# Is it possible to prove that I have half a key to decrypt file, to someone who has other half, without disclosing my part?

Is it possible to prove that I have half a key to decrypt file, to someone who has other half, without disclosing my part? Or better yet, could you suggest a place where I can read about solved and unsolvable practical cryptographic problems like this one?

However if you relax the scenario, and allow the distributor to convey an extra piece of information to both parties, then this can be achieved. Have the distributor distribute a second piece of information to both parties, for this example let it be Hash(First Half) XOR Hash(Second Half)