Access Token

An Access Token is used in OAuth 2.0 and OpenID Connect for granting a client application access to a user's data on a resource server. Acting as a bearer token, it enables the client to perform authorized actions on behalf of the user. Access Tokens are designed to be short-lived to enhance security, with the possibility of being refreshed. Detailed specifications and use cases for Access Tokens are provided in the OAuth 2.0 specification.


The Authentication Context Class Reference (ACR) value in OpenID Connect specifies the authentication context class that the authentication performed satisfied. It"s useful for clients needing assurance about the authentication context, such as the use of multi-factor authentication. ACR values and their significance are discussed in OpenID Connect Core 1.0.


Authentication Methods References (AMR) in OpenID Connect indicate the methods used in the authentication process, such as passwords, biometrics, or OTP. AMR values provide insight into the security level of the authentication performed. Their usage and examples are provided in OpenID Connect Core 1.0.


Argon2 is a password-hashing function that won the Password Hashing Competition and is designed to resist both memory and time-based attacks. More details can be found at GitHub Repository of PHC Winner Argon2.


ASP.NET MVC is a web application framework developed by Microsoft, which implements the model-view-controller pattern. More details are available at Microsoft Docs.


Authentication confirms a user's claimed identity in OpenID Connect, typically through credentials like passwords or biometrics. It is a core component, enabling secure user verification. OpenID Connect defines several authentication mechanisms to cater to different requirements, elaborated in OpenID Connect Core 1.0.

Authorization Code Flow

The Authorization Code Flow in OAuth 2.0 and OpenID Connect is a secure method for obtaining both authentication and authorization data. It involves exchanging an authorization code for tokens, ideal for server-side applications requiring high security. This flow is detailed in OpenID Connect Core 1.0 and RFC 6749.

Authorization Codes

The Authorization Code is a temporary, intermediary token used in the Authorization Code Flow. Issued after a user"s authentication and consent, it"s exchanged for an access token and possibly a refresh token through a secure server-to-server transaction. This process keeps access tokens secure and prevents them from being exposed in environments like web browsers, enhancing security. The code is generally short-lived and designed for single use to reduce interception risks.

Authorization Endpoint

The Authorization Endpoint plays a crucial role in OAuth 2.0 and OpenID Connect by initiating the authentication and consent process. It is where the client redirects the user to authenticate and approve or deny access to their data. Successful authentication and consent lead to the issuance of an authorization code or tokens. This endpoint's operation is detailed in both the OAuth 2.0 specification and the OpenID Connect Core 1.0.

Authorization Server

The Authorization Server is a pivotal component in OAuth 2.0 and OpenID Connect, tasked with authenticating the user, obtaining their consent, and issuing tokens to clients. This server ensures that access to resources is secured, allowing only authorized clients to obtain access tokens. It plays a vital role in controlling access to protected resources and is extensively detailed in OAuth 2.0 and OpenID Connect specifications.

Authorization Server Issuer Identifier

The Authorization Server Issuer Identifier uniquely identifies the issuer of tokens in OAuth 2.0, enhancing security by ensuring that tokens can be correctly attributed to their issuing server. This identifier is crucial for the validation of tokens by relying parties. Its importance and implementation details are discussed within the OAuth 2.0 documentation, providing a framework for secure token issuance and management.


The Authorized Party (AZP) claim in OpenID Connect ID Tokens specifies the client ID of the authorized party for which the token was issued. This claim is crucial for identifying the rightful audience of the token, ensuring that tokens are used by the intended client. More about the AZP claim can be found in OpenID Connect Core 1.0.


Back-channel communication

Back-channel communication is a secure, server-to-server information exchange over HTTPS, critical for OAuth 2.0 and OpenID Connect operations like token exchange. This method ensures that data passes securely between trusted servers, a security cornerstone outlined in both OpenID Connect and OAuth 2.0.

Back-Channel Logout

Back-Channel Logout in OpenID Connect allows secure server-to-server communication to log out users, ensuring consistency across all user sessions. This mechanism is critical for maintaining security and is detailed in OpenID Connect Back-Channel Logout 1.0.


Bcrypt is a password hashing function designed for secure password storage by incorporating a salt and repeated hashing. Further information can be found at Wikipedia.

