Ling Ren

32 Vassar St, G890

Cambridge, MA, 02139

I am a graduate student at MIT CSAIL. My advisor is Professor Srinivas Devadas. I do research in applied cryptography, computer security and hardware. My research has been as theoretical as asymptotically better cryptographic algorithms, and as pratical as taping out a processor. I received my Bachelor's degree from Tsinghua University in Beijing, China.



For the past a few years, I worked on more efficient Oblivious RAM (ORAM) algorithms and hardware implementations. I was involved in Path ORAM, and an improved construction. Path ORAM is the simplest ORAM protocol to date. It can be written in 16 lines of pseudocode (counting endif and endfor). Path ORAM's simplicity has big impact: it can be built! In collaboration with Princeton, we taped out in 32nm technology a 25-core secure processor with an on-chip ORAM controller that encrypts, shuffles and integrity-verifies external memory. The ORAM controller has been tested to fully function at 857 MHz. The design can be found in this paper. We released our verilog source code along with test FPGA designs at

More recently, we invented Onion ORAM, the first ORAM construction with O(1) bandwidth blowup. It circumvents a known logarithmic bandwidth lower bound. A more detailed discussion on how we can (and cannot) circumvent the bound can be find in this paper.

In summer 2016, I interned at VMware Research Group. I had an amazing experience working with Dahlia Malkhi and Ittai Abraham. I worked on Solidus, a new cryptocurrency based on Byzantine consensus.

Aside from the above projects, I also worked on practical fuzzy extractors, proof of space, and ASIC resistant hash functions.

Selected Publications

Google Scholar

Ling Ren, Srinivas Devadas. Proof of Space from Stacked Expanders. Theory of Cryptography Conference (TCC), 2016b. Slides

Srinivas Devadas, Marten van Dijk, Christopher Fletcher, Ling Ren, Elaine Shi, Daniel Wichs. Onion ORAM: A Constant Bandwidth Blowup Oblivious RAM. Theory of Cryptography Conference (TCC), 2016a. Slides

Ling Ren, Christopher Fletcher, Albert Kwon, Emil Stefanov, Elaine Shi, Marten van Dijk, Srinivas Devadas. Constants Count: Practical Improvements to Oblivious RAM. USENIX Security, 2015.

Christopher Fletcher, Ling Ren, Albert Kwon, Marten van Dijk, Emil Stefanov, Dimitrios Serpanos, Srinivas Devadas. A Low-Latency, Low-Area Hardware Oblivious RAM Controller. Symposium on Field-programmable Custom Computing Machines (FCCM), 2015.

Christopher Fletcher, Ling Ren, Albert Kwon, Marten van Dijk, Srinivas Devadas. Freecursive ORAM: [Nearly] Free Recursion and Integrity Verification for Position-based ORAMs. Architectural Support for Programming Languages and Operating Systems (ASPLOS), 2015. Slides

Emil Stefanov, Marten van Dijk, Elaine Shi, Christopher Fletcher, Ling Ren, Xiangyao Yu, and Srinivas Devadas. Path ORAM: An Extremely Simple Oblivious RAM Protocol. Computer & Communications Security (CCS), 2013. Best Student Paper Award.

Ling Ren, Xiangyao Yu, Christopher Fletcher, Marten Van Dijk, and Srinivas Devadas. Design Space Exploration and Optimization of Path Oblivious RAM in Secure Processors. International Symposium on Computer Architecture (ISCA), 2013. Slides

Ling Ren, Xiaoming Chen, Yu Wang, Chenxi Zhang, and Huazhong Yang. Sparse LU Factorization for Parallel Circuit Simulation on GPU. Design Automation Conference (DAC), 2012.