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(11) | EP 0 111 381 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Improvements in and relating to autoteller systems |
| (57) An autoteller system 10 comprises an encryption module 30 for encrypting and decrypting
data on user cards and for encrypting and decrypting data communicated between it
10 and a remote host 22. The system is characterised by a key loader 58 containing
algorithm performance instructions on a ROM 88 removably connectable to the encryption
module 30 for the generation of a master key for an encryption circuit 152 to use
the master key to encrypt a sub-key for the encrypted sub-key to be used as a session
key when encrypting or decrypting data from a user card. The system is further characterised
by the keys being stored in a battery-maintained RAM 108 which is volatile if the
encryption module 30 is removed. The system is further characterised by the host 22
being operable to provide the autoteller 10 with a plurality of communication keys
where any selected named communication key can be used for encrypting and decrypting
data communicated between the system 10 and the host 22. The system 10 is yet further
characterised by the communications keys supplied to the system 10 being the result
of encryption of decryption by the encryption module 30 of sub-keys from the host
22. |