KEVM: Semantics of EVM in K
In this repository we provide a model of the EVM in K.
These may be useful for learning KEVM and K (newest to oldest):
- Jello Paper, a nice presentation of this repository.
- 20 minute tour of the semantics at 2017 Devcon3.
- KEVM 1.0 technical report, especially sections 3 and 5.
- KEVM Paper at CSF'18/FLoC.
To get support for KEVM, please join our Discord Channel.
The following files constitute the KEVM semantics:
- network.md provides the status codes which are reported to an Ethereum client on execution exceptions.
- json-rpc.md is an implementation of JSON RPC in K.
- evm-types.md provides the (functional) data of EVM (256 bit words, wordstacks, etc...).
- serialization.md provides helpers for parsing and unparsing data (hex strings, recursive-length prefix, merkle trees, etc.).
- evm.md is the main KEVM semantics, containing the configuration and transition rules of EVM.
These additional files extend the semantics to make the repository more useful:
- buf.md defines the
#bufbyte-buffer abstraction for use during symbolic execution.
- abi.md defines the Contract ABI Specification for use in proofs and easy contract/function specification.
- hashed-locations.md defines the
#hashedLocationabstraction which makes it easier to specify Solidity-generate storage layouts.
- edsl.md combines the previous three abstractions for ease-of-use.
- foundry.md adds Foundry capabilities to KEVM.
These files are used for testing the semantics itself:
- state-utils.md provides functionality for EVM initialization, setup, and querying.
- driver.md is an execution harness for KEVM, providing a simple language for describing tests/programs.
There are three backends of K available: LLVM (default) for concrete execution and Haskell (default) and Java for symbolic execution.
This repository generates the build-products for each backend in
The following are needed for building/running KEVM:
- GNU Bison, Flex, and Autoconf.
- GNU libmpfr and libtool.
- Java 8 JDK (eg. OpenJDK)
- Z3 version 4.8.15
For the exact dependencies check the Dockerfile.
KEVM requires Z3 version 4.8.15, which you may need to install from a source build if your package manager supplies a different version. To do so, follow the instructions here after checking out the correct tag in the Z3 repository:
git clone https://github.com/Z3Prover/z3.git cd z3 git checkout z3-4.8.15 python scripts/mk_make.py cd build make sudo make install
On macOS, it is easiest to install Z3 from Homebrew. If you do wish to install
from source, make sure to install it to an appropriate prefix (e.g.
on Intel machines).
On Ubuntu >= 18.04 (for example):
sudo apt-get install --yes \ autoconf bison clang-10 cmake curl flex gcc jq libboost-test-dev \ libcrypto++-dev libffi-dev libgflags-dev libjemalloc-dev libmpfr-dev \ libprocps-dev libsecp256k1-dev libssl-dev libtool libyaml-dev lld-10 \ llvm-10-tools make maven netcat-openbsd openjdk-11-jdk pkg-config \ protobuf-compiler python3 python3-dev python3-pip rapidjson-dev time \ zlib1g-dev pip3 install poetry
On Ubuntu < 18.04, you'll need to skip
libsecp256k1-dev and instead build it from source (via our
sudo pacman -S \ base base-devel boost clang cmake crypto++ curl git gmp \ gflags jdk-openjdk jemalloc libsecp256k1 lld llvm maven \ mpfr protobuf python stack yaml-cpp zlib
After installing the Command Line Tools, Homebrew, and getting the blockchain plugin, run:
brew tap kframework/k brew install java automake libtool gmp mpfr pkg-config maven libffi openssl protobuf python bash email@example.com poetry solidity make libsecp256k1
NOTE: Previous versions of these instructions required the user to use either the homebrew version of
flex or the xcode command line tools version, with the wrong option giving an error.
The current recommendation is to use the homebrew version.
If you are building on an Apple Silicon machine, ensure that your
PATH is set
up correctly before running
make deps or
make k-deps. You can do so using
direnv by copying
If the build on macOS still fails, you can also try adding the following lines to the top of your
ifeq ($(UNAME_S), Darwin) SHELL := /usr/local/bin/bash PATH := $(pwd)/.build/usr/bin:$(PATH) endif
Haskell Stack (all platforms)
- Haskell Stack.
Note that the version of the
stacktool provided by your package manager might not be recent enough. Please follow installation instructions from the Haskell Stack website linked above.
stack (if needed):
stack upgrade export PATH=$HOME/.local/bin:$PATH
kevm will work with either a (i) globally installed K, or (ii) a K submodule included in this repository.
For contributing to
kevm, it is highly recommended to go with (ii) because otherwise some of the build scripts might not work.
Follow these instructions to get and build the K submodule:
git submodule update --init --recursive -- deps/k make k-deps
If you don't need either the LLVM or Haskell backend, there are flags to skip them:
make k-deps SKIP_LLVM=true SKIP_HASKELL=true
On an Apple Silicon machine, an additional flag to
make is required to
correctly build the Haskell backend:
make k-deps APPLE_SILICON=true
You also need to get the blockchain plugin submodule and install it.
git submodule update --init --recursive -- deps/plugin make plugin-deps
Finally, you can build the semantics.
And you need to set up the virtual environment:
Which should output (towards the end), a line like this:
You should run this line in your shell, then you are in the virtual environment:
The tests are run using the supplied
make build-prove to generate some of the tests from the markdown files.
