change private key in request to pay

A private key can be interpreted into different recipient types: p2pkh,
p2wpkh, p2tr, etc...

In order for the client to import the private key and recover the UTXO,
we need to specify the descriptor type.

In this commit we change get_combined_private_key into a
get_combined_private_descriptor, where the return type is a proper
bitcoin descriptor with a WIF-formatted private key

Author: codingpeanut157

Cargo.toml

@@ -45,3 +45,4 @@ async-broadcast = "0.7.2"
 rstest = "0.25.0"
 secp256k1 = { version = "0.29" }
 reqwest = { version = "0.12", default-features = false }
+miniscript = {version = "12.3"}

crates/bcr-ebill-api/Cargo.toml

@@ -20,6 +20,7 @@ anyhow.workspace = true
 thiserror.workspace = true
 uuid.workspace = true
 bitcoin.workspace = true
+miniscript.workspace = true
 nostr-sdk.workspace = true
 nostr.workspace = true
 futures.workspace = true
@@ -29,6 +30,7 @@ bcr-ebill-persistence = { path = "../bcr-ebill-persistence" }
 bcr-ebill-transport = { path = "../bcr-ebill-transport" }
 tokio.workspace = true
 tokio_with_wasm.workspace = true
+secp256k1.workspace = true
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 reqwest = { workspace = true, features = ["json"] }

crates/bcr-ebill-api/src/external/bitcoin.rs

@@ -54,7 +54,7 @@ pub trait BitcoinClientApi: ServiceTraitBounds {
 
     fn generate_link_to_pay(&self, address: &str, sum: u64, message: &str) -> String;
 
-    fn get_combined_private_key(
+    fn get_combined_private_descriptor(
         &self,
         pkey: &bitcoin::PrivateKey,
         pkey_to_combine: &bitcoin::PrivateKey,
@@ -197,7 +197,7 @@ impl BitcoinClientApi for BitcoinClient {
         link
     }
 
-    fn get_combined_private_key(
+    fn get_combined_private_descriptor(
         &self,
         pkey: &bitcoin::PrivateKey,
         pkey_to_combine: &bitcoin::PrivateKey,
@@ -206,7 +206,19 @@ impl BitcoinClientApi for BitcoinClient {
             .inner
             .add_tweak(&Scalar::from(pkey_to_combine.inner))
             .map_err(|e| Error::PrivateKey(e.to_string()))?;
-        Ok(bitcoin::PrivateKey::new(private_key_bill, get_config().bitcoin_network()).to_string())
+        let priv_key = bitcoin::PrivateKey::new(private_key_bill, get_config().bitcoin_network());
+        let single = miniscript::descriptor::SinglePriv {
+            key: priv_key,
+            origin: None,
+        };
+        let desc_seckey = miniscript::descriptor::DescriptorSecretKey::Single(single);
+        let desc_pubkey = desc_seckey.to_public(secp256k1::global::SECP256K1).unwrap();
+        let kmap = miniscript::descriptor::KeyMap::from_iter(std::iter::once((
+            desc_pubkey.clone(),
+            desc_seckey,
+        )));
+        let desc = miniscript::Descriptor::new_pkh(desc_pubkey).unwrap();
+        Ok(desc.to_string_with_secret(&kmap))
     }
 
     fn get_mempool_link_for_address(&self, address: &str) -> String {

crates/bcr-ebill-api/src/service/bill_service/service.rs

@@ -471,12 +471,12 @@ impl BillServiceApi for BillService {
         }
 
         // The first key is always the bill key
-        let private_key = self.bitcoin_client.get_combined_private_key(
+        let private_descriptor = self.bitcoin_client.get_combined_private_descriptor(
             &BcrKeys::from_private_key(&bill_keys.private_key)?
                 .get_bitcoin_private_key(get_config().bitcoin_network()),
             &caller_keys.get_bitcoin_private_key(get_config().bitcoin_network()),
         )?;
-        return Ok(BillCombinedBitcoinKey { private_key });
+        return Ok(BillCombinedBitcoinKey { private_descriptor });
     }
 
     async fn get_detail(
@@ -827,7 +827,7 @@ impl BillServiceApi for BillService {
             Some(ref endorsee) => endorsee,
         };
 
