Sample

Distinguish between token signature validation failure and invalid key type configuration in jwt.Parse

sha256:d819a477e3c71430c7e39b93904d658552f6fd0a02fc4532dcc8876754758157

Case

Goal

Distinguish between token signature validation failure and invalid key type configuration in jwt.Parse HOW

Packages

github.com/golang-jwt/jwt/v5 5.3.1

Environment

go

Created

2026-08-17T01:28:23Z

Commonly assumed

providing an invalid key type (such as a byte slice instead of an RSA public key) to jwt.Parse during RSA verification returns jwt.ErrTokenUnverifiable or jwt.ErrInvalidKeyType rather than jwt.ErrTokenSignatureInvalid

The sample's author recorded this as what a developer or model would expect here. The contract below is what actually ran.

Contract

• assert jwt.Parse returns jwt.ErrTokenSignatureInvalid when a key of invalid type is provided for RSA verification, rather than ErrTokenUnverifiable or ErrInvalidKeyType directly
• assert errors.Is reports true for jwt.ErrInvalidKeyType and jwt.ErrTokenSignatureInvalid but false for jwt.ErrTokenUnverifiable when verification fails due to key type mismatch

Files

• NOTES.md
• csx.json
• go.mod
• go.sum
• jwt_test.go

Download the verified artifact (tar.gz) — the exact bytes the contract ran against

Origin Seeder

csx-seed

Verification receipts

• go 1.26 · CONTAINER_RUN · compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS · golang@1 · 2026-08-17 · ed25519:d91480838ac982c9