Method for encryption and transmission of digital keying data
First Claim
1. A cryptographic method for encrypting, transmitting and decrypting keying data between a master unit and at least one remote unit, comprising the steps of:
- storing in said master unit and in said remote unit a plurality of key encryption keys, said key encryption keys being addressed by means of a common addressing system in each unit;
generating a first storage address effective to identify a master key encryption key from said plurality of key encryption keys;
indexing said first storage address by a first predetermined amount to define a second storage address effective to identify a first key encryption key from said plurality of key encryption keys;
indexing said first storage address by a second predetermined amount to define a third storage address effective to identify a second key encryption key from said plurality of key encryption keys;
generating a data encryption key in said master unit, using said first key encryption key;
encrypting said data encryption key using said second key encryption key to produce an encrypted data encryption key;
downloading to said remote unit said encrypted data encryption key together with a designator value for identifying the address of said second key encryption key at said remote unit;
decrypting said encrypted data encryption key at said remote unit to reproduce said data encryption key at said remote unit;
whereby there is enabled subsequent transmission of data between said master unit and said remote unit, using said data encryption key to encrypt and decrypt said data.
1 Assignment
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Accused Products
Abstract
A method for the encryption, transmission, and subsequent decryption of digital keying data. The method utilizes the Data Encryption Standard and is implemented by means of a pair of apparatus, each of which is selectable to operate as either a master unit or remote unit. Each unit contains a set of key encryption keys which are indexed by a common indexing system. The master unit operates upon command from the remote unit to generate a data encryption key and encrypt the data encryption key using a preselected key encryption key. The encrypted data encryption key and an index designator are then downloaded to the remote unit, where the data encryption key is decrypted for subsequent use in the encryption and transmission data. Downloading of the encrypted data encryption key enables frequent change of keys without requiring manual entry or storage of keys at the remote unit.
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Citations
24 Claims
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1. A cryptographic method for encrypting, transmitting and decrypting keying data between a master unit and at least one remote unit, comprising the steps of:
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storing in said master unit and in said remote unit a plurality of key encryption keys, said key encryption keys being addressed by means of a common addressing system in each unit; generating a first storage address effective to identify a master key encryption key from said plurality of key encryption keys; indexing said first storage address by a first predetermined amount to define a second storage address effective to identify a first key encryption key from said plurality of key encryption keys; indexing said first storage address by a second predetermined amount to define a third storage address effective to identify a second key encryption key from said plurality of key encryption keys; generating a data encryption key in said master unit, using said first key encryption key; encrypting said data encryption key using said second key encryption key to produce an encrypted data encryption key; downloading to said remote unit said encrypted data encryption key together with a designator value for identifying the address of said second key encryption key at said remote unit; decrypting said encrypted data encryption key at said remote unit to reproduce said data encryption key at said remote unit; whereby there is enabled subsequent transmission of data between said master unit and said remote unit, using said data encryption key to encrypt and decrypt said data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification