, wherein the receiver uses the first authentication information to check the authenticity of the first message and stores the long-term key in response to the first message only if the authenticity of the first message is confirmed.
Claim 22
Dependent Claim
114 words
The method set forth in claim 19 wherein: the receiver has a public key for an entitlement agent; the step of adding first authentication information includes the step of making an encrypted digest of information in the first message, the digest being encrypted with a private key corresponding to the public key for the entitlement agent, and the receiver checks the authenticity of the first message by making a new digest of the information in the first message, using the public key for the entitlement agent to decrypt the first authentication information, and comparing the new digest with the decrypted first authentication information, the first message being authentic if the two are the same.
Claim 23
Dependent Claim
47 words
The method set forth in claim 20, further comprising the step of: adding second authentication information to the second message, the receiver using the second authentication information to determine whether the second message is authentic and disregarding the second message if the second message is not authentic.
Claim 24
Dependent Claim
97 words
The method set forth in claim 21 wherein: the second message is associated with an entitlement agent; the step of adding second authentication information includes the step of making a digest of information in the second message and a secret shared by the entitlement agent and the receiver; and the receiver checks the authenticity of the second message by making a new digest of the information in the second message and the shared secret and comparing the new digest with the digest of the second message, the second message being authentic if the two are the same.
Claim 25
Dependent Claim
20 words
The method set forth in claim 22 wherein: the shared secret includes at least a portion of the long-term key.
Claim 26
Dependent Claim
31 words
The method set forth in claim 23 wherein: the long-term key is stored in a secure element; and the step of making the digest is carried out in the secure element.
Claim 27
Dependent Claim
62 words
The method set forth in claim 20 wherein: the private key for the entitlement agent and the long-term key are stored in a secure element; the public key is stored in a certified form; and the steps of using the public key for the receiver to encrypt the first message and making the encrypted digest are carried out in the secure element.
Claim 28
Dependent Claim
30 words
The method set forth in claim 25 further comprising the steps of: obtaining the long-term key from the secure element; and using the long-term key to produce the short-term key.
Claim 29
Dependent Claim
73 words
The method set forth in claim 16 wherein: the first message and the second message each includes an indication of an entitlement agent; and the receiver further responds to the first message by associating the long-term key with the entitlement agent identified by the indication in the first message and responds to the second message by using the indication of the entitlement agent in the second message to locate the stored long-term key.
Claim 30
Dependent Claim
66 words
The method set forth in claim 27 wherein: the first message and the second message each further includes a key identifier for the long-term key, the receiver further responding to the first message by associating the long-term key with the key identifier from the first message and responding to the second message by using the key identifier from the second message to locate the long-term key.
Claim 31
Dependent Claim
152 words
The method set forth in claim 28 wherein: the second message further includes an entitlement specifier specifying an entitlement; and the method further comprises the step of sending a third message to the receiver, the contents of the third message including an entitlement agent specifier and an entitlement specifier and the contents of the third message having been encrypted using the public key for the receiver; and the receiver responds to the third message by using the private key to decrypt the contents of the third message, storing the entitlement specifier in association with the entitlement agent specified by the entitlement agent specifier, determining whether the entitlement specifier in the second message matches a stored entitlement specifier associated with the entitlement agent specified in the second message, and performing the step of using the key derivation value and the long-term key to obtain the short-term key only if a match is found.
Claim 32
Dependent Claim
43 words
The method set forth in claim 29 wherein: there is plurality of entitlement agents; a plurality of long-term keys are associated with a given entitlement agent; and a plurality of entitlements for at least one receiver are associated with a given entitlement agent.
Claim 33
Dependent Claim
140 words
The method set forth in claim 27 wherein: the second message further includes an entitlement specifier specifying an entitlement; and the method further comprises the step of sending a third message to the receiver, the contents of the third message including an entitlement agent specifier and an entitlement specifier and the contents of the third message having been encrypted using the public key for the receiver, the receiver responding to the third message by using the private key to decrypt the contents of the third message, storing the entitlement specifier in association with the entitlement specifier in the second message matches a stored entitlement specifier associated with the entitlement agent specified in the second message, and performing the step of using the key derivation value and the long-term key to obtain the short-term key only if a match is found.
Claim 34
Dependent Claim
27 words
The method set forth in claim 31 wherein: there is a plurality of entitlement agents; and a plurality of entitlements are associated with a given entitlement agent.
Claim 35
Dependent Claim
54 words
The method set forth in claim 31, further comprising the step of adding authentication information to the third message, the receiver using the authentication information to check the authenticity of the third message and storing the long-term key in response to the third message only if the authenticity of the third message is confirmed.
