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1 : : // Copyright (c) 2009-2010 Satoshi Nakamoto
2 : : // Copyright (c) 2009-2022 The Bitcoin Core developers
3 : : // Distributed under the MIT software license, see the accompanying
4 : : // file COPYING or http://www.opensource.org/licenses/mit-license.php.
5 : :
6 : : #ifndef BITCOIN_SCRIPT_SIGNINGPROVIDER_H
7 : : #define BITCOIN_SCRIPT_SIGNINGPROVIDER_H
8 : :
9 : : #include <addresstype.h>
10 : : #include <attributes.h>
11 : : #include <key.h>
12 : : #include <pubkey.h>
13 : : #include <script/keyorigin.h>
14 : : #include <script/script.h>
15 : : #include <sync.h>
16 : :
17 : : struct ShortestVectorFirstComparator
18 : : {
19 : 0 : bool operator()(const std::vector<unsigned char>& a, const std::vector<unsigned char>& b) const
20 : : {
21 [ # # ]: 0 : if (a.size() < b.size()) return true;
22 [ # # ]: 0 : if (a.size() > b.size()) return false;
23 : 0 : return a < b;
24 : 0 : }
25 : : };
26 : :
27 : 0 : struct TaprootSpendData
28 : : {
29 : : /** The BIP341 internal key. */
30 : : XOnlyPubKey internal_key;
31 : : /** The Merkle root of the script tree (0 if no scripts). */
32 : : uint256 merkle_root;
33 : : /** Map from (script, leaf_version) to (sets of) control blocks.
34 : : * More than one control block for a given script is only possible if it
35 : : * appears in multiple branches of the tree. We keep them all so that
36 : : * inference can reconstruct the full tree. Within each set, the control
37 : : * blocks are sorted by size, so that the signing logic can easily
38 : : * prefer the cheapest one. */
39 : : std::map<std::pair<std::vector<unsigned char>, int>, std::set<std::vector<unsigned char>, ShortestVectorFirstComparator>> scripts;
40 : : /** Merge other TaprootSpendData (for the same scriptPubKey) into this. */
41 : : void Merge(TaprootSpendData other);
42 : : };
43 : :
44 : : /** Utility class to construct Taproot outputs from internal key and script tree. */
45 [ + - ][ + - ]: 24474 : class TaprootBuilder
46 : : {
47 : : private:
48 : : /** Information about a tracked leaf in the Merkle tree. */
49 : 0 : struct LeafInfo
50 : : {
51 : : std::vector<unsigned char> script; //!< The script.
52 : : int leaf_version; //!< The leaf version for that script.
53 : : std::vector<uint256> merkle_branch; //!< The hashing partners above this leaf.
54 : : };
55 : :
56 : : /** Information associated with a node in the Merkle tree. */
57 : 0 : struct NodeInfo
58 : : {
59 : : /** Merkle hash of this node. */
60 : : uint256 hash;
61 : : /** Tracked leaves underneath this node (either from the node itself, or its children).
62 : : * The merkle_branch field of each is the partners to get to *this* node. */
63 : : std::vector<LeafInfo> leaves;
64 : : };
65 : : /** Whether the builder is in a valid state so far. */
66 : 24474 : bool m_valid = true;
67 : :
68 : : /** The current state of the builder.
69 : : *
70 : : * For each level in the tree, one NodeInfo object may be present. m_branch[0]
71 : : * is information about the root; further values are for deeper subtrees being
72 : : * explored.
73 : : *
74 : : * For every right branch taken to reach the position we're currently
75 : : * working in, there will be a (non-nullopt) entry in m_branch corresponding
76 : : * to the left branch at that level.
77 : : *
78 : : * For example, imagine this tree: - N0 -
79 : : * / \
80 : : * N1 N2
81 : : * / \ / \
82 : : * A B C N3
83 : : * / \
84 : : * D E
85 : : *
86 : : * Initially, m_branch is empty. After processing leaf A, it would become
87 : : * {nullopt, nullopt, A}. When processing leaf B, an entry at level 2 already
88 : : * exists, and it would thus be combined with it to produce a level 1 one,
89 : : * resulting in {nullopt, N1}. Adding C and D takes us to {nullopt, N1, C}
90 : : * and {nullopt, N1, C, D} respectively. When E is processed, it is combined
91 : : * with D, and then C, and then N1, to produce the root, resulting in {N0}.
92 : : *
93 : : * This structure allows processing with just O(log n) overhead if the leaves
94 : : * are computed on the fly.
