Add SignetBlockScript/Buf for signet challenge scripts

diff --git a/bitcoin/src/blockdata/script/mod.rs b/bitcoin/src/blockdata/script/mod.rs
index ab54f748..5340ccde 100644
--- a/bitcoin/src/blockdata/script/mod.rs
+++ b/bitcoin/src/blockdata/script/mod.rs
@@ -84,9 +84,9 @@ pub use primitives::script::ScriptBufDecoderError;
 pub use primitives::script::{
     RedeemScript, RedeemScriptBuf, RedeemScriptSizeError, RedeemScriptTag, Script, ScriptBuf,
     ScriptBufDecoder, ScriptEncoder, ScriptHash, ScriptHashableTag, ScriptPubKey, ScriptPubKeyBuf,
-    ScriptPubKeyTag, ScriptSig, ScriptSigBuf, ScriptSigTag, Tag, TapScript, TapScriptBuf,
-    TapScriptTag, WScriptHash, WitnessScript, WitnessScriptBuf, WitnessScriptSizeError,
-    WitnessScriptTag,
+    ScriptPubKeyTag, ScriptSig, ScriptSigBuf, ScriptSigTag, SignetBlockScript,
+    SignetBlockScriptBuf, SignetBlockScriptTag, Tag, TapScript, TapScriptBuf, TapScriptTag,
+    WScriptHash, WitnessScript, WitnessScriptBuf, WitnessScriptSizeError, WitnessScriptTag,
 };
 
 pub(crate) use self::borrowed::ScriptExtPriv;
diff --git a/bitcoin/src/lib.rs b/bitcoin/src/lib.rs
index 98e890b7..4ee552b9 100644
--- a/bitcoin/src/lib.rs
+++ b/bitcoin/src/lib.rs
@@ -138,8 +138,9 @@ pub use primitives::{
     merkle_tree::{TxMerkleNode, WitnessMerkleNode},
     script::{
         RedeemScript, RedeemScriptBuf, RedeemScriptTag, ScriptHashableTag, ScriptPubKey,
-        ScriptPubKeyBuf, ScriptPubKeyTag, ScriptSig, ScriptSigBuf, ScriptSigTag, Tag, TapScript,
-        TapScriptBuf, TapScriptTag, WitnessScript, WitnessScriptBuf, WitnessScriptTag,
+        ScriptPubKeyBuf, ScriptPubKeyTag, ScriptSig, ScriptSigBuf, ScriptSigTag, SignetBlockScript,
+        SignetBlockScriptBuf, SignetBlockScriptTag, Tag, TapScript, TapScriptBuf, TapScriptTag,
+        WitnessScript, WitnessScriptBuf, WitnessScriptTag,
     },
     transaction::{
         Ntxid, OutPoint, Transaction, TxIn, TxOut, Txid, Version as TransactionVersion, Wtxid,
diff --git a/bitcoin/src/network/params.rs b/bitcoin/src/network/params.rs
index b5f9af7c..37876e8f 100644
--- a/bitcoin/src/network/params.rs
+++ b/bitcoin/src/network/params.rs
@@ -12,13 +12,13 @@
 //!
 //! ```
 //! use bitcoin::network::Params;
-//! use bitcoin::{WitnessScript, WitnessScriptBuf, Network, Target};
+//! use bitcoin::{SignetBlockScript, SignetBlockScriptBuf, Network, Target};
 //!
 //! const POW_TARGET_SPACING: u32 = 120; // Two minutes.
 //!
 //! pub struct CustomParams {
 //!     params: Params,
-//!     challenge_script: WitnessScriptBuf,
+//!     challenge_script: SignetBlockScriptBuf,
 //! }
 //!
 //! impl CustomParams {
@@ -28,7 +28,7 @@
 //!         params.pow_target_spacing = POW_TARGET_SPACING;
 //!
 //!         // This would be something real (see BIP-00325).
-//!         let challenge_script = WitnessScriptBuf::new();
+//!         let challenge_script = SignetBlockScriptBuf::new();
 //!
 //!         Self {
 //!             params,
@@ -37,7 +37,7 @@
 //!     }
 //!
 //!     /// Returns the custom signet challenge script.
-//!     pub fn challenge_script(&self) -> &WitnessScript { &self.challenge_script }
+//!     pub fn challenge_script(&self) -> &SignetBlockScript { &self.challenge_script }
 //! }
 //!
 //! impl AsRef<Params> for CustomParams {
diff --git a/primitives/src/lib.rs b/primitives/src/lib.rs
index d4646b6e..db48b833 100644
--- a/primitives/src/lib.rs
+++ b/primitives/src/lib.rs
@@ -88,7 +88,8 @@ pub use self::{
     },
     script::{
         RedeemScript, RedeemScriptBuf, ScriptPubKey, ScriptPubKeyBuf, ScriptSig, ScriptSigBuf,
-        TapScript, TapScriptBuf, WitnessScript, WitnessScriptBuf,
+        SignetBlockScript, SignetBlockScriptBuf, TapScript, TapScriptBuf, WitnessScript,
+        WitnessScriptBuf,
     },
     transaction::{Transaction, TxIn, TxOut},
     witness::Witness,
diff --git a/primitives/src/script/mod.rs b/primitives/src/script/mod.rs
index 6406a558..b9a83da1 100644
--- a/primitives/src/script/mod.rs
+++ b/primitives/src/script/mod.rs
@@ -27,7 +27,7 @@ use crate::prelude::{Borrow, BorrowMut, Box, Cow, ToOwned, Vec};
 pub use self::{
     borrowed::{Script, ScriptEncoder},
     owned::{ScriptBuf, ScriptBufDecoder, ScriptBufDecoderError},
-    tag::{Tag, RedeemScriptTag, ScriptPubKeyTag, ScriptSigTag, TapScriptTag, WitnessScriptTag},
+    tag::{Tag, RedeemScriptTag, ScriptPubKeyTag, ScriptSigTag, SignetBlockScriptTag, TapScriptTag, WitnessScriptTag},
 };
 #[doc(inline)]
 pub use crate::hash_types::{
@@ -58,6 +58,12 @@ pub type ScriptSigBuf = ScriptBuf<ScriptSigTag>;
 /// A `scriptSig` decoder.
 pub type ScriptSigBufDecoder = ScriptBufDecoder<ScriptSigTag>;
 
