diff --git a/protonmail/adresses.go b/protonmail/adresses.go
index 9d4e96c..66e785b 100644
--- a/protonmail/adresses.go
+++ b/protonmail/adresses.go
@@ -6,6 +6,23 @@ type (
 	AddressType   int
 )
 
+const (
+	AddressSendDisabled AddressSend = iota
+	AddressSendPrimary
+	AddressSendSecondary
+)
+
+const (
+	AddressDisabled AddressStatus = iota
+	AddressEnabled
+)
+
+const (
+	AddressOriginal AddressType = iota
+	AddressAlias
+	AddressCustom
+)
+
 type Address struct {
 	ID          string
 	DomainID    string
@@ -17,5 +34,5 @@ type Address struct {
 	DisplayName string
 	Signature   string // HTML
 	HasKeys     int
-	Keys        []*Key
+	Keys        []*PrivateKey
 }
diff --git a/protonmail/keys.go b/protonmail/keys.go
index 400c7d2..b5b6a3b 100644
--- a/protonmail/keys.go
+++ b/protonmail/keys.go
@@ -9,7 +9,7 @@ import (
 	"golang.org/x/crypto/openpgp"
 )
 
-type Key struct {
+type PrivateKey struct {
 	ID          string
 	Version     int
 	PublicKey   string
@@ -18,6 +18,17 @@ type Key struct {
 	Activation  interface{} // TODO
 }
 
+func (priv *PrivateKey) Entity() (*openpgp.Entity, error) {
+	keyRing, err := openpgp.ReadArmoredKeyRing(strings.NewReader(priv.PrivateKey))
+	if err != nil {
+		return nil, err
+	}
+	if len(keyRing) == 0 {
+		return nil, errors.New("private key is empty")
+	}
+	return keyRing[0], nil
+}
+
 type RecipientType int
 
 const (
diff --git a/protonmail/messages.go b/protonmail/messages.go
index 9030d8a..32d9f58 100644
--- a/protonmail/messages.go
+++ b/protonmail/messages.go
@@ -196,6 +196,15 @@ type MessageKeyPacket struct {
 
 type MessagePackageType int
 
+const (
+	MessagePackageInternal         MessagePackageType = 1
+	MessagePackageEncryptedOutside                    = 2
+	MessagePackageClear                               = 4
+	MessagePackageInlinePGP                           = 8
+	MessagePackagePGPMIME                             = 16
+	MessagePackageMIME                                = 32
+)
+
 type MessagePackage struct {
 	Address    string
 	Type       MessagePackageType
@@ -210,10 +219,14 @@ type MessagePackage struct {
 type MessageOutgoing struct {
 	ID string
 
+	// Only if there's a recipient without a public key
 	ClearBody      string
-	ExpirationTime int64
 	AttachmentKeys []*AttachmentKey
-	Packages       []*MessagePackage
+
+	// Only if message expires
+	ExpirationTime int // duration in seconds
+
+	Packages []*MessagePackage
 }
 
 func (c *Client) SendMessage(msg *MessageOutgoing) (sent, parent *Message, err error) {
diff --git a/protonmail/users.go b/protonmail/users.go
index 091764d..dc35b4a 100644
--- a/protonmail/users.go
+++ b/protonmail/users.go
@@ -61,7 +61,7 @@ type User struct {
 	VPN                interface{} // TODO
 	Delinquent         int
 	Addresses          []*Address
-	Keys               []*Key
+	Keys               []*PrivateKey
 }
 
 func (c *Client) GetCurrentUser() (*User, error) {