Tapscript support, part 1

include/wally.hpp

@@ -534,6 +534,18 @@ inline int descriptor_canonicalize(const DESCRIPTOR& descriptor, uint32_t flags,
     return detail::check_ret(__FUNCTION__, ret);
 }
 
+template <class DESCRIPTOR>
+inline int descriptor_derive_bip32_key(const DESCRIPTOR& descriptor, size_t index, uint32_t variant, uint32_t multi_index, uint32_t child_num, uint32_t flags, struct ext_key* output) {
+    int ret = ::wally_descriptor_derive_bip32_key(detail::get_p(descriptor), index, variant, multi_index, child_num, flags, output);
+    return detail::check_ret(__FUNCTION__, ret);
+}
+
+template <class DESCRIPTOR>
+inline int descriptor_derive_bip32_key_alloc(const DESCRIPTOR& descriptor, size_t index, uint32_t variant, uint32_t multi_index, uint32_t child_num, uint32_t flags, struct ext_key** output) {
+    int ret = ::wally_descriptor_derive_bip32_key_alloc(detail::get_p(descriptor), index, variant, multi_index, child_num, flags, output);
+    return detail::check_ret(__FUNCTION__, ret);
+}
+
 inline int descriptor_free(struct wally_descriptor* descriptor) {
     int ret = ::wally_descriptor_free(descriptor);
     return detail::check_ret(__FUNCTION__, ret);
@@ -623,6 +635,60 @@ inline int descriptor_get_num_variants(const DESCRIPTOR& descriptor, uint32_t* v
     return detail::check_ret(__FUNCTION__, ret);
 }
 
+template <class DESCRIPTOR, class BYTES_OUT>
+inline int descriptor_get_taproot_control_block(const DESCRIPTOR& descriptor, uint32_t leaf_index, uint32_t multi_index, uint32_t child_num, uint32_t flags, BYTES_OUT& bytes_out, size_t* written) {
+    int ret = ::wally_descriptor_get_taproot_control_block(detail::get_p(descriptor), leaf_index, multi_index, child_num, flags, bytes_out.data(), bytes_out.size(), written);
+    return detail::check_ret(__FUNCTION__, ret);
+}
+
+template <class DESCRIPTOR>
+inline int descriptor_get_taproot_control_block_len(const DESCRIPTOR& descriptor, uint32_t leaf_index, uint32_t multi_index, uint32_t child_num, uint32_t flags, size_t* written) {
+    int ret = ::wally_descriptor_get_taproot_control_block_len(detail::get_p(descriptor), leaf_index, multi_index, child_num, flags, written);
+    return detail::check_ret(__FUNCTION__, ret);
+}
+
+template <class DESCRIPTOR, class BYTES_OUT>
+inline int descriptor_get_taproot_leaf_hash(const DESCRIPTOR& descriptor, uint32_t leaf_index, uint32_t multi_index, uint32_t child_num, uint32_t flags, BYTES_OUT& bytes_out) {
+    int ret = ::wally_descriptor_get_taproot_leaf_hash(detail::get_p(descriptor), leaf_index, multi_index, child_num, flags, bytes_out.data(), bytes_out.size());
+    return detail::check_ret(__FUNCTION__, ret);
+}
+
+template <class DESCRIPTOR>
+inline int descriptor_get_taproot_leaf_key_index(const DESCRIPTOR& descriptor, uint32_t leaf_index, uint32_t key_index, uint32_t* value_out) {
+    int ret = ::wally_descriptor_get_taproot_leaf_key_index(detail::get_p(descriptor), leaf_index, key_index, value_out);
+    return detail::check_ret(__FUNCTION__, ret);
+}
+
+template <class DESCRIPTOR>
+inline int descriptor_get_taproot_leaf_num_keys(const DESCRIPTOR& descriptor, uint32_t leaf_index, uint32_t* value_out) {
+    int ret = ::wally_descriptor_get_taproot_leaf_num_keys(detail::get_p(descriptor), leaf_index, value_out);
+    return detail::check_ret(__FUNCTION__, ret);
+}
+
+template <class DESCRIPTOR, class BYTES_OUT>
+inline int descriptor_get_taproot_leaf_script(const DESCRIPTOR& descriptor, uint32_t leaf_index, uint32_t multi_index, uint32_t child_num, uint32_t flags, BYTES_OUT& bytes_out, size_t* written) {
+    int ret = ::wally_descriptor_get_taproot_leaf_script(detail::get_p(descriptor), leaf_index, multi_index, child_num, flags, bytes_out.data(), bytes_out.size(), written);
+    return detail::check_ret(__FUNCTION__, ret);
+}
+
+template <class DESCRIPTOR>
+inline int descriptor_get_taproot_leaf_script_len(const DESCRIPTOR& descriptor, uint32_t leaf_index, uint32_t multi_index, uint32_t child_num, uint32_t flags, size_t* written) {
+    int ret = ::wally_descriptor_get_taproot_leaf_script_len(detail::get_p(descriptor), leaf_index, multi_index, child_num, flags, written);
+    return detail::check_ret(__FUNCTION__, ret);
+}
+
+template <class DESCRIPTOR, class BYTES_OUT>
+inline int descriptor_get_taproot_merkle_root(const DESCRIPTOR& descriptor, uint32_t multi_index, uint32_t child_num, uint32_t flags, BYTES_OUT& bytes_out) {
+    int ret = ::wally_descriptor_get_taproot_merkle_root(detail::get_p(descriptor), multi_index, child_num, flags, bytes_out.data(), bytes_out.size());
+    return detail::check_ret(__FUNCTION__, ret);
+}
+
+template <class DESCRIPTOR>
+inline int descriptor_get_taproot_num_leaves(const DESCRIPTOR& descriptor, uint32_t* value_out) {
+    int ret = ::wally_descriptor_get_taproot_num_leaves(detail::get_p(descriptor), value_out);
+    return detail::check_ret(__FUNCTION__, ret);
+}
+
 template <class DESCRIPTOR, class VARS_IN>
 inline int descriptor_parse(const DESCRIPTOR& descriptor, const VARS_IN& vars_in, uint32_t network, uint32_t flags, struct wally_descriptor** output) {
     int ret = ::wally_descriptor_parse(detail::get_p(descriptor), detail::get_p(vars_in), network, flags, output);

