Stream/block cipher crytographic system
First Claim
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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Abstract
The system disclosed comprises a dual function cryptographic system capable of operating in either a stream or block cipher mode. Further, with minimal alteration the system is capable of performing either encoding or decoding functions. The system requires three inputs, the first of which is the raw data, and the second two inputs comprise a first and a second unique user supplied key. One of the keys is utilized to control a permutation function for both the stream and block cipher mode and the other key is combined directly with the data in the block cipher mode prior to a series of non-linear transformations. In the stream encipherment mode of operation the second key is entered in its entirety into the system where it is successively and continuously transformed as a function of said first key whereby the function of said system becomes a pseudo-random number generator whose output is serially combined with the raw data to form the stream enciphered cryptogram.
300 Citations
14 Claims
- 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.
- 11. A key-controlled cryptographic system capable of selectively performing stream or block cryptographic transformations on an incoming data set, said system including means for accepting and storing two user supplied binary keys, means for entering said data set into said system in stream or block form depending upon the cryptographic transformation mode being utilized, a main reconfiguration means comprising a shift register and including means for loading said main reconfiguration means with data whose input is a function of one of said user supplied keys, a transformation element operatively connected to said main reconfiguration means including means for extracting data from a source field of said main reconfiguration means, performing a nonaffine transformation thereon and returning same to a destination field in said main reconfiguration means through a permutation means controlled by the other of said user supplied keys, means actuable to cause said transformation element to interact with said main reconfiguration means to perform the aforementioned transformations each time said main reconfiguration means is shifted a bit position, means for selectively utilizing the output of said main reconfiguration means as a full cryptographically transformed block of data in the block mode of operation or a pseudo-random number stream which is to be cryptographically combined with said incoming data set when in the stream mode of operation.
Specification