Single Sign-On (SSO) lets users access multiple applications through one authenticated login instead of entering separate credentials for every system. For organizations evaluating centralized identity and access, Integer Cloud’s SSO solution provides a starting point for understanding how SSO can fit into a broader authentication strategy.
Employees rarely work in just one application. A typical workday might involve email, CRM, project management, HR systems, analytics tools, cloud storage, and several business applications. Signing into each one separately creates friction for users and gives IT teams more credentials and access points to manage.
What is Single Sign-On (SSO)?
Single Sign-On is an authentication method that lets a user access multiple applications after authenticating through a central identity system once.
Instead of maintaining a separate username and password for every application, the user signs in through an Identity Provider (IdP). The IdP verifies the user's identity and establishes an authenticated session. Connected applications can then rely on that established trust rather than asking the user to enter credentials again.
For example, an employee might sign into the company's identity portal in the morning and then open the CRM, collaboration platform, HR application, and internal tools without repeatedly entering a password.
SSO is therefore more than a convenient login screen. It creates a centralized authentication model where an organization's digital identity can be used across multiple trusted applications. Standards such as SAML and OpenID Connect make it possible for the identity provider and applications to exchange the information required for authentication.
Types of Single Sign-On
There are several types of single sign on, depending on the environment and authentication approach:
- Enterprise Single Sign-On: Used by organizations to give employees centralized access to business applications.
- Federated Single Sign-On: Extends trust between separate organizations or security domains, allowing identities to be recognized across systems.
- Social Single Sign-On: Allows users to sign in using an existing identity from a consumer identity provider, such as a social or personal account.
- Cloud-Based SSO: Provides centralized authentication for cloud and SaaS applications through an identity provider.
- On-Premises SSO: Supports applications and identity infrastructure hosted within an organization's own environment.
- Passwordless Single Sign-On: Combines SSO with passwordless authentication methods such as passkeys, security keys, or other phishing-resistant credentials.
Why Single Sign-On Matters
Managing passwords becomes increasingly difficult as the number of applications grows. Users may create similar passwords across services, reuse credentials, or rely on password managers and repeated password resets just to keep up.
That creates problems for both users and IT teams. Password fatigue can lead to poor security habits, while every additional login creates another authentication experience to manage.
SSO reduces that burden by moving authentication to a central identity service. Users have fewer credentials to remember, while IT teams gain a central place to apply authentication policies and control application access.
The result can be a smoother digital workplace, faster access to applications, and less time spent dealing with routine login problems.
How Single Sign-On (SSO) Works
The basic SSO authentication flow can be understood as a conversation between three parties: the user, the Identity Provider, and the Service Provider.
Consider an employee opening a business application they have not accessed during the current session.
Step 1 – User Attempts to Access an Application
The user visits an application, known as the Service Provider (SP). If the application does not have an active session for that user, it sends the user toward the organization's identity provider for authentication.
Step 2 – Identity Provider Authenticates the User
The Identity Provider checks whether the user already has an authenticated session. If not, the user completes the required authentication process.
Depending on the organization's security policy, this may include a password, multifactor authentication, device checks, conditional access rules, or passwordless authentication.
Step 3 – Authentication Token is Generated
After successful authentication, the identity provider provides information that allows the application to establish trust in the user's identity.
With SAML, this commonly takes the form of a signed SAML assertion. With OIDC, an ID token is used to communicate authentication information. The exact flow depends on the protocol and application configuration.
Step 4 – Service Provider Grants Access
The application validates the response and determines whether the user is allowed to access it. Authentication establishes who the user is; authorization determines what that user can access.
If the checks succeed, the application creates its own session for the user.
Step 5 – User Accesses Other Connected Applications
When the user opens another connected application, they may not need to authenticate again because the identity provider session is already established.
The second application can perform its own authentication flow with the trusted identity provider, allowing the user to continue without another manual login.
This is the part users experience as "sign in once." Behind the scenes, multiple applications still establish their own sessions and apply their own authorization rules.
Understanding the Core Components of an SSO Architecture
A typical single sign on architecture contains several connected components that work together.
Identity Provider (IdP)
The Identity Provider is responsible for authenticating users and providing trusted identity information to applications. Microsoft Entra ID, Okta, and other identity platforms can act as IdPs.
The IdP can also enforce policies such as MFA and conditional access before allowing an application to establish a session.
Service Provider (SP)
The Service Provider is the application the user wants to access. It trusts the identity provider to authenticate the user and receives the appropriate authentication information.
In a SAML setup, for example, the application acts as the service provider while the identity platform acts as the identity provider.
User Directory
The directory stores or connects to information about users, groups, and identity attributes. Enterprise environments may use services such as Active Directory or LDAP alongside a cloud identity platform.
This information can help determine which applications a user should be able to access.