Bearer Token Usage

Bearer Token Usage in OAuth 2.0 and OpenID Connect involves the client presenting the bearer token to access protected resources. The possession of the token grants the bearer access, emphasizing the importance of secure transmission mechanisms. Bearer tokens must be protected from unauthorized access and theft, as outlined in RFC 6750, which discusses the security considerations and best practices for bearer token usage.



Claims in OpenID Connect are pieces of information asserted about a user, such as the user's name or email address. These are included in the ID Token and are essential for conveying user identity information securely between the provider and the client. The standard set of claims and their usage is defined in OpenID Connect Core 1.0.

Client Application

Client Application is a software that interacts with OpenID Connect servers to authenticate users and obtain access tokens. Detailed information can be found at OpenID Connect Core 1.0.

Client Secret

A Client Secret acts as a password for the client application to authenticate itself to the authorization server. It ensures only registered and verified clients can request tokens and access user information.

Confidential Client

In OAuth 2.0 and OpenID Connect, a Confidential Client securely stores credentials like a client secret. Operating in controlled environments, these clients authenticate when requesting tokens, enhancing security. Details are in RFC 6749.


Consent in OpenID Connect is the user's explicit approval to share identity information with a client application. It is a foundational aspect of user privacy and data protection, requiring clear user agreement. The protocol for consent and its critical role in secure data sharing is outlined in OpenID Connect Core 1.0.


Cross-Origin Resource Sharing (CORS) is a web technology that allows resources to be requested across different origins, enhancing the security and functionality of web applications. It enables web applications to interact with resources hosted on different domains securely. CORS is crucial for modern web development, allowing APIs and services to be more accessible and secure. Implementing guidelines can be found at Fetch Living Standard.


Device Authorization Grant

The Device Authorization Grant is an OAuth 2.0 extension enabling devices with no browser or limited input capability to authenticate and authorize users. It facilitates user interaction on a secondary device, enhancing accessibility for a wide range of devices. This grant type is particularly useful for IoT devices and smart appliances. Detailed guidance on its implementation can be found in RFC 8628, providing a comprehensive framework for device-based authorization.


Dependency Injection (DI) is a design pattern that allows for Inversion of Control between classes and their dependencies, enhancing modularity and testability. For more official details, visit Microsoft Docs.


Discovery mechanisms in OpenID Connect enable clients to automatically find information about OpenID Providers, such as endpoints and capabilities, simplifying integration and configuration processes. This automated discovery is detailed in the OpenID Connect Discovery 1.0 specification.

Discovery Document

The Discovery Document in OpenID Connect is a JSON document that contains key configuration information about the OpenID Provider, including supported features and available endpoints. This document facilitates dynamic discovery and interaction with the provider, enhancing client integration. Detailed in the OpenID Connect Discovery 1.0 specification, it supports automatic client configuration.

Dynamic Client Registration

Dynamic Client Registration in OAuth 2.0 allows clients to register with authorization servers dynamically, facilitating easier integration and management of client credentials. This process is key for scalable and flexible client management, as elaborated in RFC 7591.



In OAuth 2.0 and OpenID Connect, an Endpoint is a specific URL where a web service can be accessed by a client application. These endpoints enable the structured and secure exchange of information, such as authentication, authorization, token issuance, and user information retrieval. The proper configuration and use of endpoints are critical for the security and functionality of authentication flows, as elaborated in both OAuth 2.0 and OpenID Connect standards.

Essential Claim

An Essential Claim in OpenID Connect specifies a claim that the client application deems necessary for its operation. These claims are vital for the application's functionality, and their absence may impair the application's ability to function properly. The mechanism for requesting essential claims allows for greater assurance in the authentication process. The use and requirements for essential claims are discussed in the OpenID Connect Core 1.0 specification.


Front-channel communication

Front-channel communication involves the direct transmission of information through the user's browser, commonly used in authentication and authorization protocols for redirecting users and conveying responses. Despite its susceptibility to interception, it's secured with SSL/TLS and careful token handling. The strategic use of front-channel communication in securely managing user interactions is detailed in OpenID Connect and OAuth 2.0 documentation.

Front-Channel Logout

The Front-Channel Logout process in OpenID Connect provides a method for logging out users across multiple applications using the browser's front channel, ensuring a unified logout experience. Details on implementing this logout mechanism are provided in the OpenID Connect Front-Channel Logout 1.0.


Hexagonal Architecture

The Hexagonal Architecture, or Ports and Adapters, structures an application to promote separation of concerns. Core logic resides at the center, while interactions with the outside world occur through 'ports' with corresponding 'adapters'. This approach facilitates easy component swapping and testing, supporting clean and maintainable code.

Hybrid Flow

The Hybrid Flow in OpenID Connect combines elements of the Authorization Code and Implicit Flows, offering flexibility in how tokens are returned to the client. It's useful for applications requiring immediate access to an ID Token while also needing an authorization code to obtain an access token. The Hybrid Flow is elaborated in OpenID Connect Core 1.0.


ID / Identifier

An ID or Identifier in OpenID Connect is a crucial element, like the ID Token, representing the authenticated user's identity information. It ensures unique identification across participating systems. Identifiers like 'sub' are essential for user distinction. For in-depth details, see OpenID Connect Core 1.0.

ID Token / Identity Token

An ID Token in OpenID Connect is a JSON Web Token (JWT) that contains authenticated user identity information. Issued by the Authorization Server, it includes claims like the issuer, subject, and audience, essential for verifying the user's identity. ID Tokens facilitate secure and efficient user authentication across different applications. The concept and usage of ID Tokens are detailed within OpenID Connect Core 1.0.


Identification within OpenID Connect protocol involves presenting a unique identifier such as a username or email. This initial action is distinct from authentication; it merely signals the system to recognize the user's claimed identity. It's the critical first link in the authentication chain, leading to subsequent verification stages. Detailed guidance on identification can be found in the OpenID Connect Core 1.0 specification.


Identity in OpenID Connect represents a set of claims about a user, authenticated by an Identity Provider (IdP). It includes essential information like the user's name and email. OpenID Connect utilizes identity to secure and simplify authentication across various services. See more in OpenID Connect Core 1.0.

Identity Provider

An Identity Provider (IdP) authenticates users and manages digital identities within OpenID Connect and SAML protocols. By enabling SSO, IdPs improve security and user experience. More on IdPs is in OpenID Connect Core 1.0.

Implicit Flow

The Implicit Flow in OpenID Connect was designed for clients incapable of securely maintaining a client secret, such as browser-based applications. It directly returns tokens to the client following authentication, bypassing the need for an authorization code exchange. This flow, specified in OpenID Connect Core 1.0, is less recommended due to security concerns.

Introspection Endpoint

The Introspection Endpoint in OAuth 2.0 allows clients to query the state of a token, confirming its validity and scope. This endpoint enhances security by enabling real-time validation of tokens, as outlined in RFC 7662.


An Issuer in OpenID Connect is responsible for user authentication and token issuance, identified by a unique URI. They play a pivotal role in maintaining secure user authentication. The role of the Issuer is elaborated in OpenID Core 1.0 specification, accessible at OpenID Connect Core 1.0.



JWT Secured Authorization Request (JAR) enhances OAuth 2.0 by allowing clients to send requests as JWTs, securing parameters against tampering. This approach adds an additional layer of security and is documented in RFC 9101.


The JSON Object Signing and Encryption (JOSE) suite of standards enables secure transmission of JSON objects through signing and encryption. It comprises JWT, JWS, JWE, and JWK, each playing a crucial role in web security by ensuring data integrity, authentication, and confidentiality. JOSE is pivotal in protocols like OpenID Connect and OAuth 2.0, securing data exchanges in various applications. More on JOSE standards can be explored at RFC 7515 (JWS) and related documents.


The JSON Web Algorithms (JWA) standard defines cryptographic algorithms for use in the context of JSON-based data structures, including JWTs, JWS, and JWE. It ensures interoperability by specifying commonly agreed-upon algorithms for digital signatures, encryption, and key management. JWA is a foundational component of the JOSE framework, facilitating secure data exchange in web security protocols. Specification details can be found at RFC 7518.


