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Stream/block cipher crytographic system

  • US 4,316,055 A
  • Filed: 12/30/1976
  • Issued: 02/16/1982
  • Est. Priority Date: 12/30/1976
  • Status: Expired due to Term
First Claim
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1. A key-controlled cryptographic system capable of selectively performing stream or block mode cryptographic transformations on an incoming data set, said system including means for storing a user supplied key, means for entering said data set into said system for cryptographic transformation, a main reconfiguration means comprising a shift register whose input is a function of said user supplied key, a transformation element operatively connected to said main reconfiguration means for cryptographically transforming data located in said main reconfiguration means, means for causing said transformation element to perform consecutive cryptographic transformations of data located in said main reconfiguration means for a predetermined number of cycles, means for selectively utilizing the complete contents of said main reconfiguration means as a full cryptographically transformed block of data in block mode operation, or a pseudo-random number stream which is combined serially in an inverse mathematical function with said incoming data set in serial mode operation.

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