发明授权
US06941284B2 Method for dynamically using cryptographic keys in a postage meter 有权
在邮资计费器中动态使用加密密钥的方法

Method for dynamically using cryptographic keys in a postage meter
摘要:
A postage meter includes a vault that accounts for postage dispensed by the postage meter; and a printhead module having a printhead for printing the postage dispensed; a smart card chip having a ROM having software code stored therein; an EEPROM having an encrypted key and executable code stored therein, a CPU; a RAM; and a flash memory having an encrypted pointer data file stored therein. During power-up of the postage meter the encrypted pointer data file is read from the flash memory into the RAM by the CPU, the CPU uses the executable code to decrypt the encrypted pointer data file to obtain from the software code components parts of a decryption key and to assemble in the ram the decryption key from the component parts, the CPU uses the assembled decryption key and the executable code to decrypt the encrypted cryptographic key, and the CPU stores the decrypted cryptographic key in a secure area of the EEPROM, erases the decryption key and the encrypted pointer data file from the RAM, erases the encrypted cryptographic key and executable code from the EEPROM, and erases the pointer data file from the flash memory.
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