No, it's any 5 of the 15. You do the procedure for each of the 15c5 = 3003 groups of 5.
Each person is part of 1001 groups and has a separate 256-bit number for each group. To recombine the numbers, each of the 5 needs to select the number corresponding to that group.
I think this works just as well as SSS for small/moderate sized groups. It's a little less elegant because you need to know which group you're participating in at decode-time, and because it's not scalable (but there are few serious applications that need the scalability).
Each person is part of 1001 groups and has a separate 256-bit number for each group. To recombine the numbers, each of the 5 needs to select the number corresponding to that group.
I think this works just as well as SSS for small/moderate sized groups. It's a little less elegant because you need to know which group you're participating in at decode-time, and because it's not scalable (but there are few serious applications that need the scalability).