Implement GetArmoredWithCustomHeaders (#48)

* Implement GetArmoredWithCustomHeaders

ArmorWithTypeAndCustomHeaders can be reused by other PGP armoured
objects.

* Update linting, and lint accordingly

`godot` has been improved and `goerr113` has been added (and ignored
here).

* Add custom headers for keys

* Minor comment changes

Co-authored-by: Aron Wussler <aron@wussler.it>

.golangci.yml

@@ -21,6 +21,7 @@ linters:
     - gochecknoglobals  # Checks that no globals are present in Go code [fast: true, auto-fix: false]
     - gochecknoinits    # Checks that no init functions are present in Go code [fast: true, auto-fix: false]
     - golint            # Golint differs from gofmt. Gofmt reformats Go source code, whereas golint prints out style mistakes [fast: true, auto-fix: false]
+    - goerr113          # Golang linter to check the errors handling expressions [fast: true, auto-fix: false]
     - gomnd             # An analyzer to detect magic numbers. [fast: true, auto-fix: false]
     - lll               # Reports long lines [fast: true, auto-fix: false]
     - testpackage       # Makes you use a separate _test package [fast: true, auto-fix: false]

CHANGELOG.md

@@ -4,6 +4,24 @@ 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
+- Key Armoring with custom headers
+```go
+(key *Key) ArmorWithCustomHeaders(comment, version string) (string, error)
+(key *Key) GetArmoredPublicKeyWithCustomHeaders(comment, version string) (string, error)
+```
+- Message armoring with custom headers
+```go
+(msg *PGPMessage) GetArmoredWithCustomHeaders(comment, version string) (string, error)
+```
+
+### Changed
+- Improved key and message armoring testing
+
+### Fixed
+- Public key armoring headers
+
 ## [2.0.1] - 2020-05-01
 ### Security
 - Updated underlying crypto library

armor/armor.go

@@ -26,9 +26,35 @@ func ArmorWithTypeBuffered(w io.Writer, armorType string) (io.WriteCloser, error
 
 // ArmorWithType armors input with the given armorType.
 func ArmorWithType(input []byte, armorType string) (string, error) {
+	return armorWithTypeAndHeaders(input, armorType, internal.ArmorHeaders)
+}
+
+// ArmorWithTypeAndCustomHeaders armors input with the given armorType and
+// headers.
+func ArmorWithTypeAndCustomHeaders(input []byte, armorType, version, comment string) (string, error) {
+	headers := make(map[string]string)
+	if version != "" {
+		headers["Version"] = version
+	}
+	if comment != "" {
+		headers["Comment"] = comment
+	}
+	return armorWithTypeAndHeaders(input, armorType, headers)
+}
+
+// Unarmor unarmors an armored input into a byte array.
+func Unarmor(input string) ([]byte, error) {
+	b, err := internal.Unarmor(input)
+	if err != nil {
+		return nil, err
+	}
+	return ioutil.ReadAll(b.Body)
+}
+
+func armorWithTypeAndHeaders(input []byte, armorType string, headers map[string]string) (string, error) {
 	var b bytes.Buffer
 
-	w, err := armor.Encode(&b, armorType, internal.ArmorHeaders)
+	w, err := armor.Encode(&b, armorType, headers)
 
 	if err != nil {
 		return "", err
@@ -41,12 +67,3 @@ func ArmorWithType(input []byte, armorType string) (string, error) {
 	}
 	return b.String(), nil
 }
-
-// Unarmor unarmors an armored key.
-func Unarmor(input string) ([]byte, error) {
-	b, err := internal.Unarmor(input)
-	if err != nil {
-		return nil, err
-	}
-	return ioutil.ReadAll(b.Body)
-}

crypto/key.go

@@ -16,7 +16,6 @@ import (
 	"github.com/pkg/errors"
 
 	openpgp "golang.org/x/crypto/openpgp"
-	xarmor "golang.org/x/crypto/openpgp/armor"
 	packet "golang.org/x/crypto/openpgp/packet"
 )
 
