Update documentation
Signed-off-by: Gabor Mezei <gabor.mezei@arm.com>
diff --git a/library/ssl_tls13_invasive.h b/library/ssl_tls13_invasive.h
index 1008b2d..a025dbe 100644
--- a/library/ssl_tls13_invasive.h
+++ b/library/ssl_tls13_invasive.h
@@ -32,7 +32,10 @@
* \brief Take the input keying material \p ikm and extract from it a
* fixed-length pseudorandom key \p prk.
*
- * \param alg A hash function.
+ * \param alg The HMAC algorithm to use
+ * (\c #PSA_ALG_HMAC( PSA_ALG_XXX ) value such that
+ * PSA_ALG_XXX is a hash algorithm and
+ * #PSA_ALG_IS_HMAC(\p alg) is true).
* \param salt An optional salt value (a non-secret random value);
* if the salt is not provided, a string of all zeros
* of the length of the hash provided by \p alg is used