JSON Web Encryption (JWE) provides a structured way to encrypt JSON objects, ensuring confidentiality of data within a JSON structure. Part of the JOSE framework, JWE is crucial for secure data transmission in web applications, including scenarios requiring privacy and data protection. It complements JWS and JWT in providing a comprehensive suite for data security. Learn more about JWE at RFC 7516.


A JSON Web Key (JWK) is a JSON format for representing cryptographic keys. This format allows for easy sharing and usage of keys in web environments, supporting various cryptographic operations essential for secure data exchange, including signing and encryption. JWKs are fundamental in the JOSE specification for managing keys in a standardized way. Detailed information on JWK can be found in RFC 7517.


A JSON Web Key Set (JWKS) is a collection of JSON Web Keys (JWK) used to distribute public keys. Clients use these keys to verify the signature of JWTs, enhancing the security of digital communications in web applications. The JWKS format is an essential aspect of secure key management within the JOSE framework, supporting protocols such as OpenID Connect and OAuth 2.0. For detailed information, visit RFC 7517.


JSON Web Signature (JWS) represents digital signatures or Message Authentication Codes (MACs) for JSON objects, ensuring data integrity and secure message transmission. It is a fundamental part of the JOSE framework, used widely in web security protocols to validate the authenticity of information exchanges. JWS plays a critical role in securing JSON Web Tokens (JWTs) among other data structures. For more details, see RFC 7515.


JSON Web Token (JWT) is a compact, URL-safe method of representing claims securely between two parties. Used in authentication and information exchange, JWTs contain encoded JSON objects, including claims and signatures, ensuring data integrity and authentication. They are integral to OAuth 2.0 and OpenID Connect for secure user authentication. Detailed standards are outlined in RFC 7519.

JWT Profile for OAuth 2.0 Access Tokens

The JWT Profile for OAuth 2.0 Access Tokens standardizes their format as JWT, improving interoperability and security by enabling structured claims. This profile facilitates consistent token handling across services, as discussed in RFC 9068.


Logout Token

A Logout Token is used in OpenID Connect's logout processes to securely convey logout signals between the OpenID Provider and the relying party. It is a JSON Web Token that includes specific claims related to the logout event, ensuring consistent session management across different applications. The use and format of Logout Tokens are specified in OpenID Connect Back-Channel Logout 1.0, facilitating secure and synchronized logout functionalities.


Mutual TLS Client Authentication

Mutual TLS Client Authentication in OAuth 2.0 enhances security by requiring both the client and server to authenticate via TLS, ensuring a higher level of trust. This method is particularly vital in sensitive transactions and is outlined in RFC 8705.

MVC Controller

MVC Controller in the context of MVC architecture, refers to the component that handles user input, processes requests, and returns responses. More details can be found at Microsoft Docs.



NCache is an in-memory distributed caching solution for .NET and Java applications, designed to boost application performance by reducing database load. More information is available at NCache Official Site.


The Nonce parameter in OpenID Connect prevents replay attacks by ensuring that an ID Token cannot be used more than once. It's a unique string included in the authentication request and validated in the ID Token response. Nonce usage is critical for maintaining the integrity of the authentication process, as discussed in OpenID Connect Core 1.0.

NuGet Package

NuGet Package is a single ZIP file with the .nupkg extension that contains compiled code (DLLs), related files, and a descriptive manifest for use within .NET projects. More details are available at Microsoft Docs.


OAuth 2.0

OAuth 2.0 is a widely adopted authorization framework that enables applications to secure designated access to user resources without exposing user credentials. It supports a variety of grant types to accommodate different client types and authorization flows, providing a flexible and robust security model. OAuth 2.0 lays the groundwork for building secure and scalable authentication and authorization solutions, as extensively detailed in RFC 6749.

OAuth 2.0 DPoP

OAuth 2.0 DPoP (Demonstrating Proof-of-Possession) introduces a method for clients to demonstrate possession of a cryptographic key, enhancing security by binding tokens to client proofs. This mechanism prevents token replay attacks, significantly increasing OAuth 2.0 security, as outlined in RFC 8705.

OpenID Configuration / Discovery Endpoint

The Discovery Endpoint returns OpenID Provider Metadata, facilitating automatic client configuration. This endpoint is a cornerstone of the OpenID Connect Discovery process, enabling clients to find provider information efficiently. More on this can be found in OpenID Connect Discovery 1.0.