@@ -190,6 +189,7 @@ func (key *Key) Serialize() ([]byte, error) {
 	return buffer.Bytes(), err
 }
 
+// Armor returns the armored key as a string with default gopenpgp headers.
 func (key *Key) Armor() (string, error) {
 	serialized, err := key.Serialize()
 	if err != nil {
@@ -199,21 +199,36 @@ func (key *Key) Armor() (string, error) {
 	return armor.ArmorWithType(serialized, constants.PrivateKeyHeader)
 }
 
-// GetArmoredPublicKey returns the armored public keys from this keyring.
-func (key *Key) GetArmoredPublicKey() (s string, err error) {
-	var outBuf bytes.Buffer
-	aw, err := xarmor.Encode(&outBuf, openpgp.PublicKeyType, nil)
+// ArmorWithCustomHeaders returns the armored key as a string, with
+// the given headers. Empty parameters are omitted from the headers.
+func (key *Key) ArmorWithCustomHeaders(comment, version string) (string, error) {
+	serialized, err := key.Serialize()
 	if err != nil {
 		return "", err
 	}
 
-	if err = key.entity.Serialize(aw); err != nil {
-		_ = aw.Close()
+	return armor.ArmorWithTypeAndCustomHeaders(serialized, constants.PrivateKeyHeader, version, comment)
+}
+
+// GetArmoredPublicKey returns the armored public keys from this keyring.
+func (key *Key) GetArmoredPublicKey() (s string, err error) {
+	serialized, err := key.GetPublicKey()
+	if err != nil {
 		return "", err
 	}
 
-	err = aw.Close()
-	return outBuf.String(), err
+	return armor.ArmorWithType(serialized, constants.PublicKeyHeader)
+}
+
+// GetArmoredPublicKeyWithCustomHeaders returns the armored public key as a string, with
+// the given headers. Empty parameters are omitted from the headers.
+func (key *Key) GetArmoredPublicKeyWithCustomHeaders(comment, version string) (string, error) {
+	serialized, err := key.GetPublicKey()
+	if err != nil {
+		return "", err
+	}
+
+	return armor.ArmorWithTypeAndCustomHeaders(serialized, constants.PublicKeyHeader, version, comment)
 }
 
 // GetPublicKey returns the unarmored public keys from this keyring.

crypto/key_test.go

@@ -73,13 +73,25 @@ func TestArmorKeys(t *testing.T) {
 		t.Fatal("Cannot armor unprotected EC key:" + err.Error())
 	}
 
-	rTest := regexp.MustCompile("(?s)^-----BEGIN PGP PRIVATE KEY BLOCK-----.*-----END PGP PRIVATE KEY BLOCK-----$")
+	rTest := regexp.MustCompile(`(?s)^-----BEGIN PGP PRIVATE KEY BLOCK-----.*Version: GopenPGP [0-9]+\.[0-9]+\.[0-9]+.*-----END PGP PRIVATE KEY BLOCK-----$`)
 	assert.Regexp(t, rTest, noPasswordRSA)
 	assert.Regexp(t, rTest, noPasswordEC)
 	assert.Regexp(t, rTest, keyTestArmoredRSA)
 	assert.Regexp(t, rTest, keyTestArmoredEC)
 }
 
+func TestArmorKeysWithCustomHeader(t *testing.T) {
+	comment := "User-defined private key comment"
+	version := "User-defined private key version"
+	armored, err := keyTestRSA.ArmorWithCustomHeaders(comment, version)
+	if err != nil {
+		t.Fatal("Could not armor the private key:", err)
+	}
+
+	assert.Contains(t, armored, "Comment: "+comment)
+	assert.Contains(t, armored, "Version: "+version)
+}
+
 func TestLockUnlockKeys(t *testing.T) {
 	testLockUnlockKey(t, keyTestArmoredRSA, keyTestPassphrase)
 	testLockUnlockKey(t, keyTestArmoredEC, keyTestPassphrase)
@@ -257,7 +269,7 @@ func TestFailCheckIntegrity(t *testing.T) {
 	assert.Exactly(t, false, isVerified)
 }
 
