Method for dynamically using cryptographic keys in a postage meter

A method for dynamically creating in an electronic chip, after its manufacture, a cryptographic key having a plurality of component parts, the method comprising the steps of:

• storing software code in a memory device of the electronic chip;
• creating a data file having a plurality of pointers, each of the plurality of pointers corresponding to one of the plurality of component parts by identifying a location in the memory device where a portion of the software code is the same as the corresponding one of the component parts;
• providing the data file to the electronic chip;
• using the plurality of pointers within the electronic chip to obtain the plurality of component parts from the stored software code;
• and
• assembling the cryptographic key in the electronic chip using the plurality of component parts obtained from the stored software code;
• wherein the memory device is a ROM;
• wherein the electronic chip is a smart card chip including the ROM, an EEPROM having an encrypted key, a decryption algorithm, and executable code stored therein, a CPU, and a RAM;
• the electronic chip is part of a postage meter that also includes a vault that accounts for postage dispensed by the postage meter and a print-head that includes the electronic chip and a print-head for printing the postage dispensed, the print-head further includes a flash memory in which the data file is stored in encrypted form;
• and
• further comprising the steps of during power-up of the postage meter the encrypted data file is read from flash memory into the RAM by the CPU;
• the CPU uses the executable code to decrypt the encrypted data file to obtain the plurality of pointers, the CPU uses the plurality of pointers to obtain from the software code component parts of the cryptographic key and to assemble in RAM the cryptographic key from the component parts;
• the CPU uses the assembled cryptographic key and the decryption algorithm to decrypt the encrypted key;
• the CPU stores the decrypted encrypted key in a secure area of the EEPROM, erases the assembled cryptographic key, and the encrypted data file from the RAM, erases the encrypted key, the decryption algorithm, and executable code from EEPROM, and erases the encrypted data file from the flash memory.