Unbalanced labelled (private) set intersection (ulpsi)

This repository implements "unbalanced labelled private set intersection" where client's set stays private and server's set is public and client's set is way smaller than server's set. Moreover, instead of returning boolean flag indicating items at intersection, server returns labels corresponding to items at intersection. Implementation is based on protocol introduced in https://github.com/microsoft/APSI without privacy of server's set.

For now query parameters are fixed. Both item and its corresponding label should be of size 256 bits and client's set may contain upto 4096 items. Server's set can be arbitrarily large.

The implementation is not optimised for memory nor for performance and was only intended to test the client-server communication cost. If either memory and performance seem to be bottleneck, they can be improved upon.

Checkout notes for implementation details.

Run

Note Protoc compiler >= 23.4 is required. You can install it from here. Alternatively, if you are on linux then try running the following script.

First cd into ./server and run setup with desired server's set size.

For example, we run setup with 1M server set size.

export MIL=1000000
cargo run --release -- setup $MIL

Depending on the set size, setup might take anywhere between a few minutes to an hour.

After setting up the server, randomly generate client set. For example, with server set size set to 1000000, to randomly generate client set of size 4000 run the following:

cargo run --release -- gen-client-set $MIL 4000

This stores the client_set.bin file under ./../data/1000000

Finally, start the server. For example, if you ran setup for 1M then run the following:

cargo run --release -- setup $MIL

To test whether server returns corresponding labels to items in client set randomly generated above, switch to client directory. Then run

cargo run --release -- ./path/to/client_set.bin

If you ran gen-client-set for server set size 1M and client set 4000, as above, then set the path to ./../data/1000000/client_set.bin.

Note By default client set size defaults to max. capacity 4096. This is because other parameters are somewhat optimal when client set size is set to 4096. You may choose to decrease max. capacity of client set size by setting ht_size in PsiParams::default to some power of 2 >= 512. However, I should note that although this should reduce client-server and server-client communication cost, the costs will not be optimal. Most certainly the cost for smaller client set sizes can be reduced by brute forcing and finding optimal parameters.

Benchmarks

Machine	Client set size	Server set size	Item size (bits)	Label size (bits)	Client upload cost (MB)	Client download cost (MB)	Server runtime (ms)
x2idn.16xlarge	512	10M	256	256	2.55	5.27	2566
x2idn.16xlarge	512	100M	256	256	2.55	44.83	16873
x2idn.16xlarge	512	300M	256	256	2.55	132.74	48922

Machine	Client set size	Server set size	Item size (bits)	Label size (bits)	Client upload cost (MB)	Client download cost (MB)	Server runtime (ms)
x2idn.16xlarge	1024	10M	256	256	5.10	6.05	2897
x2idn.16xlarge	1024	100M	256	256	5.10	45.71	17450
x2idn.16xlarge	1024	300M	256	256	5.10	133.62	49256

Machine	Client set size	Server set size	Item size (bits)	Label size (bits)	Client upload cost (MB)	Client download cost (MB)	Server runtime (ms)
x2idn.16xlarge	2048	10M	256	256	10.19	8.20	3764
x2idn.16xlarge	2048	100M	256	256	10.19	47.27	17717
x2idn.16xlarge	2048	100M	256	256	10.19	135.28	49617

Machine	Client set size	Server set size	Item size (bits)	Label size (bits)	Client upload cost (MB)	Client download cost (MB)	Server runtime (ms)
x2idn.16xlarge	4000	10M	256	256	21	11.6	4798
x2idn.16xlarge	4000	16M	256	256	21	14.1	5906
x2idn.16xlarge	4000	100M	256	256	21	51.2	18881
x2idn.16xlarge	4000	200M	256	256	21	94.6	33976
x2idn.16xlarge	4000	300M	256	256	21	138.512	49806
x2idn.16xlarge	4000	500M	256	256	21	227	80676

Note Notice the oddity that only for server set size 10M, client download cost and server runtime gets worse as client set size increases. This is because, for benchmarks, we have re-used optimal parameters for client set size 4096 across all client set sizes.

To do's

1. Reduce run-time memory by storing item_data and label_data of InnerBox as buffers instead of Array2<u32>.
2. Replace prints logging.
3. Enable updating server's set at run-time.