Add calculation of elements AssetId

Author: philipr-za

src/genesis.rs

@@ -0,0 +1,93 @@
+// Rust Elements Library
+// Written by
+//   The Elements developers
+//
+// To the extent possible under law, the author(s) have dedicated all
+// copyright and related and neighboring rights to this software to
+// the public domain worldwide. This software is distributed without
+// any warranty.
+//
+// You should have received a copy of the CC0 Public Domain Dedication
+// along with this software.
+// If not, see <http://creativecommons.org/publicdomain/zero/1.0/>.
+//
+
+//! Helpers to calculate the genesis block for a given network.
+
+use crate::hashes::{sha256, Hash, HashEngine};
+use crate::opcodes::OP_TRUE;
+use crate::pset::serialize::Serialize;
+use crate::{script, Script};
+
+/// Parameters that influence chain consensus. The contents of the genesis block for a given network
+/// are defined by these values.
+#[derive(Clone, Debug)]
+pub struct NetworkParams {
+    /// The network identifier string that elementsd accepts as the `chain` config argument
+    pub network_id: String,
+    /// This network's Fedpeg script
+    pub fedpeg_script: Script,
+    /// This network's `sign_block_script`
+    pub sign_block_script: Script,
+    /// How many free coins are present in this network
+    pub initial_free_coins: u64,
+}
+
+impl NetworkParams {
+    /// New custom network params
+    pub fn new(
+        network_id: String,
+        fedpeg_script: Script,
+        sign_block_script: Script,
+        initial_free_coins: u64,
+    ) -> NetworkParams {
+        NetworkParams {
+            network_id,
+            fedpeg_script,
+            sign_block_script,
+            initial_free_coins,
+        }
+    }
+
+    /// Network params for Liquid mainnet
+    pub fn liquidv1() -> Self {
+        NetworkParams {
+            network_id: "liquidv1".to_string(),
+            // Can be verified at https://github.com/ElementsProject/elements/blob/27c2fb6b7de404908f9ef2eb5c98c9989d1ab8e4/src/chainparams.cpp#L1243
+            fedpeg_script: Script::from_hex_no_prefix("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").expect("constant fedpeg script parse"),
+            // Can be verified at https://github.com/ElementsProject/elements/blob/27c2fb6b7de404908f9ef2eb5c98c9989d1ab8e4/src/chainparams.cpp#L1193
+            sign_block_script: Script::from_hex_no_prefix("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").expect("constant sign_block_script parse"),
+            initial_free_coins: 0,
+        }
+    }
+
+    /// Network params for Liquid testnet
+    pub fn liquidtestnet() -> Self {
+        NetworkParams {
+            network_id: "liquidtestnet".to_string(),
+            fedpeg_script: script::Builder::new().push_opcode(OP_TRUE).into_script(),
+            // Can be verified at https://github.com/ElementsProject/elements/blob/27c2fb6b7de404908f9ef2eb5c98c9989d1ab8e4/src/chainparams.cpp#L1108
+            sign_block_script: Script::from_hex_no_prefix("51210217e403ddb181872c32a0cd468c710040b2f53d8cac69f18dad07985ee37e9a7151ae").expect("constant sign_block_script parse"),
+            initial_free_coins: 2_100_000_000_000_000,
+        }
+    }
+
+    /// Network params for a custom Elements network with defaults
+    pub fn custom_network(network_id: String, fedpeg_script: Option<Script>, sign_block_script: Option<Script>, initial_free_coins: Option<u64>) -> Self {
+        NetworkParams {
+            network_id,
+            fedpeg_script: fedpeg_script.unwrap_or_else(|| script::Builder::new().push_opcode(OP_TRUE).into_script()),
+            sign_block_script: sign_block_script.unwrap_or_else(|| script::Builder::new().push_opcode(OP_TRUE).into_script()),
+            initial_free_coins: initial_free_coins.unwrap_or(0),
+        }
+    }
+}
+
+/// Hash commitment of network parameters for a given Network
+pub fn commit_to_custom_network_parameters(params: &NetworkParams) -> Vec<u8> {
+    let mut eng = sha256::Hash::engine();
+    eng.input(params.network_id.clone().as_bytes());
+    eng.input(format!("{:x}", params.fedpeg_script).as_bytes());
+    eng.input(format!("{:x}", params.sign_block_script).as_bytes());
+    sha256::Hash::from_engine(eng).serialize()
+}

src/issuance.rs

@@ -16,12 +16,13 @@
 
 use std::io;
 use std::str::FromStr;
-
 use crate::encode::{self, Encodable, Decodable};
 use crate::hashes::{self, hash_newtype, sha256, sha256d, Hash};
 use crate::fast_merkle_root::fast_merkle_root;
 use secp256k1_zkp::Tag;
+use crate::genesis::{commit_to_custom_network_parameters, NetworkParams};
 use crate::transaction::OutPoint;
+use crate::Txid;
 
 /// The zero hash.
 const ZERO32: [u8; 32] = [
@@ -75,6 +76,14 @@ impl AssetId {
         0x3d, 0x1c, 0x04, 0xed, 0xe9, 0x79, 0x02, 0x6f,
     ]));
 
