What is identity authentication and how does it work?

Identity authentication is the process of validating that presented user identity against pre-established, trusted information. It is done to ensure that only legitimate users get to interact with sensitive data or systems, and unauthorized entities are kept out.

The two main steps of a typical authentication process are:

1. Authentication identification

In the identification phase, the access manager receives and parses the details presented by the user to ensure that the information is in a format the system can understand and process.

2. Identity Matching/Verification

After identification, the system verifies the user’s authenticity by comparing the parsed credentials against stored, known and trusted information within the relevant identity repository. For example:

• If the user presents a password, it gets hashed and compared against the stored hash of the user’s password.
• If it’s a fingerprint, the scanned biometric data is matched against the enrolled biometric template.

If the credentials match, and multi-factor authentication (MFA) is enabled in the identity management system, additional factors (like OTPs, fingerprints or hardware tokens) are authenticated.

Finally, based on the results of the identity matches, the system either grants or denies access.

Identity authentication and identity verification are often considered the same (or similar), but in reality, they are quite different.

As we discussed above, authentication validates a user’s claimed identity during an active login or access attempt. It involves:

• Dynamic checks (e.g., passwords, biometric scans OTPs)
• Session-based security (expiring tokens, time-bound access)
• Multi-layered defenses (MFA, risk-based authentication)
• Verifying machine and non-human identities

Identity verification, on the other hand, is a one-time process that happens during the registration phase, i.e., when a new user signs up for a service. It involves:

• Document checks (e.g., scanning a government ID, passport or utility bill)
• Biometric enrollment (storing fingerprints or facial recognition data for future authentication)
• Third-party validation (credit bureau checks, KYC processes in banking)

The main difference here is that verification establishes trust in an identity at signup, whereas authentication maintains security over time.

A typical identity authentication workflow looks like this:

1. A user attempts to log in or access a secured application, service or resource.
2. The system parses the user’s credentials to check whether they meet basic requirements (e.g., correct email format, password length). If the input is invalid (e.g., wrong syntax), the system rejects the request.
3. If the credentials are structurally valid, the system queries its identity database (e.g., LDAP, Active Directory or a cloud-based IAM solution) to check for a matching user profile.
4. If the user is accessing a sensitive system, the system may prompt them to provide secondary or tertiary authentication factors (e.g., biometrics, smart cards or hardware tokens etc.)
5. If the credentials match, the system checks the user’s permissions (or roles, if RBAC is configured) to determine the level of access they should receive.
6. Finally, the system issues an access token (e.g., JWT, OAuth or session cookie) which temporarily stores the user’s authentication state and allows them to access the secured application/resource.

Federated identity authentication lets users log in to multiple cloud services using a single set of credentials. Here’s how it works:

1. When a user tries to access a cloud-based SaaS app, the app redirects the user to a centralized identity provider (like Microsoft Entra ID, Google Workspace or One Identity).
2. The identity provider (IdP) verifies the user's identity and, if successful, issues a security token. This token, which is usually a SAML or OIDC token, is passed back to the SaaS app over a secure SSL/TLS connection.
3. The app then uses the token to grant access without ever seeing the user’s password.

This model supports secure Single Sign-On (SSO) and is scalable. Tokens are short-lived, signed and transmitted over encrypted channels, which limits exposure to common attacks like credential theft or session hijacking.

Biometric authentication is a strong alternative to traditional password-based authentication. Here are some of its benefits:

• No need to remember passwords
• Fast and convenient for users
• Harder to spoof than traditional credentials
• Tied to a specific person, not just a device
• Can be great as a secondary authentication factor

However, to avoid common biometric authentication risks, such as spoofing, data theft or compliance issues, organizations need strong governance controls. For example:

• Store biometric data in encrypted systems
• Avoid keeping raw biometric data; use templates instead
• Apply strict access controls to biometric databases
• Regularly audit biometric systems and usage logs
• Ensure compliance with privacy regulations (like GDPR or CCPA)

As identity becomes the front line of defense in cloud environments, modern organizations are moving beyond simple login methods to adopt advanced authentication systems that combine strong security with efficient governance.

Here are some features of these modern systems:

• Link authentication events to entitlement reviews, so access rights are automatically reviewed and adjusted over time
• Support for just-in-time access, where elevated privileges are only granted when needed, and then revoked automatically
• Integration with privileged access management tools (like One Identity Safeguard) to secure critical resources
• Built-in scalability to handle large volumes of login requests without delays or failures
• Continuous authentication that monitors user behavior to detect compromised accounts early
• Role-based access controls that adjust dynamically based on user activity and risk level

Why One Identity is a strong choice

One Identity brings together several identity and access management (IAM) features into one unified identity platform:

• Adaptive multi-factor authentication that changes based on risk level
• Password management tools to reduce reset requests and weak credentials
• Automated provisioning and deprovisioning of users across cloud and on-prem apps
• A policy engine that supports step-up authentication using methods like YubiKey, RSA SecurID or one-time passwords
• Centralized control for IT teams to manage access policies, user roles and audit logs in one place

This combination of automation, flexibility and strong governance makes the One Identity Fabric well-suited for organizations looking to strengthen security without adding complexity.

Finally, let’s explore some common issues related to identity authentication, and how to debug them:

Incorrect time synchronization

Authentication protocols like Kerberos and SAML rely on accurate system clocks. If there’s a time mismatch, token validation can fail.

Troubleshooting:

• Check if the system clock is out of sync with the identity provider or domain controller
• Use NTP (Network Time Protocol) to keep clocks aligned across all systems
• Restart authentication services after correcting time settings

Expired or invalid certificates

Expired or untrusted SSL/TLS certificates or SAML signing certificates can cause failures during token exchange.

Troubleshooting:

• Check certificate expiry dates on both IdP and service provider sides
• Replace or renew expired certificates
• Ensure that the certificate chain is valid and trusted by all involved systems

Misconfigured identity provider settings

Wrong URLs, incorrect metadata or mismatched identifiers can block communication between the identity provider and the service.

Troubleshooting:

• Double-check SAML/OIDC configuration settings: ACS URL, Entity ID and metadata URLs etc.
• Verify that the identity provider has the correct service provider settings
• Use tools like SAML-tracer to inspect failed login responses

Identity authentication is an important security mechanism that helps verify users before granting access to secure systems or data. As organizations grow and shift to cloud-based environments, well-governed authentication methods become increasingly critical for security and operational stability.