<!DOCTYPE HTML>
<html lang="en" class="sidebar-visible no-js light">
<head>
<!-- Book generated using mdBook -->
<meta charset="UTF-8">
<title>confidential_transfer - Zero Network Documentation</title>
<!-- Custom HTML head -->
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<meta name="description" content="">
<meta name="viewport" content="width=device-width, initial-scale=1">
<meta name="theme-color" content="#ffffff" />
<link rel="icon" href="favicon.svg">
<link rel="shortcut icon" href="favicon.png">
<link rel="stylesheet" href="css/variables.css">
<link rel="stylesheet" href="css/general.css">
<link rel="stylesheet" href="css/chrome.css">
<link rel="stylesheet" href="css/print.css" media="print">
<!-- Fonts -->
<link rel="stylesheet" href="FontAwesome/css/font-awesome.css">
<link rel="stylesheet" href="fonts/fonts.css">
<!-- Highlight.js Stylesheets -->
<link rel="stylesheet" href="highlight.css">
<link rel="stylesheet" href="tomorrow-night.css">
<link rel="stylesheet" href="ayu-highlight.css">
<!-- Custom theme stylesheets -->
<!-- MathJax -->
<script async src="https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.1/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>
</head>
<body>
<!-- Provide site root to javascript -->
<script>
var path_to_root = "";
var default_theme = window.matchMedia("(prefers-color-scheme: dark)").matches ? "navy" : "light";
</script>
<!-- Work around some values being stored in localStorage wrapped in quotes -->
<script>
try {
var theme = localStorage.getItem('mdbook-theme');
var sidebar = localStorage.getItem('mdbook-sidebar');
if (theme.startsWith('"') && theme.endsWith('"')) {
localStorage.setItem('mdbook-theme', theme.slice(1, theme.length - 1));
}
if (sidebar.startsWith('"') && sidebar.endsWith('"')) {
localStorage.setItem('mdbook-sidebar', sidebar.slice(1, sidebar.length - 1));
}
} catch (e) { }
</script>
<!-- Set the theme before any content is loaded, prevents flash -->
<script>
var theme;
try { theme = localStorage.getItem('mdbook-theme'); } catch(e) { }
if (theme === null || theme === undefined) { theme = default_theme; }
var html = document.querySelector('html');
html.classList.remove('no-js')
html.classList.remove('light')
html.classList.add(theme);
html.classList.add('js');
</script>
<!-- Hide / unhide sidebar before it is displayed -->
<script>
var html = document.querySelector('html');
var sidebar = 'hidden';
if (document.body.clientWidth >= 1080) {
try { sidebar = localStorage.getItem('mdbook-sidebar'); } catch(e) { }
sidebar = sidebar || 'visible';
}
html.classList.remove('sidebar-visible');
html.classList.add("sidebar-" + sidebar);
</script>
<nav id="sidebar" class="sidebar" aria-label="Table of contents">
<div class="sidebar-scrollbox">
<ol class="chapter"><li class="chapter-item expanded "><a href="0_0_zero_network.html"><strong aria-hidden="true">1.</strong> Zero Network</a></li><li class="chapter-item expanded "><a href="1_0_overview.html"><strong aria-hidden="true">2.</strong> Overview</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="1_1_what_is_privacy.html"><strong aria-hidden="true">2.1.</strong> What is Privacy</a></li><li class="chapter-item expanded "><a href="1_2_hide_transfer_amount.html"><strong aria-hidden="true">2.2.</strong> Hide Transfer Amount</a></li><li class="chapter-item expanded "><a href="1_3_gas_limit.html"><strong aria-hidden="true">2.3.</strong> Gas Limit</a></li><li class="chapter-item expanded "><a href="1_4_zero_knowledge_scheme.html"><strong aria-hidden="true">2.4.</strong> Zero Knowledge Scheme</a></li><li class="chapter-item expanded "><a href="1_5_transaction_constraints.html"><strong aria-hidden="true">2.5.