include/wally_descriptor.h

@@ -7,6 +7,7 @@
 extern "C" {
 #endif
 
+struct ext_key;
 struct wally_map;
 /** An opaque type holding a parsed minscript/descriptor expression */
 struct wally_descriptor;
@@ -22,25 +23,29 @@ struct wally_descriptor;
 #define WALLY_MINISCRIPT_DEPTH_SHIFT      16 /** Shift to convert maximum depth to flags */
 
 /*** miniscript-features Miniscript/Descriptor feature flags */
-#define WALLY_MS_IS_RANGED        0x001 /** Allows key ranges via ``*`` */
-#define WALLY_MS_IS_MULTIPATH     0x002 /** Allows multiple paths via ``<a;b;c>`` */
-#define WALLY_MS_IS_PRIVATE       0x004 /** Contains at least one private key */
-#define WALLY_MS_IS_UNCOMPRESSED  0x008 /** Contains at least one uncompressed key */
-#define WALLY_MS_IS_RAW           0x010 /** Contains at least one raw key */
-#define WALLY_MS_IS_DESCRIPTOR    0x020 /** Contains only descriptor expressions (no miniscript) */
-#define WALLY_MS_IS_X_ONLY        0x040 /** Contains at least one x-only key */
-#define WALLY_MS_IS_PARENTED      0x080 /** Contains at least one key key with a parent key origin */
-#define WALLY_MS_IS_ELEMENTS      0x100 /** Contains Elements expressions or was parsed as Elements */
-#define WALLY_MS_IS_SLIP77        0x200 /** A confidential ct() descriptor with SLIP-77 blinding */
-#define WALLY_MS_IS_ELIP150       0x400 /** A confidential ct() descriptor with ELIP-150 blinding */
-#define WALLY_MS_IS_ELIP151       0x800 /** A confidential ct() descriptor with ELIP-151 blinding */
-#define WALLY_MS_ANY_BLINDING_KEY 0xE00 /** SLIP-77, ELIP-150 or ELIP-151 blinding key present */
+#define WALLY_MS_IS_RANGED        0x0001 /** Allows key ranges via ``*`` */
+#define WALLY_MS_IS_MULTIPATH     0x0002 /** Allows multiple paths via ``<a;b;c>`` */
+#define WALLY_MS_IS_PRIVATE       0x0004 /** Contains at least one private key */
+#define WALLY_MS_IS_UNCOMPRESSED  0x0008 /** Contains at least one uncompressed key */
+#define WALLY_MS_IS_RAW           0x0010 /** Contains at least one raw key */
+#define WALLY_MS_IS_DESCRIPTOR    0x0020 /** Contains only descriptor expressions (no miniscript) */
+#define WALLY_MS_IS_X_ONLY        0x0040 /** Contains at least one x-only key */
+#define WALLY_MS_IS_PARENTED      0x0080 /** Contains at least one key with a parent key origin */
+#define WALLY_MS_IS_ELEMENTS      0x0100 /** Contains Elements expressions or was parsed as Elements */
+#define WALLY_MS_IS_SLIP77        0x0200 /** A confidential ct() descriptor with SLIP-77 blinding */
+#define WALLY_MS_IS_ELIP150       0x0400 /** A confidential ct() descriptor with ELIP-150 blinding */
+#define WALLY_MS_IS_ELIP151       0x0800 /** A confidential ct() descriptor with ELIP-151 blinding */
+#define WALLY_MS_IS_TAPROOT       0x1000 /** Contains a tr() taproot expression */
+#define WALLY_MS_IS_TAPSCRIPT     0x2000 /** Contains a tr(key,{...}) tapscript tree expression */
+#define WALLY_MS_ANY_BLINDING_KEY 0x0E00 /** SLIP-77, ELIP-150 or ELIP-151 blinding key present */
 
