On Wed, 2024-01-03 at 17:11 +0200, Jarkko Sakkinen wrote: > > + u8 ec_point_x[EC_PT_SZ]; > > + u8 ec_point_y[EC_PT_SZ]; > > And also prefix these similarly with hmac. This isn't in itself an HMAC; it's the public point of the P-256 key derived from the null seed (effectively it's a public key). It's used to exchange secret information with the TPM, like a salt for the HMAC sessions but it's a thing in its own right (and is bound to the null name). I suppose null_key_x/y is better. James