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Adding brief explaination
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Signed-off-by: Harshil Jani <harshiljani2002@gmail.com>
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@Harshil-Jani
Harshil-Jani committed Jul 10, 2023
1 parent 980664b commit 85f793b
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55 changes: 39 additions & 16 deletions examples/plan_spend.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -29,7 +29,25 @@ fn main() {
"023fc33527afab09fa97135f2180bcd22ce637b1d2fbcb2db748b1f2c33f45b2b4",
];

// Defining the taproot descriptor
// The taproot descriptor combines different spending paths and conditions, allowing the funds to be spent using
// different methods depending on the desired conditions.

// tr({A},{{pkh({B}),{{multi_a(1,{C},{D}),and_v(v:pk({E}),after(10))}}}}) represents a taproot spending policy.
// Let's break it down:
//
// * Key Spend Path
// {A} represents the public key for the taproot key spending path.
//
// * Script Spend Paths
// {B} represents the public key for the pay-to-pubkey-hash (P2PKH) spending path.
// The multi_a(1,{C},{D}) construct represents a 1-of-2 multi-signature script condition.
// It requires at least one signature from {C} and {D} to spend funds using the script spend path.
// The and_v(v:pk({E}),after(10)) construct represents a combination of a P2PK script condition and a time lock.
// It requires a valid signature from {E} and enforces a time lock of 10 blocks on spending funds.

// By constructing transactions using this taproot descriptor and signing them appropriately,
// you can create flexible spending policies that enable different spending paths and conditions depending on the
// transaction's inputs and outputs.
let s = format!(
"tr({},{{pkh({}),{{multi_a(1,{},{}),and_v(v:pk({}),after(10))}}}})",
keys[0], keys[1], keys[2], keys[3], keys[4]
Expand Down Expand Up @@ -127,17 +145,24 @@ fn main() {
value: amount * 4 / 5,
});

// Plan the Transaction using available assets
// Consider that out of all the keys required to sign the descriptor spend path we only have some handful of assets.
// We can plan the PSBT with only few assets(keys or hashes) if that are enough for satisfying any policy.
//
// Here for example assume that we only have two keys available.
// Key A and Key B (as seen from the descriptor above)
// We have to add the keys to `Asset` and then obtain plan with only available signatures if the descriptor can be satisfied.
let mut assets = Assets::new();
assets = assets.add(DescriptorPublicKey::from_str(keys[0]).unwrap()); // Master Key for Key Spend Path
assets = assets.add(DescriptorPublicKey::from_str(keys[1]).unwrap()); // Script Spend Path
assets = assets.add(DescriptorPublicKey::from_str(keys[0]).unwrap()); // Master Key for Key Spend Path - Key A
assets = assets.add(DescriptorPublicKey::from_str(keys[1]).unwrap()); // Script Spend Path - Key B

// Obtain the result of the plan based on provided assets
let result = bridge_descriptor.clone().get_plan(&assets);
// Obtain the Plan based on available Assets
let plan = bridge_descriptor.clone().get_plan(&assets).unwrap();

// Creating PSBT Input
let mut input = psbt::Input::default();
result.unwrap().update_psbt_input(&mut input);
plan.update_psbt_input(&mut input);

// Update the PSBT input from the result which we have obtained from the Plan.
input
.update_with_descriptor_unchecked(&bridge_descriptor)
.unwrap();
Expand All @@ -148,15 +173,13 @@ fn main() {
psbt.outputs.push(psbt::Output::default());

// Use private keys to sign
let sk1 = master_private_key.inner;
let sk2 = backup1_private.inner;

// In the following example we have signed the descriptor with master key
// which will allow the transaction to be key spend type.
// Any other key apart from master key is part of script policies and it
// will sign for script spend path if it satisfies.
sign_taproot_psbt(&sk1, &mut psbt, &secp256k1); // Key Spend
sign_taproot_psbt(&sk2, &mut psbt, &secp256k1); // Script Spend
let key_a = master_private_key.inner;
let key_b = backup1_private.inner;

// Taproot script can be signed when we have either Key spend or Script spend or both.
// Here you can try to verify by commenting one of the spend path or try signing with both.
sign_taproot_psbt(&key_a, &mut psbt, &secp256k1); // Key Spend - With Key A
sign_taproot_psbt(&key_b, &mut psbt, &secp256k1); // Script Spend - With Key B

