Controlled use of cryptographic keys via generating station established control values
First Claim
1. A method for controlling the use of a cryptographic key at a using station by a generating station in a network of generating and using stations by transmitting said cryptographic key with a control value specifying the use of said cryptographic key from the generating station which generates the cryptographic key to at least two designated using stations one of which may be the generating station, each of said generating and using stations having a cryptographic facility which securely stores a master key, said method comprising the steps of:
- storing in a data base at a generating station a plurality of encrypted secret transport keys unique to each of said using stations and indexed by identifications of said using stations, said encrypted secret transport keys being encrypted under a variant of said master key;
generating a command for the generation and distribution of a cryptographic key with a controlled use to at least two designated using stations in said network; and
in response to said command, generating a random key in said cryptographic facility of the generating station as said cryptographic key;
accessing the encrypted secret transport keys for the designated using stations using the identification for the using stations;
decrypting in said cryptographic facility of the generating station the accessed secret transport keys for the designated using stations using said variant of said master key;
combining in said cryptographic facility of the generating station the decrypted secret transport keys with the generated cryptographic key to produce a combined function f1 for each designated using station;
reading a control value for said cryptographic key for each said designated using station;
combining in said cryptographic facility of the generating station the generated cryptographic key with said control value for each said designated using station to produce a combined function f2 ;
transmitting said combined functions f1 and f2 for each said designated using station to the corresponding designated using stations;
storing said encrypted secret transport key at a designated using station indexed by the identification of said using station;
requesting a cryptographic operation requiring the use of the cryptographic key generated by said generating station in combination with a control value;
accessing said encrypted secret transport key and temporarily storing in the cryptographic facility of said designated using station said encrypted secret transport key together with said control value and said combined functions f1 and f2 transmitted from said generating station; and
determining if said requested cryptographic operation at said designated using station is permitted.
1 Assignment
0 Petitions
Accused Products
Abstract
A method for controlling the use of a cryptographic key at a using station by a generating station in a network of generating and using stations is disclosed. A control value specifying the use of the cryptographic key is transmitted with a generated cryptographic key to at least two designated using stations one of which may be the generating station. Each of the generating and using stations have cryptographic facilities that securely store a master key. Two techniques are described for controlling the use of the cryptographic key. In the first, the key and the control value are authenticated via a special authentication code before use by the using station. In the second, the key and control value are coupled during key generation such that the key is recovered only if a correct control value is specified. In addition, two techniques are described for controlling who may use the cryptographic key. In the first, each using station has a unique secret transport key shared with the generating station which generates the key in such a way that it can be recovered or regenerated only by the designated using station possessing the correct secret transport key. In the second, secret transport keys are shared by pairs of using stations and cryptographic separation is achieved by using public or nonsecret values unique to each using station.
195 Citations
22 Claims
-
1. A method for controlling the use of a cryptographic key at a using station by a generating station in a network of generating and using stations by transmitting said cryptographic key with a control value specifying the use of said cryptographic key from the generating station which generates the cryptographic key to at least two designated using stations one of which may be the generating station, each of said generating and using stations having a cryptographic facility which securely stores a master key, said method comprising the steps of:
-
storing in a data base at a generating station a plurality of encrypted secret transport keys unique to each of said using stations and indexed by identifications of said using stations, said encrypted secret transport keys being encrypted under a variant of said master key; generating a command for the generation and distribution of a cryptographic key with a controlled use to at least two designated using stations in said network; and in response to said command, generating a random key in said cryptographic facility of the generating station as said cryptographic key; accessing the encrypted secret transport keys for the designated using stations using the identification for the using stations; decrypting in said cryptographic facility of the generating station the accessed secret transport keys for the designated using stations using said variant of said master key; combining in said cryptographic facility of the generating station the decrypted secret transport keys with the generated cryptographic key to produce a combined function f1 for each designated using station; reading a control value for said cryptographic key for each said designated using station; combining in said cryptographic facility of the generating station the generated cryptographic key with said control value for each said designated using station to produce a combined function f2 ; transmitting said combined functions f1 and f2 for each said designated using station to the corresponding designated using stations; storing said encrypted secret transport key at a designated using station indexed by the identification of said using station; requesting a cryptographic operation requiring the use of the cryptographic key generated by said generating station in combination with a control value; accessing said encrypted secret transport key and temporarily storing in the cryptographic facility of said designated using station said encrypted secret transport key together with said control value and said combined functions f1 and f2 transmitted from said generating station; and determining if said requested cryptographic operation at said designated using station is permitted. - View Dependent Claims (2, 3, 4, 5)
