Method and apparatus for controlling the use of a public key, based on the level of import integrity for the key
First Claim
1. In a public key cryptographic system including a pair of cryptographic devices communicating using a public key algorithm, a method for limiting the use of a public key to applications not requiring a level of integrity greater than a received level of integrity for the public key, comprising the steps of:
- generating a public key and private key as a pair;
storing said public key at a first device in said system;
storing at said first device a control vector associated with said public key, having a first field;
transmitting from said first device, over a communications link to a second cryptographic device, said public key and said control vector, using a selected one of a plurality of levels of integrity for the transmission;
testing at said second device said public key and said control vector to determine a received level of integrity thereof, as it is received at said second device;
writing at said second device a value into said first field of said control vector characterizing said received level of integrity; and
limiting cryptographic applications for said public key, to said received level of integrity characterized by said first field in said control vector.
2 Assignments
0 Petitions
Accused Products
Abstract
A method and apparatus in a public crypto system, control the use of a public key, based on the level of import integrity for the public key. The method and apparatus generate a control vector associated with the public key, having a history field. The public key and the control vector are transmitted from the location of generation over a communications link to a receiving location, using the selected one of a plurality of levels of import integrity for the transmission. At the receiving location, the public key and the control vector are tested to determine the actual level of import integrity for the transmission. Then, a value is written into the history field of the control vector which characterizes the actual level of import integrity. Thereafter, cryptographic applications for the public key are limited by control vector checking, to only those applications which have a required level of integrity which is not greater than the actual level of import integrity characterized by the history field in the control vector.
50 Citations
30 Claims
-
1. In a public key cryptographic system including a pair of cryptographic devices communicating using a public key algorithm, a method for limiting the use of a public key to applications not requiring a level of integrity greater than a received level of integrity for the public key, comprising the steps of:
-
generating a public key and private key as a pair; storing said public key at a first device in said system; storing at said first device a control vector associated with said public key, having a first field; transmitting from said first device, over a communications link to a second cryptographic device, said public key and said control vector, using a selected one of a plurality of levels of integrity for the transmission; testing at said second device said public key and said control vector to determine a received level of integrity thereof, as it is received at said second device; writing at said second device a value into said first field of said control vector characterizing said received level of integrity; and limiting cryptographic applications for said public key, to said received level of integrity characterized by said first field in said control vector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. In a public key cryptographic system including a pair of cryptographic devices communicating using a public key algorithm, an apparatus for limiting the use of a public key to applications not requiring a level of integrity greater than a received level of integrity for the public key, comprising:
-
first means for generating a public key and private key as a pair; second means coupled to said first means, for storing said public key at a first device in said system; third means coupled to said second means, for storing at said first device a control vector associated with said public key, having a first field; fourth means coupled to said second and third means, for transmitting from said first device, over a communications link to a second cryptographic device, said public key and said control vector, using a selected one of a plurality of levels of integrity for the transmission; fifth means coupled to said communications link, for testing at said second device said public key and said control vector to determine a received level of integrity thereof; sixth means coupled to said fifth means, for writing at said second device a value into said first field of said control vector characterizing said received level of integrity; and seventh means coupled to said sixth means, for limiting cryptographic applications for said public key, to said received level of integrity characterized by said first field in said control vector. - View Dependent Claims (12)
-
-
13. In a data processing network including a pair of communicating cryptographic devices, a method for limiting the use of a communicated key to applications not requiring a level of integrity greater than a received level of integrity for the key, comprising the steps of:
-
storing a key in a first cryptographic device in said network; storing at said first device a control vector associated with said key, having a first field; transmitting from said first device, over a communications link to a second cryptographic device in said network, said key and said control vector, using a selected one of a plurality of levels of integrity for the transmission; testing at said second device said key and said control vector to determine a received level of integrity thereof; writing at said second device a value into said first field of said control vector characterizing said received level of integrity; and limiting cryptographic applications for said key, to said received level of integrity characterized by said first field in said control vector. - View Dependent Claims (14)
-
-
15. In a data processing network including a pair of communicating cryptographic devices, a method for limiting the use of a communicated key to applications not requiring a level of integrity greater than a received level of integrity for the key, comprising the steps of:
