Portable electronic device capable of registering subprograms

Details Portable electronic device capable of registering subprograms Portable electronic device capable of registering subprograms

1990-11-27

1993-04-13

Gregory, Bernarr E.

Cryptography

Electric signal modification

Having production of printed copy

380 4, 380 23, 380 25, 380 49, 235380, 34082531, 371 211, 371 401, H04L 900

Patent

active

052029239

ABSTRACT:
After registration of a subprogram is completed, a flag indicating that the subprogram has been registered is set. The flag is referred to in response to a subprogram registration request from an IC card reader/writer. Registration of the subprogram is performed only when the flag is not set. A BCC of the subprogram is calculated and stored in a memory upon subprogram registration. When the registered subprogram is to be executed, a BCC of the subprogram read out from the memory is calculated and compared with the BCC stored in the memory. The subprogram is executed only when the two BCCs coincide with each other. If the subprogram has been registered, a BCC check is performed for the registered subprogram. If the BCC check indicates an error, registration of the subprogram is enabled.

REFERENCES:
patent: 4118789 (1978-10-01), Casto et al.
patent: 4827512 (1989-05-01), Hirokawa et al.
patent: 4939353 (1990-07-01), Iijima

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