-func TestArmorPublicKey(t *testing.T) {
+func TestGetPublicKey(t *testing.T) {
 	publicKey, err := keyTestRSA.GetPublicKey()
 	if err != nil {
 		t.Fatal("Expected no error while obtaining public key, got:", err)
@@ -265,19 +277,21 @@ func TestArmorPublicKey(t *testing.T) {
 
 	decodedKey, err := NewKey(publicKey)
 	if err != nil {
-		t.Fatal("Expected no error while creating public key ring, got:", err)
+		t.Fatal("Expected no error while creating public key, got:", err)
 	}
 
 	privateFingerprint := keyTestRSA.GetFingerprint()
 	publicFingerprint := decodedKey.GetFingerprint()
 
+	assert.False(t, decodedKey.IsPrivate())
+	assert.True(t, keyTestRSA.IsPrivate())
 	assert.Exactly(t, privateFingerprint, publicFingerprint)
 }
 
 func TestGetArmoredPublicKey(t *testing.T) {
 	privateKey, err := NewKeyFromArmored(readTestFile("keyring_privateKey", false))
 	if err != nil {
-		t.Fatal("Expected no error while unarmouring private key, got:", err)
+		t.Fatal("Expected no error while unarmoring private key, got:", err)
 	}
 
 	s, err := privateKey.GetArmoredPublicKey()
@@ -309,6 +323,47 @@ func TestGetArmoredPublicKey(t *testing.T) {
 	}
 
 	assert.Exactly(t, eb, b)
+
+	publicKey, err := keyTestRSA.GetArmoredPublicKey()
+	if err != nil {
+		t.Fatal("Expected no error while obtaining armored public key, got:", err)
+	}
+
+	decodedKey, err := NewKeyFromArmored(publicKey)
+	if err != nil {
+		t.Fatal("Expected no error while creating public key from armored, got:", err)
+	}
+
+	assert.False(t, decodedKey.IsPrivate())
+	assert.True(t, keyTestRSA.IsPrivate())
+	assert.Contains(t, publicKey, "Version: GopenPGP")
+
+	privateFingerprint := keyTestRSA.GetFingerprint()
+	publicFingerprint := decodedKey.GetFingerprint()
+
+	assert.Exactly(t, privateFingerprint, publicFingerprint)
+}
+
+func TestGetArmoredPublicKeyWithCustomHeaders(t *testing.T) {
+	comment := "User-defined public key comment"
+	version := "User-defined public key version"
+	armored, err := keyTestRSA.GetArmoredPublicKeyWithCustomHeaders(comment, version)
+	if err != nil {
+		t.Fatal("Could not armor the public key:", err)
+	}
+
+	assert.Contains(t, armored, "Comment: "+comment)
+	assert.Contains(t, armored, "Version: "+version)
+}
+
+func TestGetArmoredPublicKeyWithEmptyCustomHeaders(t *testing.T) {
+	armored, err := keyTestRSA.GetArmoredPublicKeyWithCustomHeaders("", "")
+	if err != nil {
+		t.Fatal("Could not armor the public key:", err)
+	}
+
+	assert.NotContains(t, armored, "Version")
+	assert.NotContains(t, armored, "Comment")
 }
 
 func TestGetSHA256FingerprintsV4(t *testing.T) {

crypto/keyring_test.go

@@ -12,12 +12,10 @@ import (
 
 var testSymmetricKey []byte
 
-// Corresponding key in testdata/keyring_privateKey
+// Password for key in testdata/keyring_privateKeyLegacy: "123".
+// Corresponding key in testdata/keyring_privateKey.
 var testMailboxPassword = []byte("apple")
 
