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 <outputtype.h> 9 #include <script/script.h> 10 #include <script/sign.h> 11 #include <script/signingprovider.h> 12 13 #include <optional> 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 /** Map key expression index -> last hardened xpub */ 26 ExtPubKeyMap m_last_hardened_xpubs; 27 28 public: 29 /** Cache a parent xpub 30 * 31 * @param[in] key_exp_pos Position of the key expression within the descriptor 32 * @param[in] xpub The CExtPubKey to cache 33 */ 34 void CacheParentExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub); 35 /** Retrieve a cached parent xpub 36 * 37 * @param[in] key_exp_pos Position of the key expression within the descriptor 38 * @param[in] xpub The CExtPubKey to get from cache 39 */ 40 bool GetCachedParentExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const; 41 /** Cache an xpub derived at an index 42 * 43 * @param[in] key_exp_pos Position of the key expression within the descriptor 44 * @param[in] der_index Derivation index of the xpub 45 * @param[in] xpub The CExtPubKey to cache 46 */ 47 void CacheDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, const CExtPubKey& xpub); 48 /** Retrieve a cached xpub derived at an index 49 * 50 * @param[in] key_exp_pos Position of the key expression within the descriptor 51 * @param[in] der_index Derivation index of the xpub 52 * @param[in] xpub The CExtPubKey to get from cache 53 */ 54 bool GetCachedDerivedExtPubKey(uint32_t key_exp_pos, uint32_t der_index, CExtPubKey& xpub) const; 55 /** Cache a last hardened xpub 56 * 57 * @param[in] key_exp_pos Position of the key expression within the descriptor 58 * @param[in] xpub The CExtPubKey to cache 59 */ 60 void CacheLastHardenedExtPubKey(uint32_t key_exp_pos, const CExtPubKey& xpub); 61 /** Retrieve a cached last hardened xpub 62 * 63 * @param[in] key_exp_pos Position of the key expression within the descriptor 64 * @param[in] xpub The CExtPubKey to get from cache 65 */ 66 bool GetCachedLastHardenedExtPubKey(uint32_t key_exp_pos, CExtPubKey& xpub) const; 67 68 /** Retrieve all cached parent xpubs */ 69 const ExtPubKeyMap GetCachedParentExtPubKeys() const; 70 /** Retrieve all cached derived xpubs */ 71 const std::unordered_map<uint32_t, ExtPubKeyMap> GetCachedDerivedExtPubKeys() const; 72 /** Retrieve all cached last hardened xpubs */ 73 const ExtPubKeyMap GetCachedLastHardenedExtPubKeys() const; 74 75 /** Combine another DescriptorCache into this one. 76 * Returns a cache containing the items from the other cache unknown to current cache 77 */ 78 DescriptorCache MergeAndDiff(const DescriptorCache& other); 79 }; 80 81 /** \brief Interface for parsed descriptor objects. 82 * 83 * Descriptors are strings that describe a set of scriptPubKeys, together with 84 * all information necessary to solve them. By combining all information into 85 * one, they avoid the need to separately import keys and scripts. 86 * 87 * Descriptors may be ranged, which occurs when the public keys inside are 88 * specified in the form of HD chains (xpubs). 89 * 90 * Descriptors always represent public information - public keys and scripts - 91 * but in cases where private keys need to be conveyed along with a descriptor, 92 * they can be included inside by changing public keys to private keys (WIF 93 * format), and changing xpubs by xprvs. 94 * 95 * Reference documentation about the descriptor language can be found in 96 * doc/descriptors.md. 97 */ 98 struct Descriptor { 99 virtual ~Descriptor() = default; 100 101 /** Whether the expansion of this descriptor depends on the position. */ 102 virtual bool IsRange() const = 0; 103 104 /** Whether this descriptor has all information about signing ignoring lack of private keys. 105 * This is true for all descriptors except ones that use `raw` or `addr` constructions. */ 106 virtual bool IsSolvable() const = 0; 107 108 /** Convert the descriptor back to a string, undoing parsing. */ 109 virtual std::string ToString() const = 0; 110 111 /** Whether this descriptor will return one scriptPubKey or multiple (aka is or is not combo) */ 112 virtual bool IsSingleType() const = 0; 113 114 /** Convert the descriptor to a private string. This fails if the provided provider does not have the relevant private keys. */ 115 virtual bool ToPrivateString(const SigningProvider& provider, std::string& out) const = 0; 116 117 /** 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. */ 118 virtual bool ToNormalizedString(const SigningProvider& provider, std::string& out, const DescriptorCache* cache = nullptr) const = 0; 119 120 /** Expand a descriptor at a specified position. 