Authentication Tokens & Sessions
Tokens carry authentication or authorization information between trusted systems. Sessions maintain the user's authenticated state so that applications do not require credentials on every request.
The specific token and session behavior depends on the protocol and architecture being used.
Authentication Protocols Used in Single Sign-On
SSO depends on standards that allow applications and identity providers to establish trust and exchange authentication information.
SAML remains common in enterprise environments, particularly where established SaaS applications already support it. OIDC is built on OAuth 2.0 and is widely suited to modern applications, websites, mobile applications, and APIs. OAuth itself is primarily about authorization rather than proving a user's identity.
The Role of SSO in Identity and Access Management (IAM)
SSO is an important part of Identity and Access Management (IAM), but it is not the entire IAM strategy.
SSO focuses primarily on authentication and the user experience around accessing applications. IAM covers a much broader set of responsibilities, including identity creation, access policies, authorization, provisioning, deprovisioning, governance, and lifecycle management.
In larger organizations, IAM may also include Customer Identity and Access Management (CIAM), identity governance, privileged access controls, and automated user lifecycle processes.
A useful way to think about it is that SSO answers, "How can this user authenticate across these applications?" IAM addresses the wider question of "Who is this user, what should they be able to access, and how should that access change over time?"
Benefits of Single Sign-On
Better User Experience
Users can access connected applications without repeatedly entering credentials, reducing login friction throughout the workday.
Increased Employee Productivity
Less time spent signing into applications and resolving routine password problems leaves employees with more time for their actual work.
Stronger Security
Centralized authentication gives security teams a better place to enforce authentication policies, MFA, session controls, and other safeguards.
Reduced Help Desk Costs
Password resets and login issues can consume IT support time. Reducing the number of application-specific credentials can reduce some of that operational burden.
Less Shadow IT
When legitimate applications are easier to access through approved identity systems, employees have less reason to create workarounds or use unauthorized accounts.
Simplified User Lifecycle Management
When SSO is combined with provisioning and deprovisioning capabilities, organizations can make it easier to grant and remove access as employees join, change roles, or leave.
Easier Compliance and Auditing
Centralized identity systems can provide a clearer view of authentication activity, application access, and policy enforcement, which can support security reviews and audit processes.
Is Single Sign-On Secure?
SSO can be secure, but SSO by itself is not a complete security strategy.
The concentration of authentication in one identity provider means that protecting the primary identity account becomes especially important. If an attacker compromises that account, the potential impact can extend to multiple connected applications.
Organizations should therefore pair SSO with controls such as:
- MFA to add another verification factor
- Conditional access based on user, device, location, or risk
- Adaptive authentication that responds to changes in risk
- Device trust and endpoint security controls
- Zero Trust principles that avoid assuming trust simply because a user has authenticated
- Phishing-resistant authentication, including passkeys and security keys where appropriate
The goal is not simply to make login easier. It is to establish strong identity verification and make access decisions based on the organization's security policies.
Challenges and Limitations of Single Sign-On
SSO introduces clear benefits, but it also creates dependencies that need to be managed.
The identity provider becomes a critical part of the organization's access infrastructure. An outage affecting the IdP can prevent users from signing into multiple applications. A compromised identity account can also have a wider impact than a single application credential.
Integration complexity is another consideration. Older applications may not support modern federation protocols, while different applications may require different configurations.
Organizations also need to plan for certificate expiration, session management, account recovery, identity synchronization, application ownership, and user lifecycle changes. Microsoft recommends considering administrative roles, certificates, shared and guest accounts, licensing, and the available SSO method when planning a deployment.
How to Choose the Right SSO Solution
Choosing an SSO provider should start with the applications and identity environment you already have rather than with a feature checklist alone.
Consider:
- Application integrations: Does the provider support the SaaS, custom, legacy, and on-premises applications you actually use?
- Protocol support: Does it support SAML, OIDC, OAuth, and other protocols required by your applications?
- Scalability: Can it support your employee, customer, partner, and application growth?
- Security controls: Look for MFA, conditional access, session policies, audit capabilities, and phishing-resistant authentication options.
- Availability: Review uptime commitments, resilience, recovery capabilities, and operational history.
- Lifecycle management: Consider whether the platform can support provisioning, deprovisioning, directory synchronization, and role-based access.
- Administration: Evaluate how easily IT teams can configure applications, troubleshoot authentication issues, and manage policies.
For organizations evaluating an SSO implementation, the right choice is usually the one that fits the existing identity architecture while giving security and IT teams room to evolve it.
Conclusion
Single Sign-On (SSO) simplifies access by centralizing authentication across applications while supporting stronger identity management. When combined with IAM, MFA, and Zero Trust, it can help organizations build more secure and manageable access environments.
As passwordless authentication and passkeys continue to gain adoption, SSO is becoming an important part of modern identity security. If you're evaluating SSO for your organization, explore Integer Cloud.