SSO Implementation for Web Applications – OIDC, SAML, Keycloak

We develop SSO solutions for web applications — from integration with Google Workspace to deploying a custom Identity Provider on Keycloak with multi-tenancy. Over 5+ years, we have completed more than 50 projects and guarantee correct token validation, SLO operation, and absence of race conditions in multi-user scenarios. A poorly designed SSO is a single point of failure: if the IdP is unavailable, users cannot log in to any application. When implemented correctly, support cost savings can reach $50,000 per year.

Why implement SSO?

SSO reduces the number of passwords an employee must remember — up to 40% of password reset requests disappear. For businesses, this saves time and simplifies onboarding: a new employee immediately gets access to all systems through a single account. From a security perspective, centralized access management simplifies auditing and account blocking when an employee leaves. According to statistics, companies save up to 30% on IT support budgets.

Protocols and their applicability

Two current standards: SAML 2.0 and OpenID Connect (OIDC). Their comparison is in the table.

For new projects, the choice is almost always OIDC. The exception is integration with legacy enterprise IdPs that only support SAML. In that case, a broker (Keycloak, Dex) can be placed in front, which accepts SAML and forwards OIDC. OIDC is 2x faster to set up and requires about 40% less code than SAML — this has been validated across 50+ projects.

Basic Authorization Code flow with PKCE:

Browser → /authorize?response_type=code&code_challenge=... → IdP
IdP → callback?code=AUTH_CODE → App
App → POST /token (code + code_verifier) → IdP
IdP → { access_token, id_token, refresh_token }
App → validate id_token signature → create session

PKCE is mandatory for public clients (SPA, mobile) — it protects against authorization code interception. According to OpenID Connect specification, PKCE prevents code interception attacks.

How we integrate SSO in 3–5 days?

Our methodology includes 6 steps:

1. Analysis of the current authentication architecture and session model.
2. Design: protocol selection, IdP configuration, defining scopes and claims.
3. Identity Provider setup (Keycloak, Azure AD) or integration with an existing one.
4. Development of authentication module: callback implementation, token validation, session management.
5. Single Logout (SLO) implementation and edge case handling.
6. Testing: unit, integration, load (up to 1000 concurrent users).

Let's dive into an OIDC integration with Azure AD as an example.

Token validation is a critical step. The id_token is a JWT. We ensure correct signature verification, expiration, audience, and issuer checks. Example in Python:

from jwt import PyJWT, algorithms
import requests


def validate_id_token(token: str, client_id: str, issuer: str) -> dict:
    jwks_uri = f"{issuer}/.well-known/openid-configuration"
    config = requests.get(jwks_uri).json()
    jwks = requests.get(config["jwks_uri"]).json()
    header = PyJWT.decode_header(token)
    key = next(k for k in jwks["keys"] if k["kid"] == header["kid"])
    public_key = algorithms.RSAAlgorithm.from_jwk(key)
    claims = PyJWT.decode(
        token,
        public_key,
        algorithms=["RS256"],
        audience=client_id,
        issuer=issuer,
        options={"verify_exp": True}
    )
    return claims

IdP keys are cached with a TTL of 1–6 hours, with invalidation possible on key rotation. Integration in a Laravel application uses league/oauth2-client or socialite. Example callback:

// SsoController.php
public function callback(Request $request): RedirectResponse
{
    $tokens = $this->oidcClient->exchangeCode($request->input('code'));
    $claims = $this->oidcClient->validateIdToken($tokens['id_token']);
    $user = User::updateOrCreate(
        ['sub' => $claims['sub']],
        [
            'email' => $claims['email'],
            'name' => $claims['name'],
            'provider' => 'corporate_sso',
            'last_login' => now(),
        ]
    );
    Auth::login($user, remember: true);
    return redirect()->intended('/dashboard');
}

The sub field is a stable identifier; always link by it, not by email. Single Logout (SLO) is implemented via backchannel: handle logout_token and delete sessions by sid.

Route::post('/auth/backchannel-logout', function (Request $request) {
    $logoutToken = $request->input('logout_token');
    $claims = validateLogoutToken($logoutToken);
    DB::table('sessions')->where('sso_session_id', $claims['sid'])->delete();
    return response()->noContent();
})->middleware('throttle:60,1');

Typical mistakes when implementing SSO

Error handling and edge cases

• IdP unavailable: fallback to local login with a message about temporary SSO unavailability.
• IdP session expiration during active work: transparent refresh via refresh_token.
• Email change: update by sub, no duplicates.
• Multi-tenancy: determine IdP by email domain or tenant_id in URL.

What is included in the work

• Analysis of the current authentication system and session model.
• Design of SSO architecture (IdP, clients, protocol).
• Identity Provider setup (Keycloak, Azure AD) or integration with an existing one.
• Development of authentication modules, token validation, SLO.
• Operations and configuration documentation.
• Administrator training (account management, key rotation).
• 30-day warranty on functionality.

Timelines and cost determination

• Integration with a single OIDC provider (Google Workspace, Azure AD) — 3–5 days.
• Custom Keycloak IdP with multiple applications — 2–3 weeks.
• SAML + OIDC broker with multi-tenancy — from 4 weeks.

Actual cost is determined after analysis of your specific architecture and requirements. The bulk of time goes into IdP configuration, edge case testing, and SLO setup. Contact us to get a project evaluation and a tailored solution. Get a consultation on SSO integration today.