seals: add TxoSeal constructors

consensus/src/tx.rs

@@ -36,6 +36,7 @@ use crate::{
 };
 
 #[derive(Wrapper, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, From)]
+#[wrapper(AsSlice)]
 #[derive(StrictType, StrictDumb, StrictEncode, StrictDecode)]
 #[strict_type(lib = LIB_NAME_BITCOIN)]
 #[cfg_attr(

seals/src/txout.rs

@@ -28,8 +28,8 @@ use std::cmp::Ordering;
 
 use amplify::confinement::TinyOrdMap;
 use amplify::{ByteArray, Bytes, Bytes32};
-use bc::{Outpoint, Tx, Txid};
-use commit_verify::{mpc, CommitId, ReservedBytes, StrictHash};
+use bc::{Outpoint, Tx, Txid, Vout};
+use commit_verify::{mpc, CommitId, Digest, DigestExt, ReservedBytes, Sha256, StrictHash};
 use single_use_seals::{ClientSideWitness, PublishedWitness, SealWitness, SingleUseSeal};
 use strict_encoding::StrictDumb;
 
@@ -180,6 +180,26 @@ impl<D: dbc::Proof> Ord for TxoSeal<D> {
     }
 }
 
+impl<D: dbc::Proof> TxoSeal<D> {
+    pub fn vout_no_fallback(vout: Vout, noise_seed: impl AsRef<[u8]>) -> Self {
+        Self::no_fallback(Outpoint::new(Txid::from([0xFFu8; 32]), vout), noise_seed)
+    }
+
+    pub fn no_fallback(outpoint: Outpoint, noise_seed: impl AsRef<[u8]>) -> Self {
+        let mut engine = Sha256::new();
+        engine.input_raw(noise_seed.as_ref());
+        engine.input_raw(outpoint.txid.as_ref());
+        engine.input_raw(&outpoint.vout.to_u32().to_be_bytes());
+        let mut noise = [0xFFu8; 40];
+        noise[..32].copy_from_slice(&engine.finish());
+        Self {
+            primary: outpoint,
+            secondary: TxoSealExt::Noise(Noise(noise.into())),
+            _phantom: PhantomData,
+        }
+    }
+}
+
 impl<D: dbc::Proof> SingleUseSeal for TxoSeal<D> {
     type Message = Bytes32;
     type PubWitness = Tx;