Computing device communication with replay protection
AssigneeSun Microsystems, Inc.
InventorThomas V. Johnson
Life of this patent
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Abstract
A replay attack prevention technique uses a secret algorithm exchanged between client and servers computers. The algorithm is used to periodically alter a special replay key. The replay key may then be used to alter the message sent or alter the digest appended to the message such that the message and or its digest varies as time progresses. An unscrupulous third party who replays a stolen operation message would be unaware of the replay key and its variation. Any stolen message that is replayed by the third party would not include the time varying aspect as expected by the server computer. The server computer would thus be able to detect the attempted fraud. The secret replay key may be exchanged during the communication session in an encrypted form, or may be exchanged earlier.
Claims21
A system for preventing a replay attack comprising:
- a transmission medium for transmitting information;
- a client computing device arranged to connect to said transmission medium, said client computing device including
- a message to be sent over said transmission medium,
- a cryptographic key, and
- a plurality of alteration algorithms for periodically changing said cryptographic key, whereby a value to be appended to said message may be periodically changed;
- a server computing device arranged to connect to said transmission medium and receive said message and said appended value, said server computing device including
- said cryptographic key, and
- said plurality of alteration algorithms,
- whereby-said server may calculate its own version of said value to compare with said received value to prevent a replay attack.
A method for preventing a replay attack comprising:
- exchanging a plurality of key alteration algorithms between a client computing device and a server computing device;
- exchanging a cryptographic key between said client and said server;
- calculating a value using said key alteration algorithm;
- appending said value to a message;
- transmitting said message and said appended value from said client to said server;
- calculation of its own version of said value by said server using said key alteration algorithm;
- and
- comparison of said received value to said calculated value by said server, whereby a replay attack is prevented.
A method for preventing a replay attack comprising:
- exchanging a plurality of key alteration algorithms between a client computing device and a server computing device;
- exchanging a cryptographic key between said client and said server;
- receiving a message and an appended value from said client;
- calculating of its own version of said value by said server using said key alteration algorithm;
- and
- comparing said received value to said calculated value by said server, whereby a replay attack is prevented.
Dependencies are inferred from the claim text.