transaction::Builder::add_transparent_input()

Cargo.lock

@@ -144,6 +144,11 @@ dependencies = [
  "ppv-lite86 0.2.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "cc"
+version = "1.0.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "cfg-if"
 version = "0.1.9"
@@ -551,6 +556,16 @@ dependencies = [
  "rand_core 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "ripemd160"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "block-buffer 0.7.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "digest 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "opaque-debug 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "rustc_version"
 version = "0.2.3"
@@ -564,6 +579,14 @@ name = "scopeguard"
 version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 
+[[package]]
+name = "secp256k1"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "cc 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
 [[package]]
 name = "semver"
 version = "0.9.0"
@@ -673,6 +696,8 @@ dependencies = [
  "rand 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_core 0.5.1 (registry+https://github.com/rust-lang/crates.io-index)",
  "rand_xorshift 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "ripemd160 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "secp256k1 0.15.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "sha2 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
@@ -708,6 +733,7 @@ dependencies = [
 "checksum byte-tools 0.3.1 (registry+https://github.com/rust-lang/crates.io-index)" = "e3b5ca7a04898ad4bcd41c90c5285445ff5b791899bb1b0abdd2a2aa791211d7"
 "checksum byteorder 1.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "a7c3dd8985a7111efc5c80b44e23ecdd8c007de8ade3b96595387e812b957cf5"
 "checksum c2-chacha 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "7d64d04786e0f528460fc884753cf8dddcc466be308f6026f8e355c41a0e4101"
+"checksum cc 1.0.45 (registry+https://github.com/rust-lang/crates.io-index)" = "4fc9a35e1f4290eb9e5fc54ba6cf40671ed2a2514c3eeb2b2a908dda2ea5a1be"
 "checksum cfg-if 0.1.9 (registry+https://github.com/rust-lang/crates.io-index)" = "b486ce3ccf7ffd79fdeb678eac06a9e6c09fc88d33836340becb8fffe87c5e33"
 "checksum constant_time_eq 0.1.4 (registry+https://github.com/rust-lang/crates.io-index)" = "995a44c877f9212528ccc74b21a232f66ad69001e40ede5bcee2ac9ef2657120"
 "checksum crossbeam 0.7.2 (registry+https://github.com/rust-lang/crates.io-index)" = "2d818a4990769aac0c7ff1360e233ef3a41adcb009ebb2036bf6915eb0f6b23c"
@@ -752,8 +778,10 @@ dependencies = [
 "checksum rand_hc 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ca3129af7b92a17112d59ad498c6f81eaf463253766b90396d39ea7a39d6613c"
 "checksum rand_os 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)" = "a788ae3edb696cfcba1c19bfd388cc4b8c21f8a408432b199c072825084da58a"
 "checksum rand_xorshift 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)" = "77d416b86801d23dde1aa643023b775c3a462efc0ed96443add11546cdf1dca8"
+"checksum ripemd160 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ad5112e0dbbb87577bfbc56c42450235e3012ce336e29c5befd7807bd626da4a"
 "checksum rustc_version 0.2.3 (registry+https://github.com/rust-lang/crates.io-index)" = "138e3e0acb6c9fb258b19b67cb8abd63c00679d2851805ea151465464fe9030a"
 "checksum scopeguard 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "b42e15e59b18a828bbf5c58ea01debb36b9b096346de35d941dcb89009f24a0d"
+"checksum secp256k1 0.15.0 (registry+https://github.com/rust-lang/crates.io-index)" = "e0344a794ff109f85547039536028e12f313178ac1545e49fdf16a530d900a7b"
 "checksum semver 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "1d7eb9ef2c18661902cc47e535f9bc51b78acd254da71d375c2f6720d9a40403"
 "checksum semver-parser 0.7.0 (registry+https://github.com/rust-lang/crates.io-index)" = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 "checksum sha2 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)" = "7b4d8bfd0e469f417657573d8451fb33d16cfe0989359b93baf3a1ffc639543d"

zcash_primitives/Cargo.toml

@@ -25,11 +25,16 @@ log = "0.4"
 pairing = { version = "0.15.0", path = "../pairing" }
 rand = "0.7"
 rand_core = "0.5.1"
+ripemd160 = { version = "0.8", optional = true }
+secp256k1 = { version = "=0.15.0", optional = true }
 sha2 = "0.8"
 
 [dev-dependencies]
 hex-literal = "0.2"
 rand_xorshift = "0.2"
 
+[features]
+transparent-inputs = ["ripemd160", "secp256k1"]
+
 [badges]
 maintenance = { status = "actively-developed" }

zcash_primitives/src/transaction/builder.rs

@@ -24,6 +24,12 @@ use crate::{
     JUBJUB,
 };
 
+#[cfg(feature = "transparent-inputs")]
+use crate::{
+    legacy::Script,
+    transaction::components::{OutPoint, TxIn},
+};
+
 const DEFAULT_TX_EXPIRY_DELTA: u32 = 20;
 
 /// If there are any shielded inputs, always have at least two shielded outputs, padding
@@ -130,6 +136,50 @@ impl SaplingOutput {
     }
 }
 
