Does "SHA-256/192" use different initial values from SHA-256?

Question

I've seen some mentions of a "SHA-256/192" online. Clearly, this means the output of SHA-256 is truncated to 192 bits, but does it also use different Initial Values like SHA-512/256?

Answer 1

No, it is just the truncated as mentioned in NIST SP 800-208

$\operatorname{SHA-256/192}(M)$
$T_{192}(\operatorname{SHA-256}(M))$, the most significant (i.e., leftmost) 192 bits of the SHA-256 hash of M.

Where $T$ stands for the truncation.

This is specific to $\operatorname{SHA-256/192}(M)$. The other truncated version specified in FIPS PUB 180-4 uses different Initial Values for domain separation. See more detail in this answer;

• Why does SHA2-224 use different IV's than SHA2-256?

Note that although it is pointed out by Poncho that the domain separation is not important in the context of SP 800-208, when you start to use it out of the context, you may be open to attacks. Always be careful!