Data encryption system and method
AssigneeNEC Corporation
InventorYukiyasu Tsunoo
Life of this patent
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Abstract
A data encryption system implemented by running on a cache-equipped computer an encryption program including transformation tables each of which contains a predetermined number of entries. All or necessary ones of the transformation tables are loaded into the cache memory before encryption/decryption process. This causes encryption/decryption time to be made substantially equal independently of the number of operation entries for the transformation table. It is very difficult to extract plain texts used to determine a key differential, resulting in difficulties in cryptanalysis.
Claims12
A data encryption system for performing encryption/decryption of a given plain/cipher text using transformation tables which transforms bit strings of the given plain/cipher text, comprising:
- a memory for storing an encryption program including the transformation tables, each of which contains a predetermined number of entries, wherein a targeted transformation table is previously identified from the transformation tables depending on whether the targeted transformation table exhibits a trend of increasing in the number of operation entries as a length of encryption time becomes longer;
- a program-controlled processor for executing the encryption program;
- a cache memory placed between the memory and the program-controlled processor;
- and
- an entry loading section that loads all transformation tables into the cache memory, wherein the targeted transformation table is loaded after the other transformation tables have been loaded into the cache memory.
A data encryption program stored on a computer readable medium, the program operable to cause a cache-equipped computer to perform encryption/decryption of a given plain/cipher text using transformation tables which transforms bit strings of the given plain/cipher text, comprising steps of:
- a) receiving plain/cipher text;
- b) generating the transformation tables each of which contains a predetermined number of entries, wherein a targeted transformation table is previously identified from the transformation tables depending on whether the targeted transformation table exhibits a trend of increasing in the number of operation entries as a length of encryption time becomes longer;
- c) loading transformation tables other than the targeted transformation table into the cache memory, and after having loaded the transformation tables other than the targeted transformation table, loading the targeted transformation table into the cache memory;
- d) performing data transformation of bit strings of the given plain/cipher text;
- and
- e) outputting transformed plain/cipher text.
A data encryption method for performing encryption/decryption of a given plain/cipher text using transformation tables which transforms bit strings of the given plain/cipher text, the method comprising steps of:
- a) generating the transformation tables each of which contains a predetermined number of entries, wherein a targeted transformation table is previously identified from the transformation tables depending on whether the targeted transformation table exhibits a trend of increasing in the number of operation entries as a length of encryption time becomes longer;
- b) loading transformation tables other than the targeted transformation table into a cache memory of a computer, and after having loaded the transformation tables other than the targeted transformation table, loading at least one part of the targeted transformation table into the cache memory;
- and
- loading at least one part of the targeted transformation table into a cache memory of a computer;
- and
- c) performing data transformation of bit strings of the given plain/cipher text.
Dependencies are inferred from the claim text.