The following subsume all other tests:
make test: All of the quick tests.
make test-all: All of the quick and slow tests.
These are the individual test-suites (all of these can be suffixed with
-all to also run slow tests):
make test-vm: VMTests from the Ethereum Test Set.
make test-bchain: Subset of BlockchainTests from the Ethereum Test Set.
make test-proof: Proofs from the Verified Smart Contracts.
make test-interactive: Tests of the
When running tests with the
Makefile, you can specify the
TEST_CONCRETE_BACKEND (for concrete tests), or
TEST_SYMBOLIC_BACKEND (for proofs).
After building, the
kevm executable will be located in the
The one in the project root is a build artifact, don't use it.
To make sure you are using the correct
kevm, add this directory to your
Alternatively, if you work on multiple checkouts of
evm-semantics, or other semantics, you could add the relative path
.build/usr/bin to your
Do note, however, that this is a security concern.
You can call
kevm help to get a quick summary of how to use the script.
Run the file
kevm run tests/ethereum-tests/LegacyTests/Constantinople/VMTests/vmArithmeticTest/add0.json --schedule DEFAULT --mode VMTESTS
To run proofs, you can similarly use
For example, to prove one of the specifications:
kevm prove tests/specs/erc20/ds/transfer-failure-1-a-spec.k --verif-module VERIFICATION
You can also debug proofs interactively:
kevm prove tests/specs/erc20/ds/transfer-failure-1-a-spec.k --verif-module VERIFICATION --debugger --debug-script kscript --backend haskell
kscript is a file containing
For example, we advise to put an alias for outputting the current configuration as a pretty-printed term (as opposed to raw
alias konfig = config | kast -i kore -o pretty -d .build/usr/lib/kevm/haskell /dev/stdin
Building with Nix
We now support building KEVM using nix flakes.
To set up nix flakes you will need to be on
nix 2.4 or higher and follow the instructions here.
For example, if you are on a standard Linux distribution, such as Ubuntu, first install nix
and then enable flakes by editing either
/etc/nix/nix.conf and adding:
experimental-features = nix-command flakes
This is needed to expose the Nix 2.0 CLI and flakes support that are hidden behind feature-flags.
By default, Nix will build the project and its transitive dependencies from
source, which can take up to an hour. We recommend setting up
the binary cache to speed up the build
process significantly. You will also need to add the following sections to
/etc/nix/nix.conf or, if you are a trusted user,
~/.config/nix/nix.conf (if you don't know what a "trusted user" is, you probably want to do the former):
trusted-public-keys = ... hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ= substituters = ... https://cache.iog.io
i.e. if the file was originally
substituters = https://cache.nixos.org trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
it will now read
substituters = https://cache.nixos.org https://cache.iog.io trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY= hydra.iohk.io:f/Ea+s+dFdN+3Y/G+FDgSq+a5NEWhJGzdjvKNGv0/EQ=
To build KEVM, run:
nix build .#kevm
This will build all of KEVM and K and put a link to the resulting binaries in the
Note: Mac users, especially those running M1/M2 Macs may find nix segfaulting on occasion. If this happens, try running the nix command like this:
GC_DONT_GC=1 nix build .
If you want to temporarily add the
kevm binary to the current shell, run
nix shell .#kevm
Profiling with Nix
Nix can also be used to quickly profile different versions of the haskell backend. Simply run
nix build github:runtimeverification/evm-semantics#profile \ --override-input k-framework/haskell-backend github:runtimeverification/haskell-backend/<HASH> \ -o prof-<HASH>
<HASH> with the commit you want to run profiling against.
If you want to profile against a working version of the haskell backend repo, simply
cd into the root of the repo and run
nix build github:runtimeverification/evm-semantics#profile \ --override-input k-framework/haskell-backend $(pwd) \ -o prof-my-feature
To compare profiles, you can use
nix run github:runtimeverification/evm-semantics#compare-profiles -- prof-my-feature prof-<HASH>
This will produce a nice table with the times for both versions of haskell-backend.
#profile pre-pends the output of
kore-exec --version to the profile run, which is then used as a tag by the
Therefore, any profiled local checkout of haskell-backend will report as
dirty-ghc8107 in the resulting table.
.build up-to-date while developing
make buildneeds to be re-run if you touch any of this repos files.
make depsneeds to be re-run if there is an update of the K submodule (you did
git submodule update --init --recursive -- deps/kand it actually did something).
- If both
buildneed to be re-run, you need to do
make cleanis a safe way to remove the
.builddirectory, but then you need to re-run
make deps(should be quick this time) and
This repository can build two pieces of documentation for you, the Jello Paper and the 2017 Devcon3 presentation.
For the presentations in the
media directory, you'll need
pdflatex, commonly provided with
sudo apt install texlive-full pandoc
To build all the PDFs (presentations and reports) available in the
media/ directory, use:
- EVM Yellowpaper: Original specification of EVM.
- LEM Semantics of EVM
For more information about The K Framework, refer to these sources:
- The K Tutorial
- Semantics-Based Program Verifiers for All Languages
- Reachability Logic Resources
- Matching Logic Resources
- Logical Frameworks: Discussion of logical frameworks.