pyevmasm

pyevmasm is an assembler and disassembler library for the Ethereum Virtual Machine (EVM). It includes a commandline utility and a Python API.

CLI Examples with evmasm

evmasm is a commandline utility that uses pyevmasm to assemble or disassemble EVM:

``` usage: evmasm -h [-bi] [-bo] [-i [INPUT]] [-o [OUTPUT]] [-f FORK]

pyevmasm the EVM assembler and disassembler

optional arguments: -h, --help show this help message and exit -a, --assemble Assemble EVM instructions to opcodes -d, --disassemble Disassemble EVM to opcodes -t, --print-opcode-table List supported EVM opcodes -bi, --binary-input Binary input mode (-d only) -bo, --binary-output Binary output mode (-a only) -i [INPUT], --input [INPUT] Input file, default=stdin -o [OUTPUT], --output [OUTPUT] Output file, default=stdout -f FORK, --fork FORK Fork, default: byzantium. Possible: frontier, homestead, tangerinewhistle, spuriousdragon, byzantium, constantinople, serenity. Also an unsigned block number is accepted to select the fork. ```

Disassembling the preamble of compiled contract:

$ echo -n "608060405260043610603f57600035" | evmasm -d 00000000: PUSH1 0x80 00000002: PUSH1 0x40 00000004: MSTORE 00000005: PUSH1 0x4 00000007: CALLDATASIZE 00000008: LT 00000009: PUSH1 0x3f 0000000b: JUMPI 0000000c: PUSH1 0x0 0000000e: CALLDATALOAD

Python API Examples

```

from pyevmasm import instructiontables, disassemblehex, disassembleall, assemblehex instructiontable = instructiontables['byzantium'] instructiontable[20] Instruction(0x14, 'EQ', 0, 2, 1, 3, 'Equality comparision.', None, 0) instructiontable['EQ'] Instruction(0x14, 'EQ', 0, 2, 1, 3, 'Equality comparision.', None, 0) instrs = list(disassembleall(binascii.unhexlify('608060405260043610603f57600035'))) instrs.insert(1, instructiontable['JUMPI']) a = assemblehex(instrs) a '0x60805760405260043610603f57600035' print(disassemblehex(a)) PUSH1 0x80 JUMPI PUSH1 0x40 MSTORE ... assemble_hex('PUSH1 0x40\nMSTORE\n') '0x604052' ```

Installation

Python >=2.7 or Python >=3.3 is required.

Install the latest stable version using pip: pip install pyevmasm

Or, install the library from source: git clone https://github.com/trailofbits/pyevmasm cd pyevmasm python setup.py install --user

Documentation

https://pyevmasm.readthedocs.io

New issues, feature requests, and contributions are welcome. Join us in #ethereum channel on the Empire Hacking Slack to discuss Ethereum security tool development.