Merge pull request #932 from altkdf/alex/add-taproot-transactions

feat(schnorr,bitcoin): CRP-2533 add taproot transactions and improvements

rust/basic_bitcoin/Makefile

@@ -6,8 +6,32 @@ all: deploy
 deploy:
 	dfx deploy basic_bitcoin --argument '(variant { regtest })'
 
+.PHONY: regtest_topup
+.SILENT: regtest_topup
+regtest_topup:
+	P2PKH_ADDR=$(shell dfx canister call basic_bitcoin get_p2pkh_address | tr -d '()') && \
+	P2TR_SCRIPT_SPEND_ADDR=$(shell dfx canister call basic_bitcoin get_p2tr_script_spend_address | tr -d '()') && \
+	P2TR_SCRIPT_KEY_SPEND_ADDR=$(shell dfx canister call basic_bitcoin get_p2tr_raw_key_spend_address | tr -d '()') && \
+	TOPUP_CMD_P2PKH="bitcoin-cli -rpcport=8333 sendtoaddress $${P2PKH_ADDR} 1" && \
+	TOPUP_CMD_P2TR_SCRIPT_SPEND="bitcoin-cli -rpcport=8333 sendtoaddress $${P2TR_SCRIPT_SPEND_ADDR} 1" && \
+	TOPUP_CMD_P2TR_RAW_KEY_SPEND="bitcoin-cli -rpcport=8333 sendtoaddress $${P2TR_SCRIPT_KEY_SPEND_ADDR} 1" && \
+	eval "$${TOPUP_CMD_P2PKH}" && \
+	eval "$${TOPUP_CMD_P2PKH}" && \
+	eval "$${TOPUP_CMD_P2PKH}" && \
+	eval "$${TOPUP_CMD_P2TR_SCRIPT_SPEND}" && \
+	eval "$${TOPUP_CMD_P2TR_SCRIPT_SPEND}" && \
+	eval "$${TOPUP_CMD_P2TR_SCRIPT_SPEND}" && \
+	eval "$${TOPUP_CMD_P2TR_RAW_KEY_SPEND}" && \
+	eval "$${TOPUP_CMD_P2TR_RAW_KEY_SPEND}" && \
+	eval "$${TOPUP_CMD_P2TR_RAW_KEY_SPEND}" && \
+	bitcoin-cli -rpcport=8333 -generate 6
+
 .PHONY: clean
 .SILENT: clean
 clean:
 	rm -rf .dfx
+	rm -rf dist
+	rm -rf node_modules
+	rm -rf src/declarations
+	rm -f .env
 	cargo clean

rust/basic_bitcoin/README.md

@@ -11,20 +11,27 @@ This tutorial will walk you through how to deploy a sample [canister smart contr
 
 ## Architecture
 
-This example internally leverages the [ECDSA API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-ecdsa_public_key)
-and [Bitcoin API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-bitcoin-api) of the Internet Computer.
+This example internally leverages the [ECDSA
+API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-ecdsa_public_key),
+[Schnorr API](https://org5p-7iaaa-aaaak-qckna-cai.icp0.io/docs#ic-sign_with_schnorr), and [Bitcoin
+API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-bitcoin-api)
+of the Internet Computer.
 
 For a deeper understanding of the ICP < > BTC integration, see the [Bitcoin integration documentation](https://wiki.internetcomputer.org/wiki/Bitcoin_Integration).
 
 ## Prerequisites
 
-* [x] Install the [IC SDK](https://internetcomputer.org/docs/current/developer-docs/setup/install/index.mdx).
+* [x] Install the [IC
+  SDK](https://internetcomputer.org/docs/current/developer-docs/setup/install/index.mdx).
+  For local testing, `dfx >= 0.22.0-beta.0` is required.
 
 ## Step 1: Building and deploying sample code
 
 ### Clone the smart contract
 
-This tutorial has the **same smart contract** written in different programming languages: in [Motoko](https://internetcomputer.org/docs/current/developer-docs/backend/motoko/index.md) and [Rust](https://internetcomputer.org/docs/current/developer-docs/backend/rust/index.md).
+This tutorial has the same smart contract written in
+[Motoko](https://internetcomputer.org/docs/current/developer-docs/backend/motoko/index.md)
+using ECDSA and Bitcoin API but currently not Schnorr API.
 
 You can clone and deploy either one, as they both function in the same way.
 