-
storing a key at a first cryptographic device in said network; storing at said first device a control vector associated with said key, having a first field; transmitting from said first device, over a communications link to a second cryptographic device in said network, said key and said control vector, using a selected one of a plurality of levels of integrity for the transmission; testing at said second device said key and said control vector to determine a received level of integrity thereof; writing at said second device a value into said first field of said control vector characterizing said received level of integrity; encrypting at said second device said key under a key expression which is the exclusive OR product of a master key and said control vector, forming an encrypted form of said key; receiving at said second device a request to perform a cryptographic application with said key, characterized by a required level of integrity; checking at said second device said first field of said control vector and determining that said required level of integrity is not greater than said received level of integrity; decrypting at said second device said encrypted form of said key under said key expression if said required level of integrity is not greater than said received level of integrity; and performing at said second device said cryptographic application with said key. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23)
-
-
24. In a data processing network including a pair of cryptographic devices communicating using a public key algorithm, a method for limiting the use of a public key to applications not requiring a level of integrity greater than a received level of integrity for the public key, comprising the steps of:
-
storing a first public key and a first private key as a pair at a first device in said network; storing a first control vector associated with said first public key, having a first field, at said first device; storing a second public key and a second control vector associated with said second public key, having a second field, at said first device; transmitting from said first device, over a communications link to a second cryptographic device in said network, said first public key and said first control vector, using a selected one of a plurality of levels of integrity for the transmission; testing at said second device, said first public key and said first control vector to determine a received level of integrity thereof; writing a value into said first field of said first control vector characterizing said received level of integrity, at said second device; forming a digital signature characterizing said second public key and said second control vector, using said first private key at said first device; transmitting from said first device to said second device, said second public key, said second control vector and said digital signature; testing at said second device said second public key, said second control vector and said digital signature using said first public key; copying said value in said first field of said first control vector into said second field of said second control vector, characterizing said received level of integrity of said first public key; whereby said received level of integrity of said first public key is attributed as the level of integrity for said second public key. - View Dependent Claims (25, 26)
-
-
27. In a data processing network including a pair of communicating cryptographic devices, a method for limiting the use of a communicated key to applications requiring a level of integrity greater than a received level of integrity for the key, comprising the steps of:
-
storing a key and a control vector associated with said key, having a first field, in a first cryptographic device in said network; transmitting from said first device, over a communications link to a second cryptographic device in said network, said key and said control vector, using a selected one of a plurality of levels of integrity for the transmission; testing at said second device said key to determine a received level of integrity thereof; writing at said second device a value into said first field of said control vector characterizing said received level of integrity; and limiting cryptographic applications for said key, to said received level of integrity characterized by said first field in said control vector.
-
-
28. In a data processing network including a pair of cryptographic devices communicating using a public key algorithm, a method for limiting the use of a public key to applications not requiring a level of integrity greater than a received level of integrity for the public key, comprising the steps of:
-
storing a first public key and a first private key as a pair at a first device in said network; storing a second public key at said first device; transmitting from said first device, over a communications link to a second cryptographic device in said network, said first public key, using a selected one of a plurality of levels of integrity for the transmission; testing at said second device, said first public key to determine a received level of integrity thereof; storing a first control vector associated with said first public key, having a first field, at said second device; writing a value into said first field of said first control vector characterizing said received level of integrity, at said second device; forming a digital signature characterizing said second public key, using said first private key at said first device; transmitting from said first device to said second device, said second public key and said digital signature; testing at said second device said second public key and said digital signature using said first public key; storing a second control vector associated with said second public key, having a second field, at said second device; copying said value in said first field of said first control vector into said second field of said second control vector, characterizing said received level of integrity of said first public key; whereby said received level of integrity of said first public key is attributed as the level of integrity for said second public key. - View Dependent Claims (29, 30)
-
Specification