epg: Use unibyte string to decode percent escapes

* lisp/epg.el (epg--status-USERID_HINT, epg--status-*SIG)
(epg--status-IMPORTED): Call epg--decode-percent-escape-as-utf-8.
(epg--decode-percent-escape): Convert STRING to unibyte.
(epg--decode-percent-escape-as-utf-8): New function.  (Bug#36098)

Copyright-paperwork-exempt: yes

1 files changed, 9 insertions, 10 deletions

diff --git a/lisp/epg.el b/lisp/epg.el
index e8bdd1536ff..a8b5a408a89 100644
--- a/lisp/epg.el
+++ b/lisp/epg.el
@@ -776,9 +776,7 @@ callback data (if any)."
              (user-id (match-string 2 string))
              (entry (assoc key-id epg-user-id-alist)))
         (condition-case nil
-            (setq user-id (decode-coding-string
-                           (epg--decode-percent-escape user-id)
-                           'utf-8))
+            (setq user-id (epg--decode-percent-escape-as-utf-8 user-id))
           (error))
         (if entry
             (setcdr entry user-id)
@@ -905,9 +903,7 @@ callback data (if any)."
         (condition-case nil
             (if (eq (epg-context-protocol context) 'CMS)
                 (setq user-id (epg-dn-from-string user-id))
-              (setq user-id (decode-coding-string
-                             (epg--decode-percent-escape user-id)
-                             'utf-8)))
+              (setq user-id (epg--decode-percent-escape-as-utf-8 user-id)))
           (error))
         (if entry
             (setcdr entry user-id)
@@ -1183,9 +1179,7 @@ callback data (if any)."
              (user-id (match-string 2 string))
              (entry (assoc key-id epg-user-id-alist)))
         (condition-case nil
-            (setq user-id (decode-coding-string
-                           (epg--decode-percent-escape user-id)
-                           'utf-8))
+            (setq user-id (epg--decode-percent-escape-as-utf-8 user-id))
           (error))
         (if entry
             (setcdr entry user-id)
@@ -2026,6 +2020,7 @@ If you are unsure, use synchronous version of this function
     (epg-reset context)))
 
 (defun epg--decode-percent-escape (string)
+  (setq string (string-to-unibyte string))
   (let ((index 0))
     (while (string-match "%\\(\\(%\\)\\|\\([0-9A-Fa-f][0-9A-Fa-f]\\)\\)"
                          string index)
@@ -2033,11 +2028,15 @@ If you are unsure, use synchronous version of this function
           (setq string (replace-match "%" t t string)
                 index (1- (match-end 0)))
         (setq string (replace-match
-                      (string (string-to-number (match-string 3 string) 16))
+                      (byte-to-string
+                       (string-to-number (match-string 3 string) 16))
                       t t string)
               index (- (match-end 0) 2))))
     string))
 
+(defun epg--decode-percent-escape-as-utf-8 (string)
+  (decode-coding-string (epg--decode-percent-escape string) 'utf-8))
+
 (defun epg--decode-hexstring (string)
   (let ((index 0))
     (while (eq index (string-match "[0-9A-Fa-f][0-9A-Fa-f]" string index))