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Distribution of international SessionKeys

The following steps must be executed to create Alice's SessionKey to Bob :

1. Alice asks her TA (TA_Alice) for a SessionKey giving the ID-numbers of the sender (herself) and the receiver (Bob)
2. based on this information, TA_Alice constructs a stamp (ID sender + ID receiver)
3. TA_Alice encrypts this stamp with his PrivateKey to generate the SessionKey from Alice to Bob (K_ses)
4. TA_Alice sends an encrypted message to Bob's TA (TA_Bob) containing the SessionKey, K_ses, and the stamp
5. in return, TA_Bob sends the third and fourth blocks which Alice needs, to forward later to Bob.
6. TA_Alice reconstructs Alice's PrivateKeys (direct and inverse) : K_Alice, K^-1_Alice
7. TA_Alice computes the SessionKeys (direct, inverse, inverse complementary and inverse of inverse complementary) : K_ses, K^-1_ses , K_comp (=[11...1] XOR K^-1_ses) and K^-1_comp
8. TA_Alice sends 4 different encrypted blocks to Alice :
   • the first block contains the SessionKey from Alice to Bob, K_ses , encrypted with the inverse PrivateKey of Alice, K^-1_Alice
   • the second block contains the stamp (ID of sender + ID of receiver) encrypted with the inverse SessionKey
   • the third block contains the inverse SessionKey from Alice to Bob, K^-1_ses, encrypted first with the inverse PrivateKey of Bob, K^-1_Bob, and then with the inverse PrivateKey of Alice, K^-1_Alice.
   • the last block contains the stamp first encrypted with the inverse of the inverse complementary SessionKey, K^-1_comp, and then with the inverse SessionKey, K^-1_ses.

Alice and Bob use the blocks as if in a national environment :

• the first block permits Alice to reconstruct the SessionKey whenever she sends a message to Bob. The SessionKey is NOT recorded by Alice...
• the second block permits Alice to verify that the received blocks are related to the SessionKey between herself and Bob.
• Alice includes the third and fourth blocks in all the messages sent to Bob.
• the third block permits Bob to decipher all the messages sent by Alice.
• with the last block, Bob verifies that the SessionKey was generated as a combination of TA_Alice and TA_Bob.