121 * 122 * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored. 123 * @param[in] provider The provider to query for private keys in case of hardened derivation. 124 * @param[out] output_scripts The expanded scriptPubKeys. 125 * @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`). 126 * @param[out] write_cache Cache data necessary to evaluate the descriptor at this point without access to private keys. 127 */ 128 virtual bool Expand(int pos, const SigningProvider& provider, std::vector<CScript>& output_scripts, FlatSigningProvider& out, DescriptorCache* write_cache = nullptr) const = 0; 129 130 /** Expand a descriptor at a specified position using cached expansion data. 131 * 132 * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored. 133 * @param[in] read_cache Cached expansion data. 134 * @param[out] output_scripts The expanded scriptPubKeys. 135 * @param[out] out Scripts and public keys necessary for solving the expanded scriptPubKeys (may be equal to `provider`). 136 */ 137 virtual bool ExpandFromCache(int pos, const DescriptorCache& read_cache, std::vector<CScript>& output_scripts, FlatSigningProvider& out) const = 0; 138 139 /** Expand the private key for a descriptor at a specified position, if possible. 140 * 141 * @param[in] pos The position at which to expand the descriptor. If IsRange() is false, this is ignored. 142 * @param[in] provider The provider to query for the private keys. 143 * @param[out] out Any private keys available for the specified `pos`. 144 */ 145 virtual void ExpandPrivate(int pos, const SigningProvider& provider, FlatSigningProvider& out) const = 0; 146 147 /** @return The OutputType of the scriptPubKey(s) produced by this descriptor. Or nullopt if indeterminate (multiple or none) */ 148 virtual std::optional<OutputType> GetOutputType() const = 0; 149 }; 150 151 /** Parse a `descriptor` string. Included private keys are put in `out`. 152 * 153 * If the descriptor has a checksum, it must be valid. If `require_checksum` 154 * is set, the checksum is mandatory - otherwise it is optional. 155 * 156 * If a parse error occurs, or the checksum is missing/invalid, or anything 157 * else is wrong, `nullptr` is returned. 158 */ 159 std::unique_ptr<Descriptor> Parse(const std::string& descriptor, FlatSigningProvider& out, std::string& error, bool require_checksum = false); 160 161 /** Get the checksum for a `descriptor`. 162 * 163 * - If it already has one, and it is correct, return the checksum in the input. 164 * - If it already has one that is wrong, return "". 165 * - If it does not already have one, return the checksum that would need to be added. 166 */ 167 std::string GetDescriptorChecksum(const std::string& descriptor); 168 169 /** Find a descriptor for the specified `script`, using information from `provider` where possible. 170 * 171 * A non-ranged descriptor which only generates the specified script will be returned in all 172 * circumstances. 173 * 174 * For public keys with key origin information, this information will be preserved in the returned 175 * descriptor. 176 * 177 * - If all information for solving `script` is present in `provider`, a descriptor will be returned 178 * which is IsSolvable() and encapsulates said information. 179 * - Failing that, if `script` corresponds to a known address type, an "addr()" descriptor will be 180 * returned (which is not IsSolvable()). 181 * - Failing that, a "raw()" descriptor is returned. 182 */ 183 std::unique_ptr<Descriptor> InferDescriptor(const CScript& script, const SigningProvider& provider); 184 185 #endif // BITCOIN_SCRIPT_DESCRIPTOR_H 186