Variable size key cipher and method and device using the same

Abstract

An encryption device and method and decryption device and method which implement a bit-based encryption scheme and hardware design. The encryption device includes a random number generator, receiving a main key, determining a working key using at least one random number and outputting a working key, a model, receiving the main key, the working key and plain text to be encoded and generating at least two frequency counts. The encryption device further includes an encoder, which outputs encoded text based on the working key, the plain text and the at least two frequency counts. The encryption device and method and decryption device and method progress encrypted text that is based upon a stream structure with an unlimited key length and may be compressed by 50%. The encoded text is changeable with different environments even for the same plain text and the same key. Operations of the hardware design are based on arithmetic additions and shifts, and not multiplications and divisions. As a result, the hardware design is simple and applicable to cryptography and e-commerce.

1 . An encryption device, comprising: 
 a random number generator, receiving a main key, determining a working key using at least one random number and outputting the working key;    a model, receiving the main key, the working key and plain text and generating at least two frequency counts; and    an encoder, outputting cipher text, based on the working key, the plain text, and the at least two frequency counts.    
     
     
         2 . The encryption device of  claim 1 , wherein the working key produced by said random number generator is variable length.  
     
     
         3 . The encryption device of  claim 1 , wherein said encoder output is variable.  
     
     
         4 . The encryption device of  claim 1 , wherein the working key and the main key are different.  
     
     
         5 . The encryption device of  claim 1 , wherein said model includes at least one frequency table containing the at least two frequency counts.  
     
     
         6 . The encryption device of  claim 1 , wherein the at least one frequency table is stored in a RAM.  
     
     
         7 . The encryption device of  claim 1 , wherein the ciphered text output by said encoder is based on a bit-based processing scheme.  
     
     
         8 . The encryption device of  claim 5 , wherein the at least one frequency table includes the working key.  
     
     
         9 . A method of encrypting, comprising: 
 processing random bits and key bits to generate at least one frequency table; and    encoding plain text using the at least one frequency table.    
     
     
         10 . The method of  claim 9 , wherein said processing step includes generating a random bit string of a length equal to a key.  
     
     
         11 . The method of  claim 9 , wherein said processing step, different key bits produce a different at least one frequency table.  
     
     
         12 . The method of  claim 9 , wherein said encoding step output is variable.  
     
     
         13 . The method of  claim 9 , wherein the ciphered text output by said encoder is based on a bit-based processing scheme.  
     
     
         14 . The method of  claim 11 , wherein the at least one frequency table includes the working key.  
     
     
         15 . A decryption device, comprising: 
 a model, receiving a main key, a working key and plain text and generating at least two frequency counts;    a decoder, outputting plain text, based on the working key, the main key, the plain text, the at least two frequency counts, and    a random number generator, receiving the plain text and determining the working key using at least one random number and outputting the working key to said model.    
     
     
         16 . The decryption device of  claim 15 , wherein the working key produced by said random number generator is variable length.  
     
     
         17 . The decryption device of  claim 15 , wherein said decoder output is variable.  
     
     
         18 . The decryption device of  claim 15 , wherein the working key and the main key are different.  
     
     
         19 . The decryption device of  claim 15 , wherein said model includes at least one frequency table containing the at least two frequency counts.  
     
     
         20 . The decryption device of  claim 1 , wherein the at least one frequency table is stored in a RAM.  
     
     
         21 . The decryption device of  claim 15 , wherein the ciphered text output by said encoder is based on a bit-based processing scheme.  
     
     
         22 . The decryption device of  claim 19 , wherein the at least one frequency table includes the working key.  
     
     
         23 . A method of decrypting, comprising: 
 processing random bits and key bits to generate at least one frequency table; and    decoding cipher text using the at least one frequency table.    
     
     
         24 . The method of  claim 23 , wherein said processing step includes generating a random bit string of a length equal to a key.  
     
     
         25 . The method of  claim 23 , wherein said processing step, different key bits produce a different at least one frequency table.  
     
     
         26 . The method of  claim 23 , wherein said decoding step output is variable.