Add KeyIDs public API functionality (#76)

* Add public KeyIDs functions

* Add signature keyIDs functions

* Lint code

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 (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)
@@ -18,7 +19,15 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Extraction of encryption key IDs from a PGP message, i.e. the IDs of the keys used in the encryption of the session key
 ```go
-(msg *PGPMessage) getEncryptionKeyIDs() ([]uint64, bool)
+(msg *PGPMessage) GetEncryptionKeyIDs() ([]uint64, bool)
+(msg *PGPMessage) GetHexEncryptionKeyIDs() ([]uint64, bool)
+```
+
+- Extraction of signing key IDs from a PGP message, i.e. the IDs of the keys used in the signature of the message 
+    (of all the readable, unencrypted signature packets)
+```go
+(msg *PGPMessage) GetSignatureKeyIDs() ([]uint64, bool)
+(msg *PGPMessage) GetHexSignatureKeyIDs() ([]string, bool)
 ```
 
 - Getter for the x/crypto Entity (internal components of an OpenPGP key) from Key struct
@@ -37,16 +46,48 @@ DecryptBinaryMessageArmored(privateKey string, passphrase []byte, ciphertext str
 (key *Key) ToPublic() (publicKey *Key, err error) 
 ```
 
+- Helpers to handle detached signatures
+```go
+EncryptSignArmoredDetached(
+    publicKey, privateKey string,
+    passphrase, plainData []byte,
+) (ciphertext, signature string, err error)
+
+DecryptVerifyArmoredDetached(
+	publicKey, privateKey string,
+	passphrase []byte,
+	ciphertext string,
+	armoredSignature string,
+) (plainData []byte, err error)
+```
+
+- `EncryptSignArmoredDetachedMobileResult` Struct (with its helper) to allow detached signature + encryption in one pass
+```go
+type EncryptSignArmoredDetachedMobileResult struct {
+	Ciphertext, Signature string
+}
+
+EncryptSignArmoredDetachedMobile(
+	publicKey, privateKey string,
+	passphrase, plainData []byte,
+) (wrappedTuple *EncryptSignArmoredDetachedMobileResult, err error)
+```
+
 ### Changed
 - Improved key and message armoring testing
 - `EncryptSessionKey` now creates encrypted key packets for each valid encryption key in the provided keyring. 
     Returns a byte slice with all the concatenated key packets.
-- Use aes256 chiper for message encryption with password.
+- Use aes256 cipher for password-encrypted messages.
+- The helpers `EncryptSignMessageArmored`, `DecryptVerifyMessageArmored`, `DecryptVerifyAttachment`, and`DecryptBinaryMessageArmored`
+    now accept private keys as public keys and perform automatic casting if the keys are locked.
 
 ### Fixed
 - Public key armoring headers
 - `EncryptSessionKey` throws an error when invalid encryption keys are provided
 - Session keys' size is now checked against the expected value to prevent panics
+- Hex Key IDs returned from `(key *Key) GetHexKeyID() string` are now correctly padded
+- Avoid panics in `(msg *PGPMessage) GetEncryptionKeyIDs() ([]uint64, bool)` by breaking the packet.next cycle on specific packet types
+- Prevent the server time from going backwards in `UpdateTime`
 
 ## [2.0.1] - 2020-05-01
 ### Security

crypto/key.go

@@ -332,7 +332,7 @@ func (key *Key) PrintFingerprints() {
 
 // GetHexKeyID returns the key ID, hex encoded as a string.
 func (key *Key) GetHexKeyID() string {
-	return strconv.FormatUint(key.GetKeyID(), 16)
+	return keyIDToHex(key.GetKeyID())
 }
 
 // GetKeyID returns the key ID, encoded as 8-byte int.
@@ -465,3 +465,8 @@ func generateKey(
 