 /*** ms-canonicalization-flags Miniscript/Descriptor canonicalization flags */
 #define WALLY_MS_CANONICAL_NO_CHECKSUM 0x01 /** Do not include a checksum */
 
 #define WALLY_MS_BLINDING_KEY_INDEX 0xffffffff /* Key index for confidential blinding key */
 
+#define WALLY_DESCRIPTOR_TAPTREE_MAX_DEPTH 128 /* BIP-341: maximum taptree depth */
+
 /**
  * Parse an output descriptor or miniscript expression.
  *
@@ -306,6 +311,49 @@ WALLY_CORE_API int wally_descriptor_get_key_origin_path_str(
     size_t index,
     char **output);
 
+
+/**
+ * Derive a BIP32 extended key from a parsed output descriptor or miniscript expression.
+ *
+ * :param descriptor: Parsed output descriptor or miniscript expression.
+ * :param index: The zero-based index of the key to get, or `WALLY_MS_BLINDING_KEY_INDEX`
+ *|    to fetch the descriptors blinding key representaton (if any).
+ * :param variant: The variant of descriptor to derive from. See `wally_descriptor_get_num_variants`.
+ * :param multi_index: The multi-path item to derive from. See `wally_descriptor_get_num_paths`.
+ * :param child_num: The BIP32 child number to derive, or 0 for static descriptors.
+ * :param flags: Use `BIP32_FLAG_KEY_PUBLIC` to return public keys from private keys,
+ *|    and `BIP32_FLAG_SKIP_HASH` to avoid populating the derived key fingerprint.
+ * :param output: Destination for the resulting derived key.
+ *
+ * .. note:: The returned key may be bare (have only the public or private key populated).
+ *|    x-only bare keys have a prefix byte of 0x00. The caller can use `wally_descriptor_get_key_features` to
+ *|    determine the type of a given key before extracting data from it.
+ *
+ * .. note:: SLIP77 blinding keys are returned in the private key of the extended key.
+ */
+WALLY_CORE_API int wally_descriptor_derive_bip32_key(
+    const struct wally_descriptor *descriptor,
+    size_t index,
+    uint32_t variant,
+    uint32_t multi_index,
+    uint32_t child_num,
+    uint32_t flags,
+    struct ext_key *output);
+
+/**
+ * Derive a BIP32 extended key from a parsed output descriptor or miniscript expression.
+ *
+ * See `wally_descriptor_derive_bip32_key`.
+ */
+WALLY_CORE_API int wally_descriptor_derive_bip32_key_alloc(
+    const struct wally_descriptor *descriptor,
+    size_t index,
+    uint32_t variant,
+    uint32_t multi_index,
+    uint32_t child_num,
+    uint32_t flags,
+    struct ext_key **output);
+
 /**
  * Get the maximum length of a script corresponding to an output descriptor.
  *
@@ -406,6 +454,170 @@ WALLY_CORE_API int wally_descriptor_to_addresses(
     char **output,
     size_t num_outputs);
 
