How deeply does Software Security for Developers cover token introspection?

Defines the request-response flow and operational drawbacks, but does not specify implementation code or endpoint configuration.

Token introspection

As explained in Software Security for Developers

Token introspection is a validation process in which a service queries an issuer or authorization server to obtain the status and metadata of a token.

Token introspection validates an access token by having the resource server ask the identity provider (IdP) whether the token is still valid. It is especially useful for opaque tokens, which contain no readable data and cannot be validated locally. section 12.2.1 section 12.2.2

Validating an opaque token

A backend receives an access token, sends it to the IdP, and accepts or rejects the request based on the IdP’s response. This central check is straightforward, but every validation requires an HTTP request. section 12.2.1

Consider the operational tradeoffs before choosing introspection:

It tightly couples applications to the IdP; an IdP outage prevents token validation. section 12.2.1
Frequent validation requests increase IdP load, token exposure, and latency. section 12.2.1
Signed, nonopaque tokens can instead be validated with cryptographic methods and an IdP-provided public key. section 12.2.1

How Software Security for Developers covers it

Cover of Software Security for Developers

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Also explained in

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Spring Security in Action, Second EditionToken introspection is an OAuth protocol operation in which a resource server asks an authorization server whether a token is valid and requests its associated metadata.
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Secure APIsA token introspection endpoint is an authorization-server endpoint that returns metadata about an access token to an authorized client or resource server.

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Related concepts

opaque tokenused by · An opaque token is an access token whose contents are not directly interpretable by its recipient, typically requiring server-side validation or lookup.
revocationused by · Revocation is the invalidation or withdrawal of a previously issued credential, key, certificate, token, or permission before or when its authorization ends.
resource serverused by · A resource server is a service that hosts protected resources, validates access credentials such as tokens, and enforces authorization for client requests.
identity provideruses · An identity provider is a system that authenticates users or other entities and supplies identity information or authentication assertions to relying applications and services.
JSON Web Tokenalternative to · A JSON Web Token is a compact, URL-safe representation of claims encoded as a JSON object and protected by a digital signature, message authentication code, or encryption.
authorization serveruses · An authorization server is an OAuth component that authenticates clients or resource owners, obtains authorization, and issues credentials such as authorization codes and access tokens.

This explainer was generated by Manning's knowledge graph from the text of Software Security for Developers. The section links point to the parts of the book it draws on.