proofbundle lab files from "A Forged Receipt That Verifies" (blog.shellnetsecurity.com)
Everything runs in Docker. Tested on Docker Desktop for Mac (Apple silicon).

1. ./run.sh              builds pb-lab (proofbundle 6.3.1, needs network once), then runs
                         lab.sh inside it with --network none. Output goes to lab-output.txt;
                         generated keys and receipts land in ./work.
2. docker build -f Dockerfile.v210 -t pb-lab:2.1.0 .
   ./cross_version.sh    July's 2.1.0 vs 6.3.1, each verifying the other's receipt.

lab-output.txt and cross-version-output.txt are the real outputs quoted in the post.
Signing keys are generated fresh on every run, so your public keys will differ from mine.
./work holds private keys (signer.key, attacker.key, signer2.key). They are lab keys; delete the folder when done.