/tmp/bitcoin/src/script/descriptor.h

Source
// 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 <outputtype.h>
#include <pubkey.h>
#include <uint256.h>
#include <util/expected.h>

#include <cstddef>
#include <cstdint>
#include <memory>
#include <optional>
#include <set>
#include <string>
#include <string_view>
#include <unordered_map>
#include <vector>

class CScript;
class SigningProvider;
struct FlatSigningProvider;

using ExtPubKeyMap = std::unordered_map<uint32_t, CExtPubKey>;

/** Cache for single descriptor's derived extended pubkeys */
class DescriptorCache {
private:
    /** Map key expression index -> map of (key derivation index -> xpub) */
    std::unordered_map<uint32_t, ExtPubKeyMap> 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<uint32_t, ExtPubKeyMap> 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;

    /** Convert the descriptor to the canonical string.
     * The canonical string is the same as the public string but always uses h as the hardened indicator
     */
    virtual std::string ToCanonicalString() 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<CScript>& 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<CScript>& 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<OutputType> GetOutputType() const = 0;

    /** Get the size of the scriptPubKey for this descriptor. */
    virtual std::optional<int64_t> 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<int64_t> MaxSatisfactionWeight(bool use_max_sig) const = 0;

    /** Get the maximum size number of stack elements for satisfying this descriptor. */
    virtual std::optional<int64_t> 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<CPubKey>& pubkeys, std::set<CExtPubKey>& 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<std::string> 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;
};

/** Validate the numeric bounds of a descriptor key-expression range
 *  [low, high] (high inclusive). On success returns an Expected with no
 *  value; on failure returns the first violated invariant's user-facing
 *  message.
 */
util::Expected<void, std::string> CheckDescriptorRangeBounds(int64_t low, int64_t high);

/** 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<std::unique_ptr<Descriptor>> 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<Descriptor> InferDescriptor(const CScript& script, const SigningProvider& provider);

/** Hash of the COMPAT string representation of the descriptor that is not supposed to change over time.
 * Due to the hash's usage in previous versions, the COMPAT string is computed with some quirks.
 *
 * The hash is the sha256 of the public descriptor using apostrophes as the hardened indicator, except inside of
 * Miniscript expressions, where the public serialization is used as provided.
*/
uint256 CompatDescriptorHash(const Descriptor& desc);

