Patent ID: 7437756

Claim:
A method for securely exchanging data between a first data processing unit and a second data processing unit comprising: establishing a secure communication channel between said first data processing unit and said second data processing unit; making a first message available at said second data processing unit; making a same predetermined message annex available at each of said first and second data processing units; generating a second message in said second data processing unit by appending said predetermined message annex, that is available at said second data processing unit, to said first message, generating a third message in said second data processing unit by encrypting said second message using a secret key that is available only in said first data processing unit and in said second data processing unit; transmitting said third message to said first data processing unit via said secure communication channel; decrypting said third message in said first data processing unit utilizing said secret key, and checking said second message as to integrity in an integrity check in said first data processing unit by isolating said annex from said second message and checking whether said annex matches the predetermined annex that is available at said first data processing unit; generating a positive confirmation message and transmitting said confirmation message from said first data processing unit to said second data processing unit if the integrity of said second message is confirmed in said integrity check; and generating a negative confirmation message and transmitting said negative confirmation message from said first data processing unit to said second data processing unit if the integrity of said second message is not confirmed in said integrity check.