// Copyright (c) 2018-present The Bitcoin Core developers // Distributed under the MIT software license, see the accompanying // file COPYING or http://www.opensource.org/licenses/mit-license.php. #ifndef BITCOIN_SCRIPT_DESCRIPTOR_H #define BITCOIN_SCRIPT_DESCRIPTOR_H #include #include #include #include #include #include #include #include #include #include #include #include class CScript; class SigningProvider; struct FlatSigningProvider; using ExtPubKeyMap = std::unordered_map; /** Cache for single descriptor's derived extended pubkeys */ class DescriptorCache { private: /** Map key expression index -> map of (key derivation index -> xpub) */ std::unordered_map m_derived_xpubs; /** Map key expression index -> parent xpub */ ExtPubKeyMap m_parent_xpubs; /** Map key expression index -> last hardened xpub */ ExtPubKeyMap m_last_hardened_xpubs; public: /** Cache a parent xpub * * @param[in] key_exp_pos Position of the key expression within the descriptor * @param[in] xpub The CExtPubKey to cache */ void CacheParentExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub); /** Retrieve a cached parent xpub * * @param[in] key_exp_pos Position of the key expression within the descriptor * @param[out] xpub The CExtPubKey to get from cache */ bool GetCachedParentExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const; /** Cache an xpub derived at an index * * @param[in] key_exp_pos Position of the key expression within the descriptor * @param[in] der_index Derivation index of the xpub * @param[in] xpub The CExtPubKey to cache */ void CacheDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, const CExtPubKey& xpub); /** Retrieve a cached xpub derived at an index * * @param[in] key_exp_pos Position of the key expression within the descriptor * @param[in] der_index Derivation index of the xpub * @param[out] xpub The CExtPubKey to get from cache */ bool GetCachedDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, CExtPubKey& xpub) const; /** Cache a last hardened xpub * * @param[in] key_exp_pos Position of the key expression within the descriptor * @param[in] xpub The CExtPubKey to cache */ void CacheLastHardenedExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub); /** Retrieve a cached last hardened xpub * * @param[in] key_exp_pos Position of the key expression within the descriptor * @param[out] xpub The CExtPubKey to get from cache */ bool GetCachedLastHardenedExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const; /** Retrieve all cached parent xpubs */ ExtPubKeyMap GetCachedParentExtPubKeys() const; /** Retrieve all cached derived xpubs */ std::unordered_map GetCachedDerivedExtPubKeys() const; /** Retrieve all cached last hardened xpubs */ ExtPubKeyMap GetCachedLastHardenedExtPubKeys() const; /** Combine another DescriptorCache into this one. * Returns a cache containing the items from the other cache unknown to current cache */ DescriptorCache MergeAndDiff(const DescriptorCache& other); }; /** \brief Interface for parsed descriptor objects. * * Descriptors are strings that describe a set of scriptPubKeys, together with * all information necessary to solve them. By combining all information into * one, they avoid the need to separately import keys and scripts. * * Descriptors may be ranged, which occurs when the public keys inside are * specified in the form of HD chains (xpubs). * * Descriptors always represent public information - public keys and scripts - * but in cases where private keys need to be conveyed along with a descriptor, * they can be included inside by changing public keys to private keys (WIF * format), and changing xpubs by xprvs. * * Reference documentation about the descriptor language can be found in * doc/descriptors.md. */ struct Descriptor { virtual ~Descriptor() = default; /** Whether the expansion of this descriptor depends on the position. */ virtual bool IsRange() const = 0; /** Whether this descriptor has all information about signing ignoring lack of private keys. * This is true for all descriptors except ones that use `raw` or `addr` constructions. */ virtual bool IsSolvable() const = 0; /** Convert the descriptor back to a string, undoing parsing. */ virtual std::string ToString(bool compat_format=false) const = 0; /** Whether this descriptor will return at most one scriptPubKey or multiple (aka is or is not combo) */ virtual bool IsSingleType() const = 0; /** Whether the given provider has all private keys required by this descriptor. * @return `false` if the descriptor doesn't have any keys or subdescriptors, * or if the provider does not have all private keys required by * the descriptor. */ virtual bool HavePrivateKeys(const SigningProvider& provider) const = 0; /** Convert the descriptor to a private string. This uses public keys if the relevant private keys are not in the SigningProvider. * If none of the relevant private keys are available, the output string in the "out" parameter will not contain any private key information, * and this function will return "false". * @param[in] provider The SigningProvider to query for private keys. * @param[out] out The resulting descriptor string, containing private keys if available. * @returns true if at least one private key available. */ virtual bool ToPrivateString(const SigningProvider& provider, std::string& out) const = 0; /** Convert the descriptor to a normalized string. Normalized descriptors have the xpub at the last hardened step. This fails if the provided provider does not have the private keys to derive that xpub. */ virtual bool ToNormalizedString(const SigningProvider& provider, std::string& out, const DescriptorCache* cache = nullptr) const = 0; /** Whether the descriptor can be used to produce its address(es) without needing a cache or private keys. */ virtual bool CanSelfExpand() const = 0; /** Expand a descriptor at a specified position. * * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored. * @param[in] provider The provider to query for private keys in case of hardened derivation. * @param[out] output_scripts The expanded scriptPubKeys. * @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`). * @param[out] write_cache Cache data necessary to evaluate the descriptor at this point without access to private keys. */ virtual bool Expand(int pos, const SigningProvider& provider, std::vector& output_scripts, FlatSigningProvider& out, DescriptorCache* write_cache = nullptr) const = 0; /** Expand a descriptor at a specified position using cached expansion data. * * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored. * @param[in] read_cache Cached expansion data. * @param[out] output_scripts The expanded scriptPubKeys. * @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`). */ virtual bool ExpandFromCache(int pos, const DescriptorCache& read_cache, std::vector& output_scripts, FlatSigningProvider& out) const = 0; /** Expand the private key for a descriptor at a specified position, if possible. * * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored. * @param[in] provider The provider to query for the private keys. * @param[out] out Any private keys available for the specified `pos`. */ virtual void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const = 0; /** @return The OutputType of the scriptPubKey(s) produced by this descriptor. Or nullopt if indeterminate (multiple or none) */ virtual std::optional GetOutputType() const = 0; /** Get the size of the scriptPubKey for this descriptor. */ virtual std::optional ScriptSize() const = 0; /** Get the maximum size of a satisfaction for this descriptor, in weight units. * * @param use_max_sig Whether to assume ECDSA signatures will have a high-r. */ virtual std::optional MaxSatisfactionWeight(bool use_max_sig) const = 0; /** Get the maximum size number of stack elements for satisfying this descriptor. */ virtual std::optional MaxSatisfactionElems() const = 0; /** Return all (extended) public keys for this descriptor, including any from subdescriptors. * * @param[out] pubkeys Any public keys * @param[out] ext_pubs Any extended public keys */ virtual void GetPubKeys(std::set& pubkeys, std::set& ext_pubs) const = 0; /** Whether this descriptor produces any scripts with the Expand functions */ virtual bool HasScripts() const = 0; /** Semantic/safety warnings (includes subdescriptors). */ virtual std::vector Warnings() const = 0; /** Get the maximum key expression index. Used only for tests */ virtual uint32_t GetMaxKeyExpr() const = 0; /** Get the number of key expressions in this descriptor. Used only for tests */ virtual size_t GetKeyCount() const = 0; }; /** Parse a `descriptor` string. Included private keys are put in `out`. * * If the descriptor has a checksum, it must be valid. If `require_checksum` * is set, the checksum is mandatory - otherwise it is optional. * * If a parse error occurs, or the checksum is missing/invalid, or anything * else is wrong, an empty vector is returned. */ std::vector> Parse(std::string_view descriptor, FlatSigningProvider& out, std::string& error, bool require_checksum = false); /** Get the checksum for a `descriptor`. * * - If it already has one, and it is correct, return the checksum in the input. * - If it already has one that is wrong, return "". * - If it does not already have one, return the checksum that would need to be added. */ std::string GetDescriptorChecksum(const std::string& descriptor); /** Find a descriptor for the specified `script`, using information from `provider` where possible. * * A non-ranged descriptor which only generates the specified script will be returned in all * circumstances. * * For public keys with key origin information, this information will be preserved in the returned * descriptor. * * - If all information for solving `script` is present in `provider`, a descriptor will be returned * which is IsSolvable() and encapsulates said information. * - Failing that, if `script` corresponds to a known address type, an "addr()" descriptor will be * returned (which is not IsSolvable()). * - Failing that, a "raw()" descriptor is returned. */ std::unique_ptr InferDescriptor(const CScript& script, const SigningProvider& provider); /** Unique identifier that may not change over time, unless explicitly marked as not backwards compatible. * This is not part of BIP 380, not guaranteed to be interoperable and should not be exposed to the user. */ uint256 DescriptorID(const Descriptor& desc); #endif // BITCOIN_SCRIPT_DESCRIPTOR_H