I had identical locks in my ancestral family home, judging by the mechanism if your photos with the lock cover removed. They will take an Ilco #2B or possibly #7B. You have to buy both keys and try them, but in the end, it will be much cheaper than the services of a locksmith. plus, the Ilco keys are solid steel and are good and durable. This can be important for old doors, which can sometiems take quite a bit of physical effort and hard key-turning to lock and unlock. Good luck!