thblt / badsig

A collection of GnuPG signed documents for automated signature verification testing.

Badsig

This repository is a collection of text files along with GnuPG signatures, to facilitate testing of automated signature verification software. If you plan to use this repository, please read the full README before proceeding and use your best judgment when implementing these cases.

Please notice that it’s your job to verify that the contents of this repository work as described, as expected or as would make sense, that the testing situations it describes are correctly described and match your real-world situations you’ll be facing, and so on. As the famous license says, I’m sharing this in the hope that it may be useful to others, but I don’t guarantee anything about it, not even that it does what it pretends to do, or that it makes any sense.

The signatures

You probably want to use the signed files in the signatures directory.

The file names are made of three components, and are to be read as follows:

Valid or Invalid

Whether the signature is valid or not. In Invalid file, the message has been tampered with after the signature.

KOK or KEXP

Whether the key is currently valid or has expired.

SOK or SEXP

Whether the signature is currently valid or has expired (yes, signatures do expire)

There’s also two special cases:

Unsigned

as the name suggests, this file isn’t signed.

Corrupted

the signature has been damaged and no verification can take place.

Using the cases

It takes more than just verifying each case to test all possible situation. A good test suite using these files would need to at least:

• Verify the files without the public keys in the keyring. Having signed contents but no public key is a very common case.
• Revoke the public keys, or the signature subkey, before verifying again.
• Change the keys’ ownertrust to make sure your code correctly rejects signature from untrusted keys.

A good test suite using these files would look like:

gnupg --delete-key [e-mail]
gnupg --delete-key [e-mail]
run_tests(case=missing-keys)

gnupg --import gnupg/badsig.key
gnupg --import gnupg/badsig-expired.key
run_tests(case=default)

gnupg --import-ownertrust < gnupg/never.ownertrust
run_tests(case=untrusted)

Security information

You should obviously not blindly trust random public keys from the internet.

Both the keys UIDs are on the standard example domain example.com as described in RFC 2606 and RFC 6761, so they won’t conflict with any actual email addresses.

Known limitations

This was written for parsing the output of git verify-[tag|commit] --raw. Git accepts only a single signer per object, so all these files are signed with a single key. Would you need to handle multiple signers, feel free to update mksigns.sh and send a PR!