如何在不共享人与人之间实际字符串的情况下比较两个人的两个字符串列表？

Question

For example, how can the owner of list A compare identify how many of their strings exist in List B without ever seeing List B?

List A            List B
abcdef            abcdef
ghijkl            mnopqr
stuvwx            stuvwx
yz0123            

The result should be two. As in, List A has 2 strings found in List B. This is easy enough if lists are shared in open text. But how can this answer be found without the owner of List A seeing List B?

Answer 1

您可以哈希两个列表中的字符串，然后比较哈希值。

Answer 2

If users A and B are peers with no real "system" to handle the transactions between them, then:

1. Each user enters their list into their session or client software.
2. The session or client software hashes the members of the list.
3. The session or client software then queries a database for matching hashes from user B.
4. If other users need to compare their lists with user A, the session or client software stores all hashes for user A's list in the database under records for user A.

However, if there is a real system (server) between the two users, it is able to see everyone's list entries and communicate matches back to the users.