+#[cfg(feature = "transparent-inputs")]
+struct TransparentInputInfo {
+    sk: secp256k1::SecretKey,
+    pubkey: [u8; secp256k1::constants::PUBLIC_KEY_SIZE],
+    coin: TxOut,
+}
+
+#[cfg(feature = "transparent-inputs")]
+struct TransparentInputs {
+    secp: secp256k1::Secp256k1<secp256k1::SignOnly>,
+    inputs: Vec<TransparentInputInfo>,
+}
+
+#[cfg(feature = "transparent-inputs")]
+impl Default for TransparentInputs {
+    fn default() -> Self {
+        TransparentInputs {
+            secp: secp256k1::Secp256k1::gen_new(),
+            inputs: Default::default(),
+        }
+    }
+}
+
+#[cfg(not(feature = "transparent-inputs"))]
+#[derive(Default)]
+struct TransparentInputs;
+
+impl TransparentInputs {
+    fn input_sum(&self) -> Amount {
+        #[cfg(feature = "transparent-inputs")]
+        {
+            self.inputs
+                .iter()
+                .map(|input| input.coin.value)
+                .sum::<Amount>()
+        }
+
+        #[cfg(not(feature = "transparent-inputs"))]
+        {
+            Amount::zero()
+        }
+    }
+}
+
 /// Metadata about a transaction created by a [`Builder`].
 #[derive(Debug, PartialEq)]
 pub struct TransactionMetadata {
@@ -176,6 +226,7 @@ pub struct Builder<R: RngCore + CryptoRng> {
     anchor: Option<Fr>,
     spends: Vec<SpendDescriptionInfo>,
     outputs: Vec<SaplingOutput>,
+    legacy: TransparentInputs,
     change_address: Option<(OutgoingViewingKey, PaymentAddress<Bls12>)>,
 }
 
@@ -215,6 +266,7 @@ impl<R: RngCore + CryptoRng> Builder<R> {
             anchor: None,
             spends: vec![],
             outputs: vec![],
+            legacy: TransparentInputs::default(),
             change_address: None,
         }
     }
@@ -273,6 +325,39 @@ impl<R: RngCore + CryptoRng> Builder<R> {
         Ok(())
     }
 
+    /// Adds a transparent coin to be spent in this transaction.
+    #[cfg(feature = "transparent-inputs")]
+    pub fn add_transparent_input(
+        &mut self,
+        sk: secp256k1::SecretKey,
+        utxo: OutPoint,
+        coin: TxOut,
+    ) -> Result<(), Error> {
+        if coin.value.is_negative() {
+            return Err(Error::InvalidAmount);
+        }
+
+        let pubkey = secp256k1::PublicKey::from_secret_key(&self.legacy.secp, &sk).serialize();
+        match coin.script_pubkey.address() {
+            Some(TransparentAddress::PublicKey(hash)) => {
+                use ripemd160::Ripemd160;
+                use sha2::{Digest, Sha256};
+
+                if &hash[..] != &Ripemd160::digest(&Sha256::digest(&pubkey))[..] {
+                    return Err(Error::InvalidAddress);
+                }
+            }
+            _ => return Err(Error::InvalidAddress),
+        }
+
+        self.mtx.vin.push(TxIn::new(utxo));
+        self.legacy
+            .inputs
+            .push(TransparentInputInfo { sk, pubkey, coin });
+
+        Ok(())
+    }
+
     /// Adds a transparent address to send funds to.
     pub fn add_transparent_output(
         &mut self,
@@ -320,8 +405,7 @@ impl<R: RngCore + CryptoRng> Builder<R> {
         //
 
         // Valid change
-        let change = self.mtx.value_balance
-            - self.fee
+        let change = self.mtx.value_balance - self.fee + self.legacy.input_sum()
             - self
                 .mtx
                 .vout
@@ -524,6 +608,26 @@ impl<R: RngCore + CryptoRng> Builder<R> {
                 .map_err(|()| Error::BindingSig)?,
         );
 
+        // Transparent signatures
+        #[cfg(feature = "transparent-inputs")]
+        {
+            for (i, info) in self.legacy.inputs.iter().enumerate() {
+                sighash.copy_from_slice(&signature_hash_data(
+                    &self.mtx,
+                    consensus_branch_id,
+                    SIGHASH_ALL,
+                    Some((i, &info.coin.script_pubkey, info.coin.value)),
+                ));
+
+                let msg = secp256k1::Message::from_slice(&sighash).expect("32 bytes");
+                let sig = self.legacy.secp.sign(&msg, &info.sk);
+
+                // P2PKH scriptSig
+                self.mtx.vin[i].script_sig =
+                    Script::default() << &sig.serialize_compact()[..] << &info.pubkey[..];
+            }
+        }
+
         Ok((
             self.mtx.freeze().expect("Transaction should be complete"),
             tx_metadata,

zcash_primitives/src/transaction/components.rs

@@ -44,11 +44,20 @@ impl OutPoint {
 #[derive(Debug)]
 pub struct TxIn {
     pub prevout: OutPoint,
-    script_sig: Script,
+    pub script_sig: Script,
     pub sequence: u32,
 }
 
 impl TxIn {
+    #[cfg(feature = "transparent-inputs")]
+    pub fn new(prevout: OutPoint) -> Self {
+        TxIn {
+            prevout,
+            script_sig: Script::default(),
+            sequence: std::u32::MAX,
+        }
+    }
+
     pub fn read<R: Read>(mut reader: &mut R) -> io::Result<Self> {
         let prevout = OutPoint::read(&mut reader)?;
         let script_sig = Script::read(&mut reader)?;