Deriving keys used to securely process electronic messages

A computer program product for use in a distributed system including a first message processor that is communicatively coupled to one or more other message processors such that the first message processor and the one or more other message processors can communicate by transferring electronic messages, the computer program product for implementing a method for the first message processor to express to at least one of the other message processors how to derive a key that can be used to securely process an electronic message, the computer program product comprising one or more computer-readable media having stored thereon the following:

• computer-executable instructions for exchanging information with the at least one other message processor;
• computer-executable instructions for computing a key sequence based on the exchanged information such that any one of a plurality of keys may be derived from the key sequence depending on key derivation data;
• computer-executable instructions for generating key derivation data that can be used to derive a particular key from among the plurality of keys;
• and
• computer-executable instructions for sending a security token that includes the generated key derivation data to express to the at least one other message processor how to derive the particular key from the computed key sequence such that an electronic message may be securely processed using the particular key.

A computer program product for use in a distributed system including a first message processor that is communicatively coupled to one or more other message processors such that the first message processor and the one or more other message processors can communicate by transferring electronic messages, the computer program product for implementing a method for a second message processor from among the one or more other message processors to receive an expression of how to derive a key that can be used to securely process an electronic message, the computer program product comprising one or more computer-readable media having stored thereon the following:

• computer-executable instructions for exchanging information with the first message processor;
• computer-executable instructions for computing a key sequence based on the exchanged information such that any one of a plurality of keys may be derived from the key sequence depending on key derivation data;
• and
• computer-executable instructions for receiving a security token including key derivation data that expresses how to derive a particular key from the computed key sequence such that an electronic message may be securely processed using the particular key.