EEPROM User Area Size
The integrated EEPROM is 1024 bits (128 bytes) is size. The size of the EEPROM user area available is determined by the length of the serial number and description strings programmed into the EEPROM. If these strings are long, there may not be enough user area available to store the encrypted data required. The D2XX function FT_EE_UASize returns the size of the user area in bytes and can be used to verify the required space is available before attempting to write data to the EEPROM.
Strong Encryption Method
In order to maintain security, a strong encryption method should be implemented. There are many standard encryption routines (DES, 3DES, AES, Blowfish and many more) that may be used, or a unique encryption method may be chosen. A strong encryption key should also be chosen to maximise security.