</strong> Transaction Constraints</a></li></ol></li><li class="chapter-item expanded "><a href="2_0_transaction_constraints.html"><strong aria-hidden="true">3.</strong> Transaction Constraints</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="2_1_confidential_transfer.html"><strong aria-hidden="true">3.1.</strong> Confidential Transfer</a></li><li class="chapter-item expanded "><a href="2_2_confidential_smart_contract.html"><strong aria-hidden="true">3.2.</strong> Confidential Smart Contract</a></li></ol></li><li class="chapter-item expanded "><a href="3_0_primitive.html"><strong aria-hidden="true">4.</strong> Primitive</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="3_1_crypto.html"><strong aria-hidden="true">4.1.</strong> Crypto</a></li><li class="chapter-item expanded "><a href="3_2_jubjub.html"><strong aria-hidden="true">4.2.</strong> Jubjub</a></li><li class="chapter-item expanded "><a href="3_3_bls12_381.html"><strong aria-hidden="true">4.3.</strong> Bls12 381</a></li><li class="chapter-item expanded "><a href="3_4_elgamal.html"><strong aria-hidden="true">4.4.</strong> ElGamal</a></li><li class="chapter-item expanded "><a href="3_5_pairing.html"><strong aria-hidden="true">4.5.</strong> Pairing</a></li></ol></li><li class="chapter-item expanded "><a href="4_0_pallet.html"><strong aria-hidden="true">5.</strong> Pallet</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="4_1_plonk.html"><strong aria-hidden="true">5.1.</strong> Plonk</a></li><li class="chapter-item expanded "><a href="4_2_encrypted_balance.html"><strong aria-hidden="true">5.2.</strong> Encrypted Balance</a></li><li class="chapter-item expanded "><a href="4_3_confidential_transfer.html"><strong aria-hidden="true">5.3.</strong> Confidential Transfer</a></li></ol></li><li class="chapter-item expanded "><a href="5_0_related_tools.html"><strong aria-hidden="true">6.</strong> Related Tools</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="5_1_stealth_address.html"><strong aria-hidden="true">6.1.</strong> Stealth Address</a></li><li class="chapter-item expanded "><a href="5_2_pedersen_commitment.html"><strong aria-hidden="true">6.2.</strong> Pedersen Commitment</a></li><li class="chapter-item expanded "><a href="5_3_non_interactive_zero_knowlege_proof.html"><strong aria-hidden="true">6.3.</strong> Non Interactive Zero Knowledge Proof</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="5_3_1_qap.html"><strong aria-hidden="true">6.3.1.</strong> QAP</a></li><li class="chapter-item expanded "><a href="5_3_2_polynomial_commitment.html"><strong aria-hidden="true">6.3.2.</strong> Polynomial Commitment</a></li><li class="chapter-item expanded "><a href="5_3_3_homomorphic_encryption.html"><strong aria-hidden="true">6.3.3.</strong> Homomorphic Encryption</a></li></ol></li></ol></li><li class="chapter-item expanded "><a href="6_0_tutorial.html"><strong aria-hidden="true">7.</strong> Tutorial</a></li><li><ol class="section"><li class="chapter-item expanded "><a href="6_1_plonk_pallet.html"><strong aria-hidden="true">7.1.</strong> pallet-plonk</a></li><li class="chapter-item expanded "><a href="6_2_confidential_transfer.html" class="active"><strong aria-hidden="true">7.2.</strong> confidential_transfer</a></li></ol></li><li class="chapter-item expanded "><a href="7_0_frequent_errors.html"><strong aria-hidden="true">8.</strong> Frequent Errors</a></li></ol>
</div>
<div id="sidebar-resize-handle" class="sidebar-resize-handle"></div>
</nav>
<div id="page-wrapper" class="page-wrapper">
<div class="page">
<div id="menu-bar-hover-placeholder"></div>
<div id="menu-bar" class="menu-bar sticky bordered">
<div class="left-buttons">
<button id="sidebar-toggle" class="icon-button" type="button" title="Toggle Table of Contents" aria-label="Toggle Table of Contents" aria-controls="sidebar">
