Omnilock Script

Omnilock is a Lock Script designed for interoperability. It comes with built-in support for verification of transaction signing methods used in Bitcoin, Ethereum, EOS, Dogecoin and more. It also includes a regulation compliance module, which allows an administrator to revoke tokens held by users under certain circumstances.

How Omnilock Works

An Omnilock Script has the following structure:

Code hash: Omnilock script code hash
Hash type: Omnilock script hash type
Args: <21 byte auth> <Omnilock args>

There are 2 key fields in args:

• auth: for authentication, generally with a pubkey hash in its content
• Omnilock args: for extra checking control, allowing different modes to be enabled in the same Omnilock args

The Omnilock args can be without mode (when Omnilock flags = 0), while the auth must be present. The functionality of Omnilock Script without mode is almost the same as a traditional SECP256K1/blake160 Lock Script. The Omnilock Script can be considered as a traditional Lock Script with additional checking/modes.

Authentication

An authentication (auth) is a 21-byte data structure containing the following components:

<1 byte flag> <20 bytes auth content>

Depending on the value of the flag, the auth content has the following interpretations:

• 0x0: It represents the blake160 hash of a secp256k1 public key. The Lock Script performs secp256k1 signature verification, the same as the SECP256K1/blake160 lock.

• 0x01: It follows the unlocking method used by Ethereum. The signing message hash (sighash_all, see reference implementation) is converted as following: "0x" + hex(signing message hash)

  The hex operator converts the binary into a hex string.

• 0x03: It follows the unlocking method used by Tron. The signing message hash is converted as follows: "0x" + hex(signing message hash)

• 0x04: It follows the unlocking method used by Bitcoin. The signing message hash is required to be converted as follows: "CKB (Bitcoin Layer) transaction: 0x" + hex(signing message hash)

  This way, it facilitates a neat presentation of messages on wallet interfaces, such as UniSat and OKX.

• 0x05: It follows the unlocking method used by Dogecoin. The signing message hash is converted as follows: "0x" + hex(signing message hash)

• 0x12: It follows the unlocking same method as 0x02, with the signing message hash to be converted as follows: "CKB transaction: 0x" + hex(signing message hash)

  This way, it facilitates a neat presentation of messages on wallet interfaces, such as MetaMask.

• 0x06: It follows the same unlocking method used by CKB MultiSig with a minor modification. When a message is calculated for signing, there is a step to clear the witnesses. In Omnilock, this involves clearing the entire lock field in witnesses. But in CKB MultiSig Script, it is only a partial clearance. This part is used as signatures followed by multisig_script.

• 0xFC: It represents the blake160 hash of a Lock Script that checks if the current transaction contains an input Cell with a matching Lock Script. Otherwise, it would return with an error, similar to P2SH in BTC.

• 0xFD: It represents the blake160 hash of a preimage that contains exec information used to delegate signature verification to another Script via exec.

• 0xFE: It represents the blake160 hash of a preimage that contains dynamic linking information used to delegate signature verification to the dynamic linking Script. The interface described in Swappable Signature Verification Protocol Spec is used here.

Omnilock args

The structure of Omnilock args is as follows:

<1 byte Omnilock flags> <32 byte AdminList cell Type ID, optional> <2 bytes minimum ckb/udt in ACP, optional> <8 bytes since for time lock, optional> <32 bytes type script hash for supply, optional>

Name	Flags	Affected Args	Affected Args Size (byte)	Affected Witness
administrator mode	0b00000001	AdminList cell Type ID	32	omni_identity/signature in OmniLockWitnessLock
anyone-can-pay mode	0b00000010	minimum ckb/udt in ACP	2	N/A
time-lock mode	0b00000100	since for timelock	8	N/A
supply mode	0b00001000	type script hash for supply	32	N/A

You can check out the details for different modes at RFC.

Witness Structure

When unlocking an Omnilock, the corresponding witness must be a proper WitnessArgs data structure in Molecule format. In the lock field of the WitnessArgs, an OmniLockWitnessLock structure must be present as follows:

import xudt_rce;

array Auth[byte; 21];

table Identity {
    identity: Auth,
    proofs: SmtProofEntryVec,
}
option IdentityOpt (Identity);

// the data structure used in lock field of witness
table OmniLockWitnessLock {
    signature: BytesOpt,
    omni_identity: IdentityOpt,
    preimage: BytesOpt,
}

To learn the detail of witness in Omnilock, check out the RFC

Script Deployed Info

The Omnilock spec has been deployed to CKB's Mainnet Mirana and Testnet Pudge. The following are the deployment details:

Mainnet

parameter	value
code_hash	0x9b819793a64463aed77c615d6cb226eea5487ccfc0783043a587254cda2b6f26
hash_type	type
tx_hash	0xc76edf469816aa22f416503c38d0b533d2a018e253e379f134c3985b3472c842
index	0x0
dep_type	code

Testnet

parameter	value
code_hash	0xf329effd1c475a2978453c8600e1eaf0bc2087ee093c3ee64cc96ec6847752cb
hash_type	type
tx_hash	0x3d4296df1bd2cc2bd3f483f61ab7ebeac462a2f336f2b944168fe6ba5d81c014
index	0x0
dep_type	code

---

Offchain SDK Examples

Rust SDK

The following example demonstrates creating, signing, and sending a transaction using the Omnilock Script with the Rust SDK.

omnilock-example.rs

use ckb_sdk::{
    constants::ONE_CKB,
    transaction::{
        builder::{CkbTransactionBuilder, SimpleTransactionBuilder},
        handler::{omnilock, HandlerContexts},
        input::InputIterator,
        signer::{SignContexts, TransactionSigner},
        TransactionBuilderConfiguration,
    },
    unlock::OmniLockConfig,
    Address, CkbRpcClient, NetworkInfo,
};
use ckb_types::{
    h256,
    packed::CellOutput,
    prelude::{Builder, Entity, Pack},
};
use std::{error::Error as StdErr, str::FromStr};

fn main() -> Result<(), Box<dyn StdErr>> {
    let network_info = NetworkInfo::testnet();
    let sender = Address::from_str("ckt1qrejnmlar3r452tcg57gvq8patctcgy8acync0hxfnyka35ywafvkqgqgpy7m88v3gxnn3apazvlpkkt32xz3tg5qq3kzjf3")?;
    let receiver = Address::from_str("ckt1qzda0cr08m85hc8jlnfp3zer7xulejywt49kt2rr0vthywaa50xwsqv5dsed9par23x4g58seaw58j3ym5ml2hs8ztche")?;

    let configuration = TransactionBuilderConfiguration::new_with_network(network_info.clone())?;

    let iterator = InputIterator::new_with_address(&[sender.clone()], configuration.network_info());
    let mut builder = SimpleTransactionBuilder::new(configuration, iterator);

    let output = CellOutput::new_builder()
        .capacity((128 * ONE_CKB).pack())
        .lock((&receiver).into())
        .build();
    builder.add_output_and_data(output.clone(), ckb_types::packed::Bytes::default());
    builder.set_change_lock((&sender).into());

    let omni_cfg = OmniLockConfig::from_addr(&sender).unwrap();
    let context = omnilock::OmnilockScriptContext::new(omni_cfg.clone(), network_info.url.clone());

    let mut contexts = HandlerContexts::default();
    contexts.add_context(Box::new(context) as Box<_>);

    let mut tx_with_groups = builder.build(&mut contexts)?;

    let json_tx = ckb_jsonrpc_types::TransactionView::from(tx_with_groups.get_tx_view().clone());
    println!("tx: {}", serde_json::to_string_pretty(&json_tx).unwrap());

    let private_key = h256!("0x6c9ed03816e3111e49384b8d180174ad08e29feb1393ea1b51cef1c505d4e36a");
    TransactionSigner::new(&network_info).sign_transaction(
        &mut tx_with_groups,
        &SignContexts::new_omnilock(
            [secp256k1::SecretKey::from_slice(private_key.as_bytes())?].to_vec(),
            omni_cfg,
        ),
    )?;

    let json_tx = ckb_jsonrpc_types::TransactionView::from(tx_with_groups.get_tx_view().clone());
    println!("tx: {}", serde_json::to_string_pretty(&json_tx).unwrap());

    let tx_hash = CkbRpcClient::new(network_info.url.as_str())
        .send_transaction(json_tx.inner, None)
        .expect("send transaction");
    // example tx: 0xc0c9954a3299b540e63351146a301438372abf93682d96c7cce691c334dd5757
    println!(">>> tx {} sent! <<<", tx_hash);

    Ok(())
}

Other example:

• Omnilock Multisig Example