-// Corresponding key in testdata/keyring_privateKeyLegacy
-// const testMailboxPasswordLegacy = [][]byte{ []byte("123") }
-
 var (
 	keyRingTestPrivate  *KeyRing
 	keyRingTestPublic   *KeyRing

crypto/message.go

@@ -48,7 +48,7 @@ type PGPSplitMessage struct {
 }
 
 // A ClearTextMessage is a signed but not encrypted PGP message,
-// i.e. the ones beginning with -----BEGIN PGP SIGNED MESSAGE-----
+// i.e. the ones beginning with -----BEGIN PGP SIGNED MESSAGE-----.
 type ClearTextMessage struct {
 	Data      []byte
 	Signature []byte
@@ -217,6 +217,12 @@ func (msg *PGPMessage) GetArmored() (string, error) {
 	return armor.ArmorWithType(msg.Data, constants.PGPMessageHeader)
 }
 
+// GetArmoredWithCustomHeaders returns the armored message as a string, with
+// the given headers. Empty parameters are omitted from the headers.
+func (msg *PGPMessage) GetArmoredWithCustomHeaders(comment, version string) (string, error) {
+	return armor.ArmorWithTypeAndCustomHeaders(msg.Data, constants.PGPMessageHeader, version, comment)
+}
+
 // GetBinaryDataPacket returns the unarmored binary datapacket as a []byte.
 func (msg *PGPSplitMessage) GetBinaryDataPacket() []byte {
 	return msg.DataPacket

crypto/message_test.go

@@ -178,3 +178,39 @@ func TestMultipleKeyMessageEncryption(t *testing.T) {
 	}
 	assert.Exactly(t, message.GetString(), decrypted.GetString())
 }
+
+func TestMessageGetArmoredWithCustomHeaders(t *testing.T) {
+	var message = NewPlainMessageFromString("plain text")
+
+	ciphertext, err := keyRingTestPublic.Encrypt(message, keyRingTestPrivate)
+	if err != nil {
+		t.Fatal("Expected no error when encrypting, got:", err)
+	}
+	comment := "User-defined comment"
+	version := "User-defined version"
+	armored, err := ciphertext.GetArmoredWithCustomHeaders(comment, version)
+	if err != nil {
+		t.Fatal("Could not armor the ciphertext:", err)
+	}
+
+	assert.Contains(t, armored, "Comment: "+comment)
+	assert.Contains(t, armored, "Version: "+version)
+}
+
+func TestMessageGetArmoredWithEmptyHeaders(t *testing.T) {
+	var message = NewPlainMessageFromString("plain text")
+
+	ciphertext, err := keyRingTestPublic.Encrypt(message, keyRingTestPrivate)
+	if err != nil {
+		t.Fatal("Expected no error when encrypting, got:", err)
+	}
+	comment := ""
+	version := ""
+	armored, err := ciphertext.GetArmoredWithCustomHeaders(comment, version)
+	if err != nil {
+		t.Fatal("Could not armor the ciphertext:", err)
+	}
+
+	assert.NotContains(t, armored, "Version")
+	assert.NotContains(t, armored, "Comment")
+}

crypto/mime_test.go

@@ -6,10 +6,9 @@ import (
 	"github.com/stretchr/testify/assert"
 )
 
-// Corresponding key in testdata/mime_privateKey
+// Corresponding key in testdata/mime_privateKey.
 var MIMEKeyPassword = []byte("test")
 
-// define call back interface
 type Callbacks struct {
 	Testing *testing.T
 }

helper/base_test.go

@@ -20,7 +20,7 @@ func readTestFile(name string, trimNewlines bool) string {
 	return string(data)
 }
 
-// Corresponding key in ../crypto/testdata/keyring_privateKey
+// Corresponding key in ../crypto/testdata/keyring_privateKey.
 var testMailboxPassword = []byte("apple")
 
 func init() {