Method and apparatus for relaying digitally signed messages
First Claim
1. A method of transferring a digitally signed message from a first gateway to a second gateway via a communication channel, said method comprising the steps of:
- receiving an original message at said first gateway, said original message having an original digital signature associated therewith;
verifying an authenticity of said original digital signature with respect to said original message at said first gateway;
deriving, at the first gateway, target information from said original message based on predefined rules;
reducing, at the first gateway, said original message by replacing non-target information with said target information to create a reduced message, said target information having a lower information content than said non-target information;
determining a gateway digital signature for said reduced message thereby preserving an accurate and verifiable digital signature when transferred over the communication channel;
sending said reduced message and said gateway digital signature from said first gateway to said second gateway via said communication channel wherein said reduced message occupies less bandwidth than said original message;
predicting, at said second gateway, said non-target information based on said predefined rules and said target information, said predicted non-target information differing from said non-target information; and
expanding said reduced message by replacing said target information with said predicted non-target information.
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Accused Products
Abstract
A communication network (10) includes any number of interconnected nodes (20), including a sending node (22), a sending gateway (24), a receiving gateway (26), and a destination node (28). A low capacity or expensive communication channel (30) resides between the sending and receiving gateways (24, 26). An original digitally signed message is sent from the sending node (22) toward the destination node (28). When the original message arrives at the sending gateway (24), the original signature is verified. If verified, the sending gateway (24) shrinks the original message into a reduced message and re-signs the message with a gateway digital signature before sending the message onward through the communication channel (30) toward the destination node (28). The destination node (28) verifies the gateway digital signature against the reduced message and is not required to de-compress the reduced message into a precise duplicate of the original message.
106 Citations
14 Claims
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1. A method of transferring a digitally signed message from a first gateway to a second gateway via a communication channel, said method comprising the steps of:
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receiving an original message at said first gateway, said original message having an original digital signature associated therewith; verifying an authenticity of said original digital signature with respect to said original message at said first gateway; deriving, at the first gateway, target information from said original message based on predefined rules; reducing, at the first gateway, said original message by replacing non-target information with said target information to create a reduced message, said target information having a lower information content than said non-target information; determining a gateway digital signature for said reduced message thereby preserving an accurate and verifiable digital signature when transferred over the communication channel; sending said reduced message and said gateway digital signature from said first gateway to said second gateway via said communication channel wherein said reduced message occupies less bandwidth than said original message; predicting, at said second gateway, said non-target information based on said predefined rules and said target information, said predicted non-target information differing from said non-target information; and expanding said reduced message by replacing said target information with said predicted non-target information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 11)
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8. A communication network for transferring a digitally signed message between gateways coupled via a communication channel, each of said gateways comprising:
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a first port for receiving an original message having a destination reachable through said communication channel, said original message having an original digital signature associated therewith; a controller coupled to said first port and configured to verify said original digital signature with respect to said original message, to derive target information from said original message based on predefined rules, to reduce said original message into a reduced message according to predefined rules by replacing non-target information with said target information to create said reduced message, said target information having a lower information content than said non-target information, and to determine a gateway digital signature for said reduced message thereby preserving an accurate and verifiable digital signature when transferred over said communication channel; and a second port coupled to said controller, said second port being configured to send said reduced message and said gateway digital signature to another gateway via said communication channel wherein said reduced message occupies less bandwidth than said original message and thereby allows the use of low capacity transmission networks. - View Dependent Claims (9, 10)
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12. A method of transferring a digitally signed voice message received at a first gateway via a first communication channel to a second gateway via a second communication channel, said first communication channel having greater bandwidth than said second communication channel, said method comprising the steps of:
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receiving, via said first communication channel, a voice message at said first gateway, said voice message having an original digital signature associated therewith; verifying an authenticity of said original digital signature; deriving coefficients for said voice message based on coding techniques; reducing said voice message by replacing an original voice signal portion of said voice message with said coefficients to create a reduced message; determining a gateway digital signature for said reduced message; sending said reduced message and said gateway digital signature from said first gateway to said second gateway via said second communication channel, said reduced message occupying less bandwidth than said voice message; predicting, at said second gateway, said original voice signal portion based on said coding techniques and said coefficients, said predicted voice signal differing from said original voice signal portion; and expanding said reduced message by replacing said coefficients with said predicted voice signal.
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13. A method of transferring a digitally signed page message from a first gateway via a first communication channel to a second gateway via a second communication channel, said first communication channel having greater bandwidth than said second communication channel, said method comprising the steps of:
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receiving, via said first communication channel, a page message at said first gateway, said page message having an original digital signature associated therewith; verifying an authenticity of said original digital signature; deriving target information for said page message based on predefined rules; reducing said page message by replacing non-target information with said target information to create a reduced message; determining a gateway digital signature for said reduced message; sending said reduced message and said gateway digital signature from said first gateway to said second gateway via said second communication channel, said reduced message occupying less bandwidth than said page message; predicting, at said second gateway, said non-target information based on said predefined rules and target information, said predicted non-target information differing from said non-target information; and expanding said reduced message by replacing said target information with said predicted non-target information.
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14. A communication network for transferring a digitally signed message from a first gateway to a second gateway coupled, said first gateway coupled to said second gateway via a communication channel, said second gateway comprising:
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a first port for receiving said digitally signed message, said digitally signed message having a digital signature associated with said first gateway, said digitally signed message having a data portion representing target information; a controller coupled to said first port and configured to verify said digital signature with respect to said digitally signed message, to predict non-target information based on predefined rules and said target information, to expand said digitally signed message by replacing said target information with said predicted non-target information; and a second port coupled to said controller, said second port being configured to send said predicted non-target information to a destination node.
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Specification