Update document for SM2 stuffs

[oweals/openssl.git] / doc / man3 / EVP_DigestSignInit.pod

diff --git a/doc/man3/EVP_DigestSignInit.pod b/doc/man3/EVP_DigestSignInit.pod
index fe2be7bbf58dcb4a23a6785249f33cec31bfa5c8..773de87efac4dd48214b80201d35771dce19567b 100644 (file)
--- a/doc/man3/EVP_DigestSignInit.pod
+++ b/doc/man3/EVP_DigestSignInit.pod
@@ -28,8 +28,15 @@ EVP_MD_CTX_new() before calling this function. If B<pctx> is not NULL, the
 EVP_PKEY_CTX of the signing operation will be written to B<*pctx>: this can
 be used to set alternative signing options. Note that any existing value in
 B<*pctx> is overwritten. The EVP_PKEY_CTX value returned must not be freed
-directly by the application (it will be freed automatically when the EVP_MD_CTX
-is freed). The digest B<type> may be NULL if the signing algorithm supports it.
+directly by the application if B<ctx> is not assigned an EVP_PKEY_CTX value before
+being passed to EVP_DigestSignInit() (which means the EVP_PKEY_CTX is created
+inside EVP_DigestSignInit() and it will be freed automatically when the
+EVP_MD_CTX is freed).
+
+The digest B<type> may be NULL if the signing algorithm supports it.
+
+No B<EVP_PKEY_CTX> will be created by EVP_DigsetSignInit() if the passed B<ctx>
+has already been assigned one via L<EVP_MD_CTX_set_ctx(3)>. See also L<SM2(7)>.
 
 Only EVP_PKEY types that support signing can be used with these functions. This
 includes MAC algorithms where the MAC generation is considered as a form of