@@ -33,11 +40,9 @@ To clone and build the smart contract in **Rust**:
 ```bash
 git clone https://github.com/dfinity/examples
 cd examples/rust/basic_bitcoin
-git submodule update --init --recursive
+cargo build --release --target wasm32-unknown unknown
 ```
 
-**If you choose Rust and are using MacOS, you'll need to install Homebrew and run `brew install llvm` to be able to compile the example.**
-
 ### Acquire cycles to deploy
 
 Deploying to the Internet Computer requires [cycles](https://internetcomputer.org/docs/current/developer-docs/setup/cycles) (the equivalent of "gas" in other blockchains). You can get free cycles from the [cycles faucet](https://internetcomputer.org/docs/current/developer-docs/setup/cycles/cycles-faucet.md).
@@ -53,8 +58,12 @@ dfx deploy --network=ic basic_bitcoin --argument '(variant { testnet })'
 - `--network=ic` tells the command line to deploy the smart contract to the mainnet ICP blockchain
 - `--argument '(variant { testnet })'` passes the argument `testnet` to initialize the smart contract, telling it to connect to the Bitcoin testnet
 
-**We're initializing the canister with `variant { testnet }` so that the canister connects to the [Bitcoin testnet](https://en.bitcoin.it/wiki/Testnet). To be specific, this connects to `Testnet3`, which is the current Bitcoin test network used by the Bitcoin community.**
-
+**We're initializing the canister with `variant { testnet }` so that the
+canister connects to the [Bitcoin testnet](https://en.bitcoin.it/wiki/Testnet).
+To be specific, this connects to `Testnet3`, which is the current Bitcoin test
+network used by the Bitcoin community. This means that the addresses generated
+in the smart contract can only be used to receive or send funds only on Bitcoin
+testnet.**
 
 If successful, you should see an output that looks like this:
 
@@ -70,80 +79,134 @@ Candid:
 
 Your canister is live and ready to use! You can interact with it using either the command line or using the Candid UI, which is the link you see in the output above.
 
-In the output above, to see the Candid Web UI for your bitcoin canister, you would use the URL `https://a4gq6-oaaaa-aaaab-qaa4q-cai.raw.icp0.io/?id=<YOUR-CANISTER-ID>`. Here are the two methods you will see:
+In the output above, to see the Candid Web UI for your bitcoin canister, you
+would use the URL
+`https://a4gq6-oaaaa-aaaab-qaa4q-cai.raw.icp0.io/?id=<YOUR-CANISTER-ID>`. Candid
+Web UI will contain all methods implemented by the canister.
 
-* `public_key`
-* `sign`
+The `basic_bitcoin` example is deployed on mainnet for illustration purposes and
+is interacting with Bitcoin testnet. It has the URL
+https://a4gq6-oaaaa-aaaab-qaa4q-cai.raw.icp0.io/?id=vvha6-7qaaa-aaaap-ahodq-cai
+and serves up the Candid web UI for this particular canister deployed on
+mainnet.
 
