Mutual authentication system and method for protection of postal security devices and infrastructure

A method of mutually authenticating a postal security device and an infrastructure, said infrastructure initializing said postal security device, said postal security device having a unique identification number, a PSD public key, and a PSD private key corresponding to said PSD public key, said infrastructure having a provider public key and a provider private key corresponding to said provider public key, the method comprising:

• said infrastructure obtaining said unique identification number of said postal security device and deriving a secret key from said unique identification number and a master key;
• said infrastructure preparing a signed provider key record using said provider public key and said provider private key, said signed provider key record including said provider public key and a first digital signature;
• said infrastructure creating a first message authentication code using said signed provider key record and said secret key and sending said signed provider key record and said first message authentication code to said postal security device;
• said postal security device authenticating said signed provider key record using said first message authentication code;
• said postal security device authenticating said provider public key using said first digital signature;
• said postal security device preparing a signed PSD key record using said PSD public key and said PSD private key, said signed PSD key record including said PSD public key and a second digital signature;
• said postal security device preparing a second message authentication code using said signed PSD key record and said secret key and sending said signed PSD key record and said second message authentication code to said infrastructure;
• said infrastructure authenticating said signed PSD key record using said second message authentication code;
• said infrastructure authenticating said PSD public key using said second digital signature;
• said postal security device generating a random nonce, storing said random nonce, and sending said random nonce to said infrastructure;
• said infrastructure encrypting said random nonce using said secret key and sending the encrypted random nonce to said postal security device;
• and
• said postal security device decrypting said encrypted random nonce using the secret key and comparing said decrypted random nonce to said stored random nonce.