Addressing comments.
diff --git a/src/core/channel/context.h b/src/core/channel/context.h
index 85de60d..ac5796b 100644
--- a/src/core/channel/context.h
+++ b/src/core/channel/context.h
@@ -44,6 +44,6 @@
 typedef struct {
   void *value;
   void (*destroy)(void *);
-} grpc_call_context;
+} grpc_call_context_element;
 
 #endif /* GRPC_INTERNAL_CORE_CHANNEL_CONTEXT_H */
diff --git a/src/core/security/client_auth_filter.c b/src/core/security/client_auth_filter.c
index 9e11989..72002ee 100644
--- a/src/core/security/client_auth_filter.c
+++ b/src/core/security/client_auth_filter.c
@@ -125,7 +125,7 @@
   call_data *calld = elem->call_data;
   channel_data *chand = elem->channel_data;
   grpc_client_security_context *ctx =
-      (grpc_client_security_context *)op->contexts[GRPC_CONTEXT_SECURITY].value;
+      (grpc_client_security_context *)op->context[GRPC_CONTEXT_SECURITY].value;
   char *service_url = NULL;
   grpc_credentials *channel_creds =
       chand->security_connector->request_metadata_creds;
diff --git a/src/core/security/security_context.c b/src/core/security/security_context.c
index c9fcff6..14c194c 100644
--- a/src/core/security/security_context.c
+++ b/src/core/security/security_context.c
@@ -109,6 +109,8 @@
 
 /* --- grpc_auth_context --- */
 
+static grpc_auth_property_iterator empty_iterator = {NULL, 0, NULL};
+
 grpc_auth_context *grpc_auth_context_create(grpc_auth_context *chained,
                                             size_t property_count) {
   grpc_auth_context *ctx = gpr_malloc(sizeof(grpc_auth_context));
@@ -138,6 +140,7 @@
       }
       gpr_free(ctx->properties);
     }
+    gpr_free(ctx);
   }
 }
 
@@ -146,19 +149,22 @@
   return ctx->peer_identity_property_name;
 }
 
-grpc_auth_property_iterator *grpc_auth_context_property_iterator(
+int grpc_auth_context_peer_is_authenticated(
     const grpc_auth_context *ctx) {
-  grpc_auth_property_iterator *it;
-  if (ctx == NULL) return NULL;
-  it = gpr_malloc(sizeof(grpc_auth_property_iterator));
-  memset(it, 0, sizeof(grpc_auth_property_iterator));
-  it->ctx = ctx;
+  return ctx->peer_identity_property_name == NULL ? 0 : 1;
+}
+
+grpc_auth_property_iterator grpc_auth_context_property_iterator(
+    const grpc_auth_context *ctx) {
+  grpc_auth_property_iterator it = empty_iterator;
+  if (ctx == NULL) return it;
+  it.ctx = ctx;
   return it;
 }
 
 const grpc_auth_property *grpc_auth_property_iterator_next(
     grpc_auth_property_iterator *it) {
-  if (it == NULL) return NULL;
+  if (it == NULL || it->ctx == NULL) return NULL;
   while (it->index == it->ctx->property_count) {
     if (it->ctx->chained == NULL) return NULL;
     it->ctx = it->ctx->chained;
@@ -179,28 +185,22 @@
   }
 }
 
-grpc_auth_property_iterator *grpc_auth_context_find_properties_by_name(
+grpc_auth_property_iterator grpc_auth_context_find_properties_by_name(
     const grpc_auth_context *ctx, const char *name) {
-  grpc_auth_property_iterator *it;
-  if (ctx == NULL || name == NULL) return NULL;
-  it = grpc_auth_context_property_iterator(ctx);
-  it->name = gpr_strdup(name);
+  grpc_auth_property_iterator it = empty_iterator;
+  if (ctx == NULL || name == NULL) return empty_iterator;
+  it.ctx = ctx;
+  it.name = name;
   return it;
 }
 
-grpc_auth_property_iterator *grpc_auth_context_peer_identity(
+grpc_auth_property_iterator grpc_auth_context_peer_identity(
     const grpc_auth_context *ctx) {
-  if (ctx == NULL || ctx->peer_identity_property_name == NULL) return NULL;
+  if (ctx == NULL) return empty_iterator;
   return grpc_auth_context_find_properties_by_name(
       ctx, ctx->peer_identity_property_name);
 }
 
-void grpc_auth_property_iterator_destroy(grpc_auth_property_iterator *it) {
-  if (it == NULL) return;
-  if (it->name != NULL) gpr_free(it->name);
-  gpr_free(it);
-}
-
 grpc_auth_property grpc_auth_property_init_from_cstring(const char *name,
                                                         const char *value) {
   grpc_auth_property prop;
diff --git a/src/core/security/security_context.h b/src/core/security/security_context.h
index 60a3177..d8909cd 100644
--- a/src/core/security/security_context.h
+++ b/src/core/security/security_context.h
@@ -42,12 +42,6 @@
 
