Valgrind cleanup of signing
signing_cert is owned by us while verifying, but the data we were writing to it while signing was not (directly) owned by us, so don't free it. Or well. Don't write it to a class member.
signing_cert is owned by us while verifying, but the data we were writing to it while signing was not (directly) owned by us, so don't free it. Or well. Don't write it to a class member.