Cryptographic data integrity with serial bit processing and pseudo-random generators
First Claim
1. A cryptographic data integrity binary representation generator system for use with a second processor acting on said binary representation, or a transformation thereof, to produce a signal indicating, with an overwhelming probability whether said binary representation was generated according to said generator system, said generator system comprising:
- means for consecutively transforming a cleartext message bit mi into a bit ei using bits k1i and k2i from keys k1 and k2 according to the following equation;
space="preserve" listing-type="equation">e.sub.i =k1.sub.i XOR m.sub.i XOR k2.sub.i ;
andmeans for generating successive bits k1i+1 and k2i+1 from a decision machine having finite state information using (k1i XOR mi) and k2i as inputs, said keys k1 and k2 having initial state information defining said bits k1i and k2i, wherein said binary representation consists of a string of consecutive bits ei, ei+1, ei+2, etc.
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Abstract
A new structure for a secret key cryptography algorithm uses double exclusive-or (XOR) encryption (ei =k1i XOR mi XOR k21), analogue to a stream cipher arrangement, but providing data integrity protection. The double XOR encryption creates an inner sequence, for example si =k1i XOR mi for the encryption process, si =k2i XOR ei for the decryption process, which is unknown to the adversary and is used as a starting point for feedback on the very key streams used in the encryption of following bits of the message. In its preferred embodiment, this structure is the Frogbit data integrity algorithm which uses 10 independent pseudo-random sources. The Frogbit algorithm is well suited to the design and implementation of "semi-proprietary" ciphers, where the overall design is publicly known and peer-reviewed but a significant amount of the implementation specification is left open to private customization. The Frogbit algorithm is a means to create computer programs and microprocessor-based devices that are harder to crack with reverse engineering than with the prior art.
73 Citations
6 Claims
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1. A cryptographic data integrity binary representation generator system for use with a second processor acting on said binary representation, or a transformation thereof, to produce a signal indicating, with an overwhelming probability whether said binary representation was generated according to said generator system, said generator system comprising:
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means for consecutively transforming a cleartext message bit mi into a bit ei using bits k1i and k2i from keys k1 and k2 according to the following equation;
space="preserve" listing-type="equation">e.sub.i =k1.sub.i XOR m.sub.i XOR k2.sub.i ;and means for generating successive bits k1i+1 and k2i+1 from a decision machine having finite state information using (k1i XOR mi) and k2i as inputs, said keys k1 and k2 having initial state information defining said bits k1i and k2i, wherein said binary representation consists of a string of consecutive bits ei, ei+1, ei+2, etc. - View Dependent Claims (2, 3, 6)
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4. The binary representation generator system as claimed in 2, wherein said plurality of pseudo-random generators make use of different algorithms.
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5. The binary representation generator system as claimed in 3, wherein said plurality of pseudo-random generators make use of different algorithms.
Specification