Claim 36
Dependent Claim
111 words
The method set forth in claim 33 wherein: the receiver has a public key for an entitlement agent; the step of adding authentication information includes the step of making an encrypted digest of information in the third message, the digest being encrypted with a private key corresponding to the public key for the entitlement agent; and the receiver checks the authenticity of the third message by making a new digest of the information in the third message, using the public key for the entitlement agent to decrypt the authentication information, and comparing the new digest with the decrypted authentication information, the third message being authentic if the two are the same.
Claim 37
Dependent Claim
66 words
The method set forth in claim 34 wherein: the private key for the entitlement agent and the long-term key are stored in a secured element; the public key is stored in a certified form; and the steps of using the public key for the receiver to encrypt the third message and making the encrypted digest using the private key are carried out in the secure element.
Claim 38
Dependent Claim
174 words
A receiver for receiving and decrypting an instance of a service that has been encrypted with a short-term key, the receiver having a public key, and the receiver comprising: a memory that contains the private key corresponding to the receiver's public key; a service decryptor that uses the short-term key to decrypt the instance of the service; a first message interpreter that responds to a first message received in the receiver, the first message's contents, including a long-term key, having been encrypted using the receiver's public key and the first message interpreter responding to the first message by decrypting the contents and storing the long-term key in the memory; and a second message interpreter that responds to a second message received in the receiver together with the instance of the service, the second message's contents including a key derivation value and the second message interpreter responding to the second message by using the key derivation value and the long-term key to obtain the short-term key and providing the short-term key to the service decryptor.
Claim 39
Dependent Claim
174 words
A receiver for receiving and decrypting an instance of a service that has been encrypted with a short-term key, the receiver having a public key, and the receiver comprising: a memory that contains the private key corresponding to the receiver's public key; a service decryptor that uses the short-term key to decrypt the instance of the service; a first message interpreter that responds to a first message received in the receiver, the first message's contents, including a long-term key, having been encrypted using the receiver's public key and the first message interpreter responding to the first message by decrypting the contents and storing the long-term key in the memory; and a second message interpreter that responds to a second message received in the receiver together with the instance of the service, the second message's contents including a key derivation value and the second message interpreter responding to the second message by using the key derivation value and the long-term key to obtain the short-term key and providing the short-term key to the service decryptor.
Claim 40
Dependent Claim
42 words
The receiver set forth in claim 36 further comprising: a secure element for implementing at least in part, the memory, the first message interpreter, and the second message interpreter and for storing, within the memory, the private key and the long-term key.
Claim 41
Dependent Claim
53 words
The receiver set forth in claim 36 wherein: the first message further includes first authentication information; and the first message interpreter further responds to the first message by using the first authentication information to determine whether the first message is authentic and disregarding the first message if the first message is not authentic.
Claim 42
Dependent Claim
100 words
The method set forth in claim 38 wherein: a public key for an entitlement agent is stored in the memory; the first authentication information is a digest of information in the first message, the digest being encrypted with a private key corresponding to the public key for the entitlement agent; and the first message interpreter determines whether the first message is authentic by making a new digest of the information in the first message, decrypting the authentication information, and comparing the new digest with the decrypted first authentication information, the first message being authentic if the two are the same.
Claim 43
Dependent Claim
53 words
The receiver set forth in claim 36, wherein: the second message further includes second authentication information; and the second message interpreter further responds to the second message by using the second authentication information to determine whether the second message is authentic and disregarding the second message if the second message is not authentic.
Claim 44
Dependent Claim
89 words
The receiver of claim 40, wherein: the second message is associated with an entitlement agent; and the second message interpreter makes a digest of information in the second message and a secret shared by the entitlement agent and the receiver, wherein the receiver checks the authenticity of the second message by making a new digest of the information in the second message and the shared secret and comparing the new digest with the digest of the second message, the second message being authentic when the two are the same.
Claim 45
Dependent Claim
20 words
The method of claim 1, wherein said receiver is included in a set top terminal of a cable television system.
Claim 46
Dependent Claim
30 words
The method of claim 42, wherein said instance of service is transmitted in a downstream direction from head end equipment of the cable television system to said set top terminal.
Claim 47
Dependent Claim
56 words
The method of claim 1, wherein: said receiver is included in head end equipment of a cable television system; said first and second messages original in a set top terminal of the cable television system; said instance of service comprises data generated by said set top terminal; and said long term key comprises a session key.
Claim 48
Dependent Claim
26 words
The method of claim 44, wherein said data is transmitted upstream, through the cable television system, from said set top terminal to said head end equipment.
Claim 49
Dependent Claim
63 words
The method of claim 1, wherein: said first message comprises an entitlement management message including authorization information; said second message comprises an entitlement control message including service identification information that identifies the instance of service; and said instance is service is decrypted only when said service identification information is equivalent to said authorization information, thereby preventing replay attacks on said instance of service.
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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) | 2003-12-05 | 2004-06-05 | 2004-12-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-12-05 | 2008-06-05 | 2008-12-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-12-05 | 2012-06-05 | 2012-12-05 | $7700.00 | Window Closed / Lapsed |