# Mojo-V: Secret Computation for RISC-V **Mojo-V** (pronounced *“mojo-five”*) is a new RISC-V extension that introduces privacy-oriented programming capabilities for RISC-V. Mojo-V implements secret computation, enabling secure, efficient, and data-oblivious execution without reliance on fragile software and programmer trust. By sequestering sensitive data in dedicated secret registers and encrypting memory under a third-party key, Mojo-V prevents disclosures and enforces computation that is both blind (no direct disclosures) and silent (no side channel leakage). The design integrates seamlessly into the existing RISC-V ISA with only a mode bit and four new instructions, enforced entirely at decode. Early results show near-native execution speeds while offering over 5-7 orders of magnitude performance improvement compared to fully homomorphic encryption (FHE), with a clear roadmap for integration into CPUs, GPUs, and specialized accelerators. To learn more... - Here is an intro video describing Mojo-V: https://www.youtube.com/watch?v=HUT46TcNyyM - Slides that give an overview of the Mojo-V project: https://drive.google.com/file/d/1VVzZqYHvQgnKMgXZjg7I_cX2GzF7awSN The current Mojo-V ISA Extension Specification (release 0.92): - [In PDF format.] (https://drive.google.com/file/d/1pargKATFoQdy94i6bI3P_9mfNA_GsYSw) To contact the developers of Mojo-V: - Email: [mojov-devs@umich.edu](mailto:mojov-devs@umich.edu) # 🧩 Mojo-V Reference Platform — Release 0.92 ## 🚧 Project Status The Mojo-V reference platform release 0.92 implements secret integer and floating-point computation using a fixed symmetric key cipher. Mojo-V supports three encryption modes: fast, strong, and proof-carrying. As of this release, 64-bit secret computation is fully secretized and this early reference platform can be used for software development and red-teaming. Additional capabilities will be rolled out in future releases, including PKI support, LLVM compiler support, 32-bit RISC-V support, VIP-Bench benchmarks support, etc. **Specification Version:** 0.92 (November 2025) **Contact:** [mojov-devs@umich.edu](mailto:mojov-devs@umich.edu) ## Current components 1. **Mojo-V ISA Spec v0.92** - released in `doc/` 2. **Spike (Instruction Set Simulator) Implementation** - Mojo-V integrated into `riscv-isa-sim`, nearly feature-complete - Missing only: Public-Key Infrastructure (PKI) support (currently uses fixed keys with a Simon-128 cipher) - To run Spike with Mojo-V extensions enabled, add the `--isa=rv64gc_zicond_zkmojov_zicntr` flag when running `spike` 3. **Mojo-V Bringup-Bench Benchmarks** - Hand-coded examples (e.g., bubble-sort) showing Mojo-V working secret computation - Full battery of security tests for RV64GC+Mojo-V Note, the remainder of the Bringup-bench benchmarks have NOT been ported to Mojo-V, as yet. ## ⚙️ Building and Running the Mojo-V Reference Platform ### A. Install a RISC-V LLVM Compiler You’ll need an LLVM-based RISC-V cross-compiler capable of producing `RV64GC` binaries. Here is a good place to start: https://clang.llvm.org/get_started.html ### B. Clone the Mojo-V Repository ```bash git clone https://github.com/toddmaustin/mojo-v.git cd mojo-v ``` ### C. Build the RISC-V Spike simulator with Mojo-V Support ```bash sudo apt-get install device-tree-compiler libboost-regex-dev libboost-system-dev cd riscv-isa-sim mkdir build cd build ../configure --prefix=$RISCV make ``` ### D. Build and Run Mojo-V Bringup-Bench Benchmark Tests 1. **Build the Spike device driver** ```bash cd bringup-bench/target make ``` 2. **Configure your compiler** Edit `../Makefile` and set `TARGET_CC` for the `mojov` target to the location of your LVM Clang-based RISC-V compiler. 3. **Build and test** ```bash cd .. # go to the top-level bringup-bench directory make mojov-tests # run all Mojo-V tests ``` As an alternative, you can run an individual benchmark by going into its directory and running the following command. ```bash cd ../mojov-test make TARGET=mojov clean build test ``` ## 🧪 Mojo-V Bringup-Bench Benchmarks Overview | Program | Description | |:---------|:-------------| | `mojov-test` | Intro example from slides | | `mojov-test1` | Secret-register and encrypted-memory semantics tests | | `mojov-test2` | Hand-coded data-oblivious integer bubble-sort benchmark with Mojo-V fast encryption (int,fast) | | `mojov-test3` | Hand-coded data-oblivious floating-point bubble-sort benchmark with Mojo-V fast encryption (fp,fast) | | `mojov-test4` | Hand-coded data-oblivious integer bubble-sort benchmark with Mojo-V strong encryption (int,strong) | | `mojov-test5` | Hand-coded data-oblivious floating-point bubble-sort benchmark with Mojo-V strong encryption (fp,strong) | | `mojov-pctests` | Hand-coded integrity checking test suite for RV64GC+Mojo-V that includes positive and negative tests for Mojo-V's proof-carrying encryption format (proofcarrying) | | `mojov-sectests` | Hand-coded security test suite for RV64GC+Mojo-V that includes 130 pos + 245 neg tests == 375 total (int,fp,fast,strong) | All test benchmarks are hand-coded assembly programs demonstrating Mojo-V ISA rules and security semantics. The other Bringup-Bench benchmarks have not yet been ported to Mojo-V. --- ## Code Licensing All of the Mojo-V related code in this repo is released under the license of the tool it modified (e.g., Spike, LLVM, Bringup-Bench). Please see the tools' respective directories for licensing details. --- ## 💬 Questions & Feedback We welcome contributions, bug reports, and suggestions! 📧 **Email:** [mojov-devs@umich.edu](mailto:mojov-devs@umich.edu) 🌐 **Project Home:** [https://github.com/toddmaustin/mojo-v](https://github.com/toddmaustin/mojo-v)