From b01f065b251063bcab64bdab933e998ea4315ee1 Mon Sep 17 00:00:00 2001
From: Andrew Gallagher <andrewg@andrewg.com>
Date: Tue, 3 Dec 2024 10:45:30 +0000
Subject: [PATCH] Emit armor headers in deterministically sorted order (#255)

---
 openpgp/armor/encode.go | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/openpgp/armor/encode.go b/openpgp/armor/encode.go
index 112f98b8..550efddf 100644
--- a/openpgp/armor/encode.go
+++ b/openpgp/armor/encode.go
@@ -7,6 +7,7 @@ package armor
 import (
 	"encoding/base64"
 	"io"
+	"sort"
 )
 
 var armorHeaderSep = []byte(": ")
@@ -159,8 +160,15 @@ func encode(out io.Writer, blockType string, headers map[string]string, checksum
 		return
 	}
 
-	for k, v := range headers {
-		err = writeSlices(out, []byte(k), armorHeaderSep, []byte(v), newline)
+	keys := make([]string, len(headers))
+	i := 0
+	for k := range headers {
+		keys[i] = k
+		i++
+	}
+	sort.Strings(keys)
+	for _, k := range keys {
+		err = writeSlices(out, []byte(k), armorHeaderSep, []byte(headers[k]), newline)
 		if err != nil {
 			return
 		}