Add a CHANGES.md entry for the "tmp_dh" functions/macros
Describe the tmp_dh deprecations, and what applications should do instead.
@@ -23,6 +23,21 @@ OpenSSL 3.0
### Changes between 1.1.1 and 3.0 [xx XXX xxxx]
+ * The functions SSL_CTX_set_tmp_dh_callback and SSL_set_tmp_dh_callback, as
+ well as the macros SSL_CTX_set_tmp_dh() and SSL_set_tmp_dh() have been
+ deprecated. These are used to set the Diffie-Hellman (DH) parameters that
+ are to be used by servers requiring ephemeral DH keys. Instead applications
+ should consider using the built-in DH parameters that are available by
+ calling SSL_CTX_set_dh_auto() or SSL_set_dh_auto(). If custom parameters are
+ necessary then applications can use the alternative functions
+ SSL_CTX_set0_tmp_dh_pkey() and SSL_set0_tmp_dh_pkey(). There is no direct
+ replacement for the "callback" functions. The callback was originally useful
+ in order to have different parameters for export and non-export ciphersuites.
+ Export ciphersuites are no longer supported by OpenSSL. Use of the callback
+ functions should be replaced by one of the other methods described above.
+
+ *Matt Caswell*
+
* The -crypt option to the passwd command line tool has been removed.
*Paul Dale*
