Sorry, the full text HTML version of the Canadian patent application number 2,177,622 is not available. Only the abstract and the claims are reproduced below. The technology disclosed in the U.S. patent application number 08/853,455 is roughly equivalent. Or you may read the scholarly web contents describing the Frogbit cipher. You may also contact the Canadian Intellectual Property Office (CIPO) to obtain copies of the Canadian patent application number 2,177,622.
A cryptographic method to ensure data integrity is disclosed. It uses pseudo-random bit generators. An apparatus implementing the method is also disclosed. The method provides data integrity protection and confidentiality protection at once, using a shared secret key. A variant provides data integrity protection only, using a shared secret key. A variant of the disclosed method lifts the restriction on re-use of a secret key in the case of a stream cipher. Yet another variant provides a secure hash function of the type used in digital signature schemes, this time requiring no secret key. For each bit of the original message, the present invention uses one of ten independent pseudo-random bit generators as a key stream source for double stream cipher encryption. A unique heuristic algorithm changes the following generator selection out of the group of ten. This arrangement corresponds to a new definition for a "perfect data integrity cipher", where the illicit modification of a single bit in the ciphertext causes a permanent and random alteration of the remaining portion of the message recovered by the legitimate receiver. The disclosed method improves the cryptographic security of pseudo-random generation algorithms.
The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:
1. An encryption and data integrity field generation cryptographic method where
2. A decryption and data integrity field verification cryptographic method where
3. The cryptographic method as in claim 1 or 2 where the said heuristic algorithm uses the run length encoding.
4. The cryptographic method as in claim 1 or 2 where
5. The cryptographic method as in claim 4 where the said internal state of the said heuristic algorithm includes a permuted list of distinct values for said index into the said array of independent pseudo-random number generators.
6. The cryptographic method as in claim 5 where the said heuristic algorithm includes a fixed permutation table.
7. An apparatus implementing the method as in claim 1, 2, 3, 4, 5, or 6.
8. The cryptographic method as in claim 4 or 5 where the implementation details of the said array of independent pseudo-random number generators are shrouded in secrecy.
9. The cryptographic method as in claim 1, 2, 3, 4, 5, 6, or 8, where message salting is used.
10. The cryptographic method as in claim 1, 2, 3, 4, 5, 6, 8, or 9 where the said internal state of the said heuristic algorithm is encoded to produce a data integrity value representative of the plaintext.
11. The cryptographic method as in claim 1, 2, 3, 4, 5, 6, 8, or 9 where a checksum data field is appended to the plaintext to produce a data integrity value representative of the plaintext.
12. The cryptographic method as in claim 1, 2, 3, 4, 5, 6, 8, or 9 where the Cipher Block Chaining mode of operation is used to produce a data integrity value representative of the plaintext.
13. The cryptographic method as in claim 10 or 12 where the said plaintext is transmitted in the clear from the legitimate sender to the legirimate receiver.
14. The cryptographic method as in claim 4, 5, 6, or 8 where
15. The cryptographic method as in claim 4, 5, 6, or 8 where
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