Electronic keying scheme for locking data
First Claim
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1. In a digital processing system for providing security of data stored in the system, apparatus for protecting data in a memory of the system comprising:
- key means for storing a psuedorandom combination number, said key means corresponding to a key holder;
first memory means for storing encrypted data;
second memory means for storing decrypted data, corresponding to said encrypted data;
decryption/encryption means connected between said first memory means and said second memory means, said decryption/encryption means operating to encrypt data for storage in said first memory means and further operating to decrypt data for storage in said second memory means;
control means connected to said key means and to said decryption/encryption means, said control means operating in response to said pseudorandom combination number of said key means to produce a key variable to allow said decryption of data of said first memory means for access by said key holder to said second memory means; and
said control means further operating to write a second psuedorandom combination number in said key means for subsequent accesses by said key holder.
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Abstract
A data locking system which modifies data in accordance with a renewable key variable derived from the exclusive ORing of a pseudorandom combination number from an external source means with an altered key variable.
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Citations
15 Claims
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1. In a digital processing system for providing security of data stored in the system, apparatus for protecting data in a memory of the system comprising:
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key means for storing a psuedorandom combination number, said key means corresponding to a key holder; first memory means for storing encrypted data; second memory means for storing decrypted data, corresponding to said encrypted data; decryption/encryption means connected between said first memory means and said second memory means, said decryption/encryption means operating to encrypt data for storage in said first memory means and further operating to decrypt data for storage in said second memory means; control means connected to said key means and to said decryption/encryption means, said control means operating in response to said pseudorandom combination number of said key means to produce a key variable to allow said decryption of data of said first memory means for access by said key holder to said second memory means; and said control means further operating to write a second psuedorandom combination number in said key means for subsequent accesses by said key holder. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for protecting data in a memory of a digital processing system, said method for protecting data in a memory comprising the steps of:
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reading a first psuedorandom number from a key of a key holder; combining said key with an encrypted key stored in a first memory to produce a key variable; decrypting previously encrypted data stored in a second memory using said key variable; storing said decrypted data in a third memory, said decrypted data for use and modification by said key holder; generating first and second psuedorandom numbers; encrypting said previously decrypted data of said third memory with said first psuedorandom number; second storing said encrypted data in said second memory; forming an encrypted key variable from said first and second psuedorandom numbers; and third storing said second psuedorandom number in said key of said key holder. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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Specification