 /* Property names are always NULL terminated. */
 
-struct grpc_auth_property_iterator {
-  const grpc_auth_context *ctx;
-  size_t index;
-  char *name;
-};
-
 struct grpc_auth_context {
   struct grpc_auth_context *chained;
   grpc_auth_property *properties;
diff --git a/src/core/security/server_auth_filter.c b/src/core/security/server_auth_filter.c
index 0337232..1823f75 100644
--- a/src/core/security/server_auth_filter.c
+++ b/src/core/security/server_auth_filter.c
@@ -77,17 +77,17 @@
   /* initialize members */
   calld->unused = 0;
 
-  GPR_ASSERT(initial_op && initial_op->contexts != NULL &&
+  GPR_ASSERT(initial_op && initial_op->context != NULL &&
              chand->security_connector->auth_context != NULL &&
-             initial_op->contexts[GRPC_CONTEXT_SECURITY].value == NULL);
+             initial_op->context[GRPC_CONTEXT_SECURITY].value == NULL);
 
   /* Create a security context for the call and reference the auth context from
      the channel. */
   server_ctx = grpc_server_security_context_create();
   server_ctx->auth_context =
       grpc_auth_context_ref(chand->security_connector->auth_context);
-  initial_op->contexts[GRPC_CONTEXT_SECURITY].value = server_ctx;
-  initial_op->contexts[GRPC_CONTEXT_SECURITY].destroy =
+  initial_op->context[GRPC_CONTEXT_SECURITY].value = server_ctx;
+  initial_op->context[GRPC_CONTEXT_SECURITY].destroy =
       grpc_server_security_context_destroy;
 }
 
diff --git a/src/core/surface/call.c b/src/core/surface/call.c
index 0169ce3..db76c3a 100644
--- a/src/core/surface/call.c
+++ b/src/core/surface/call.c
@@ -206,7 +206,7 @@
   received_status status[STATUS_SOURCE_COUNT];
 
   /* Contexts for various subsystems (security, tracing, ...). */
-  grpc_call_context contexts[GRPC_CONTEXT_COUNT];
+  grpc_call_context_element context[GRPC_CONTEXT_COUNT];
 
   /* Deadline alarm - if have_alarm is non-zero */
   grpc_alarm alarm;
@@ -290,7 +290,7 @@
     initial_op.recv_state = &call->recv_state;
     initial_op.on_done_recv = call_on_done_recv;
     initial_op.recv_user_data = call;
-    initial_op.contexts = call->contexts;
+    initial_op.context = call->context;
     call->receiving = 1;
     GRPC_CALL_INTERNAL_REF(call, "receiving");
     initial_op_ptr = &initial_op;
@@ -344,8 +344,8 @@
     grpc_mdelem_unref(c->send_initial_metadata[i].md);
   }
   for (i = 0; i < GRPC_CONTEXT_COUNT; i++) {
-    if (c->contexts[i].destroy) {
-      c->contexts[i].destroy(c->contexts[i].value);
+    if (c->context[i].destroy) {
+      c->context[i].destroy(c->context[i].value);
     }
   }
   grpc_sopb_destroy(&c->send_ops);
@@ -1048,7 +1048,7 @@
 static void execute_op(grpc_call *call, grpc_transport_op *op) {
   grpc_call_element *elem;
   elem = CALL_ELEM_FROM_CALL(call, 0);
-  op->contexts = call->contexts;
+  op->context = call->context;
   elem->filter->start_transport_op(elem, op);
 }
 
@@ -1289,15 +1289,15 @@
 
 void grpc_call_context_set(grpc_call *call, grpc_context_index elem, void *value,
                            void (*destroy)(void *value)) {
-  if (call->contexts[elem].destroy) {
-    call->contexts[elem].destroy(call->contexts[elem].value);
+  if (call->context[elem].destroy) {
+    call->context[elem].destroy(call->context[elem].value);
   }
-  call->contexts[elem].value = value;
-  call->contexts[elem].destroy = destroy;
+  call->context[elem].value = value;
+  call->context[elem].destroy = destroy;
 }
 
 void *grpc_call_context_get(grpc_call *call, grpc_context_index elem) {
-  return call->contexts[elem].value;
+  return call->context[elem].value;
 }
 
 gpr_uint8 grpc_call_is_client(grpc_call *call) { return call->is_client; }
diff --git a/src/core/transport/transport.h b/src/core/transport/transport.h
index dd6bee8..6f8d39e 100644
--- a/src/core/transport/transport.h
+++ b/src/core/transport/transport.h
@@ -79,7 +79,7 @@
   grpc_mdstr *cancel_message;
 
   /* Indexes correspond to grpc_context_index enum values */
-  grpc_call_context *contexts;
+  grpc_call_context_element *context;
 } grpc_transport_op;
 
 /* Callbacks made from the transport to the upper layers of grpc. */