-
-
6. A method for controlling the use of a cryptographic key at a using station by a generating station in a network of generating and using stations by transmitting said cryptographic key with a control value specifying the use of said cryptographic key from the generating station which generates the cryptographic key to at least two designated using stations one of which may be the generating station, each of said generating and using stations having a cryptographic facility which securely stores a master key and a nonsecret value unique to each using station, said method at a generating station comprising the steps of:
-
storing in a first data base a plurality of encrypted secret transport keys unique to each pair of using stations in said network and indexed by identifications of pairs of using stations sharing a secret transport key, said encrypted secret transport keys being encrypted under a variant of said master key; storing in a second data base a plurality of nonsecret values unique to each using station in said network and indexed by identifications of said using stations; generating a command for the generation and distribution of a cryptographic key with a controlled use to at least two designated using stations in said network; and in response to said command, generating a random number in said cryptographic facility; accessing the encrypted secret transport keys shared by designated using stations using the identifications for the using station pairs sharing the encrypted secret transport keys; accessing the nonsecret values for the designated using stations using the identifications for the designated using stations; decrypting in said cryptographic facility of the generating station the accessed secret transport keys using said variant of said master key; combining in said cryptographic facility of the generating station the generated random number with the decrypted secret transport keys to produce a combined function f for each of the designated using stations; combining in said cryptographic facility of the generating station the decrypted secret transport key with said combined function f3 to generate said cryptographic key; reading a control value for said cryptographic key for each said designated using station; for each said designated using station, combining the generated cryptographic key with the control value and the nonsecret value for the designated using station to produce a combined function f4 for the designated using station; and transmitting said combined functions f3 and f4 for each said designated using station to the corresponding designated using stations. - View Dependent Claims (7, 8, 9, 10, 11, 12)
-
-
13. A method for controlling the use of a cryptographic key at a using station by a generating station in a network of generating and using stations by transmitting said cryptographic key with a control value specifying the use of said cryptographic key from the generating station which generates the cryptographic key to at least two designated using stations one of which may be the generating station, each of said generating and using stations having a cryptographic facility which securely stores a master key, said method at a generating station comprising the steps of:
-
storing in a data base a plurality of encrypted secret transport keys unique to each of said using stations and indexed by indentifications of said using stations, said incrypted secret transport keys being encrypted under a variant of said master key; generating a command for the generation and distribution of a cryptographic key with a controlled use to at least two designated using stations in said network; and in response to said command, generating a random key in said cryptographic facility as said cryptographic key; accessing the encrypted secret transport keys for the designated using stations using the identification for the using stations; decrypting in said cryptographic facility of the generating station the accessed secret transport keys for the designated using stations using said variant of said master key; reading a control value for said cryptographic key for each said designated using station; combining in said cryptographic facility of the generating station the decrypted secret transport keys with the generated cryptographic key and the control value for each designated using station to produce a first combined function for each designated using station; and transmitting said combined function for each said designated using station to the corresponding designated using stations. - View Dependent Claims (14, 15, 16, 17)
-
-
18. A method for controlling the use of a cryptographic key at a using station by a generating station in a network of generating and using stations by transmitting said cryptographic key with a control value specifying the use of said cryptographic key from the generating station which generates the cryptographic key to at least two designated using stations one of which may be the generating station, each of said generating and using stations having a cryptographic facility which securely stores a master key and a nonsecret value for each of said using stations, said method at a generating station comprising the steps of:
-
storing in a first data base a plurality of encrypted secret transport keys unique to each pair of using stations in said network and indexed by identifications of pairs of using stations sharing a secret transport key, said encrypted secret transport keys being encrypted under a variant of said master key; storing in a second data base a plurality of nonsecret values unique to each using station in said network and indexed by identifications of said using stations; generating a command for the generation and distribution of a cryptographic key with a controlled use to at least two designated using stations in said network; and in response to said command, generating a random key in said cryptographic facility as said cryptographic key; accessing the encrypted secret transport keys shared by designated using stations using the identifications for the using station pairs sharing the encrypted secret transport keys; accessing the nonsecret values for the designated using stations using the identifications for the designated using stations; decrypting in said cryptographic facility of the generating station the accessed secret transport keys using said variant of said master key; reading a control value for said cryptographic key for each said designated using station; combining in said cryptographic facility of the generating station the generated cryptographic key with the decrypted secret transport key, control value and nonsecret value for each designated using station to produce a combined function f6 for each of the designated using stations; and transmitting said combined function f6 for each said designated using station to the corresponding designated using stations. - View Dependent Claims (19, 20, 21, 22)
-
Specification