diff --git a/devel/schemata b/devel/schemata
index 72feb7b7..28332c6b 100644
--- a/devel/schemata
+++ b/devel/schemata
@@ -4,9 +4,9 @@ format (currently JSON and S-Expressions).
 []'s indicate lists.  List items can be marked with a '?', meaning
 they are optional; or a '*', meaning there can be zero or more of that
 item.  {}'s indicate an object that maps from field identifiers to
-values.  An object field marked '?' is optional.  |'s indicate
-alternates (e.g., int|string means something can be an int or a
-string).
+values.  An object field marked '?' is optional; one marked with '*'
+can repeat (with a different name). |'s indicate alternates (e.g.,
+int|string means something can be an int or a string).
 
 For S-Expression output, lists are printed delimited by () instead of
 []. Objects are printed as p-lists, i.e. lists where the keys and values
@@ -48,6 +48,9 @@ threadid = string
 # Message ID, sans "id:"
 messageid = string
 
+# E-mail header name, sans trailing colon, like "Subject" or "In-Reply-To"
+header_name = string
+
 notmuch show schema
 -------------------
 
@@ -88,9 +91,15 @@ crypto = {
                   status:      sigstatus,
                   # was the set of signatures described under encrypted cover?
                   encrypted:   bool,
+                  # which of the headers is covered by sigstatus?
+                  headers:     [header_name*]
                 },
     decrypted?: {
                   status: msgdecstatus,
+                  # map encrypted headers that differed from the outside headers.
+                  # the value of each item in the map is what that field showed externally
+                  # (maybe null if it was not present in the external headers).
+                  header-mask:  { header_name*: string|null }
                 }
 }
 
diff --git a/notmuch-show.c b/notmuch-show.c
index b1f6a4bb..4dfe9c1d 100644
--- a/notmuch-show.c
+++ b/notmuch-show.c
@@ -645,6 +645,12 @@ format_part_sprinter (const void *ctx, sprinter_t *sp, mime_node_t *node,
 			sp->map_key (sp, "encrypted");
 			sp->boolean (sp, msg_crypto->signature_encrypted);
 		    }
+		    if (msg_crypto->payload_subject) {
+			sp->map_key (sp, "headers");
+			sp->begin_list (sp);
+			sp->string (sp, "Subject");
+			sp->end (sp);
+		    }
 		    sp->end (sp);
 		}
 		if (msg_crypto->decryption_status != NOTMUCH_MESSAGE_DECRYPTED_NONE) {
@@ -652,6 +658,21 @@ format_part_sprinter (const void *ctx, sprinter_t *sp, mime_node_t *node,
 		    sp->begin_map (sp);
 		    sp->map_key (sp, "status");
 		    sp->string (sp, msg_crypto->decryption_status == NOTMUCH_MESSAGE_DECRYPTED_FULL ? "full" : "partial");
+
+		    if (msg_crypto->payload_subject) {
+			const char *subject = g_mime_message_get_subject GMIME_MESSAGE (node->part);
+			if (subject == NULL || strcmp (subject, msg_crypto->payload_subject)) {
+			    /* protected subject differs from the external header */
+			    sp->map_key (sp, "header-mask");
+			    sp->begin_map (sp);
+			    sp->map_key (sp, "Subject");
+			    if (subject == NULL)
+				sp->null (sp);
+			    else
+				sp->string (sp, subject);
+			    sp->end (sp);
+			}
+		    }
 		    sp->end (sp);
 		}
 	    }
diff --git a/test/T356-protected-headers.sh b/test/T356-protected-headers.sh
index 8a8fef6a..68d431e9 100755
--- a/test/T356-protected-headers.sh
+++ b/test/T356-protected-headers.sh
@@ -22,7 +22,7 @@ test_json_nodes <<<"$output" \
 test_begin_subtest "verify protected header is visible with decryption"
 output=$(notmuch show --decrypt=true --format=json id:protected-header@crypto.notmuchmail.org)
 test_json_nodes <<<"$output" \
-                'crypto:[0][0][0]["crypto"]={"decrypted": {"status": "full"}}' \
+                'crypto:[0][0][0]["crypto"]={"decrypted": {"status": "full", "header-mask": {"Subject": "Subject Unavailable"}}}' \
                 'subject:[0][0][0]["headers"]["Subject"]="This is a protected header"'
 
 test_begin_subtest "misplaced protected headers should not be made visible during decryption"
@@ -58,7 +58,7 @@ test_json_nodes <<<"$output" \
 test_begin_subtest "verify nested message/rfc822 protected header is visible"
 output=$(notmuch show --decrypt=true --format=json id:nested-rfc822-message@crypto.notmuchmail.org)
 test_json_nodes <<<"$output" \
-                'crypto:[0][0][0]["crypto"]={"decrypted": {"status": "full"}}' \
+                'crypto:[0][0][0]["crypto"]={"decrypted": {"status": "full", "header-mask": {"Subject": "Subject Unavailable"}}}' \
                 'subject:[0][0][0]["headers"]["Subject"]="This is a message using draft-melnikov-smime-header-signing"'
 
 test_done