oidc-jwt-verifier 0.1.4

Shared, hardened JWT verification core for OIDC/JWKS issuers

oidc-jwt-verifier

oidc-jwt-verifier is a small, framework-agnostic JWT verification core for OIDC/JWKS issuers.

It is designed to be shared by higher-level adapters (Dash, Bottle, Lambda, FastAPI) while keeping security decisions centralized and consistent.

Install

pip install oidc-jwt-verifier

For development:

uv pip install -e ".[dev]"

Quickstart

from oidc_jwt_verifier import AuthConfig, JWTVerifier

config = AuthConfig(
    issuer="https://example-issuer/",
    audience="https://example-api",
    jwks_url="https://example-issuer/.well-known/jwks.json",
    allowed_algs=("RS256",),
    required_scopes=("read:users",),
)

verifier = JWTVerifier(config)
claims = verifier.verify_access_token(token)

Secure-by-default behavior

The verifier:

• Verifies signature, iss, aud, exp, and nbf (when present).
• Uses an explicit algorithm allowlist and rejects alg=none.
• Enforces minimum cryptographic key lengths by default (configurable via enforce_minimum_key_length).
• Fails closed on malformed tokens, JWKS fetch errors, timeouts, missing keys, and missing kid.
• Never derives a JWKS URL from token headers, and rejects tokens that include jku, x5u, or crit.
• Supports Auth0-style multi-audience tokens (aud as an array) and enforces required scopes and permissions.

Auth0 guidance for API token validation calls out validating the JWT and then checking aud and scopes in the scope claim. See the Auth0 docs for details.

Error handling

The public exception type is AuthError.

AuthError carries:

• code: stable, machine-readable reason
• status_code: 401 (authentication) or 403 (authorization)
• www_authenticate_header(): an RFC 6750 compatible WWW-Authenticate value for Bearer auth

from oidc_jwt_verifier import AuthError

try:
    claims = verifier.verify_access_token(token)
except AuthError as err:
    status = err.status_code
    www_authenticate = err.www_authenticate_header()

Why this library

JWT verification for APIs is easy to get mostly right while still missing important security and interoperability details. This library is a small, framework-agnostic core that centralizes conservative verification policy (claims, algorithms, header handling) and authorization checks (scopes/permissions) so you can reuse it across projects.

For comparisons against common alternatives (PyJWT directly, discovery-driven verifiers, framework integrations), see docs/alternatives.md.

Contributing

We use Conventional Commits to automate releases via release-please.

Commit prefixes:

• feat: - New feature (bumps PATCH pre-v1.0)
• feat!: - Breaking change (bumps MINOR pre-v1.0)
• fix: - Bug fix (bumps PATCH)
• docs: - Documentation only
• chore: - Maintenance tasks
• refactor: - Code refactoring
• test: - Test changes
• perf: - Performance improvements

PRs without conventional commit prefixes will not trigger releases.

References

• Auth0: Validate Access Tokens: https://auth0.com/docs/secure/tokens/access-tokens/validate-access-tokens
• Auth0: Validate JSON Web Tokens: https://auth0.com/docs/secure/tokens/json-web-tokens/validate-json-web-tokens
• RFC 8725: JSON Web Token Best Current Practices: https://datatracker.ietf.org/doc/html/rfc8725
• RFC 9700: Best Current Practice for OAuth 2.0 Security: https://www.rfc-editor.org/info/rfc9700
• PyJWT docs and examples: https://pyjwt.readthedocs.io/en/stable/usage.html