/// <summary>
/// Benutzer anmelden
/// </summary>
/// <param name="username">Benutzer</param>
/// <param name="password">Kennwort</param>
/// <returns>true wenn Anmeldung erfolgreich, andernfalls false</returns>
public async Task <bool> login(string username, string password)
{
string usernameBase64 = Util.StringToBase64String(username);
try
{
HttpResponseMessage response = await client.GetAsync(usernameBase64);
if (response.IsSuccessStatusCode)
{
user = new Models.User();
var jsonString = await response.Content.ReadAsStringAsync();
var model = JsonConvert.DeserializeObject <Models.LoginResponse>(jsonString);
user.Username = username;
user.publickey = model.pubkey_user;
user.salt_masterkey = Convert.FromBase64String(model.salt_masterkey);
user.privatekey = EncryptLogic.toDecryptPrivateKey(model.privkey_user_enc, password, user.salt_masterkey);
return(true);
}
else
{
throw new HttpRequestException(response.RequestMessage.Method + ":"
+ response.RequestMessage.RequestUri.AbsolutePath
+ Environment.NewLine +
"HTTP-Statuscode: " + (int)response.StatusCode + " - " + response.StatusCode);
}
} catch (Exception ex) {
Util.Log(ex.Message);
}
return(false);
}
/// <summary>
/// Eine Nachricht holen
/// </summary>
/// <returns>Nachricht(ViewMessage)</returns>
public async Task <Models.ViewMessage> getMessage()
{
try
{
string usernameBase64 = Util.StringToBase64String(user.Username);
var request = new Models.GetMessageRequest();
request.timestamp = Convert.ToString(Util.UnixTimeNow());
//Anfrage signieren
request.sig_utime = EncryptLogic.createSignGetMessageRequest(request.timestamp, user.Username, user.privatekey);
string url = String.Format(usernameBase64 + "/messages?timestamp={0}&sig_utime={1}",
request.timestamp, HttpUtility.UrlEncode(request.sig_utime));
HttpResponseMessage response = await client.GetAsync(url);
if (response.IsSuccessStatusCode)
{
var jsonString = await response.Content.ReadAsStringAsync();
var content = JsonConvert.DeserializeObject <Models.Message>(jsonString);
//Signatur prüfen (Ob die Nachricht verändert wurde)
string publickey = await getPublicKeyFromUser(content.sender);
if (!EncryptLogic.verfiyInnerEnvelope(content, publickey))
{
throw new Exception("Die Nachricht ist nicht verifiziert.");
}
//IV
byte[] iv = Convert.FromBase64String(content.iv);
//Key_recipient_enc(Symmetrischer Schlüssel verschlüsselt) entschlüsseln
byte[] key_recipient_enc = Convert.FromBase64String(content.key_recipient_enc);
byte[] key_recipient = EncryptLogic.toDecryptKeyRecipient(key_recipient_enc, user.privatekey);
//Cipher(verschlüsselte Nachricht) entschlüsseln
byte[] cipher_bytes = Convert.FromBase64String(content.cipher);
string msg_dec = EncryptLogic.toDecryptMessage(cipher_bytes, key_recipient, iv);
var vm = new Models.ViewMessage();
vm.sender = content.sender;
vm.content = msg_dec;
return(vm);
}
else
{
throw new HttpRequestException(response.RequestMessage.Method + ":"
+ response.RequestMessage.RequestUri.AbsolutePath
+ Environment.NewLine +
"HTTP-Statuscode: " + (int)response.StatusCode + " - " + response.StatusCode);
}
} catch (Exception ex) {
Util.Log(ex.Message);
}
return(null);
}
/// <summary>
/// Nachricht verschicken
/// </summary>
/// <param name="receiver">Empfänger</param>
/// <param name="msg">Nachricht</param>
/// <returns>true wenn erfolgreich, andernfalls false</returns>
public async Task <bool> sendMessage(string receiver, string msg)
{
try
{
string usernameBase64 = Util.StringToBase64String(user.Username);
//Symmetrischen Schlüssel und IV erzeugen
byte[] key_recipient;
byte[] iv;
EncryptLogic.createAESKeyAndIV(out key_recipient, out iv);
//Nachricht mit dem Symmetrischen Schlüssel und IV verschlüsseln.
byte[] msg_enc = EncryptLogic.toEncryptMessage(msg, key_recipient, iv);
//PublicKey vom Empfänger holen
string pubkey_rcv = await getPublicKeyFromUser(receiver);
//Symmetrischen Schlüssel mit dem PublicKey vom Empfänger verschlüsseln.
byte[] key_recipient_enc = EncryptLogic.toEncryptKeyRecipient(key_recipient, pubkey_rcv);
Models.Message inner_envelope = new Models.Message();
inner_envelope.sender = user.Username;
inner_envelope.cipher = Convert.ToBase64String(msg_enc);
inner_envelope.iv = Convert.ToBase64String(iv);
inner_envelope.key_recipient_enc = Convert.ToBase64String(key_recipient_enc);
//Inneren Umschlag signieren
inner_envelope.sig_recipient = EncryptLogic.createSignInnerEnvelope(inner_envelope, user.privatekey);
Models.SendMessageRequest request = new Models.SendMessageRequest();
request.envelope = inner_envelope;
request.recipient = receiver;
request.timestamp = Convert.ToString(Util.UnixTimeNow());
//Äußeren Umschlag signieren
request.sig_service = EncryptLogic.createSignOuterEnvelope(inner_envelope, request.timestamp, request.recipient, user.privatekey);
HttpResponseMessage response = await client.PostAsJsonAsync(usernameBase64 + "/message", request);
if (response.IsSuccessStatusCode)
{
return(true);
}
else
{
throw new HttpRequestException(response.RequestMessage.Method + ":"
+ response.RequestMessage.RequestUri.AbsolutePath
+ Environment.NewLine +
"HTTP-Statuscode: " + (int)response.StatusCode + " - " + response.StatusCode);
}
} catch (Exception ex) {
Util.Log(ex.Message);
}
return(false);
}
/// <summary>
/// Neuen Benutzer registrieren und anmelden
/// </summary>
/// <param name="username">Benutzername</param>
/// <param name="password">Kennwort</param>
/// <returns>true wenn registrieren erfolgreich, andernfalls false</returns>
public async Task <bool> register(string username, string password)
{
try
{
string usernameBase64 = Util.StringToBase64String(username);
Models.RegisterRequest request = new Models.RegisterRequest();
//Den salt_masterkey erstellen
byte[] salt_masterkey = EncryptLogic.createSalt(64);
request.salt_masterkey = Convert.ToBase64String(salt_masterkey);
//Das Schlüsselpaar erstellen
string publickey = null;
string privatekey = null;
EncryptLogic.createRSAKeyPair(out privatekey, out publickey);
//Den PublicKey in Base64 konventieren
request.pubkey_user = publickey;
//Den PrivateKey verschlüsseln und in Base64 konventieren
string encryptedprivkey = EncryptLogic.toEncryptPrivateKey(privatekey, password, salt_masterkey);
request.privkey_user_enc = encryptedprivkey;
HttpResponseMessage response = await client.PostAsJsonAsync(usernameBase64, request);
if (response.IsSuccessStatusCode)
{
return(await login(username, password));
}
else
{
throw new HttpRequestException(response.RequestMessage.Method + ":"
+ response.RequestMessage.RequestUri.AbsolutePath
+ Environment.NewLine +
"HTTP-Statuscode: " + (int)response.StatusCode + " - " + response.StatusCode);
}
} catch (Exception ex) {
Util.Log(ex.Message);
}
return(false);
}