#endif // BITCOIN_SCRIPT_DESCRIPTOR_H

Coverage Report

Created: 2026-09-21 19:49

Line	Count	Source
1		// Copyright (c) 2018-present The Bitcoin Core developers
2		// Distributed under the MIT software license, see the accompanying
3		// file COPYING or http://www.opensource.org/licenses/mit-license.php.
4
5		#ifndef BITCOIN_SCRIPT_DESCRIPTOR_H
6		#define BITCOIN_SCRIPT_DESCRIPTOR_H
7
8		#include <outputtype.h>
9		#include <pubkey.h>
10		#include <uint256.h>
11		#include <util/expected.h>
12
13		#include <cstddef>
14		#include <cstdint>
15		#include <memory>
16		#include <optional>
17		#include <set>
18		#include <string>
19		#include <string_view>
20		#include <unordered_map>
21		#include <vector>
22
23		class CScript;
24		class SigningProvider;
25		struct FlatSigningProvider;
26
27		using ExtPubKeyMap = std::unordered_map<uint32_t, CExtPubKey>;
28
29		/** Cache for single descriptor's derived extended pubkeys */
30		class DescriptorCache {
31		private:
32		/** Map key expression index -> map of (key derivation index -> xpub) */
33		std::unordered_map<uint32_t, ExtPubKeyMap> m_derived_xpubs;
34		/** Map key expression index -> parent xpub */
35		ExtPubKeyMap m_parent_xpubs;
36		/** Map key expression index -> last hardened xpub */
37		ExtPubKeyMap m_last_hardened_xpubs;
38
39		public:
40		/** Cache a parent xpub
41		*
42		* @param[in] key_exp_pos Position of the key expression within the descriptor
43		* @param[in] xpub The CExtPubKey to cache
44		*/
45		void CacheParentExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub);
46		/** Retrieve a cached parent xpub
47		*
48		* @param[in] key_exp_pos Position of the key expression within the descriptor
49		* @param[out] xpub The CExtPubKey to get from cache
50		*/
51		bool GetCachedParentExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const;
52		/** Cache an xpub derived at an index
53		*
54		* @param[in] key_exp_pos Position of the key expression within the descriptor
55		* @param[in] der_index Derivation index of the xpub
56		* @param[in] xpub The CExtPubKey to cache
57		*/
58		void CacheDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, const CExtPubKey& xpub);
59		/** Retrieve a cached xpub derived at an index
60		*
61		* @param[in] key_exp_pos Position of the key expression within the descriptor
62		* @param[in] der_index Derivation index of the xpub
63		* @param[out] xpub The CExtPubKey to get from cache
64		*/
65		bool GetCachedDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, CExtPubKey& xpub) const;
66		/** Cache a last hardened xpub
67		*
68		* @param[in] key_exp_pos Position of the key expression within the descriptor
69		* @param[in] xpub The CExtPubKey to cache
70		*/
71		void CacheLastHardenedExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub);
72		/** Retrieve a cached last hardened xpub
73		*
74		* @param[in] key_exp_pos Position of the key expression within the descriptor
75		* @param[out] xpub The CExtPubKey to get from cache
76		*/
77		bool GetCachedLastHardenedExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const;
78
79		/** Retrieve all cached parent xpubs */
80		ExtPubKeyMap GetCachedParentExtPubKeys() const;
81		/** Retrieve all cached derived xpubs */
82		std::unordered_map<uint32_t, ExtPubKeyMap> GetCachedDerivedExtPubKeys() const;
83		/** Retrieve all cached last hardened xpubs */
84		ExtPubKeyMap GetCachedLastHardenedExtPubKeys() const;
85
86		/** Combine another DescriptorCache into this one.
87		* Returns a cache containing the items from the other cache unknown to current cache
88		*/
89		DescriptorCache MergeAndDiff(const DescriptorCache& other);
90		};
91
92		/** \brief Interface for parsed descriptor objects.
93		*
94		* Descriptors are strings that describe a set of scriptPubKeys, together with
95		* all information necessary to solve them. By combining all information into
96		* one, they avoid the need to separately import keys and scripts.
97		*
98		* Descriptors may be ranged, which occurs when the public keys inside are
99		* specified in the form of HD chains (xpubs).
100		*
101		* Descriptors always represent public information - public keys and scripts -
102		* but in cases where private keys need to be conveyed along with a descriptor,
103		* they can be included inside by changing public keys to private keys (WIF
104		* format), and changing xpubs by xprvs.
105		*
106		* Reference documentation about the descriptor language can be found in
107		* doc/descriptors.md.
108		*/
109		struct Descriptor {
110	336k	virtual ~Descriptor() = default;
111
112		/** Whether the expansion of this descriptor depends on the position. */
113		virtual bool IsRange() const = 0;
114
115		/** Whether this descriptor has all information about signing ignoring lack of private keys.
116		* This is true for all descriptors except ones that use `raw` or `addr` constructions. */
117		virtual bool IsSolvable() const = 0;
118
119		/** Convert the descriptor back to a string, undoing parsing. */
120		virtual std::string ToString(bool compat_format=false) const = 0;
121
122		/** Convert the descriptor to the canonical string.
123		* The canonical string is the same as the public string but always uses h as the hardened indicator
124		*/
125		virtual std::string ToCanonicalString() const = 0;
126
127		/** Whether this descriptor will return at most one scriptPubKey or multiple (aka is or is not combo) */
128		virtual bool IsSingleType() const = 0;
129
130		/** Whether the given provider has all private keys required by this descriptor.
131		* @return `false` if the descriptor doesn't have any keys or subdescriptors,
132		* or if the provider does not have all private keys required by
133		* the descriptor.
134		*/
135		virtual bool HavePrivateKeys(const SigningProvider& provider) const = 0;
136
137		/** Convert the descriptor to a private string. This uses public keys if the relevant private keys are not in the SigningProvider.
138		* If none of the relevant private keys are available, the output string in the "out" parameter will not contain any private key information,
139		* and this function will return "false".
140		* @param[in] provider The SigningProvider to query for private keys.
141		* @param[out] out The resulting descriptor string, containing private keys if available.
