zhlink 0.1.3

Self-contained Python library for ZHCASH addresses, balances, ZHC sends, and USDZ gas-free sends.

ZHLink Python Library

zhlink is a self-contained Python library for ZHCASH.

The public API is intentionally small:

• create a new ZHC address;
• check ZHC + USDZ balance;
• send native ZHC from a private key;
• dry-run/read ZHCASH smart contracts with callcontract;
• send payable ZHCASH smart-contract calls from a private key;
• send ZHC, USDZ or any ZRC-20 token to many recipients from a JSON plan;
• send USDZ with admin-paid ZHC gas;
• optionally read extra ZRC-20 token balances.

The raw transaction engine is bundled inside the package. Normal users only import zhlink.

Install

Recommended Python:

• Python 3.10 or newer is required.
• Python 3.10 and 3.11 are the safest choices for deployment.
• Python 3.12 should work.
• Python 3.9 and older are not supported.

From PyPI:

pip install zhlink

From this folder:

cd /root/wallet/zhlink
python3 -m venv .venv
. .venv/bin/activate
pip install -e .

For direct local use without install:

cd /root/wallet/zhlink
export PYTHONPATH=/root/wallet/zhlink

Create Address

from zhlink import create_address

wallet = create_address()

print(wallet.address)
print(wallet.priv_key)

Private keys are generated locally. The library never sends private keys to ZeroScan or RPC.

Get Balance

By default get_balance returns ZHC and USDZ.

from zhlink import get_balance

balance = get_balance("Z...")

print(balance["zhc"])
print(balance["usdz"])

Extra ZRC-20 tokens can be requested when needed:

from zhlink import get_balance

balance = get_balance(
    "Z...",
    tokens={"EDS": "dc71958156a945d3071374521e1a7a42f5ba8038"},
)

print(balance["tokens"]["EDS"])

Send ZHC

from zhlink import send_zhc

result = send_zhc(
    private_key_wif="L...",
    to_address="Z...",
    amount="1.25",
)

print(result)

The sender address is derived from the private key automatically.

Smart Contracts

Use call_contract before any contract transaction. It calls ZHCASH callcontract through configured public RPC endpoints and returns the raw execution result plus common fields.

from zhlink import call_contract

result = call_contract(
    contract_address="a48d0ee7365ce1add8e595de4d54344239f8ca28",
    data_hex="70a08231...",
    from_address="Z...",  # optional
    gas=1_000_000,
)

print(result["output"])

Use send_to_contract for a real payable contract call.

from zhlink import send_to_contract

result = send_to_contract(
    private_key_wif="L...",
    contract_address="...",
    data_hex="...",
    amount="0",        # ZHC sent to the contract, if needed
    gas=1_000_000,
)

print(result)

The sender address is derived locally. The function runs callcontract preflight, selects UTXO, signs locally, checks mempool when RPC is available, broadcasts through ZeroScan and falls back to RPC broadcast.

Mass Send

send_mass sends ZHC, USDZ or any ZRC-20 token to many recipients from a JSON plan.

{
  "asset": "USDZ",
  "token_contract": "a48d0ee7365ce1add8e595de4d54344239f8ca28",
  "token_decimals": 8,
  "gas": 1000000,
  "recipients": [
    {"address": "Z...", "amount": "0.1"},
    {"address": "Z...", "amount": "0.2"}
  ]
}

For native ZHC:

{
  "asset": "ZHC",
  "recipients": [
    {"address": "Z...", "amount": "1"}
  ]
}

Run an estimate first:

from zhlink import estimate_mass_send, load_mass_send_plan

plan = load_mass_send_plan("mass_send.json")
print(estimate_mass_send("L...", plan))

Then send:

from zhlink import send_mass

result = send_mass("L...", "mass_send.json")
print(result["sent_count"], result["failed_count"])

Mass-send UTXO rules:

1. One recipient uses one on-chain transaction.
2. The library never starts more transactions in one batch than confirmed UTXO currently available.
3. If there are too few UTXO and auto_prepare_utxos=True, the library splits the largest UTXO into up to 100 self-outputs.
4. Every prepared output must be at least 1 ZHC.
5. After a reorg/split, the library waits for the next block before mailing.
6. Between mailing batches it waits for the next block so change outputs become confirmed before being reused.

Manual preparation is also available:

from zhlink import prepare_mass_send_utxos

prepare_mass_send_utxos("L...", "mass_send.json", target_utxos=100)

Send USDZ Gas-Free

send_usdz_gas_free signs the USDZ transfer with the sender key and pays ZHC gas from the admin gas wallet.

from zhlink import send_usdz_gas_free

result = send_usdz_gas_free(
    sender_private_key_wif="L...",
    admin_private_key_wif="K...",
    to_address="Z...",
    amount="0.1",
)

print(result["broadcast"]["txid"])

The function does the required checks automatically:

1. derives sender/admin addresses from WIF keys;
2. checks sender USDZ balance;
3. runs callcontract dry-run;
4. loads admin gas UTXO from ZeroScan;
5. skips locally used gas UTXO;
6. builds and signs rawtx locally;
7. runs testmempoolaccept;
8. if one UTXO is rejected, tries another UTXO;
9. broadcasts through ZeroScan;
10. falls back to RPC sendrawtransaction.

For mass sends, prepare independent admin gas UTXO first. One gas-free transfer needs one spendable admin gas UTXO. The recommended ticket size is 0.5 ZHC.

from zhlink import admin_gas_wallet_info

info = admin_gas_wallet_info("K...")
print(info["suitable_gas_utxo_count"])
print(info["recommended_split_count"])

Custom RPC / ZeroScan

Defaults:

• ZeroScan API: https://ws.zeroscan.st, https://ws.zeroscan.io
• RPC: https://rpc.zeroscan.st
• USDZ contract: a48d0ee7365ce1add8e595de4d54344239f8ca28

Override them when needed:

from zhlink import ZHLinkConfig, get_balance

config = ZHLinkConfig.public_network(
    zeroscan_endpoints=("https://ws.zeroscan.st", "https://ws.zeroscan.io"),
    public_rpc_urls=("https://rpc.zeroscan.st", "https://my-node.example/rpc"),
)

print(get_balance("Z...", config=config))

Examples

Run examples one by one:

cd /root/wallet/zhlink
PYTHONPATH=. python3 examples/create_wallet.py
PYTHONPATH=. python3 examples/create_bip39_wallet.py
PYTHONPATH=. ZHLINK_ADDRESS="Z..." python3 examples/check_balance.py
PYTHONPATH=. python3 examples/send_to_contract.py
PYTHONPATH=. python3 examples/mass_send.py

Run all safe examples at once:

cd /root/wallet/zhlink
PYTHONPATH=. python3 examples/run_all_examples.py

Send examples are guarded by RUN_REAL_SEND=1 and will not broadcast by accident. Never commit real private keys.

Publishing

GitHub Actions workflow .github/workflows/python-publish.yml builds, tests, checks, and publishes the package to PyPI.

Release flow:

git tag v0.1.3
git push origin v0.1.3

The workflow uses PyPI Trusted Publishing, so the PyPI project must allow this GitHub repository/workflow as a trusted publisher.