'Initialize client credentials from encrypted string from the master.
Args:
string: The serialized DataServerEncryptedCreds proto to parse.
username: This server\'s username.
password: This server\'s password.
Returns:
self.'

def InitializeFromEncryption(self, string, username, password):

    creds_cls = data_server.DataServerEncryptedCreds
    encrypted_creds = creds_cls.FromSerializedString(string)
    payload = encrypted_creds.GetPayload(username, password)
    creds = data_server.DataServerClientCredentials.FromSerializedString(payload)
    self.client_users = {}
    for client in creds.users:
        self.client_users[client.username] = client
    return self
