This example shows a `CustomIdentityProvider` class which can perform OpenStack authentication with the `tenantId` and/or `tenantName` properties which are not supported by the default `CloudIdentityProvider`.

CustomIdentityProvider.cs

public class CloudIdentityWithProject : CloudIdentity
{
    /// <summary>
    /// Gets or sets the project ID for this identity.
    /// </summary>
    /// <value>
    /// The project ID for this identity. The value may be <c>null</c> if the particular
    /// provider supports authenticating without a project ID.
    /// </value>
    public ProjectId ProjectId
    {
        get;
        set;
    }

    /// <summary>
    /// Gets or sets the project name for this identity.
    /// </summary>
    /// <value>
    /// The project name for this identity. The value may be <c>null</c> if the particular
    /// provider supports authenticating without a project name.
    /// </value>
    public string ProjectName
    {
        get;
        set;
    }
}

public class CustomIdentityProvider : CloudIdentityProvider
{
    public override UserAccess GetUserAccess(CloudIdentity identity, bool forceCacheRefresh = false)
    {
        CloudIdentityWithProject identityWithProject = identity as CloudIdentityWithProject;
        if (identityWithProject == null)
            return base.GetUserAccess(identityWithProject, forceCacheRefresh);

        Func<UserAccess> refreshCallback =
            () =>
            {
                JObject requestBody = new JObject(
                    new JProperty("auth", new JObject(
                        new JProperty("passwordCredentials", new JObject(
                            new JProperty("username", JValue.CreateString(identityWithProject.Username)),
                            new JProperty("password", JValue.CreateString(identityWithProject.Password)))),
                        new JProperty("tenantName", JToken.FromObject(identityWithProject.ProjectName)),
                        new JProperty("tenantId", JToken.FromObject(identityWithProject.ProjectId)))));

                var response = ExecuteRESTRequest<JObject>(identity, new Uri(UrlBase, "/v2.0/tokens"), HttpMethod.POST, requestBody, isTokenRequest: true);
                if (response == null || response.Data == null)
                    return null;

                JToken userAccessObject = response.Data["access"];
                if (userAccessObject == null)
                    return null;

                UserAccess access = userAccessObject.ToObject<UserAccess>();
                if (access == null || access.Token == null)
                    return null;

                return access;
            };
        string key = string.Format("{0}:{1}/{2}", UrlBase, identityWithProject.ProjectId, identityWithProject.Username);
        var userAccess = TokenCache.Get(key, refreshCallback, forceCacheRefresh);

        return userAccess;
    }
}