+/**
+ * Get the number of taptree leaves in a taproot output descriptor.
+ *
+ * Returns WALLY_EINVAL if the descriptor is not taproot.
+ *
+ * :param descriptor: Parsed tr() output descriptor.
+ * :param value_out: Destination for the number of taptree leaves.
+ */
+WALLY_CORE_API int wally_descriptor_get_taproot_num_leaves(
+    const struct wally_descriptor *descriptor,
+    uint32_t *value_out);
+
+/**
+ * Get the script for a specific taptree leaf in a taproot output descriptor.
+ *
+ * Returns WALLY_EINVAL if the descriptor is not taproot or `leaf_index`
+ * is out of bounds.
+ *
+ * :param descriptor: Parsed tr() output descriptor.
+ * :param leaf_index: Zero-based leaf index (depth-first, left-to-right order).
+ * :param multi_index: See `wally_descriptor_get_num_paths`.
+ * :param child_num: BIP32 child number, or 0 for static descriptors.
+ * :param flags: For future use. Must be 0.
+ * :param bytes_out: Destination for the compiled tapscript.
+ * :param len: Length of ``bytes_out`` in bytes.
+ * :param written: Destination for the number of bytes written to ``bytes_out``.
+ */
+WALLY_CORE_API int wally_descriptor_get_taproot_leaf_script(
+    const struct wally_descriptor *descriptor,
+    uint32_t leaf_index,
+    uint32_t multi_index,
+    uint32_t child_num,
+    uint32_t flags,
+    unsigned char *bytes_out,
+    size_t len,
+    size_t *written);
+
+/**
+ * Get the script length for a specific taptree leaf in a taproot output descriptor.
+ *
+ * See `wally_descriptor_get_taproot_leaf_script`.
+ */
+WALLY_CORE_API int wally_descriptor_get_taproot_leaf_script_len(
+    const struct wally_descriptor *descriptor,
+    uint32_t leaf_index,
+    uint32_t multi_index,
+    uint32_t child_num,
+    uint32_t flags,
+    size_t *written);
+
+/**
+ * Get the tapleaf hash for a specific taptree leaf in a taproot output descriptor.
+ *
+ * Returns WALLY_EINVAL if the descriptor is not taproot or `leaf_index`
+ * is out of bounds.
+ *
+ * :param descriptor: Parsed tr() output descriptor.
+ * :param leaf_index: Zero-based leaf index (depth-first, left-to-right order).
+ * :param multi_index: See `wally_descriptor_get_num_paths`.
+ * :param child_num: BIP32 child number, or 0 for static descriptors.
+ * :param flags: For future use. Must be 0.
+ * :param bytes_out: Destination for the 32-byte tapleaf hash.
+ * FIXED_SIZED_OUTPUT(len, bytes_out, SHA256_LEN)
+ */
+WALLY_CORE_API int wally_descriptor_get_taproot_leaf_hash(
+    const struct wally_descriptor *descriptor,
+    uint32_t leaf_index,
+    uint32_t multi_index,
+    uint32_t child_num,
+    uint32_t flags,
+    unsigned char *bytes_out,
+    size_t len);
+
+/**
+ * Get the BIP-341 control block for spending via a specific taptree leaf.
+ *
+ * Returns WALLY_EINVAL if the descriptor is not taproot or `leaf_index`
+ * is out of bounds.
+ *
+ * :param descriptor: Parsed tr() output descriptor.
+ * :param leaf_index: Zero-based leaf index (depth-first, left-to-right order).
+ * :param multi_index: See `wally_descriptor_get_num_paths`.
+ * :param child_num: BIP32 child number, or 0 for static descriptors.
+ * :param flags: For future use. Must be 0.
+ * :param bytes_out: Destination for the control block bytes.
+ * :param len: Length of ``bytes_out`` in bytes.
+ * :param written: Destination for the number of bytes written to ``bytes_out``.