95 : : *
96 : : * As an invariant, there can never be nullopt entries at the end. There can
97 : : * also not be more than 128 entries (as that would mean more than 128 levels
98 : : * in the tree). The depth of newly added entries will always be at least
99 : : * equal to the current size of m_branch (otherwise it does not correspond
100 : : * to a depth-first traversal of a tree). m_branch is only empty if no entries
101 : : * have ever be processed. m_branch having length 1 corresponds to being done.
102 : : */
103 : : std::vector<std::optional<NodeInfo>> m_branch;
104 : :
105 : : XOnlyPubKey m_internal_key; //!< The internal key, set when finalizing.
106 : : XOnlyPubKey m_output_key; //!< The output key, computed when finalizing.
107 : : bool m_parity; //!< The tweak parity, computed when finalizing.
108 : :
109 : : /** Combine information about a parent Merkle tree node from its child nodes. */
110 : : static NodeInfo Combine(NodeInfo&& a, NodeInfo&& b);
111 : : /** Insert information about a node at a certain depth, and propagate information up. */
112 : : void Insert(NodeInfo&& node, int depth);
113 : :
114 : : public:
115 : : /** Add a new script at a certain depth in the tree. Add() operations must be called
116 : : * in depth-first traversal order of binary tree. If track is true, it will be included in
117 : : * the GetSpendData() output. */
118 : : TaprootBuilder& Add(int depth, Span<const unsigned char> script, int leaf_version, bool track = true);
119 : : /** Like Add(), but for a Merkle node with a given hash to the tree. */
120 : : TaprootBuilder& AddOmitted(int depth, const uint256& hash);
121 : : /** Finalize the construction. Can only be called when IsComplete() is true.
122 : : internal_key.IsFullyValid() must be true. */
123 : : TaprootBuilder& Finalize(const XOnlyPubKey& internal_key);
124 : :
125 : : /** Return true if so far all input was valid. */
126 : 0 : bool IsValid() const { return m_valid; }
127 : : /** Return whether there were either no leaves, or the leaves form a Huffman tree. */
128 [ - + ][ - + ]: 48948 : bool IsComplete() const { return m_valid && (m_branch.size() == 0 || (m_branch.size() == 1 && m_branch[0].has_value())); }
[ # # ]
129 : : /** Compute scriptPubKey (after Finalize()). */
130 : : WitnessV1Taproot GetOutput();
131 : : /** Check if a list of depths is legal (will lead to IsComplete()). */
132 : : static bool ValidDepths(const std::vector<int>& depths);
133 : : /** Compute spending data (after Finalize()). */
134 : : TaprootSpendData GetSpendData() const;
135 : : /** Returns a vector of tuples representing the depth, leaf version, and script */
136 : : std::vector<std::tuple<uint8_t, uint8_t, std::vector<unsigned char>>> GetTreeTuples() const;
137 : : /** Returns true if there are any tapscripts */
138 : 0 : bool HasScripts() const { return !m_branch.empty(); }
139 : : };
140 : :
141 : : /** Given a TaprootSpendData and the output key, reconstruct its script tree.
142 : : *
143 : : * If the output doesn't match the spenddata, or if the data in spenddata is incomplete,
144 : : * std::nullopt is returned. Otherwise, a vector of (depth, script, leaf_ver) tuples is
145 : : * returned, corresponding to a depth-first traversal of the script tree.