 ## Step 2: Generating a Bitcoin address
 
-Bitcoin has different types of addresses (e.g. P2PKH, P2SH). Most of these
-addresses can be generated from an ECDSA public key. The example code
-showcases how your canister can generate a [P2PKH address](https://en.bitcoin.it/wiki/Transaction#Pay-to-PubkeyHash) using the [ecdsa_public_key](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-ecdsa_public_key) API.
-
-On the Candid UI of your canister, click the "Call" button under `get_p2pkh_address` to
-generate a P2PKH Bitcoin address.
+Bitcoin has different types of addresses (e.g. P2PKH, P2SH, P2TR). You may want
+to check [this
+article](https://bitcoinmagazine.com/technical/bitcoin-address-types-compared-p2pkh-p2sh-p2wpkh-and-more)
+if you are interested in a high-level comparison of different address types.
+These addresses can be generated from an ECDSA public key or a Schnorr
+([BIP340](https://github.com/bitcoin/bips/blob/master/bip-0340.mediawiki))
+public key. The example code showcases how your canister can generate and spend
+from three types of addresses:
+1. A [P2PKH address](https://en.bitcoin.it/wiki/Transaction#Pay-to-PubkeyHash)
+   using the
+   [ecdsa_public_key](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-method-ecdsa_public_key)
+   API.
+2. A [P2TR
+   address](https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki)
+   where the funds can be spent using the raw (untweaked) internal key
+   (so-called P2TR key path spend, but untweaked). The advantage of this
+   approach compared to the one below is its significantly smaller fee per
+   transaction because checking the transaction signature is analogous to P2PK
+   but uses Schnorr instead of ECDSA. IMPORTANT: Note that
+   [BIP341](https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki#cite_note-23)
+   advises against using taproot addresses that can be spent with an untweaked
+   key. This precaution is to prevent attacks that can occur when creating
+   taproot multisigner addresses using specific multisignature schemes. However,
+   the Schnorr API of the internet computer does not support Schnorr
+   multisignatures. 
+3. A [P2TR
+   address](https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki)
+   where the funds can be spent using the provided public key with the script
+   path, where the Merkelized Alternative Script Tree (MAST) consists of a
+   single script allowing to spend funds by exactly one key.
+
+Note that P2TR *key path* spending with a tweaked key is currently not available
+on the IC because the threshold Schnorr signing interface does not allow
+applying BIP341 tweaks to the private key. In contrast, the
+tweaked public key is used to spend in the script path, which is availble on the
+IC. For a technical comparison of different ways of how single-signer P2TR
+addresses can be constructed and used, you may want to take a look at [this
+post](https://bitcoin.stackexchange.com/a/111100) by Pieter Wuille.
+
+On the Candid UI of your canister, click the "Call" button under
+`get_${type}_address` to generate a `${type}` Bitcoin address, where `${type}`
+is one of `[p2pkh, p2tr_raw_key_spend, p2tr_script_spend]`.
 
 Or, if you prefer the command line:
-
-    dfx canister --network=ic call basic_bitcoin get_p2pkh_address
-
-* The Bitcoin address you see will be different from the one above because the
-  ECDSA public key your canister retrieves is unique.
-
-* We are generating a Bitcoin testnet address, which can only be
-used for sending/receiving Bitcoin on the Bitcoin testnet.
-
+   `dfx canister --network=ic call basic_bitcoin get_${type}_address`
 
 ## Step 3: Receiving bitcoin
 
 Now that the canister is deployed and you have a Bitcoin address, it's time to receive
 some testnet bitcoin. You can use one of the Bitcoin faucets, such as [coinfaucet.eu](https://coinfaucet.eu),
 to receive some bitcoin.
 
-Enter your address and click on "Send testnet bitcoins". This example will use the Bitcoin address `n31eU1K11m1r58aJMgTyxGonu7wSMoUYe7`, but you will use your address. The canister will be receiving 0.011 test BTC on the Bitcoin Testnet.
+Enter your address and click on "Send testnet bitcoins". This example will use
+the Bitcoin P2PHK address `mot21Ef7HNDpDJa4CBzt48WpEX7AxNyaqx`, but you will use
+your address. The Bitcoin address you see will be different from the one above
+because the ECDSA/Schnorr public key your canister retrieves is unique.
 
 Once the transaction has at least one confirmation, which can take a few minutes,
 you'll be able to see it in your canister's balance.
 
+The addresses that have been used for the testing of this canister on Bitcoin
+testnet are `mot21Ef7HNDpDJa4CBzt48WpEX7AxNyaqx` (P2PKH,
+[transactions](https://blockstream.info/testnet/address/mot21Ef7HNDpDJa4CBzt48WpEX7AxNyaqx)),
+`tb1pkkrwg6e9s5zf3jmftu224rc5ppax26g5yzdg03rhmqw84359xgpsv5mn2y` (P2TR raw key
+spend,
+[transactions](https://blockstream.info/testnet/address/tb1pkkrwg6e9s5zf3jmftu224rc5ppax26g5yzdg03rhmqw84359xgpsv5mn2y)),
+and `tb1pnm743sjkw9tq3zf9uyetgqkrx7tauthmxnsl5dtyrwnyz9r7lu8qdtcnnc` (P2TR
+script path spend,
+[transactions](https://blockstream.info/testnet/address/tb1pnm743sjkw9tq3zf9uyetgqkrx7tauthmxnsl5dtyrwnyz9r7lu8qdtcnnc)).
+It may be useful to click on "transactions" links if you are interested in how
+they are structured.
+
 ## Step 4: Checking your bitcoin balance
 
 You can check a Bitcoin address's balance by using the `get_balance` endpoint on your canister.
 
