added code to validate EC named curve parameters

[openssl.git] / doc / man3 / EVP_MAC.pod

diff --git a/doc/man3/EVP_MAC.pod b/doc/man3/EVP_MAC.pod
index 32bf5896f804e7d981170d5bd4af6790c584cb0e..a55d8db259c099afde36ba441bfa63c98c68f521 100644 (file)
--- a/doc/man3/EVP_MAC.pod
+++ b/doc/man3/EVP_MAC.pod
@@ -202,6 +202,9 @@ For MAC implementations that use an underlying computation algorithm,
 these controls set what the algorithm should be, and the engine that
 implements the algorithm if needed.
 
+Note that not all algorithms may support all digests. HMAC does not support
+variable output length digests such as SHAKE128 or SHAKE256.
+
 B<EVP_MAC_CTRL_SET_ENGINE> takes one argument: C<ENGINE *>
 
 B<EVP_MAC_CTRL_SET_MD> takes one argument: C<EVP_MD *>