146 : : */
147 : : std::optional<std::vector<std::tuple<int, std::vector<unsigned char>, int>>> InferTaprootTree(const TaprootSpendData& spenddata, const XOnlyPubKey& output);
148 : :
149 : : /** An interface to be implemented by keystores that support signing. */
150 : 0 : class SigningProvider
151 : : {
152 : : public:
153 : 1124080 : virtual ~SigningProvider() {}
154 : 0 : virtual bool GetCScript(const CScriptID &scriptid, CScript& script) const { return false; }
155 : 0 : virtual bool HaveCScript(const CScriptID &scriptid) const { return false; }
156 : 0 : virtual bool GetPubKey(const CKeyID &address, CPubKey& pubkey) const { return false; }
157 : 0 : virtual bool GetKey(const CKeyID &address, CKey& key) const { return false; }
158 : 0 : virtual bool HaveKey(const CKeyID &address) const { return false; }
159 : 0 : virtual bool GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const { return false; }
160 : 0 : virtual bool GetTaprootSpendData(const XOnlyPubKey& output_key, TaprootSpendData& spenddata) const { return false; }
161 : 0 : virtual bool GetTaprootBuilder(const XOnlyPubKey& output_key, TaprootBuilder& builder) const { return false; }
162 : :
163 : 0 : bool GetKeyByXOnly(const XOnlyPubKey& pubkey, CKey& key) const
164 : : {
165 [ # # ]: 0 : for (const auto& id : pubkey.GetKeyIDs()) {
[ # # # ]
166 [ # # ][ # # ]: 0 : if (GetKey(id, key)) return true;
167 : : }
168 : 0 : return false;
169 : 0 : }
170 : :
171 : 0 : bool GetPubKeyByXOnly(const XOnlyPubKey& pubkey, CPubKey& out) const
172 : : {
173 [ # # ]: 0 : for (const auto& id : pubkey.GetKeyIDs()) {
[ # # # ]
174 [ # # ][ # # ]: 0 : if (GetPubKey(id, out)) return true;
175 : : }
176 : 0 : return false;
177 : 0 : }
178 : :
179 : 4356 : bool GetKeyOriginByXOnly(const XOnlyPubKey& pubkey, KeyOriginInfo& info) const
180 : : {
181 [ + - ]: 11372 : for (const auto& id : pubkey.GetKeyIDs()) {
[ - + - ]
182 [ + - ][ + + ]: 7016 : if (GetKeyOrigin(id, info)) return true;
183 : : }
184 : 0 : return false;
185 : 4356 : }
186 : : };
187 : :
188 : : extern const SigningProvider& DUMMY_SIGNING_PROVIDER;
189 : :
190 : 0 : class HidingSigningProvider : public SigningProvider
191 : : {
192 : : private:
193 : : const bool m_hide_secret;
194 : : const bool m_hide_origin;
195 : : const SigningProvider* m_provider;
196 : :
197 : : public:
198 : 0 : HidingSigningProvider(const SigningProvider* provider, bool hide_secret, bool hide_origin) : m_hide_secret(hide_secret), m_hide_origin(hide_origin), m_provider(provider) {}
199 : : bool GetCScript(const CScriptID& scriptid, CScript& script) const override;
200 : : bool GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const override;
201 : : bool GetKey(const CKeyID& keyid, CKey& key) const override;
202 : : bool GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const override;
203 : : bool GetTaprootSpendData(const XOnlyPubKey& output_key, TaprootSpendData& spenddata) const override;
204 : : bool GetTaprootBuilder(const XOnlyPubKey& output_key, TaprootBuilder& builder) const override;
205 : : };
206 : :
207 [ + - ][ + - ]: 540734 : struct FlatSigningProvider final : public SigningProvider
[ + - ][ - + ]
208 : : {
209 : : std::map<CScriptID, CScript> scripts;
210 : : std::map<CKeyID, CPubKey> pubkeys;
211 : : std::map<CKeyID, std::pair<CPubKey, KeyOriginInfo>> origins;
212 : : std::map<CKeyID, CKey> keys;
213 : : std::map<XOnlyPubKey, TaprootBuilder> tr_trees; /** Map from output key to Taproot tree (which can then make the TaprootSpendData */
214 : :
215 : : bool GetCScript(const CScriptID& scriptid, CScript& script) const override;
216 : : bool GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const override;
217 : : bool GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const override;
218 : : bool GetKey(const CKeyID& keyid, CKey& key) const override;
219 : : bool GetTaprootSpendData(const XOnlyPubKey& output_key, TaprootSpendData& spenddata) const override;
220 : : bool GetTaprootBuilder(const XOnlyPubKey& output_key, TaprootBuilder& builder) const override;
221 : :
222 : : FlatSigningProvider& Merge(FlatSigningProvider&& b) LIFETIMEBOUND;
223 : : };
224 : :
225 : : /** Fillable signing provider that keeps keys in an address->secret map */
226 : 0 : class FillableSigningProvider : public SigningProvider
227 : : {
228 : : protected:
229 : : using KeyMap = std::map<CKeyID, CKey>;
230 : : using ScriptMap = std::map<CScriptID, CScript>;
231 : :
232 : : /**
233 : : * Map of key id to unencrypted private keys known by the signing provider.
234 : : * Map may be empty if the provider has another source of keys, like an
235 : : * encrypted store.
236 : : */
237 : : KeyMap mapKeys GUARDED_BY(cs_KeyStore);
238 : :
239 : : /**
240 : : * Map of script id to scripts known by the signing provider.
