Hide the question and still get the answer.

Examples:

• What's the value of my client's yacht?
• How many of your patients would meet my clinical trial criteria?

Securely compare lists without errors.

Examples:

• Is that ad targeting an existing client?
• How many customers do we share?

Large financial wants to know the value of their VIP client's yachts. The identity of those clients has immense value. How do they query their data provider for those values without revealing the identity of their clients?

Pharmaceutical is considering developing a new diabetes drug that may not cause weight gain. Does a hospital partner have sufficient clinical trial participants? How many of the hospital's patients are 18-25, overweight and already on a diabetes medication?

Tractor manufacturer wants to study the efficiency of its engines at various temperatures. Farmers who buy the tractors want to maintain their privacy. How does the tractor manufacturer query the tractors without learning the identity of the farmers?

Insurer wants to recruit new customers by offering a discount via social media ads. Needs to know if ad target is an existing customer. Advertiser won't identify target and insurer doesn't want to reveal its customer list. Both parties want to maximize targeting. How do they identify the high value targets?

Airline screeners would like to identify planes with higher risk profiles. What flights have several low risk individuals? They cannot access the names on the low risk pool but would like count how many or on a specific flight.

Two retailers are considering a merger. At each store, what is the overlap in customers? How do they do that without revealing their client lists?