-        let private_key_to_spend = self.bitcoin_client.get_combined_private_key(
+        let descriptor_to_spend = self.bitcoin_client.get_combined_private_descriptor(
             &BcrKeys::from_private_key(&bill_keys.private_key)?
                 .get_bitcoin_private_key(get_config().bitcoin_network()),
             &caller_keys.get_bitcoin_private_key(get_config().bitcoin_network()),
@@ -872,7 +872,7 @@ impl BillServiceApi for BillService {
                         sum: currency::sum_to_string(bill.sum),
                         link_to_pay,
                         address_to_pay,
-                        private_key_to_spend: private_key_to_spend.clone(),
+                        private_descriptor_to_spend: descriptor_to_spend.clone(),
                         mempool_link_for_address_to_pay,
                         status: if is_paid {
                             PastPaymentStatus::Paid(req_to_pay.timestamp)
@@ -918,7 +918,7 @@ impl BillServiceApi for BillService {
                 sum: currency::sum_to_string(past_sell_payment.0.sum),
                 link_to_pay,
                 address_to_pay,
-                private_key_to_spend: private_key_to_spend.clone(),
+                private_descriptor_to_spend: descriptor_to_spend.clone(),
                 mempool_link_for_address_to_pay,
                 status: past_sell_payment.1,
             }));
@@ -952,7 +952,7 @@ impl BillServiceApi for BillService {
                 sum: currency::sum_to_string(past_sell_payment.0.sum),
                 link_to_pay,
                 address_to_pay,
-                private_key_to_spend: private_key_to_spend.clone(),
+                private_descriptor_to_spend: descriptor_to_spend.clone(),
                 mempool_link_for_address_to_pay,
                 status: past_sell_payment.1,
             }));

crates/bcr-ebill-api/src/service/bill_service/test_utils.rs

@@ -168,11 +168,11 @@ pub fn get_service(mut ctx: MockBillContext) -> BillService {
         .expect_check_if_paid()
         .returning(|_, _| Ok((true, 100)));
     bitcoin_client
-        .expect_get_combined_private_key()
-        .returning(|_, _| Ok(String::from("123412341234")));
+        .expect_get_combined_private_descriptor()
+        .returning(|_, _| Ok(String::from("wpkh(cNjLH9K88VEhLeinPJkgPCZJZ9vNdi2L2UiTBuEfy4gSbTsMvvJg)")));
     bitcoin_client
         .expect_get_address_to_pay()
-        .returning(|_, _| Ok(String::from("tb1qteyk7pfvvql2r2zrsu4h4xpvju0nz7ykvguyk0")));
+        .returning(|_, _| Ok(String::from("tb1qssh7nk78mm35h75dg4th77zqz4qk3eay68krf9")));
     bitcoin_client
         .expect_get_mempool_link_for_address()
         .returning(|_| {

crates/bcr-ebill-core/src/bill/mod.rs

@@ -402,7 +402,7 @@ pub enum BillRole {
 
 #[derive(Debug)]
 pub struct BillCombinedBitcoinKey {
-    pub private_key: String,
+    pub private_descriptor: String,
 }
 