OpenID Connect

OpenID Connect is a robust authentication layer on top of OAuth 2.0, allowing clients to verify the identity of end-users and obtain their profile information. It introduces ID Tokens, which carry authenticated user information, enhancing security and user experience across various services. For comprehensive standards and guidelines, refer to OpenID Connect Core 1.0.

OpenID Connect Provider

An OpenID Connect Provider (OP) is a service that authenticates users and issues tokens within the OpenID Connect framework. It facilitates secure user authentication across different services, supporting features like single sign-on (SSO) and identity federation. The OP plays a central role in the OpenID Connect ecosystem, ensuring seamless and secure access to applications. For an in-depth understanding of OpenID Providers, refer to OpenID Connect Core 1.0.

OpenID Provider Metadata

OpenID Provider Metadata describes the capabilities of an OpenID Provider, including endpoints and supported features. This information allows clients to dynamically configure themselves to interact with the provider. The metadata format is detailed in the OpenID Connect Discovery 1.0 specification.



Pushed Authorization Requests (PAR) improve security by allowing clients to send authorization requests directly to the authorization server, rather than through the user"s browser. For more information, refer to RFC 9126.


Password-Based Key Derivation Function 2 (PBKDF2) is a cryptographic algorithm that derives a secure encryption key from a password using a salt and many iterations. More information is available at RFC 2898.


Proof Key for Code Exchange (PKCE) is a security enhancement for OAuth 2.0 that mitigates authorization code interception attacks in public clients. Detailed information is available at RFC 7636.


The Pairwise Pseudonymous Identifier (PPID) in OpenID Connect enhances user privacy by assigning a unique identifier to each user-client pair, preventing tracking across applications. PPIDs ensure that user identity remains anonymous, providing a significant privacy advantage in digital interactions. The concept and implementation of PPIDs are thoroughly explained in the OpenID Connect Core 1.0, highlighting their importance in protecting user anonymity.


In the context of web authentication and authorization, Processing involves the handling and validation of tokens and claims, crucial for secure and efficient access control. This includes verifying token authenticity, extracting and utilizing user information, and enforcing access policies based on validated claims. Detailed processes and best practices for securely processing authentication and authorization data are outlined in OpenID Connect and OAuth 2.0 protocols.

Public Client

A Public Client in OAuth 2.0 and OpenID Connect refers to an application that cannot securely store client secrets, typically due to operating in an environment accessible to the user, such as browsers or mobile devices. Public clients rely on alternative flows like PKCE to maintain security. The distinction between public and confidential clients and the specific requirements for public clients are thoroughly described in RFC 6749.


Redirection Attacks

Redirection Attacks exploit unvalidated redirects in web applications, leading users to malicious sites. Further details on prevention and examples are available at CWE-601.


Redis is an in-memory data structure store, used as a database, cache, and message broker. Further details can be found at Redis Official Site.

Refresh Token

A Refresh Token is a component of OAuth 2.0 and OpenID Connect that allows a client to obtain a new access token when the current one expires. It supports seamless user access by enabling long-lived sessions without repeated authentication prompts. The mechanism for refresh token use and its critical role in maintaining user sessions is extensively covered in OAuth 2.0 specification.

Resource Indicators for OAuth 2.0

Resource Indicators for OAuth 2.0 enable clients to specify the target resource server during token requests, directing the authorization server to issue access tokens with appropriate scopes. This specification ensures more granular access control, as described in RFC 8707.

Revocation Endpoint

The Revocation Endpoint enables clients to invalidate tokens, ensuring that compromised or outdated tokens can no longer access protected resources. This mechanism is crucial for maintaining security and is described in RFC 7009.


In OAuth 2.0 and OpenID Connect, a Relying Party (RP) / Client is an application that requests and relies on authentication and authorization information provided by an Identity Provider or Authorization Server. It utilizes tokens to access user data and perform actions on behalf of the user, ensuring secure and personalized user interactions. The roles, registration, and security considerations for relying parties are detailed in OAuth 2.0 and OpenID Connect Core 1.0.

RP-Initiated Logout

RP-Initiated Logout allows a Relying Party to initiate the logout process, ensuring users can securely sign out across all sessions. This OpenID Connect feature maintains session integrity and user security, as specified in OpenID Connect RP-Initiated Logout 1.0.