 In the Candid UI, paste in your canister's address, and click on "Call":
 
-Alternatively, make the call using the command line. Be sure to replace `mheyfRsAQ1XrjtzjfU1cCH2B6G1KmNarNL` with your own generated P2PKH address:
+Alternatively, make the call using the command line. Be sure to replace `mot21Ef7HNDpDJa4CBzt48WpEX7AxNyaqx` with your own generated address:
 
 ```bash
-dfx canister --network=ic call basic_bitcoin get_balance '("mheyfRsAQ1XrjtzjfU1cCH2B6G1KmNarNL")'
+dfx canister --network=ic call basic_bitcoin get_balance '("mot21Ef7HNDpDJa4CBzt48WpEX7AxNyaqx")'
 ```
 
 Checking the balance of a Bitcoin address relies on the [bitcoin_get_balance](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-bitcoin_get_balance) API.
 
 ## Step 5: Sending bitcoin
 
-You can send bitcoin using the `send` endpoint on your canister.
+You can send bitcoin using the `send_from_${type}` endpoint on your canister, where
+`${type}` is on of `[p2pkh, p2tr_raw_key_spend, p2tr_script_spend]`.
 
 In the Candid UI, add a destination address and an amount to send. In the example
 below, we're sending 4'321 Satoshi (0.00004321 BTC) back to the testnet faucet.
 
 Via command line, the same call would look like this:
 
 ```bash
-dfx canister --network=ic call basic_bitcoin send '(record { destination_address = "tb1ql7w62elx9ucw4pj5lgw4l028hmuw80sndtntxt"; amount_in_satoshi = 4321; })'
+dfx canister --network=ic call basic_bitcoin send_from_p2pkh '(record { destination_address = "tb1ql7w62elx9ucw4pj5lgw4l028hmuw80sndtntxt"; amount_in_satoshi = 4321; })'
 ```
 
-The `send` endpoint can send bitcoin by:
+The `send_from_${type}` endpoint can send bitcoin by:
 
-1. Getting the percentiles of the most recent fees on the Bitcoin network using the [bitcoin_get_current_fee_percentiles API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-bitcoin_get_current_fee_percentiles).
-2. Fetching your unspent transaction outputs (UTXOs), using the [bitcoin_get_utxos API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-bitcoin_get_utxos).
+1. Getting the percentiles of the most recent fees on the Bitcoin network using the [bitcoin_get_current_fee_percentiles API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-method-bitcoin_get_current_fee_percentiles).
+2. Fetching your unspent transaction outputs (UTXOs), using the [bitcoin_get_utxos API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-method-bitcoin_get_utxos).
 3. Building a transaction, using some of the UTXOs from step 2 as input and the destination address and amount to send as output.
    The fee percentiles obtained from step 1 is used to set an appropriate fee.
-4. Signing the inputs of the transaction using the [sign_with_ecdsa API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-sign_with_ecdsa).
-5. Sending the signed transaction to the Bitcoin network using the [bitcoin_send_transaction API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-bitcoin_send_transaction).
-
-The `send` endpoint returns the ID of the transaction it sent to the network.
-You can track the status of this transaction using a block explorer. Once the
+4. Signing the inputs of the transaction using the
+   [sign_with_ecdsa
+   API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-method-sign_with_ecdsa)/\
+   [sign_with_schnorr](https://org5p-7iaaa-aaaak-qckna-cai.icp0.io/docs#ic-sign_with_schnorr).
+5. Sending the signed transaction to the Bitcoin network using the [bitcoin_send_transaction API](https://internetcomputer.org/docs/current/references/ic-interface-spec/#ic-method-bitcoin_send_transaction).
+
+This canister's `send_from_${type}` endpoint returns the ID of the transaction
+it sent to the network. You can track the status of this transaction using a
+[block explorer](https://en.bitcoin.it/wiki/Block_chain_browser). Once the
 transaction has at least one confirmation, you should be able to see it
 reflected in your current balance.
 
@@ -156,7 +219,7 @@ In this tutorial, you were able to:
 * Connect the canister to the Bitcoin testnet.
 * Send the canister some testnet BTC.
 * Check the testnet BTC balance of the canister.
-* Use the canister to send testnet BTC to another BTC address. 
+* Use the canister to send testnet BTC to another testnet BTC address. 
 
 This example is extensively documented in the following tutorials: