diff --git a/api/auth.go b/api/auth.go
index a128bff..5882f87 100644
--- a/api/auth.go
+++ b/api/auth.go
@@ -57,6 +57,10 @@ func (c *Client) CheckSession(ctx context.Context) bool {
 // Login gets a Session and CSRF Token from Passbolt and Stores them in the Clients Cookie Jar
 func (c *Client) Login(ctx context.Context) error {
 
+	if c.userPrivateKey == "" {
+		return fmt.Errorf("Client has no Private Key")
+	}
+
 	privateKeyObj, err := crypto.NewKeyFromArmored(c.userPrivateKey)
 	if err != nil {
 		return fmt.Errorf("Parsing User Private Key: %w", err)
diff --git a/api/client.go b/api/client.go
index 2a7833d..210e8eb 100644
--- a/api/client.go
+++ b/api/client.go
@@ -36,6 +36,8 @@ type Client struct {
 // NewClient Returns a new Passbolt Client.
 // if httpClient is nil http.DefaultClient will be used.
 // if UserAgent is "" "goPassboltClient/1.0" will be used.
+// if UserPrivateKey is "" Key Setup is Skipped to Enable using the Client for User Registration, Most other function will be broken.
+// After Registration a new Client Should be Created.
 func NewClient(httpClient *http.Client, UserAgent, BaseURL, UserPrivateKey, UserPassword string) (*Client, error) {
 	if httpClient == nil {
 		httpClient = http.DefaultClient
@@ -49,22 +51,24 @@ func NewClient(httpClient *http.Client, UserAgent, BaseURL, UserPrivateKey, User
 		return nil, fmt.Errorf("Parsing Base URL: %w", err)
 	}
 
-	// Verify that the Given Privatekey and Password are valid and work Together
-	privateKeyObj, err := crypto.NewKeyFromArmored(UserPrivateKey)
-	if err != nil {
-		return nil, fmt.Errorf("Unable to Create Key From UserPrivateKey string: %w", err)
-	}
-	unlockedKeyObj, err := privateKeyObj.Unlock([]byte(UserPassword))
-	if err != nil {
-		return nil, fmt.Errorf("Unable to Unlock UserPrivateKey using UserPassword: %w", err)
-	}
-	privateKeyRing, err := crypto.NewKeyRing(unlockedKeyObj)
-	if err != nil {
-		return nil, fmt.Errorf("Unable to Create a new Key Ring using the unlocked UserPrivateKey: %w", err)
-	}
+	// Verify that the Given Privatekey and Password are valid and work Together if we were provieded one
+	if UserPrivateKey != "" {
+		privateKeyObj, err := crypto.NewKeyFromArmored(UserPrivateKey)
+		if err != nil {
+			return nil, fmt.Errorf("Unable to Create Key From UserPrivateKey string: %w", err)
+		}
+		unlockedKeyObj, err := privateKeyObj.Unlock([]byte(UserPassword))
+		if err != nil {
+			return nil, fmt.Errorf("Unable to Unlock UserPrivateKey using UserPassword: %w", err)
+		}
+		privateKeyRing, err := crypto.NewKeyRing(unlockedKeyObj)
+		if err != nil {
+			return nil, fmt.Errorf("Unable to Create a new Key Ring using the unlocked UserPrivateKey: %w", err)
+		}
 
-	// Cleanup Secrets
-	privateKeyRing.ClearPrivateParams()
+		// Cleanup Secrets
+		privateKeyRing.ClearPrivateParams()
+	}
 
 	// Create Client Object
 	c := &Client{
diff --git a/api/encryption.go b/api/encryption.go
index 8193115..e87537e 100644
--- a/api/encryption.go
+++ b/api/encryption.go
@@ -1,19 +1,34 @@
 package api
 
-import "github.com/ProtonMail/gopenpgp/v2/helper"
+import (
+	"fmt"
+
+	"github.com/ProtonMail/gopenpgp/v2/helper"
+)
 
 // EncryptMessage encrypts a message using the users public key and then signes the message using the users private key
 func (c *Client) EncryptMessage(message string) (string, error) {
+	if c.userPrivateKey == "" {
+		return "", fmt.Errorf("Client has no Private Key")
+	} else if c.userPublicKey == "" {
+		return "", fmt.Errorf("Client has no Public Key")
+	}
 	return helper.EncryptSignMessageArmored(c.userPublicKey, c.userPrivateKey, c.userPassword, message)
 }
 
 // EncryptMessageWithPublicKey encrypts a message using the provided public key and then signes the message using the users private key
 func (c *Client) EncryptMessageWithPublicKey(publickey, message string) (string, error) {
+	if c.userPrivateKey == "" {
+		return "", fmt.Errorf("Client has no Private Key")
+	}
 	return helper.EncryptSignMessageArmored(publickey, c.userPrivateKey, c.userPassword, message)
 }
 
