Sentinel Hardware Keys Developer's Guide - Customer Connection ...

Tips and Tricks
Contents Glossary Index Troubleshooting
by your program, the update will suddenly require this work to be repeated.
If you have used the tips discussed above, it will likely be time consuming so
the illegitimate user is stuck using outdated software.
Specify Cheat Counter Value
You can specify a cheat counter value only for non-RTC Sentinel Keys.
The cheat counter value is global to the Sentinel Key. It applies to all the features
having lease attribute enabled. You can specify a the cheat counter
value right before programming hardware keys in the License Manager
screen.
If desired, you can use the Secure Update process to increment the cheat
counter in the field.
Note: You should call the SFNTQueryFeature function in your application code to
detect time tampering. In addition, the SFNTEncrypt, SFNTDecrypt, SFNT-
Sign, and SFNTGetDeviceInfo functions also check for system time tampering.
Use AES Algorithm to Encrypt Data
You can use the AES algorithm present in the Sentinel Key for encrypting
16-byte data blocks. AES has withstood intense scrutiny from the cryptography
experts and is adopted by National Institute of Standards and
Technology (NIST) as US FIPS PUB 197 in November 2001 (after a 5-year
standardization process). It is trusted by many organizations and has a
proven track record.
It provides an impenetrable security check because the AES algorithm and
the 128-bit randomly generated secret key it uses are embedded in the Sentinel
Key—not accessible to any debugging or memory dumping program.
You need to:
Call the SFNTEncrypt API function to send the plain data and have it
encrypted.
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