The key and certificate files (*.key, *.csr, *.pem) are generated by generate-test-certs.sh in this directory. It requires openssl be installed.
The certificate cbor files (*.cbor) and the signed exchange files (*.sxg) in this directory are generated using generate-test-sxgs.sh.
generate-test-sxgs.sh requires command-line tools in the webpackage repository. To install them, run:
go get -u github.com/WICG/webpackage/go/signedexchange/cmd/...
The revision of the tools used to generate the test files is 99155ec.