 // DecryptMessage decrypts a message using the users Private Key
 func (c *Client) DecryptMessage(message string) (string, error) {
+	if c.userPrivateKey == "" {
+		return "", fmt.Errorf("Client has no Private Key")
+	}
 	// We cant Verify the signature as we don't store other users public keys locally and don't know which user did encrypt it
 	//return helper.DecryptVerifyMessageArmored(c.userPublicKey, c.userPrivateKey, c.userPassword, message)
 	return helper.DecryptMessageArmored(c.userPrivateKey, c.userPassword, message)
diff --git a/api/setup.go b/api/setup.go
new file mode 100644
index 0000000..b7a941b
--- /dev/null
+++ b/api/setup.go
@@ -0,0 +1,44 @@
+package api
+
+import (
+	"context"
+	"encoding/json"
+)
+
+type SetupInstallResponse struct {
+	User `json:"user,omitempty"`
+}
+
+type AuthenticationToken struct {
+	Token string `json:"token,omitempty"`
+}
+
+type SetupCompleteRequest struct {
+	AuthenticationToken AuthenticationToken `json:"authenticationtoken,omitempty"`
+	GPGKey              GPGKey              `json:"gpgkey,omitempty"`
+	User                User                `json:"user,omitempty"`
+}
+
+// SetupInstall validates the userid and token used for Account setup, gives back the User Information
+func (c *Client) SetupInstall(ctx context.Context, userID, token string) (*SetupInstallResponse, error) {
+	msg, err := c.DoCustomRequest(ctx, "GET", "/setup/install/"+userID+"/"+token+".json", "v2", nil, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	var install SetupInstallResponse
+	err = json.Unmarshal(msg.Body, &install)
+	if err != nil {
+		return nil, err
+	}
+	return &install, nil
+}
+
+// SetupComplete Completes setup of a Passbolt Account
+func (c *Client) SetupComplete(ctx context.Context, userID string, request SetupCompleteRequest) error {
+	_, err := c.DoCustomRequest(ctx, "POST", "/setup/complete/"+userID+".json", "v2", request, nil)
+	if err != nil {
+		return err
+	}
+	return nil
+}
diff --git a/api/users.go b/api/users.go
index b71a296..5ded066 100644
--- a/api/users.go
+++ b/api/users.go
@@ -5,6 +5,8 @@ import (
 	"encoding/json"
 )
 
+const UserLocaleENUK = "en-UK"
+
 // User contains information about a passbolt User
 type User struct {
 	ID           string    `json:"id,omitempty"`
@@ -20,6 +22,7 @@ type User struct {
 	Role         *Role     `json:"role,omitempty"`
 	GPGKey       *GPGKey   `json:"gpgKey,omitempty"`
 	LastLoggedIn string    `json:"last_logged_in,omitempty"`
+	Locale       string    `json:"locale,omitempty"`
 }
 
 // Profile is a Profile
diff --git a/helper/setup.go b/helper/setup.go
new file mode 100644
index 0000000..02c0e50
--- /dev/null
+++ b/helper/setup.go
@@ -0,0 +1,66 @@
+package helper
+
+import (
+	"context"
+	"fmt"
+	"strings"
+
+	"github.com/speatzle/go-passbolt/api"
+
+	"github.com/ProtonMail/gopenpgp/v2/crypto"
+	"github.com/ProtonMail/gopenpgp/v2/helper"
+)
+
+// ParseInviteUrl Parses a Passbolt Invite URL into a user id and token
+func ParseInviteUrl(url string) (string, string, error) {
+	split := strings.Split(url, "/")
+	if len(split) < 4 {
+		return "", "", fmt.Errorf("Invite URL does not have enough slashes")
+	}
+	return split[len(split)-2], strings.TrimSuffix(split[len(split)-1], ".json"), nil
+}
+
+// SetupAccount Setup a Account for a Invited User.
+// (Use ParseInviteUrl to get the userid and token from a Invite URL)
+func SetupAccount(ctx context.Context, c *api.Client, userID, token, password string) (string, error) {
+
+	install, err := c.SetupInstall(ctx, userID, token)
+	if err != nil {
+		return "", fmt.Errorf("Get Setup Install Data: %w", err)
+	}
+
+	keyName := install.Profile.FirstName + " " + install.Profile.LastName + " " + install.Username
+
+	privateKey, err := helper.GenerateKey(keyName, install.Username, []byte(password), "rsa", 2048)
+	if err != nil {
+		return "", fmt.Errorf("Generating Private Key: %w", err)
+	}
+
+	key, err := crypto.NewKeyFromArmoredReader(strings.NewReader(privateKey))
+	if err != nil {
+		return "", fmt.Errorf("Reading Private Key: %w", err)
+	}
+
+	publicKey, err := key.GetArmoredPublicKey()
+	if err != nil {
+		return "", fmt.Errorf("Get Public Key: %w", err)
+	}
+
+	request := api.SetupCompleteRequest{
+		AuthenticationToken: api.AuthenticationToken{
+			Token: token,
+		},
+		User: api.User{
+			Locale: api.UserLocaleENUK,
+		},
+		GPGKey: api.GPGKey{
+			ArmoredKey: publicKey,
+		},
+	}
+
+	err = c.SetupComplete(ctx, userID, request)
+	if err != nil {
+		return "", fmt.Errorf("Setup Completion Failed: %w", err)
+	}
+	return privateKey, nil
+}