// Serializing and finalizing the PSBT Transaction
let serialized = psbt.serialize();
Expand Down
51 changes: 35 additions & 16 deletions examples/psbt_sign_finalize.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,9 +15,29 @@ use miniscript::psbt::{PsbtExt, PsbtInputExt};
use miniscript::{Descriptor, DescriptorPublicKey};

fn main() {
// Defining the descriptor
// Defining the descriptor keys
let secp256k1 = secp256k1::Secp256k1::new();
let s = "wsh(t:or_c(pk(027a3565454fe1b749bccaef22aff72843a9c3efefd7b16ac54537a0c23f0ec0de),v:thresh(1,pkh(032d672a1a91cc39d154d366cd231983661b0785c7f27bc338447565844f4a6813),a:pkh(03417129311ed34c242c012cd0a3e0b9bca0065f742d0dfb63c78083ea6a02d4d9),a:pkh(025a687659658baeabdfc415164528065be7bcaade19342241941e556557f01e28))))#7hut9ukn";
let keys = vec![
"027a3565454fe1b749bccaef22aff72843a9c3efefd7b16ac54537a0c23f0ec0de",
"032d672a1a91cc39d154d366cd231983661b0785c7f27bc338447565844f4a6813",
"03417129311ed34c242c012cd0a3e0b9bca0065f742d0dfb63c78083ea6a02d4d9",
"025a687659658baeabdfc415164528065be7bcaade19342241941e556557f01e28",
];
// The wsh descriptor indicates a Witness Script Hash, meaning the descriptor is for a SegWit script.
// wsh(or(pk(A),thresh(1,pkh(B),pkh(C),pkh(D))))

// Let's break it down:
// t:or_c specifies an "or" construct, which means the script can be satisfied by one of the given conditions:
// pk(A) OR thresh(1,pkh(B),pkh(C),pkh(D))
// Inside threshold condition atleast 1 out of all given conditions should satisfy.

// By constructing transactions using this wsh descriptor and signing them appropriately,
// you can create flexible spending policies that enable different spending paths and conditions depending on the
// transaction's inputs and outputs.
let s = format!(
"wsh(t:or_c(pk({}),v:thresh(1,pkh({}),a:pkh({}),a:pkh({}))))#7hut9ukn",
keys[0], keys[1], keys[2], keys[3]
);
let bridge_descriptor = Descriptor::from_str(&s).expect("parse descriptor string");

assert!(bridge_descriptor.sanity_check().is_ok());
Expand Down Expand Up @@ -116,10 +136,12 @@ fn main() {
value: amount * 4 / 5,
});

// Plan the Transaction using available assets
// The descriptor is : or(pk(A),thresh(1,pkh(B),pkh(C),pkh(D)))
// For the context of planning in this example, We will only provide the key A as an asset
// This will satisfy the pk(A) and since we have an OR, This should be sufficient to satisfy the given policy.
// Consider that out of all the keys required to sign the descriptor, we only have some handful of assets.
// We can plan the PSBT with only few assets(keys or hashes) if that are enough for satisfying any policy.
//
// Here for example assume that we only have one key available i.e Key A(as seen from the descriptor above)
// Key A is enough to satisfy the given descriptor because it is OR.
// We have to add the key to `Asset` and then obtain plan with only available signature if the descriptor can be satisfied.
let mut assets = Assets::new();
assets = assets.add(
DescriptorPublicKey::from_str(
Expand All @@ -128,12 +150,14 @@ fn main() {
.unwrap(),
);

// Obtain the result of the plan based on provided assets
let result = bridge_descriptor.clone().get_plan(&assets);
// Obtain the Plan based on available Assets
let plan = bridge_descriptor.clone().get_plan(&assets).unwrap();

// Creating a PSBT Input
let mut input = psbt::Input::default();
result.unwrap().update_psbt_input(&mut input);

// Update the PSBT input from the result which we have obtained from the Plan.
plan.update_psbt_input(&mut input);
input
.update_with_descriptor_unchecked(&bridge_descriptor)
.unwrap();
Expand All @@ -158,16 +182,11 @@ fn main() {

// Finally construct the signature and add to psbt
let sig1 = secp256k1.sign_ecdsa(&msg, &sk1);
let pk1 = backup1_private.public_key(&secp256k1);
let key_a = backup1_private.public_key(&secp256k1);
assert!(secp256k1.verify_ecdsa(&msg, &sig1, &pk1.inner).is_ok());

// Second key just in case
let sig2 = secp256k1.sign_ecdsa(&msg, &sk2);
let pk2 = backup2_private.public_key(&secp256k1);
assert!(secp256k1.verify_ecdsa(&msg, &sig2, &pk2.inner).is_ok());

psbt.inputs[0].partial_sigs.insert(
pk1,
key_a,
bitcoin::ecdsa::Signature {
sig: sig1,
hash_ty: hash_ty,
Expand Down

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