<i class="fa fa-bars"></i>
</button>
<button id="theme-toggle" class="icon-button" type="button" title="Change theme" aria-label="Change theme" aria-haspopup="true" aria-expanded="false" aria-controls="theme-list">
<i class="fa fa-paint-brush"></i>
</button>
<ul id="theme-list" class="theme-popup" aria-label="Themes" role="menu">
<li role="none"><button role="menuitem" class="theme" id="light">Light (default)</button></li>
<li role="none"><button role="menuitem" class="theme" id="rust">Rust</button></li>
<li role="none"><button role="menuitem" class="theme" id="coal">Coal</button></li>
<li role="none"><button role="menuitem" class="theme" id="navy">Navy</button></li>
<li role="none"><button role="menuitem" class="theme" id="ayu">Ayu</button></li>
</ul>
<button id="search-toggle" class="icon-button" type="button" title="Search. (Shortkey: s)" aria-label="Toggle Searchbar" aria-expanded="false" aria-keyshortcuts="S" aria-controls="searchbar">
<i class="fa fa-search"></i>
</button>
</div>
<h1 class="menu-title">Zero Network Documentation</h1>
<div class="right-buttons">
<a href="print.html" title="Print this book" aria-label="Print this book">
<i id="print-button" class="fa fa-print"></i>
</a>
</div>
</div>
<div id="search-wrapper" class="hidden">
<form id="searchbar-outer" class="searchbar-outer">
<input type="search" id="searchbar" name="searchbar" placeholder="Search this book ..." aria-controls="searchresults-outer" aria-describedby="searchresults-header">
</form>
<div id="searchresults-outer" class="searchresults-outer hidden">
<div id="searchresults-header" class="searchresults-header"></div>
<ul id="searchresults">
</ul>
</div>
</div>
<!-- Apply ARIA attributes after the sidebar and the sidebar toggle button are added to the DOM -->
<script>
document.getElementById('sidebar-toggle').setAttribute('aria-expanded', sidebar === 'visible');
document.getElementById('sidebar').setAttribute('aria-hidden', sidebar !== 'visible');
Array.from(document.querySelectorAll('#sidebar a')).forEach(function(link) {
link.setAttribute('tabIndex', sidebar === 'visible' ? 0 : -1);
});
</script>
<div id="content" class="content">
<main>
<h1 id="confidential_transfer"><a class="header" href="#confidential_transfer">confidential_transfer</a></h1>
<p>In this tutorial, we are going to generate test data and test its functionalities. We assume that you already unserstand what <a href="./2_1_confidential_transfer.html">Confidential Transfer</a> is.</p>
<p>The steps are following.</p>
<ol>
<li>Define the <code>confidential_transfer</code> as depencencies</li>
<li>Generate test data used for <code>confidential_transfer</code></li>
<li>Test funcitonalities</li>
</ol>
<h2 id="1-define-the-confidential_transfer-as-depencencies"><a class="header" href="#1-define-the-confidential_transfer-as-depencencies">1. Define the confidential_transfer as depencencies</a></h2>
<p>First of all, you need to define the <code>confidential_transfer</code>.</p>
<ul>
<li><your-pallet>/Cargo.toml</li>
</ul>
<pre><code class="language-toml">confidential_transfer = { git = "https://github.com/zero-network/zero", branch = "master", default-features = false }
pallet_encrypted_balance = { git = "https://github.com/zero-network/zero", branch = "master", default-features = false }
pallet_plonk = { git = "https://github.com/zero-network/zero", branch = "master", default-features = false }
zero_elgamal = { git = "https://github.com/zero-network/zero", branch = "master", default-features = false }
zero_bls12_381 = { git = "https://github.com/zero-network/zero", branch = "master", default-features = false }
rand_core = {version="0.6", default-features = false }
</code></pre>