+    /// The asset ID for L-BTC, Bitcoin on the Liquidtestnet network.
+    pub const LIQUIDTESTNET_BTC: AssetId = AssetId(sha256::Midstate([
+        0x49, 0x9a, 0x81, 0x85, 0x45, 0xf6, 0xba, 0xe3,
+        0x9f, 0xc0, 0x3b, 0x63, 0x7f, 0x2a, 0x4e, 0x1e,
+        0x64, 0xe5, 0x90, 0xca, 0xc1, 0xbc, 0x3a, 0x6f,
+        0x6d, 0x71, 0xaa, 0x44, 0x43, 0x65, 0x4c, 0x14,
+    ]));
+
     /// Create an [`AssetId`] from its inner type.
     pub const fn from_inner(midstate: sha256::Midstate) -> AssetId {
         AssetId(midstate)
@@ -146,6 +155,30 @@ impl AssetId {
     pub fn into_tag(self) -> Tag {
         self.0.to_byte_array().into()
     }
+
+    /// Pegged asset id for given network parameters
+    pub fn pegged_asset_id_for_network_params(params: &NetworkParams) -> AssetId {
+        match params.network_id.as_str() {
+            "liquidv1" => Self::LIQUID_BTC,
+            "liquidtestnet" => Self::LIQUIDTESTNET_BTC,
+            _ => {
+                // Else calculate the asset_id
+                Self::pegged_asset_id_for_params_and_parent_chain_hash(
+                    params,
+                    bitcoin::Network::Regtest.chain_hash(),
+                )
+            }
+        }
+    }
+
+    /// Calculate the `AssetId` for the pegged asset for a given set of network parameters assuming
+    /// a Regtest parent network
+    fn pegged_asset_id_for_params_and_parent_chain_hash(params: &NetworkParams, parent_chainhash: bitcoin::blockdata::constants::ChainHash) -> AssetId {
+        let commit = commit_to_custom_network_parameters(params);
+        let asset_outpoint = OutPoint::new(Txid::from_slice(commit.as_slice()).expect("txid"), 0);
+        let asset_entropy = AssetId::generate_asset_entropy(asset_outpoint, ContractHash::from_slice(parent_chainhash.to_bytes().as_slice()).unwrap());
+        AssetId::from_entropy(asset_entropy)
+    }
 }
 
 impl ::std::fmt::Display for AssetId {
@@ -260,7 +293,7 @@ impl<'de> ::serde::Deserialize<'de> for AssetId {
 mod test {
     use super::*;
     use std::str::FromStr;
-
+    use bitcoin::constants::ChainHash;
     use crate::hashes::sha256;
 
     #[test]
@@ -366,4 +399,52 @@ mod test {
             "6f0279e9ed041c3d710a9f57d0c02928416460c4b722ae3457a11eec381c526d",
         );
     }
+
+    #[test]
+    fn liquid_asset_ids() {
+        // Testing the two most common Regtest networks using in Liquid and CLN codebases
+        let network_params = NetworkParams::custom_network("elementsregtest".to_string(), None, None, None);
+        let asset_id = AssetId::pegged_asset_id_for_params_and_parent_chain_hash(
+            &network_params,
+            bitcoin::Network::Regtest.chain_hash(),
+        );
+
+        let elementsregtest_asset_id = AssetId(sha256::Midstate([
+            0x23, 0x0f, 0x4f, 0x5d, 0x4b, 0x7c, 0x6f, 0xa8, 0x45, 0x80, 0x6e, 0xe4,
+            0xf6, 0x77, 0x13, 0x45, 0x9e, 0x1b, 0x69, 0xe8, 0xe6, 0x0f, 0xce, 0xe2,
+            0xe4, 0x94, 0x0c, 0x7a, 0x0d, 0x5d, 0xe1, 0xb2,
+        ]));
+
+        assert_eq!(asset_id, elementsregtest_asset_id);
+
+        let network_params = NetworkParams::custom_network("liquid-regtest".to_string(), None, None, None);
+        let asset_id = AssetId::pegged_asset_id_for_params_and_parent_chain_hash(
+            &network_params,
+            bitcoin::Network::Regtest.chain_hash(),
+        );
+
+        let liquid_regtest_assetid = AssetId(sha256::Midstate([
+            0x5c, 0xe7, 0xb9, 0x63, 0xd3, 0x7f, 0x8f, 0x2d, 0x51, 0xca, 0xfb, 0xba,
+            0x92, 0x8a, 0xaa, 0x9e, 0x22, 0x0b, 0x8b, 0xbc, 0x66, 0x05, 0x71, 0x49,
+            0x9c, 0x03, 0x62, 0x8a, 0x38, 0x51, 0xb8, 0xce,
+        ]));
+
+        assert_eq!(asset_id, liquid_regtest_assetid);
+
+        let liquidv1_params = NetworkParams::liquidv1();
+        let asset_id = AssetId::pegged_asset_id_for_params_and_parent_chain_hash(
+            &liquidv1_params,
+            bitcoin::Network::Bitcoin.chain_hash(),
+        );
+
+        assert_eq!(asset_id, AssetId::LIQUID_BTC);
+
+        let liquidtestnet_params = NetworkParams::liquidtestnet();
+        let asset_id = AssetId::pegged_asset_id_for_params_and_parent_chain_hash(
+            &liquidtestnet_params,
+            ChainHash::from([0u8; 32]),
+        );
+
+        assert_eq!(asset_id, AssetId::LIQUIDTESTNET_BTC);
+    }
 }

src/lib.rs

@@ -73,6 +73,8 @@ pub mod taproot;
 mod transaction;
 // consider making upstream public
 mod endian;
+pub mod genesis;
+
 // re-export bitcoin deps which we re-use
 pub use bitcoin::hashes;
 // export everything at the top level so it can be used as `elements::Transaction` etc.