Key variable generator for an encryption/decryption device
First Claim
1. An apparatus for generating a working key variable for use in a cryptographic device, said cryptographic device including an input for incoming data, an input for a key variable and an output for translated data, said apparatus comprising:
- plug-in means, engageable with said cryptographic device by an operator, said plug-in means for initiating and controlling the generation of one of said working key variables, said plug-in means includingswitchable means, settable by said operator, said switchable means for entering an operator specified variable,memory means for storing a fixed key variable, andcontrol means for causing the transfer of said operator specified variable to the incoming data input of said cryptographic device and the transfer of said fixed key variable to the key variable input of said cryptographic device, said control means additionally for activating said cryptographic device, wherein said operator specified variable is encrypted in accordance with said fixed key variable, whereby said working key variable is produced at the translated data output of said cryptographic device; and
means, connected to the translated data output of said cryptographic device and the key variable input of said cryptographic device, said latter means for supplying said generated working key variable as the key variable input to said cryptographic device.
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Abstract
An apparatus and method for generating a unique working key variable for controlling the operation of an encryption/decryption device during each user specified time period. The apparatus generates each working key variable by encrypting a user specified value, unique for each specified time period, under control of a fixed key variable stored in the apparatus. After the user specified value has been encrypted, the apparatus utilizes the encrypted (working) key variable to control the encryption/decryption of data during the corresponding user specified time period.
57 Citations
29 Claims
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1. An apparatus for generating a working key variable for use in a cryptographic device, said cryptographic device including an input for incoming data, an input for a key variable and an output for translated data, said apparatus comprising:
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plug-in means, engageable with said cryptographic device by an operator, said plug-in means for initiating and controlling the generation of one of said working key variables, said plug-in means including switchable means, settable by said operator, said switchable means for entering an operator specified variable, memory means for storing a fixed key variable, and control means for causing the transfer of said operator specified variable to the incoming data input of said cryptographic device and the transfer of said fixed key variable to the key variable input of said cryptographic device, said control means additionally for activating said cryptographic device, wherein said operator specified variable is encrypted in accordance with said fixed key variable, whereby said working key variable is produced at the translated data output of said cryptographic device; and means, connected to the translated data output of said cryptographic device and the key variable input of said cryptographic device, said latter means for supplying said generated working key variable as the key variable input to said cryptographic device. - 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, 25, 26)
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27. A method of generating a working key variable for use in a cryptographic device, said cryptographic device including input means for accepting incoming plain text data, input means for accepting a key variable and an output for translated data, said method comprising the steps of:
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a. providing said cryptographic device with an operator selected variable and a fixed value; b1. transferring the high order byte of the provided operator selected variable into the low order byte position of said incoming plain text data means; b2. shifting the contents of said incoming plain text data means one byte position left; b3. shifting the provided operator selected variable one byte position left; b4. repeating steps b1 through b3 until the entire provided operator selected variable has been transferred into the incoming plain text data means; c. storing said fixed value in the key variable input means; d. operating said cryptographic device wherein said operator selected variable stored in said incoming plain text data means is encrypted in accordance with said fixed value stored in said key variable input means, wherby a working key variable is generated at the translated data output of said cryptographic device; and e. storing the generated working key variable in said key variable input means. - View Dependent Claims (28, 29)
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Specification