In OAuth 2.0 and OpenID Connect, Scope defines the extent of access that the client is requesting over the user's data. It's a parameter in authorization requests that specifies the desired permissions, directly influencing the data accessible via tokens. The concept and application of scopes are detailed in RFC 6749.


A Session in OpenID Connect is a state that maintains the user's authentication with the client and Identity Provider (IdP). It ensures users remain authenticated across multiple interactions, reducing the need for frequent logins. Effective session management is critical for security and user experience. The OpenID Connect Session Management specification provides detailed guidelines, available at OpenID Connect Session 1.0.

Session Management

Session Management in OpenID Connect involves maintaining and monitoring user sessions to ensure continuous authentication and a seamless user experience. It includes mechanisms for session creation, maintenance, and termination, as outlined in OpenID Connect Session Management 1.0.


SHA-512 is a cryptographic hash function that generates a 512-bit hash value, commonly used for security applications such as digital signatures and certificates. Further details can be found at NIST FIPS 180-4.


The Single Responsibility Principle (SRP) is a foundational concept in object-oriented programming, asserting that a class should have only one reason to change. This principle, part of the SOLID guidelines, emphasizes that a class should tackle one job, reducing complexity, and improving maintainability. SRP is key for achieving modular and scalable code, making it easier to debug and update. Further explanation can be found at Wikipedia.


Single Sign-On (SSO) is an authentication process that allows a user to access multiple applications with one set of login credentials. For more information, see Wikipedia.

Subject Identifier

The Subject Identifier is a unique ID for a user, issued by the OpenID Provider, ensuring user anonymity across different clients. It's fundamental for maintaining user privacy and preventing tracking. The use and significance of subject identifiers are detailed in OpenID Connect Core 1.0.


Token Endpoint

The Token Endpoint in OAuth 2.0 and OpenID Connect is where the client exchanges an authorization grant for an access token, refresh token, and sometimes an ID token. This secure exchange is crucial for accessing protected resources and is detailed in RFC 6749 and the OpenID Connect Core 1.0 specification.

Token Exchange

The Token Exchange mechanism in OAuth 2.0 enables the secure exchange of one type of token for another, facilitating flexible access control scenarios. This feature supports delegation and impersonation use cases, as specified in RFC 8693.

Token Introspection

The Token Introspection endpoint in OAuth 2.0 enables clients to query the state of a token, such as its activity and scope, ensuring that tokens are still valid and have not been revoked. This secure verification process is detailed in RFC 7662, supporting enhanced security measures.

Token Revocation

Token Revocation enables OAuth 2.0 clients to inform the Authorization Server that a particular token (access or refresh) should be invalidated, enhancing security by preventing its further use. This mechanism is critical for responding to security incidents or managing token lifecycles. The procedures for token revocation and its significance in OAuth 2.0 are outlined in RFC 7009, providing guidance on implementing secure token management practices.


User / End-User

The terms User and End-User refer to the individual in the OpenID Connect ecosystem. A User interacts with applications, while an End-User is specifically the subject of authentication in OpenID Connect. This distinction is crucial for understanding various roles within the authentication flow, as detailed in OpenID Connect Core 1.0.

User Agent

The User Agent acts on behalf of the user, typically a web browser, in OpenID Connect flows. It facilitates user interaction with the authentication and consent processes. Understanding the role of user agents is vital for implementing OpenID Connect authentication workflows, as described in OpenID Connect documentation.



Validation in web security refers to the process of verifying the authenticity and integrity of tokens and claims, ensuring that the data exchanged between parties is genuine and untampered. This step is crucial for confirming the legitimacy of user identities and the permissions granted to clients. Validation techniques and their importance in securing authentication and authorization flows are discussed in both OpenID Connect Core 1.0 and OAuth 2.0 protocols.

Voluntary Claim

Voluntary Claims in OpenID Connect are optional information pieces that an application may request from a user, providing flexibility in the authentication process. These claims can enrich user profiles or enhance application functionality without being critical for operation. The protocol for requesting and using voluntary claims, along with examples, is detailed in the OpenID Connect Core 1.0, illustrating their role in customizable user authentication and authorization.