Cryptography – Key management – Having particular key generator
Patent
1994-03-14
1995-06-13
Cain, David C.
Cryptography
Key management
Having particular key generator
380 21, H04L 900
Patent
active
054251036
ABSTRACT:
Binary data is encrypted or decrypted using a final key. The final key is formed by manipulating one or more user keys and a base key, and combining the manipulated keys using an exclusive-OR operation. The data to be encrypted or decrypted are combined with the final key using a circular exclusive-OR operation. The user and base keys are binary sequences having any number of bits. The user key may be input to the present invention directly in binary form or in any other suitable form that the present invention can interpret as a binary sequence, such as a string of ASCII-encoded alphanumeric characters. Manipulating the user key includes the steps of shuffling or permuting segments of the user key, such as bytes, circularly shifting the permuted user key by a number of bit positions, and filling a location with one or more copies of the permuted and shifted key such that the result has a length equal to that of the base key. The ordering of the segments of the user key in the permutation step and the number of bit positions by which the user key is shifted in the shifting step are determined in response to the value and position of the segments of the user key itself. Manipulating the base key includes the step of circularly shifting the base key by a number of bit positions that is determined in response to the value and position of segments of the user key.
REFERENCES:
patent: 4200770 (1980-04-01), Hellmen et al.
patent: 4819267 (1989-04-01), Cargile et al.
patent: 4897876 (1990-01-01), Davies
patent: 5115467 (1992-05-01), Esserman et al.
patent: 5241599 (1993-08-01), Bellovin et al.
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