# CoBRA (Coefficient-Based Reconstruction of Arithmetic) > Trail of Bits' C++23 simplifier for Mixed Boolean-Arithmetic (MBA) expressions, an obfuscation technique that rewrites simple computations as interleaved arithmetic, bitwise and shift operations. Given an expression and a bit width from 1 to 64, cobra-cli returns a simpler equivalent: a worklist scheduler combines signature-vector and change-of-basis techniques, semilinear handling of constant masks, polynomial recovery, decomposition of mixed products and subexpression lifting, and each result is checked on random inputs or, optionally, with a Z3 equivalence proof. The same engine is available as a library and as an optional LLVM pass plugin that simplifies MBA expressions it detects in LLVM IR. - Type: Tool - Targets: Binary - Category: Binary analysis libraries - Relationship: Foundation tool - Sources reviewed: 2026-10-20 - Added to the catalog: 2026-11-02 - Original resource: - Primary source: - Catalog page: - Record JSON: - Chinese version: [简体中文](https://awesomerea.org/zh/resources/cobra-mba-simplifier/index.md) ## Requirements & limits - Latest release at review: v1.3.0, published 2026-06-30 without prebuilt binaries. The reviewed master commit is eight commits ahead: README edits, a CI dependency bump, a fix that requires LLVM only when the pass is built, and a fix that lets cobra-core build under MSVC. - Builds from source with CMake 3.20+ and a C++23 compiler (GCC 13+, Clang 17+ or Apple Clang 16+); a dependency superbuild builds Abseil and Highway, and GoogleTest when tests are enabled. The LLVM pass plugin needs LLVM 19 to 22, runs through opt as cobra-simplify, replaces an expression only when the simplified form is cheaper and drops nuw/nsw flags. Z3 checking is compiled in only when CMake finds Z3; otherwise cobra-cli warns that --verify is ignored. CI builds with Clang 22 and LLVM 22 on Ubuntu 24.04 on every run, and with GCC 14 and on macOS 15 only for version tags; Windows is not in CI. - cobra-cli takes the obfuscated expression as text, with at most 16 variables by default, so expressions in a binary must first be recovered with other tools or reach the pass as LLVM IR. The README's known limitations are deeply interleaved mixed-polynomial MBAs that exhaust the worklist budget, a few candidates that are correct only on Boolean inputs and are reported as verify-failed, and no general logic minimization. - The README reports 1,195 tests, and DATASETS.md reports 75,023 of 75,126 parsed expressions from 35 dataset files and seven sources simplified and spot-checked (99.86%). The OSES subsets are disabled for running out of memory or taking minutes per expression, so their figures come from an earlier run; DATASETS.md says the numbers are checked on every CI run, but the reviewed CI workflow excludes the dataset benchmark tests. - Apache-2.0 for CoBRA. The test/datasets files are redistributed from third-party research projects: THIRD_PARTY_LICENSES lists most as effectively GPL-3.0-only, Loki's as AGPL-3.0-only, and the OSES and ObfuscatorX sets with unspecified or unknown licenses. ## Primary sources 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. ## More in Native binaries - [ollvm-unflattener](https://awesomerea.org/resources/ollvm-unflattener/index.md) · Tool - [GolangAnalyzerExtension](https://awesomerea.org/resources/ghidra-golanganalyzerextension/index.md) · Tool - [IDA iOS Helper](https://awesomerea.org/resources/ida-ios-helper/index.md) · Tool - [MAMBO](https://awesomerea.org/resources/mambo/index.md) · Tool - [Class Informer](https://awesomerea.org/resources/class-informer/index.md) · Tool - [Kam1n0](https://awesomerea.org/resources/kam1n0/index.md) · Tool ## About this entry The description was reviewed against primary sources. Original editorial content: MIT. Linked projects, papers and assets retain their own rights and licenses.