This branch contains the implementation of the EXTENDED S3ORAM framework from the basic S3ORAM scheme in CCS'17 that supports k-ary tree and Circuit-ORAM layout. The full paper is available here (Feel free to email me for the free version).

This project is built on CodeLite IDE. It is recommended to install CodeLite to load the full S3ORAM workspace.

• 2018-12-30: S3ORAM now has a new scheme that leverages the eviction paradigm in Circuit-ORAM. S3ORAM now also supports k-ary tree layout.
• 2017-12-25: S3ORAM now supports more than 3 servers with higher privacy levels.

1. NTL v9.10.0

2. ZeroMQ

All S3ORAM Framework configurations are located in S3ORAM/config.h.

Enable the macro #define CORAM_LAYOUT in S3ORAM/config.h.

Modify the value in the macro #define K_ARY in S3ORAM/config.h.

Disable the macro #define CORAM_LAYOUT and enable the macro #define TRIPLET_EVICTION in S3ORAM/config.h.

#define BLOCK_SIZE 128                                -> Block size (in bytes)

#define HEIGHT 4                                      -> Height of S3ORAM Tree

static const unsigned long long P = 1073742353;       -> Prime field (size should be equal to the defined TYPE_DATA)

#define NUM_SERVERS 7                                 -> Number of servers \ell.
#define PRIVACY_LEVEL 3                               -> Privacy level t. 

const long long int vandermonde[NUM_SERVERS]          -> The first row of inverse of vandermonde matrix (should be defined according to SERVER_ID from 1....n)

const std::string SERVER_ADDR[NUM_SERVERS]            -> Server IP addresses
#define SERVER_PORT 5555                              -> Define the first port for incremental to generate other ports for client-server / server-server communications

It is recommended to select EVICT_RATE = BUCKET_SIZE/2, and BUCKET_SIZE>73 to avoid bucket overflow.

The folder S3ORAM/data is required to store generated S3ORAM data structure.

Goto folder S3ORAM/ and execute

make

, which produces the binary executable file named S3ORAM in S3ORAM/Debug/.

Run the binary executable file S3ORAM, which will ask for either Client or Server mode. The S3ORAM implementation can be tested using either single machine or multiple machines:

1. Set SERVER_ADDR in S3ORAM/config.h to be localhost.
2. Set SERVER_PORT.
3. Compile the code with make in the S3ORAM/ folder.
4. Go to S3ORAM/Debug and run the compiled S3ORAM file in different Terminals, each playing the client/server role.

1. Copy the binary file S3ORAM compiled under the same configuration to running machines.
2. For first time usage, run the S3ORAM/Debug/S3ORAM file on the client machine to initialize the S3ORAM structure first.
3. Copy the folder S3ORAM/data/i/ to server i, or follow the instruction on the client machine to transmit all data to corresponding server (It is recommend to manually copy the folder to avoid interuption during tranmission).
4. For each server i, run the compiled file S3ORAM and select the server role (option 2) and the corresponding ID i.

(to be updated)

If the code is found useful, we would be appreciated if our paper can be cited with the following bibtex format

@article{10.1145/3369108, 
author = {Hoang, Thang and Yavuz, Attila A. and Guajardo, Jorge}, 
title = {A Multi-Server ORAM Framework with Constant Client Bandwidth Blowup}, 
year = {2020}, 
issue_date = {February 2020}, 
publisher = {Association for Computing Machinery}, 
address = {New York, NY, USA}, 
volume = {23}, 
number = {1}, issn = {2471-2566}, 
url = {https://doi.org/10.1145/3369108}, doi = {10.1145/3369108}, 
journal = {ACM Trans. Priv. Secur.}, 
month = feb, 
articleno = {Article 1}, 
numpages = {35}, 
keywords = {ORAM, privacy-enhancing technologies, secret sharing} }

For any inquiries, bugs, and assistance on building and running the code, please contact me at hoangm@mail.usf.edu.