<p>The <code>confidential_transfer</code> depends on <code>rand_core</code> so please import it.</p>
<h2 id="2-generate-test-data-used-for-confidential_transfer"><a class="header" href="#2-generate-test-data-used-for-confidential_transfer">2. Generate test data used for <code>confidential_transfer</code></a></h2>
<p>Secondly, we would like like to setup the Alice and Bob account on testing runtime. Define the <code>new_test_ext</code> for genesis config and reflect the testing data for runtime storage.</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>fn new_test_ext(
alice_address: u64,
alice_private_key: Fp,
alice_balance: u32,
alice_radomness: Fp,
bob_private_key: Fp,
bob_address: u64,
bob_balance: u32,
bob_radomness: Fp,
) -> sp_io::TestExternalities {
let alice_balance = EncryptedNumber::encrypt(alice_private_key, alice_balance, alice_radomness);
let bob_balance = EncryptedNumber::encrypt(bob_private_key, bob_balance, bob_radomness);
let mut t = frame_system::GenesisConfig::default()
.build_storage::<TestRuntime>()
.unwrap();
pallet_encrypted_balance::GenesisConfig::<TestRuntime> {
balances: vec![(alice_address, alice_balance), (bob_address, bob_balance)],
}
.assimilate_storage(&mut t)
.unwrap();
let mut ext = sp_io::TestExternalities::new(t);
ext.execute_with(|| System::set_block_number(1));
ext
}
<span class="boring">}</span></code></pre></pre>
<p>Thirdly, we define <code>generate_default_test_data</code> to generate parameters used for <code>confidential_transfer</code>.</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>fn generate_default_test_data() -> (u64, Fp, u16, Fp, Fp, u64, u16, Fp, u16, u16, u16) {
let mut rng = rand::thread_rng();
let alice_address = rng.gen::<u64>();
let alice_private_key = Fp::random(OsRng);
let alice_balance = rng.gen::<u16>();
let alice_radomness = Fp::random(OsRng);
let bob_private_key = Fp::random(OsRng);
let bob_address = rng.gen::<u64>();
let bob_balance = rng.gen::<u16>();
let bob_radomness = Fp::random(OsRng);
let transfer_amount = rng.gen_range(0..alice_balance);
let alice_after_balance = alice_balance - transfer_amount;
let bob_after_balance = bob_balance + transfer_amount;
(
alice_address,
alice_private_key,
alice_balance,
alice_radomness,
bob_private_key,
bob_address,
bob_balance,
bob_radomness,
transfer_amount,
alice_after_balance,
bob_after_balance,
)
}
<span class="boring">}</span></code></pre></pre>
<h2 id="3-test-funcitonalities"><a class="header" href="#3-test-funcitonalities">3. Test funcitonalities</a></h2>
<p>Finally, we combine previous sections together and test functionalities.</p>
<pre><pre class="playground"><code class="language-rust">fn main() {
let k = 14;
let label = b"verify";
let mut rng = get_rng();
let (
alice_address,
alice_private_key,
alice_balance,
alice_radomness,
bob_private_key,
bob_address,
bob_balance,
bob_radomness,
transfer_amount,
alice_after_balance,
bob_after_balance,
transfer_randomness,
) = generate_default_test_data();
new_test_ext(
alice_address,
alice_private_key,
alice_balance,
alice_radomness,
bob_private_key,
bob_address,
bob_balance,
bob_radomness,
)
.execute_with(|| {
// default balance decryption check
let alice_encrypted_balance = ConfidentialTransfer::total_balance(&alice_address);
let alice_raw_balance = alice_encrypted_balance.decrypt(alice_private_key);
let bob_encrypted_balance = ConfidentialTransfer::total_balance(&bob_address);
let bob_raw_balance = bob_encrypted_balance.decrypt(bob_private_key);
assert_eq!(alice_raw_balance.unwrap() as u16, alice_balance);
assert_eq!(bob_raw_balance.unwrap() as u16, bob_balance);
// trusted setup check
let result =
ConfidentialTransfer::trusted_setup(Origin::signed(alice_address), k, rng.clone());
assert_ok!(result);
// proof generation