 	return &Key{newEntity}, nil
 }
+
+// keyIDToHex casts a keyID to hex with the correct padding.
+func keyIDToHex(keyID uint64) string {
+	return fmt.Sprintf("%016v", strconv.FormatUint(keyID, 16))
+}

crypto/message.go

@@ -223,8 +223,8 @@ func (msg *PGPMessage) GetArmoredWithCustomHeaders(comment, version string) (str
 	return armor.ArmorWithTypeAndCustomHeaders(msg.Data, constants.PGPMessageHeader, version, comment)
 }
 
-// getEncryptionKeyIds Returns the key IDs of the keys to which the session key is encrypted.
+// GetEncryptionKeyIDs Returns the key IDs of the keys to which the session key is encrypted.
-func (msg *PGPMessage) getEncryptionKeyIDs() ([]uint64, bool) {
+func (msg *PGPMessage) GetEncryptionKeyIDs() ([]uint64, bool) {
 	packets := packet.NewReader(bytes.NewReader(msg.Data))
 	var err error
 	var ids []uint64
@@ -252,6 +252,21 @@ Loop:
 	return ids, false
 }
 
+// GetHexEncryptionKeyIDs Returns the key IDs of the keys to which the session key is encrypted.
+func (msg *PGPMessage) GetHexEncryptionKeyIDs() ([]string, bool) {
+	return getHexKeyIDs(msg.GetEncryptionKeyIDs())
+}
+
+// GetSignatureKeyIDs Returns the key IDs of the keys to which the (readable) signature packets are encrypted to.
+func (msg *PGPMessage) GetSignatureKeyIDs() ([]uint64, bool) {
+	return getSignatureKeyIDs(msg.Data)
+}
+
+// GetHexSignatureKeyIDs Returns the key IDs of the keys to which the session key is encrypted.
+func (msg *PGPMessage) GetHexSignatureKeyIDs() ([]string, bool) {
+	return getHexKeyIDs(msg.GetSignatureKeyIDs())
+}
+
 // GetBinaryDataPacket returns the unarmored binary datapacket as a []byte.
 func (msg *PGPSplitMessage) GetBinaryDataPacket() []byte {
 	return msg.DataPacket
@@ -386,6 +401,16 @@ func (msg *PGPSignature) GetArmored() (string, error) {
 	return armor.ArmorWithType(msg.Data, constants.PGPSignatureHeader)
 }
 
+// GetSignatureKeyIDs Returns the key IDs of the keys to which the (readable) signature packets are encrypted to.
+func (msg *PGPSignature) GetSignatureKeyIDs() ([]uint64, bool) {
+	return getSignatureKeyIDs(msg.Data)
+}
+
+// GetHexSignatureKeyIDs Returns the key IDs of the keys to which the session key is encrypted.
+func (msg *PGPSignature) GetHexSignatureKeyIDs() ([]string, bool) {
+	return getHexKeyIDs(msg.GetSignatureKeyIDs())
+}
+
 // GetBinary returns the unarmored signed data as a []byte.
 func (msg *ClearTextMessage) GetBinary() []byte {
 	return msg.Data
@@ -425,3 +450,48 @@ func IsPGPMessage(data string) bool {
 		constants.PGPMessageHeader + "-----")
 	return re.MatchString(data)
 }
+
+func getSignatureKeyIDs(data []byte) ([]uint64, bool) {
+	packets := packet.NewReader(bytes.NewReader(data))
+	var err error
+	var ids []uint64
+	var onePassSignaturePacket *packet.OnePassSignature
+	var signaturePacket *packet.Signature
+
+Loop:
+	for {
+		var p packet.Packet
+		if p, err = packets.Next(); err == io.EOF {
+			break
+		}
+		switch p := p.(type) {
+		case *packet.OnePassSignature:
+			onePassSignaturePacket = p
+			ids = append(ids, onePassSignaturePacket.KeyId)
+		case *packet.Signature:
+			signaturePacket = p
+			if signaturePacket.IssuerKeyId != nil {
+				ids = append(ids, *signaturePacket.IssuerKeyId)
+			}
+		case *packet.SymmetricallyEncrypted,
+			*packet.AEADEncrypted,
+			*packet.Compressed,
+			*packet.LiteralData:
+			break Loop
+		}
+	}
+	if len(ids) > 0 {
+		return ids, true
+	}
+	return ids, false
+}
+
+func getHexKeyIDs(keyIDs []uint64, ok bool) ([]string, bool) {
+	hexIDs := make([]string, len(keyIDs))
+
+	for i, id := range keyIDs {
+		hexIDs[i] = keyIDToHex(id)
+	}
+
+	return hexIDs, ok
+}

crypto/message_test.go

@@ -228,7 +228,7 @@ func TestMultipleKeyMessageEncryption(t *testing.T) {
 	assert.Exactly(t, message.GetString(), decrypted.GetString())
 }
 
-func TestMessagegetGetEncryptionKeyIDs(t *testing.T) {
+func TestMessageGetEncryptionKeyIDs(t *testing.T) {
 	var message = NewPlainMessageFromString("plain text")
 	assert.Exactly(t, 3, len(keyRingTestMultiple.entities))
 
@@ -236,7 +236,7 @@ func TestMessagegetGetEncryptionKeyIDs(t *testing.T) {
 	if err != nil {
 		t.Fatal("Expected no error when encrypting, got:", err)
 	}
-	ids, ok := ciphertext.getEncryptionKeyIDs()
+	ids, ok := ciphertext.GetEncryptionKeyIDs()
 	assert.Exactly(t, 3, len(ids))
 	assert.True(t, ok)
 	encKey, ok := keyRingTestMultiple.entities[0].EncryptionKey(time.Now())
@@ -244,6 +244,50 @@ func TestMessagegetGetEncryptionKeyIDs(t *testing.T) {
 	assert.Exactly(t, encKey.PublicKey.KeyId, ids[0])
 }
 
+func TestMessageGetHexGetEncryptionKeyIDs(t *testing.T) {
+	ciphertext, err := NewPGPMessageFromArmored(readTestFile("message_multipleKeyID", false))
+	if err != nil {
+		t.Fatal("Expected no error when reading message, got:", err)
+	}
+
+	ids, ok := ciphertext.GetHexEncryptionKeyIDs()
+	assert.Exactly(t, 2, len(ids))
+	assert.True(t, ok)
+
+	assert.Exactly(t, "76ad736fa7e0e83c", ids[0])
+	assert.Exactly(t, "0f65b7ae456a9ceb", ids[1])
+}
+
+func TestMessageGetSignatureKeyIDs(t *testing.T) {
+	var message = NewPlainMessageFromString("plain text")
+
+	signature, err := keyRingTestPrivate.SignDetached(message)
+	if err != nil {
+		t.Fatal("Expected no error when encrypting, got:", err)
+	}
+
+	ids, ok := signature.GetSignatureKeyIDs()
+	assert.Exactly(t, 1, len(ids))
+	assert.True(t, ok)
+	signingKey, ok := keyRingTestPrivate.entities[0].SigningKey(time.Now())
+	assert.True(t, ok)
+	assert.Exactly(t, signingKey.PublicKey.KeyId, ids[0])
+}
+
+func TestMessageGetHexSignatureKeyIDs(t *testing.T) {
+	ciphertext, err := NewPGPMessageFromArmored(readTestFile("message_plainSignature", false))
+	if err != nil {
+		t.Fatal("Expected no error when reading message, got:", err)
+	}
+
+	ids, ok := ciphertext.GetHexSignatureKeyIDs()
+	assert.Exactly(t, 2, len(ids))
+	assert.True(t, ok)
+
+	assert.Exactly(t, "3eb6259edf21df24", ids[0])
+	assert.Exactly(t, "d05b722681936ad0", ids[1])
+}
+
 func TestMessageGetArmoredWithCustomHeaders(t *testing.T) {
 	var message = NewPlainMessageFromString("plain text")
 

crypto/sessionkey_test.go

@@ -143,7 +143,7 @@ func TestDataPacketEncryption(t *testing.T) {
 	if err != nil {
 		t.Fatal("Unable to unarmor pgp message, got:", err)
 	}
-	ids, ok := pgpMessage.getEncryptionKeyIDs()
+	ids, ok := pgpMessage.GetEncryptionKeyIDs()
 	assert.True(t, ok)
 	assert.Exactly(t, 3, len(ids))
 

crypto/testdata/message_multipleKeyID

@@ -0,0 +1,20 @@
+-----BEGIN PGP MESSAGE-----
+Version: OpenPGP.js v3.1.3
+Comment: https://openpgpjs.org
+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+=QeVN
+-----END PGP MESSAGE-----

crypto/testdata/message_plainSignature

@@ -0,0 +1,23 @@
+-----BEGIN PGP MESSAGE-----
+Comment: https://gopenpgp.org
+Version: GopenPGP 2.0.1
+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+CGo+Qd3WrE5MqGunvDli5VK37A==
+=cPmR
+-----END PGP MESSAGE-----