From 27e84f1c71841589b52b607c58bd18fe06928363 Mon Sep 17 00:00:00 2001
From: Georg Pfuetzenreuter <georg.pfuetzenreuter@suse.com>
Date: Mon, 3 Jun 2024 14:58:23 +0200
Subject: [PATCH] Implement KeyRing.Armor()

This allows for ASCII encoding of keyrings the same way as already
implemented for individual keys.

Signed-off-by: Georg Pfuetzenreuter <georg.pfuetzenreuter@suse.com>
---
 CHANGELOG.md           |  7 +++++++
 crypto/keyring.go      | 12 ++++++++++++
 crypto/keyring_test.go |  9 +++++++++
 3 files changed, 28 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2352ffa5..a63d93d6 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+### Added
+- API to ASCII encode (armor) KeyRings:
+	```go
+	func (keyRing *KeyRing) Armor() (string, error)
+	```
+
 ## [3.1.0] 2024-11-25
 ### Added
 - Add decryption option to allow disabling the integrity tag requirement.
diff --git a/crypto/keyring.go b/crypto/keyring.go
index 35d01333..cdcc547a 100644
--- a/crypto/keyring.go
+++ b/crypto/keyring.go
@@ -7,6 +7,8 @@ import (
 
 	"github.com/ProtonMail/go-crypto/openpgp/packet"
 	openpgp "github.com/ProtonMail/go-crypto/openpgp/v2"
+	"github.com/ProtonMail/gopenpgp/v2/armor"
+	"github.com/ProtonMail/gopenpgp/v2/constants"
 	"github.com/pkg/errors"
 )
 
@@ -133,6 +135,16 @@ func (keyRing *KeyRing) Serialize() ([]byte, error) {
 	return buffer.Bytes(), nil
 }
 
+// Armor returns the armored keyring as a string with default gopenpgp headers.
+func (keyRing *KeyRing) Armor() (string, error) {
+	serialized, err := keyRing.Serialize()
+	if err != nil {
+		return "", err
+	}
+
+	return armor.ArmorWithType(serialized, constants.PublicKeyHeader)
+}
+
 // --- Extract info from key
 
 // CountEntities returns the number of entities in the keyring.
diff --git a/crypto/keyring_test.go b/crypto/keyring_test.go
index 5cd5dcd3..68964cdf 100644
--- a/crypto/keyring_test.go
+++ b/crypto/keyring_test.go
@@ -2,6 +2,7 @@ package crypto
 
 import (
 	"crypto/rsa"
+	"regexp"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -160,6 +161,14 @@ func TestSerializeParse(t *testing.T) {
 	}
 }
 
+func TestArmor(t *testing.T) {
+	armoredRing, err := keyRingTestMultiple.Armor()
+	assert.Nil(t, err)
+
+	rTest := regexp.MustCompile(`(?s)^-----BEGIN PGP PUBLIC KEY BLOCK-----.*Version: GopenPGP [0-9]+\.[0-9]+\.[0-9]+.*-----END PGP PUBLIC KEY BLOCK-----$`)
+	assert.Regexp(t, rTest, armoredRing)
+}
+
 func TestClearPrivateKey(t *testing.T) {
 	keyRingCopy, err := keyRingTestMultiple.Copy()
 	if err != nil {