###DESCRIPTION Implementation of the passive secure OT extension protocol of [1] and the active secure OT extension protocols of [2] and [3]. Implements the general OT (G_OT), correlated OT (C_OT), global correlated OT (GC_OT), sender random OT (SR_OT), and receiver random OT (RR_OT) (Definitions of the functionalities will follow). Implements the base-OTs by Naor-Pinkas [4], Peikert-Vaikuntanathan-Waters [5], and Chou-Orlandi [6]. The code is based on the OT extension implementation of [7] and uses the MIRACL libary [8] for elliptic curve arithmetic.

Update: Implemented 1-out-of-2 OT from the 1-out-of-N OT extension of [10]. Currently only works for OTs with random sender input.

###COMPILE ####Linux: Required compiler: g++

Required libraries: OpenSSL and GMP (e.g., on Ubuntu run sudo apt-get install libssl-dev libgmp-dev)

1. Compile Miracl in util/Miracl either using "bash linux" or "bash linux64" (see util/Miracl/first.txt for more information)
2. Compile OT extension by executing make

####Windows: ATTENTION: CURRENTLY NOT TESTED.

Required compiler: mingw32

Required libraries: OpenSSL (the OpenSSL library is part of msys in mingw, can be installed using mingw-get, and the Windows $PATH variable has to be set to [PATH_TO_MINGW]\msys\1.0\bin\.)

1. Compile Miracl in util/Miracl using windows32.bat
2. Set the Paths to your MSYS directory in Makefile.bat
3. Compile OT extension by invoking Makefile.bat

###USE To start OT extension, open two terminals on the same PC and call ot.exe 0 in one terminal to start OT extension as sender and call ot.exe 1 in the second terminal to start OT extension as receiver.

###NOTES An example implementation of OT extension can be found in mains/otmain.cpp.

OT related source code is found in ot/.

Different compilation flags can be set in util/constants.h.

###TBD The current version is in a prototypical state. Next steps:

1. Better documentation. Clean interfaces and source code
2. Integration into the ABY framework [10] and Miracl [8] as external GIT project
3. Test and enable support under Windows
4. Implement all functionalities for 1-out-of-N OT extension of [9]

###REFERENCES

• [1] G. Asharov, Y. Lindell, T. Schneider, M. Zohner: More Efficient Oblivious Transfer and Extensions for Faster Secure Computation (CCS'13).
• [2] G. Asharov, Y. Lindell, T. Schneider, M. Zohner: More Efficient Oblivious Transfer Extensions with Security for Malicious Adversaries. EUROCRYPT (1) 2015: 673-701.
• [3] J. B. Nielsen, P. S. Nordholt, C. Orlandi, S. S. Burra: A New Approach to Practical Active-Secure Two-Party Computation. CRYPTO 2012: 681-700.
• [4] M. Naor, B. Pinkas: Efficient oblivious transfer protocols. SODA 2001: 448-457.
• [5] C. Peikert, V. Vaikuntanathan, B. Waters: A Framework for Efficient and Composable Oblivious Transfer. CRYPTO 2008: 554-571.
• [6] T. Chou, C. Orlandi: The Simplest Protocol for Oblivious Transfer. Online at: http://eprint.iacr.org/2015/267.
• [7] S.G. Choi, K.W. Hwang, J.Katz, T. Malkin, D. Rubenstein: Secure multi-party computation of Boolean circuits with applications to privacy in on-line market-places. In CT-RSA’12. LNCS, vol. 7178, pp. 416–432.
• [8] CertiVox, Multiprecision Integer and Rational Arithmetic Cryptographic Library (MIRACL) https://github.com/CertiVox/MIRACL
• [9] V. Kolesnikov, R. Kumaresan: Improved OT Extension for Transferring Short Secrets. In CRYPTO'13 (2).
• [10] D. Demmler, T. Schneider, M. Zohner: ABY - A Framework for Efficient Mixed-Protocol Secure Two-Party Computation. NDSS 2015.