The FTDIChip-ID is readable over USB, but cannot be modified. To read the device FTDIChip-ID, the D2XX drivers need to be installed and a separate DLL to read the FTDIChip-ID is also required. This will read the unique FTDIChip-ID from the device and allow application software to check the hardware identity.
Further to using the FTDIChip-ID directly to tie hardware to application software, the FTDIChip-ID can be encrypted and then stored in the user area of the FT232R or FT245R device. The data stored in the integrated EEPROM user area can contain information in addition to the FTDIChip-ID, such as date and time information or the name of the person the device is registered to. The EEPROM user area is accessible using the D2XX EEPROM user area functions FT_EE_UASize, FT_EE_UAWrite and FT_EE_UARead.
For example, the FTDIChip-ID can be read using a DLL and then combined with a date and time, perhaps to represent a registration date or licence expiration date. All of this information can then be encrypted and stored in the EEPROM user area. Application software can then decrypt this information to determine the date stored in the EEPROM and can compare the decrypted FTDIChip-ID with the unchangeable FTDIChip-ID to confirm that the EEPROM user area has not been modified by an end user.