142		* @returns true if at least one private key available.
143		*/
144		virtual bool ToPrivateString(const SigningProvider& provider, std::string& out) const = 0;
145
146		/** 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. */
147		virtual bool ToNormalizedString(const SigningProvider& provider, std::string& out, const DescriptorCache* cache = nullptr) const = 0;
148
149		/** Whether the descriptor can be used to produce its address(es) without needing a cache or private keys. */
150		virtual bool CanSelfExpand() const = 0;
151
152		/** Expand a descriptor at a specified position.
153		*
154		* @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
155		* @param[in] provider The provider to query for private keys in case of hardened derivation.
156		* @param[out] output_scripts The expanded scriptPubKeys.
157		* @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`).
158		* @param[out] write_cache Cache data necessary to evaluate the descriptor at this point without access to private keys.
159		*/
160		virtual bool Expand(int pos, const SigningProvider& provider, std::vector<CScript>& output_scripts, FlatSigningProvider& out, DescriptorCache* write_cache = nullptr) const = 0;
161
162		/** Expand a descriptor at a specified position using cached expansion data.
163		*
164		* @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
165		* @param[in] read_cache Cached expansion data.
166		* @param[out] output_scripts The expanded scriptPubKeys.
167		* @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`).
168		*/
169		virtual bool ExpandFromCache(int pos, const DescriptorCache& read_cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0;
170
171		/** Expand the private key for a descriptor at a specified position, if possible.
172		*
173		* @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored.
174		* @param[in] provider The provider to query for the private keys.
175		* @param[out] out Any private keys available for the specified `pos`.
176		*/
177		virtual void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const = 0;
178
179		/** @return The OutputType of the scriptPubKey(s) produced by this descriptor. Or nullopt if indeterminate (multiple or none) */
180		virtual std::optional<OutputType> GetOutputType() const = 0;
181
182		/** Get the size of the scriptPubKey for this descriptor. */
183		virtual std::optional<int64_t> ScriptSize() const = 0;
184
185		/** Get the maximum size of a satisfaction for this descriptor, in weight units.
186		*
187		* @param use_max_sig Whether to assume ECDSA signatures will have a high-r.
188		*/
189		virtual std::optional<int64_t> MaxSatisfactionWeight(bool use_max_sig) const = 0;
190
191		/** Get the maximum size number of stack elements for satisfying this descriptor. */
192		virtual std::optional<int64_t> MaxSatisfactionElems() const = 0;
193
194		/** Return all (extended) public keys for this descriptor, including any from subdescriptors.
195		*
196		* @param[out] pubkeys Any public keys
197		* @param[out] ext_pubs Any extended public keys
198		*/
199		virtual void GetPubKeys(std::set<CPubKey>& pubkeys, std::set<CExtPubKey>& ext_pubs) const = 0;
200
201		/** Whether this descriptor produces any scripts with the Expand functions */
202		virtual bool HasScripts() const = 0;
203
204		/** Semantic/safety warnings (includes subdescriptors). */
205		virtual std::vector<std::string> Warnings() const = 0;
206
207		/** Get the maximum key expression index. Used only for tests */
208		virtual uint32_t GetMaxKeyExpr() const = 0;
209
210		/** Get the number of key expressions in this descriptor. Used only for tests */
211		virtual size_t GetKeyCount() const = 0;
212		};
213
214		/** Validate the numeric bounds of a descriptor key-expression range
215		* [low, high] (high inclusive). On success returns an Expected with no
216		* value; on failure returns the first violated invariant's user-facing
217		* message.
218		*/
219		util::Expected<void, std::string> CheckDescriptorRangeBounds(int64_t low, int64_t high);
220
221		/** Parse a `descriptor` string. Included private keys are put in `out`.
222		*
223		* If the descriptor has a checksum, it must be valid. If `require_checksum`
224		* is set, the checksum is mandatory - otherwise it is optional.
225		*
226		* If a parse error occurs, or the checksum is missing/invalid, or anything
227		* else is wrong, an empty vector is returned.
228		*/
229		std::vector<std::unique_ptr<Descriptor>> Parse(std::string_view descriptor, FlatSigningProvider& out, std::string& error, bool require_checksum = false);
230
231		/** Get the checksum for a `descriptor`.
232		*
233		* - If it already has one, and it is correct, return the checksum in the input.
234		* - If it already has one that is wrong, return "".
235		* - If it does not already have one, return the checksum that would need to be added.
236		*/
237		std::string GetDescriptorChecksum(const std::string& descriptor);
238
239		/** Find a descriptor for the specified `script`, using information from `provider` where possible.
240		*
241		* A non-ranged descriptor which only generates the specified script will be returned in all
242		* circumstances.
243		*
244		* For public keys with key origin information, this information will be preserved in the returned
245		* descriptor.
246		*
247		* - If all information for solving `script` is present in `provider`, a descriptor will be returned
248		* which is IsSolvable() and encapsulates said information.
249		* - Failing that, if `script` corresponds to a known address type, an "addr()" descriptor will be
250		* returned (which is not IsSolvable()).
251		* - Failing that, a "raw()" descriptor is returned.
252		*/
253		std::unique_ptr<Descriptor> InferDescriptor(const CScript& script, const SigningProvider& provider);
254
255		/** Hash of the COMPAT string representation of the descriptor that is not supposed to change over time.
256		* Due to the hash's usage in previous versions, the COMPAT string is computed with some quirks.
257		*
258		* The hash is the sha256 of the public descriptor using apostrophes as the hardened indicator, except inside of
259		* Miniscript expressions, where the public serialization is used as provided.
260		*/
261		uint256 CompatDescriptorHash(const Descriptor& desc);
262
263		#endif // BITCOIN_SCRIPT_DESCRIPTOR_H