end
end
...
The example code below is taken from the JTAG access control mechanism of the HACK@DAC'21 buggy OpenPiton SoC [REF-1364]. Access to JTAG allows users to access sensitive information in the system. Hence, access to JTAG is controlled using cryptographic authentication of the users. In this example (see the vulnerable code source), the password checker uses HMAC-SHA256 for authentication. It takes a 512-bit secret message from the user, hashes it using HMAC, and compares its output with the expected output to determine the authenticity of the user.