let pp = Plonk::public_parameter().unwrap();
let alice_public_key = GENERATOR_EXTENDED * alice_private_key;
let bob_public_key = GENERATOR_EXTENDED * bob_private_key;
let transfer_amount_scalar = Fp::from(transfer_amount as u64);
let alice_after_balance_scalar = Fp::from(alice_after_balance as u64);
let alice_balance =
EncryptedNumber::encrypt(alice_private_key, alice_balance.into(), alice_radomness);
let alice_transfer_amount = EncryptedNumber::encrypt(
alice_private_key,
transfer_amount.into(),
transfer_randomness,
);
let bob_encrypted_transfer_amount =
(GENERATOR_EXTENDED * transfer_amount_scalar) + (bob_public_key * transfer_randomness);
let alice_public_key = JubJubAffine::from(alice_public_key);
let bob_public_key = JubJubAffine::from(bob_public_key);
let bob_encrypted_transfer_amount = JubJubAffine::from(bob_encrypted_transfer_amount);
let bob_encrypted_transfer_amount_other = (GENERATOR_EXTENDED * transfer_randomness).into();
let confidential_transfer_circuit = ConfidentialTransferCircuit::new(
alice_public_key,
bob_public_key,
alice_balance,
alice_transfer_amount,
bob_encrypted_transfer_amount,
alice_private_key,
transfer_amount_scalar,
alice_after_balance_scalar,
transfer_randomness,
);
let prover = Compiler::compile::<ConfidentialTransferCircuit>(&pp, label)
.expect("failed to compile circuit");
let proof = prover
.0
.prove(&mut rng, &confidential_transfer_circuit)
.expect("failed to prove");
// confidential transfer check
let transaction_params = ConfidentialTransferTransaction::new(
alice_public_key,
bob_public_key,
alice_transfer_amount,
bob_encrypted_transfer_amount,
bob_encrypted_transfer_amount_other,
);
let result = ConfidentialTransfer::confidential_transfer(
Origin::signed(alice_address),
bob_address,
proof.0,
transaction_params,
);
assert_ok!(result);
// balance transition check
let alice_balance = ConfidentialTransfer::total_balance(&alice_address);
let alice_raw_balance = alice_balance.decrypt(alice_private_key);
let bob_balance = ConfidentialTransfer::total_balance(&bob_address);
let bob_raw_balance = bob_balance.decrypt(bob_private_key);
assert_eq!(alice_raw_balance.unwrap() as u16, alice_after_balance);
assert_eq!(bob_raw_balance.unwrap() as u16, bob_after_balance);
})
}</code></pre></pre>
<p>With above tests, we can confirm that confidential transfer works correctly. You can check the <code>confidential_transfer</code> example <a href="https://github.com/zero-network/zero/confidential_transfer.rs">here</a>. Happy hacking!</p>
</main>
<nav class="nav-wrapper" aria-label="Page navigation">
<!-- Mobile navigation buttons -->
<a rel="prev" href="6_1_plonk_pallet.html" class="mobile-nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a rel="next" href="7_0_frequent_errors.html" class="mobile-nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</a>
<div style="clear: both"></div>
</nav>
</div>
</div>
<nav class="nav-wide-wrapper" aria-label="Page navigation">
<a rel="prev" href="6_1_plonk_pallet.html" class="nav-chapters previous" title="Previous chapter" aria-label="Previous chapter" aria-keyshortcuts="Left">
<i class="fa fa-angle-left"></i>
</a>
<a rel="next" href="7_0_frequent_errors.html" class="nav-chapters next" title="Next chapter" aria-label="Next chapter" aria-keyshortcuts="Right">
<i class="fa fa-angle-right"></i>
</a>
</nav>
</div>
<script>
window.playground_copyable = true;
</script>
<script src="elasticlunr.min.js" charset="utf-8"></script>
<script src="mark.min.js" charset="utf-8"></script>
<script src="searcher.js" charset="utf-8"></script>
<script src="clipboard.min.js" charset="utf-8"></script>
<script src="highlight.js" charset="utf-8"></script>
<script src="book.js" charset="utf-8"></script>
<!-- Custom JS scripts -->
</body>
</html>
