System and method for transferring the right to decode messages in a symmetric encoding scheme
First Claim
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1. A method for encoding an original message to be passed to a recipient by way of a grantor, the method comprising the steps of:
- obtaining an encoded message representative of the original message, the encoded message having been encrypted with a symmetric encoding scheme having a first key associated with the grantor;
selecting a second key associated with the recipient;
generating a transfer key based on the first key and the second key; and
applying the transfer key in a one-way function to transform the encoded message into a transformed message, wherein the transformed message is decodable by the recipient using the second key, wherein the transfer key does not allow the recipient to determine the first key after the encoded message is transformed by the recipient using the transfer key.
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Abstract
Methods for transferring among key holders in encoding and cryptographic systems the right to decode and decrypt messages in a way that does not explicitly reveal decoding and decrypting keys used and the original messages. Such methods are more secure and more efficient than typical re-encoding and re-encryption schemes, and are useful in developing such applications as document distribution and long-term file protection.
191 Citations
11 Claims
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1. A method for encoding an original message to be passed to a recipient by way of a grantor, the method comprising the steps of:
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obtaining an encoded message representative of the original message, the encoded message having been encrypted with a symmetric encoding scheme having a first key associated with the grantor;
selecting a second key associated with the recipient;
generating a transfer key based on the first key and the second key; and
applying the transfer key in a one-way function to transform the encoded message into a transformed message, wherein the transformed message is decodable by the recipient using the second key, wherein the transfer key does not allow the recipient to determine the first key after the encoded message is transformed by the recipient using the transfer key. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification