Composite API Keys
Composite API keys combine multiple identifiers, such as project ID plus secret, public publishable key plus restricted secret, or tenant prefix with token, into one credential system. Each part scopes access differently so leaks expose limited capability and edge gateways can route requests to the correct upstream account without sharing one omnipotent key.
Technical Architecture & Deep-Dive
Stripe publishable and secret keys illustrate the pattern: browsers hold publishable keys while servers hold secrets. Other platforms embed environment slugs in key prefixes so logs reveal origin quickly.
Edge proxies should never forward composite secrets to clients. They validate incoming keys, map them to vault-stored upstream credentials, and emit slim JSON error bodies when a component is missing. Rotating one part of the composite limits blast radius compared with a single long-lived master key.
Key Architectural Benefits
Implement Composite API Keys at the Edge
Deploy lightweight API aggregation, edge caching, and secret injection in minutes without Docker containers or complex servers.
Frequently Asked Questions
Q:Are composite keys the same as OAuth?
No. Composite keys are static identifiers. OAuth issues short-lived tokens through an authorization flow with refresh semantics.
Related Architecture Concepts
An API key is a unique secret string that identifies the application calling an API and authorizes its access. Providers use keys to authenticate requests, enforce quotas, and bill usage. Anyone holding the key can act as your application, so secret keys must stay on trusted servers.
The principle of least privilege states that every user, service, and credential should have only the minimum permissions required to perform its task. For APIs, this means using restricted keys, narrow OAuth scopes, and client tokens limited to specific endpoints.
Field masking is the technique of applying a list of allowed or excluded field paths to an API response so only selected properties are returned. Masks can be allowlists that keep named fields or denylists that remove sensitive or unnecessary ones.