address comments

include/grpc/grpc_security_constants.h

@@ -57,9 +57,10 @@ typedef enum {
 } grpc_ssl_certificate_config_reload_status;
 
 typedef enum {
-  /** Server does not request client certificate. A client may present a self
-     signed or signed certificate or not present a certificate at all and any of
-     those option would be accepted. */
+  /** Server does not request client certificate.
+     The certificate presented by the client is not checked by the server at all.
+     (A client may present a self signed or signed certificate or not present a certificate at all and any of
+     those option would be accepted) */
   GRPC_SSL_DONT_REQUEST_CLIENT_CERTIFICATE,
   /** Server requests client certificate but does not enforce that the client
      presents a certificate.
@@ -68,17 +69,18 @@ typedef enum {
      the application (the necessary metadata will be available to the
      application via authentication context properties, see grpc_auth_context).
 
-     The key cert pair should still be valid for the SSL connection to be
+     The client's key certificate pair must be valid for the SSL connection to be
      established. */
   GRPC_SSL_REQUEST_CLIENT_CERTIFICATE_BUT_DONT_VERIFY,
   /** Server requests client certificate but does not enforce that the client
      presents a certificate.
 
      If the client presents a certificate, the client authentication is done by
-     the gRPC framework (the client needs to either present a signed cert or not
-     present a certificate at all for a successful connection).
+     the gRPC framework. (For a successful connection the client needs to either
+     present a certificate that can be verified against the root certificate configured by the server
+     or not present a certificate at all)
 
-     The key cert pair should still be valid for the SSL connection to be
+     The client's key certificate pair must be valid for the SSL connection to be
      established. */
   GRPC_SSL_REQUEST_CLIENT_CERTIFICATE_AND_VERIFY,
   /** Server requests client certificate and enforces that the client presents a
@@ -88,16 +90,17 @@ typedef enum {
      the application (the necessary metadata will be available to the
      application via authentication context properties, see grpc_auth_context).
 
-     The key cert pair should still be valid for the SSL connection to be
+     The client's key certificate pair must be valid for the SSL connection to be
      established. */
   GRPC_SSL_REQUEST_AND_REQUIRE_CLIENT_CERTIFICATE_BUT_DONT_VERIFY,
   /** Server requests client certificate and enforces that the client presents a
      certificate.
 
-     The cerificate presented by the client is verified by the gRPC framework
-     (the client needs to present signed certs for a successful connection).
+     The cerificate presented by the client is verified by the gRPC framework.
+     (For a successful connection the client needs to present a certificate that can be verified against
+     the root certificate configured by the server)
 
-     The key cert pair should still be valid for the SSL connection to be
+     The client's key certificate pair must be valid for the SSL connection to be
      established. */
   GRPC_SSL_REQUEST_AND_REQUIRE_CLIENT_CERTIFICATE_AND_VERIFY
 } grpc_ssl_client_certificate_request_type;