+/// A signet block/challenge script.
+pub type SignetBlockScriptBuf = ScriptBuf<SignetBlockScriptTag>;
+
+/// A reference to a signet block/challenge script.
+pub type SignetBlockScript = Script<SignetBlockScriptTag>;
+
 /// A Segwit v1 Taproot script.
 pub type TapScriptBuf = ScriptBuf<TapScriptTag>;
 
@@ -150,6 +156,11 @@ impl TryFrom<&WitnessScript> for WScriptHash {
     }
 }
 
+impl From<WitnessScriptBuf> for SignetBlockScriptBuf {
+    #[inline]
+    fn from(buf: WitnessScriptBuf) -> Self { Self::from_bytes(buf.into_bytes()) }
+}
+
 // We keep all the `Script` and `ScriptBuf` impls together since it's easier to see side-by-side.
 
 impl<T> From<ScriptBuf<T>> for Box<Script<T>> {
diff --git a/primitives/src/script/tag.rs b/primitives/src/script/tag.rs
index d5d5162b..6f9862f8 100644
--- a/primitives/src/script/tag.rs
+++ b/primitives/src/script/tag.rs
@@ -23,6 +23,11 @@ impl Tag for ScriptSigTag {}
 pub enum ScriptPubKeyTag {}
 impl Tag for ScriptPubKeyTag {}
 
+/// A signet block challenge script.
+#[derive(Clone, PartialOrd, Ord, PartialEq, Eq, Hash)]
+pub enum SignetBlockScriptTag {}
+impl Tag for SignetBlockScriptTag {}
+
 /// A Segwit v1 Taproot script.
 #[derive(Clone, PartialOrd, Ord, PartialEq, Eq, Hash)]
 pub enum TapScriptTag {}
diff --git a/primitives/src/script/tests.rs b/primitives/src/script/tests.rs
index ae701aa4..91256a3c 100644
--- a/primitives/src/script/tests.rs
+++ b/primitives/src/script/tests.rs
@@ -561,6 +561,14 @@ fn decoder_full_read_limit() {
     assert_eq!(decoder.read_limit(), 31);
 }
 
+#[test]
+fn witness_to_signet_script() {
+    let bytes = vec![0x51, 0x52, 0x53];
+    let witness = WitnessScriptBuf::from(bytes.clone());
+    let signet: SignetBlockScriptBuf = witness.into();
+    assert_eq!(signet.as_bytes(), &bytes);
+}
+
 #[test]
 fn decoder_error_display() {
     #[cfg(feature = "std")]