1 // Copyright (c) 2018-2020 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 <optional.h> 9 #include <outputtype.h> 10 #include <script/script.h> 11 #include <script/sign.h> 12 #include <script/signingprovider.h> 13 14 #include <vector> 15 16 using ExtPubKeyMap = std::unordered_map<uint32_t, CExtPubKey>; 17 18 /** Cache for single descriptor's derived extended pubkeys */ 19 class DescriptorCache { 20 private: 21 /** Map key expression index -> map of (key derivation index -> xpub) */ 22 std::unordered_map<uint32_t, ExtPubKeyMap> m_derived_xpubs; 23 /** Map key expression index -> parent xpub */ 24 ExtPubKeyMap m_parent_xpubs; 25 26 public: 27 /** Cache a parent xpub 28 * 29 * @param[in] key_exp_pos Position of the key expression within the descriptor 30 * @param[in] xpub The CExtPubKey to cache 31 */ 32 void CacheParentExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub); 33 /** Retrieve a cached parent xpub 34 * 35 * @param[in] key_exp_pos Position of the key expression within the descriptor 36 * @param[in] xpub The CExtPubKey to get from cache 37 */ 38 bool GetCachedParentExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const; 39 /** Cache an xpub derived at an index 40 * 41 * @param[in] key_exp_pos Position of the key expression within the descriptor 42 * @param[in] der_index Derivation index of the xpub 43 * @param[in] xpub The CExtPubKey to cache 44 */ 45 void CacheDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, const CExtPubKey& xpub); 46 /** Retrieve a cached xpub derived at an index 47 * 48 * @param[in] key_exp_pos Position of the key expression within the descriptor 49 * @param[in] der_index Derivation index of the xpub 50 * @param[in] xpub The CExtPubKey to get from cache 51 */ 52 bool GetCachedDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, CExtPubKey& xpub) const; 53 54 /** Retrieve all cached parent xpubs */ 55 const ExtPubKeyMap GetCachedParentExtPubKeys() const; 56 /** Retrieve all cached derived xpubs */ 57 const std::unordered_map<uint32_t, ExtPubKeyMap> GetCachedDerivedExtPubKeys() const; 58 }; 59 60 /** \brief Interface for parsed descriptor objects. 61 * 62 * Descriptors are strings that describe a set of scriptPubKeys, together with 63 * all information necessary to solve them. By combining all information into 64 * one, they avoid the need to separately import keys and scripts. 65 * 66 * Descriptors may be ranged, which occurs when the public keys inside are 67 * specified in the form of HD chains (xpubs). 68 * 69 * Descriptors always represent public information - public keys and scripts - 70 * but in cases where private keys need to be conveyed along with a descriptor, 71 * they can be included inside by changing public keys to private keys (WIF 72 * format), and changing xpubs by xprvs. 73 * 74 * Reference documentation about the descriptor language can be found in 75 * doc/descriptors.md. 76 */ 77 struct Descriptor { 78 virtual ~Descriptor() = default; 79 80 /** Whether the expansion of this descriptor depends on the position. */ 81 virtual bool IsRange() const = 0; 82 83 /** Whether this descriptor has all information about signing ignoring lack of private keys. 84 * This is true for all descriptors except ones that use `raw` or `addr` constructions. */ 85 virtual bool IsSolvable() const = 0; 86 87 /** Convert the descriptor back to a string, undoing parsing. */ 88 virtual std::string ToString() const = 0; 89 90 /** Whether this descriptor will return one scriptPubKey or multiple (aka is or is not combo) */ 91 virtual bool IsSingleType() const = 0; 92 93 /** Convert the descriptor to a private string. This fails if the provided provider does not have the relevant private keys. */ 94 virtual bool ToPrivateString(const SigningProvider& provider, std::string& out) const = 0; 95 96 /** Expand a descriptor at a specified position. 97 * 98 * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored. 99 * @param[in] provider The provider to query for private keys in case of hardened derivation. 100 * @param[out] output_scripts The expanded scriptPubKeys. 101 * @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`). 102 * @param[out] write_cache Cache data necessary to evaluate the descriptor at this point without access to private keys. 103 */ 104 virtual bool Expand(int pos, const SigningProvider& provider, std::vector<CScript>& output_scripts, FlatSigningProvider& out, DescriptorCache* write_cache = nullptr) const = 0; 105 106 /** Expand a descriptor at a specified position using cached expansion data. 107 * 108 * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored. 109 * @param[in] read_cache Cached expansion data. 110 * @param[out] output_scripts The expanded scriptPubKeys. 111 * @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`). 112 */ 113 virtual bool ExpandFromCache(int pos, const DescriptorCache& read_cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0; 114 115 /** Expand the private key for a descriptor at a specified position, if possible. 116 * 117 * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored. 118 * @param[in] provider The provider to query for the private keys. 119 * @param[out] out Any private keys available for the specified `pos`. 120 */ 121 virtual void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const = 0; 122 123 /** @return The OutputType of the scriptPubKey(s) produced by this descriptor. Or nullopt if indeterminate (multiple or none) */ 124 virtual Optional<OutputType> GetOutputType() const = 0; 125 }; 126 127 /** Parse a `descriptor` string. Included private keys are put in `out`. 128 * 129 * If the descriptor has a checksum, it must be valid. If `require_checksum` 130 * is set, the checksum is mandatory - otherwise it is optional. 131 * 132 * If a parse error occurs, or the checksum is missing/invalid, or anything 133 * else is wrong, `nullptr` is returned. 134 */ 135 std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out, std::string& error, bool require_checksum = false); 136 137 /** Get the checksum for a `descriptor`. 138 * 139 * - If it already has one, and it is correct, return the checksum in the input. 140 * - If it already has one that is wrong, return "". 141 * - If it does not already have one, return the checksum that would need to be added. 142 */ 143 std::string GetDescriptorChecksum(const std::string& descriptor); 144 145 /** Find a descriptor for the specified `script`, using information from `provider` where possible. 146 * 147 * A non-ranged descriptor which only generates the specified script will be returned in all 148 * circumstances. 149 * 150 * For public keys with key origin information, this information will be preserved in the returned 151 * descriptor. 152 * 153 * - If all information for solving `script` is present in `provider`, a descriptor will be returned 154 * which is IsSolvable() and encapsulates said information. 155 * - Failing that, if `script` corresponds to a known address type, an "addr()" descriptor will be 156 * returned (which is not IsSolvable()). 157 * - Failing that, a "raw()" descriptor is returned. 158 */ 159 std::unique_ptr<Descriptor> InferDescriptor(const CScript& script, const SigningProvider& provider); 160 161 #endif // BITCOIN_SCRIPT_DESCRIPTOR_H 162