Secure multiparty computation

MPC

• Person 1 selects a large random number, add secret to it
• Each other member add to it and pass it around
• Person 1 gets the sum + random and subtract the random
• Not secure

Secret sharing

• Obtain average number among n party using secret shares.
• Partition each secret number into n parts give n-1 to the other parties.
• Each party add up their parts and announce it.
• Add up all the parts and divide by n to get the average.