241 : : *
242 : : * This map originally just held P2SH redeemScripts, and was used by wallet
243 : : * code to look up script ids referenced in "OP_HASH160 <script id>
244 : : * OP_EQUAL" P2SH outputs. Later in 605e8473a7d it was extended to hold
245 : : * P2WSH witnessScripts as well, and used to look up nested scripts
246 : : * referenced in "OP_0 <script hash>" P2WSH outputs. Later in commits
247 : : * f4691ab3a9d and 248f3a76a82, it was extended once again to hold segwit
248 : : * "OP_0 <key or script hash>" scriptPubKeys, in order to give the wallet a
249 : : * way to distinguish between segwit outputs that it generated addresses for
250 : : * and wanted to receive payments from, and segwit outputs that it never
251 : : * generated addresses for, but it could spend just because of having keys.
252 : : * (Before segwit activation it was also important to not treat segwit
253 : : * outputs to arbitrary wallet keys as payments, because these could be
254 : : * spent by anyone without even needing to sign with the keys.)
255 : : *
256 : : * Some of the scripts stored in mapScripts are memory-only and
257 : : * intentionally not saved to disk. Specifically, scripts added by
258 : : * ImplicitlyLearnRelatedKeyScripts(pubkey) calls are not written to disk so
259 : : * future wallet code can have flexibility to be more selective about what
260 : : * transaction outputs it recognizes as payments, instead of having to treat
261 : : * all outputs spending to keys it knows as payments. By contrast,
262 : : * mapScripts entries added by AddCScript(script),
263 : : * LearnRelatedScripts(pubkey, type), and LearnAllRelatedScripts(pubkey)
264 : : * calls are saved because they are all intentionally used to receive
265 : : * payments.
266 : : *
267 : : * The FillableSigningProvider::mapScripts script map should not be confused
268 : : * with LegacyScriptPubKeyMan::setWatchOnly script set. The two collections
269 : : * can hold the same scripts, but they serve different purposes. The
270 : : * setWatchOnly script set is intended to expand the set of outputs the
271 : : * wallet considers payments. Every output with a script it contains is
272 : : * considered to belong to the wallet, regardless of whether the script is
273 : : * solvable or signable. By contrast, the scripts in mapScripts are only
274 : : * used for solving, and to restrict which outputs are considered payments
275 : : * by the wallet. An output with a script in mapScripts, unlike
276 : : * setWatchOnly, is not automatically considered to belong to the wallet if
277 : : * it can't be solved and signed for.
278 : : */
279 : : ScriptMap mapScripts GUARDED_BY(cs_KeyStore);
280 : :
281 : : void ImplicitlyLearnRelatedKeyScripts(const CPubKey& pubkey) EXCLUSIVE_LOCKS_REQUIRED(cs_KeyStore);
282 : :
283 : : public:
284 : : mutable RecursiveMutex cs_KeyStore;
285 : :
286 : : virtual bool AddKeyPubKey(const CKey& key, const CPubKey &pubkey);
287 : 0 : virtual bool AddKey(const CKey &key) { return AddKeyPubKey(key, key.GetPubKey()); }
288 : : virtual bool GetPubKey(const CKeyID &address, CPubKey& vchPubKeyOut) const override;
289 : : virtual bool HaveKey(const CKeyID &address) const override;
290 : : virtual std::set<CKeyID> GetKeys() const;
291 : : virtual bool GetKey(const CKeyID &address, CKey &keyOut) const override;
292 : : virtual bool AddCScript(const CScript& redeemScript);
293 : : virtual bool HaveCScript(const CScriptID &hash) const override;
294 : : virtual std::set<CScriptID> GetCScripts() const;
295 : : virtual bool GetCScript(const CScriptID &hash, CScript& redeemScriptOut) const override;
296 : : };
297 : :
298 : : /** Return the CKeyID of the key involved in a script (if there is a unique one). */
299 : : CKeyID GetKeyForDestination(const SigningProvider& store, const CTxDestination& dest);
300 : :
301 : : /** A signing provider to be used to interface with multiple signing providers at once. */
302 : 0 : class MultiSigningProvider: public SigningProvider {
303 : : std::vector<std::unique_ptr<SigningProvider>> m_providers;
304 : :
305 : : public:
306 : : void AddProvider(std::unique_ptr<SigningProvider> provider);
307 : :
308 : : bool GetCScript(const CScriptID& scriptid, CScript& script) const override;
309 : : bool GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const override;
310 : : bool GetKeyOrigin(const CKeyID& keyid, KeyOriginInfo& info) const override;
311 : : bool GetKey(const CKeyID& keyid, CKey& key) const override;
312 : : bool GetTaprootSpendData(const XOnlyPubKey& output_key, TaprootSpendData& spenddata) const override;
313 : : bool GetTaprootBuilder(const XOnlyPubKey& output_key, TaprootBuilder& builder) const override;
314 : : };
315 : :
316 : : #endif // BITCOIN_SCRIPT_SIGNINGPROVIDER_H
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