 #[derive(Debug)]
@@ -458,7 +458,7 @@ pub struct PastPaymentDataSell {
     pub sum: String,
     pub link_to_pay: String,
     pub address_to_pay: String,
-    pub private_key_to_spend: String,
+    pub private_descriptor_to_spend: String,
     pub mempool_link_for_address_to_pay: String,
     pub status: PastPaymentStatus,
 }
@@ -472,7 +472,7 @@ pub struct PastPaymentDataPayment {
     pub sum: String,
     pub link_to_pay: String,
     pub address_to_pay: String,
-    pub private_key_to_spend: String,
+    pub private_descriptor_to_spend: String,
     pub mempool_link_for_address_to_pay: String,
     pub status: PastPaymentStatus,
 }
@@ -486,7 +486,7 @@ pub struct PastPaymentDataRecourse {
     pub sum: String,
     pub link_to_pay: String,
     pub address_to_pay: String,
-    pub private_key_to_spend: String,
+    pub private_descriptor_to_spend: String,
     pub mempool_link_for_address_to_pay: String,
     pub status: PastPaymentStatus,
 }

crates/bcr-ebill-wasm/src/data/bill.rs

@@ -125,13 +125,13 @@ pub struct RejectActionBillPayload {
 #[derive(Tsify, Debug, Clone, Serialize)]
 #[tsify(into_wasm_abi)]
 pub struct BillCombinedBitcoinKeyWeb {
-    pub private_key: String,
+    pub private_descriptor: String,
 }
 
 impl From<BillCombinedBitcoinKey> for BillCombinedBitcoinKeyWeb {
     fn from(val: BillCombinedBitcoinKey) -> Self {
         BillCombinedBitcoinKeyWeb {
-            private_key: val.private_key,
+            private_descriptor: val.private_descriptor,
         }
     }
 }
@@ -310,7 +310,7 @@ pub struct PastPaymentDataSellWeb {
     pub sum: String,
     pub link_to_pay: String,
     pub address_to_pay: String,
-    pub private_key_to_spend: String,
+    pub private_descriptor_to_spend: String,
     pub mempool_link_for_address_to_pay: String,
     pub status: PastPaymentStatusWeb,
 }
@@ -325,7 +325,7 @@ impl From<PastPaymentDataSell> for PastPaymentDataSellWeb {
             sum: val.sum,
             link_to_pay: val.link_to_pay,
             address_to_pay: val.address_to_pay,
-            private_key_to_spend: val.private_key_to_spend,
+            private_descriptor_to_spend: val.private_descriptor_to_spend,
             mempool_link_for_address_to_pay: val.mempool_link_for_address_to_pay,
             status: val.status.into(),
         }
@@ -342,7 +342,7 @@ pub struct PastPaymentDataPaymentWeb {
     pub sum: String,
     pub link_to_pay: String,
     pub address_to_pay: String,
-    pub private_key_to_spend: String,
+    pub private_descriptor_to_spend: String,
     pub mempool_link_for_address_to_pay: String,
     pub status: PastPaymentStatusWeb,
 }
@@ -356,7 +356,7 @@ impl From<PastPaymentDataPayment> for PastPaymentDataPaymentWeb {
             sum: val.sum,
             link_to_pay: val.link_to_pay,
             address_to_pay: val.address_to_pay,
-            private_key_to_spend: val.private_key_to_spend,
+            private_descriptor_to_spend: val.private_descriptor_to_spend,
             mempool_link_for_address_to_pay: val.mempool_link_for_address_to_pay,
             status: val.status.into(),
         }
@@ -373,7 +373,7 @@ pub struct PastPaymentDataRecourseWeb {
     pub sum: String,
     pub link_to_pay: String,
     pub address_to_pay: String,
-    pub private_key_to_spend: String,
+    pub private_descriptor_to_spend: String,
     pub mempool_link_for_address_to_pay: String,
     pub status: PastPaymentStatusWeb,
 }
@@ -388,7 +388,7 @@ impl From<PastPaymentDataRecourse> for PastPaymentDataRecourseWeb {
             sum: val.sum,
             link_to_pay: val.link_to_pay,
             address_to_pay: val.address_to_pay,
-            private_key_to_spend: val.private_key_to_spend,
+            private_descriptor_to_spend: val.private_descriptor_to_spend,
             mempool_link_for_address_to_pay: val.mempool_link_for_address_to_pay,
             status: val.status.into(),
         }