+ */
+WALLY_CORE_API int wally_descriptor_get_taproot_control_block(
+    const struct wally_descriptor *descriptor,
+    uint32_t leaf_index,
+    uint32_t multi_index,
+    uint32_t child_num,
+    uint32_t flags,
+    unsigned char *bytes_out,
+    size_t len,
+    size_t *written);
+
+/**
+ * Get the BIP-341 control block for spending via a specific taptree leaf.
+ *
+ * See `wally_descriptor_get_taproot_control_block`.
+ */
+WALLY_CORE_API int wally_descriptor_get_taproot_control_block_len(
+    const struct wally_descriptor *descriptor,
+    uint32_t leaf_index,
+    uint32_t multi_index,
+    uint32_t child_num,
+    uint32_t flags,
+    size_t *written);
+
+/**
+ * Get the number of keys in a specific taptree leaf's miniscript.
+ *
+ * Returns WALLY_EINVAL if the descriptor is not taproot or `leaf_index`
+ * is out of bounds.
+ *
+ * :param descriptor: Parsed tr() output descriptor.
+ * :param leaf_index: Zero-based leaf index (depth-first, left-to-right order).
+ * :param value_out: Destination for the key count.
+ */
+WALLY_CORE_API int wally_descriptor_get_taproot_leaf_num_keys(
+    const struct wally_descriptor *descriptor,
+    uint32_t leaf_index,
+    uint32_t *value_out);
+
+/**
+ * Get the descriptor-level key index for a key within a specific taptree leaf.
+ *
+ * Returns WALLY_EINVAL if the descriptor is not taproot or `leaf_index`
+ * is out of bounds.
+ *
+ * :param descriptor: Parsed tr() output descriptor.
+ * :param leaf_index: Zero-based leaf index (depth-first, left-to-right order).
+ * :param key_index: Zero-based index of the key within the leaf's miniscript.
+ * :param value_out: Destination for the descriptor-level key index
+ *|    (suitable for use with `wally_descriptor_get_key`).
+ */
+WALLY_CORE_API int wally_descriptor_get_taproot_leaf_key_index(
+    const struct wally_descriptor *descriptor,
+    uint32_t leaf_index,
+    uint32_t key_index,
+    uint32_t *value_out);
+
+/**
+ * Get the merkle root of the taptree in a tr() descriptor.
+ *
+ * Returns WALLY_EINVAL if the descriptor does not contain a taptree.
+ *
+ * :param descriptor: Parsed tr() output descriptor.
+ * :param multi_index: See `wally_descriptor_get_num_paths`.
+ * :param child_num: BIP32 child number, or 0 for static descriptors.
+ * :param flags: For future use. Must be 0.
+ * :param bytes_out: Destination for the 32-byte merkle root.
+ * FIXED_SIZED_OUTPUT(len, bytes_out, SHA256_LEN)
+ */
+WALLY_CORE_API int wally_descriptor_get_taproot_merkle_root(
+    const struct wally_descriptor *descriptor,
+    uint32_t multi_index,
+    uint32_t child_num,
+    uint32_t flags,
+    unsigned char *bytes_out,
+    size_t len);
+
 #ifdef __cplusplus
 }
 #endif

include/wally_script.h

@@ -27,6 +27,8 @@ extern "C" {
 #define WALLY_SCRIPTPUBKEY_P2WSH_LEN  34 /** OP_0 [SHA256] */
 #define WALLY_SCRIPTPUBKEY_P2TR_LEN   34 /** OP_1 [X-ONLY-PUBKEY] */
 
+#define WALLY_LEAF_VERSION_TAPSCRIPT  0xc0 /** BIP-342 tapscript leaf version */
+
 #define WALLY_SCRIPTPUBKEY_OP_RETURN_MAX_LEN 83 /** OP_RETURN [80 bytes of data] */
 
 #define WALLY_MAX_OP_RETURN_LEN 80 /* Maximum length of OP_RETURN data push */
@@ -171,6 +173,8 @@ extern "C" {
 #define OP_NOP9 0xb8
 #define OP_NOP10 0xb9
 
+#define OP_CHECKSIGADD 0xba /* BIP-342 tapscript */
+
 #define OP_INVALIDOPCODE 0xff
 #endif  /* WALLY_DISABLE_OP_CODE */