fix(verify): surface key parsing error for malformed PEM public keys

[peralva]

By submitting a PR to this repository, you agree to the terms within the Auth0 Code of Conduct. Please see the contributing guidelines for how to create and submit a high-quality PR for this repo.

Description

When verify() receives a malformed PEM public key, createPublicKey() throws and the error is swallowed. The key material then falls back to createSecretKey(), so the allowed algorithms default to HS* and an RS256 token fails with invalid algorithm. That message hides the real problem: the key could not be parsed.

With this change, if the key material is a string or Buffer containing -----BEGIN and createPublicKey() fails, verify() returns:

JsonWebTokenError: secretOrPublicKey is not a valid PEM key: <crypto error message>

The original crypto error is available on err.inner. HMAC secrets that do not look like PEM are unaffected and still go through createSecretKey().

No public API changes. The only behavioral change is the error returned for malformed PEM key material, which previously was invalid algorithm (or, when algorithms is passed explicitly, e.g. ['RS256'], secretOrPublicKey must be an asymmetric key when using RS256).

References

• Fixes Misleading "invalid algorithm" error on malformed public key #882
• Related: Skip failed public key parse for HMAC string secrets #1047 touches the same key-resolution block in verify.js and may conflict depending on merge order.

Testing

Added tests in test/verify.tests.js for a malformed PEM public key passed:

• as a string (sync)
• as a Buffer (sync)
• as a string with a callback

They fail on master with invalid algorithm and pass with this change. The full suite (npm test) passes: 514 passing, 1 pending. eslint is clean on the changed files.

Environment: Node.js v24.12.0 on Windows 11.

• This change adds test coverage for new/changed/fixed functionality

Checklist

• I have added documentation for new/changed functionality in this PR or in auth0.com/docs
• All active GitHub checks for tests, formatting, and security are passing
• The correct base branch is being used, if not the default branch