> For the complete documentation index, see [llms.txt](https://docs.seismic.systems/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.seismic.systems/clients/python/precompiles.md).

# Precompiles

Call Mercury EVM precompiles from Python

The Python SDK exposes wrappers for six Mercury EVM precompiles (`0x64` through `0x69`).

These wrappers use plain `eth_call`, so you only need a `Web3` connection to a Seismic node. No wallet client or encryption state is required.

## Quick Start

```python
import os
from seismic_web3 import PrivateKey, create_public_client
from seismic_web3.crypto.secp import private_key_to_compressed_public_key
from seismic_web3 import precompiles as sp

w3 = create_public_client("https://testnet-1.seismictest.net/rpc")

# 1) Random bytes as int
random_val = sp.rng(w3, num_bytes=32)

# 2) Shared key from ECDH
my_sk = PrivateKey(os.urandom(32))
peer_sk = PrivateKey(os.urandom(32))
peer_pk = private_key_to_compressed_public_key(peer_sk)
shared_key = sp.ecdh(w3, sk=my_sk, pk=peer_pk)

# 3) AES-GCM encrypt/decrypt
ciphertext = sp.aes_gcm_encrypt(
    w3,
    aes_key=shared_key,
    nonce=1,
    plaintext=b"secret",
)
plaintext = sp.aes_gcm_decrypt(
    w3,
    aes_key=shared_key,
    nonce=1,
    ciphertext=bytes(ciphertext),
)

# 4) HKDF derivation
derived_key = sp.hkdf(w3, b"input key material")

# 5) secp256k1 signing
signature = sp.secp256k1_sign(w3, sk=my_sk, message="hello")
```

All wrappers also have async variants: `async_rng`, `async_ecdh`, `async_aes_gcm_encrypt`, `async_aes_gcm_decrypt`, `async_hkdf`, `async_secp256k1_sign`.

## Reference

| Precompile     | Address | Function                                                                                               | Returns    |
| -------------- | ------- | ------------------------------------------------------------------------------------------------------ | ---------- |
| RNG            | `0x64`  | [`rng(w3, num_bytes=, pers=)`](/clients/python/precompiles/rng.md)                                     | `int`      |
| ECDH           | `0x65`  | [`ecdh(w3, sk=, pk=)`](/clients/python/precompiles/ecdh.md)                                            | `Bytes32`  |
| AES Encrypt    | `0x66`  | [`aes_gcm_encrypt(w3, aes_key=, nonce=, plaintext=)`](/clients/python/precompiles/aes-gcm-encrypt.md)  | `HexBytes` |
| AES Decrypt    | `0x67`  | [`aes_gcm_decrypt(w3, aes_key=, nonce=, ciphertext=)`](/clients/python/precompiles/aes-gcm-decrypt.md) | `HexBytes` |
| HKDF           | `0x68`  | [`hkdf(w3, ikm)`](/clients/python/precompiles/hkdf.md)                                                 | `Bytes32`  |
| secp256k1 Sign | `0x69`  | [`secp256k1_sign(w3, sk=, message=)`](/clients/python/precompiles/secp256k1-sign.md)                   | `HexBytes` |


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