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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_INTERPRETER_H
7 : : #define BITCOIN_SCRIPT_INTERPRETER_H
8 : :
9 : : #include <hash.h>
10 : : #include <script/script_error.h>
11 : : #include <span.h>
12 : : #include <primitives/transaction.h>
13 : :
14 : : #include <optional>
15 : : #include <vector>
16 : : #include <stdint.h>
17 : :
18 : : class CPubKey;
19 : : class XOnlyPubKey;
20 : : class CScript;
21 : : class CTransaction;
22 : : class CTxOut;
23 : : class uint256;
24 : :
25 : : /** Signature hash types/flags */
26 : : enum
27 : : {
28 : : SIGHASH_ALL = 1,
29 : : SIGHASH_NONE = 2,
30 : : SIGHASH_SINGLE = 3,
31 : : SIGHASH_ANYONECANPAY = 0x80,
32 : :
33 : : SIGHASH_DEFAULT = 0, //!< Taproot only; implied when sighash byte is missing, and equivalent to SIGHASH_ALL
34 : : SIGHASH_OUTPUT_MASK = 3,
35 : : SIGHASH_INPUT_MASK = 0x80,
36 : : };
37 : :
38 : : /** Script verification flags.
39 : : *
40 : : * All flags are intended to be soft forks: the set of acceptable scripts under
41 : : * flags (A | B) is a subset of the acceptable scripts under flag (A).
42 : : */
43 : : enum : uint32_t {
44 : : SCRIPT_VERIFY_NONE = 0,
45 : :
46 : : // Evaluate P2SH subscripts (BIP16).
47 : : SCRIPT_VERIFY_P2SH = (1U << 0),
48 : :
49 : : // Passing a non-strict-DER signature or one with undefined hashtype to a checksig operation causes script failure.
50 : : // Evaluating a pubkey that is not (0x04 + 64 bytes) or (0x02 or 0x03 + 32 bytes) by checksig causes script failure.
51 : : // (not used or intended as a consensus rule).
52 : : SCRIPT_VERIFY_STRICTENC = (1U << 1),
53 : :
54 : : // Passing a non-strict-DER signature to a checksig operation causes script failure (BIP62 rule 1)
55 : : SCRIPT_VERIFY_DERSIG = (1U << 2),
56 : :
57 : : // Passing a non-strict-DER signature or one with S > order/2 to a checksig operation causes script failure
58 : : // (BIP62 rule 5).
59 : : SCRIPT_VERIFY_LOW_S = (1U << 3),
60 : :
61 : : // verify dummy stack item consumed by CHECKMULTISIG is of zero-length (BIP62 rule 7).
62 : : SCRIPT_VERIFY_NULLDUMMY = (1U << 4),
63 : :
64 : : // Using a non-push operator in the scriptSig causes script failure (BIP62 rule 2).
65 : : SCRIPT_VERIFY_SIGPUSHONLY = (1U << 5),
66 : :
67 : : // Require minimal encodings for all push operations (OP_0... OP_16, OP_1NEGATE where possible, direct
68 : : // pushes up to 75 bytes, OP_PUSHDATA up to 255 bytes, OP_PUSHDATA2 for anything larger). Evaluating
69 : : // any other push causes the script to fail (BIP62 rule 3).
70 : : // In addition, whenever a stack element is interpreted as a number, it must be of minimal length (BIP62 rule 4).
71 : : SCRIPT_VERIFY_MINIMALDATA = (1U << 6),
72 : :
73 : : // Discourage use of NOPs reserved for upgrades (NOP1-10)
74 : : //
75 : : // Provided so that nodes can avoid accepting or mining transactions
76 : : // containing executed NOP's whose meaning may change after a soft-fork,
77 : : // thus rendering the script invalid; with this flag set executing
78 : : // discouraged NOPs fails the script. This verification flag will never be
79 : : // a mandatory flag applied to scripts in a block. NOPs that are not
80 : : // executed, e.g. within an unexecuted IF ENDIF block, are *not* rejected.
81 : : // NOPs that have associated forks to give them new meaning (CLTV, CSV)
82 : : // are not subject to this rule.
83 : : SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS = (1U << 7),
84 : :
85 : : // Require that only a single stack element remains after evaluation. This changes the success criterion from
86 : : // "At least one stack element must remain, and when interpreted as a boolean, it must be true" to
87 : : // "Exactly one stack element must remain, and when interpreted as a boolean, it must be true".
88 : : // (BIP62 rule 6)
89 : : // Note: CLEANSTACK should never be used without P2SH or WITNESS.
90 : : // Note: WITNESS_V0 and TAPSCRIPT script execution have behavior similar to CLEANSTACK as part of their
91 : : // consensus rules. It is automatic there and does not need this flag.
92 : : SCRIPT_VERIFY_CLEANSTACK = (1U << 8),
93 : :
94 : : // Verify CHECKLOCKTIMEVERIFY
95 : : //
96 : : // See BIP65 for details.
97 : : SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY = (1U << 9),
98 : :
99 : : // support CHECKSEQUENCEVERIFY opcode
100 : : //
101 : : // See BIP112 for details
102 : : SCRIPT_VERIFY_CHECKSEQUENCEVERIFY = (1U << 10),
103 : :
104 : : // Support segregated witness
105 : : //
106 : : SCRIPT_VERIFY_WITNESS = (1U << 11),
107 : :
108 : : // Making v1-v16 witness program non-standard
109 : : //
110 : : SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_WITNESS_PROGRAM = (1U << 12),
111 : :
112 : : // Segwit script only: Require the argument of OP_IF/NOTIF to be exactly 0x01 or empty vector
113 : : //
114 : : // Note: TAPSCRIPT script execution has behavior similar to MINIMALIF as part of its consensus
115 : : // rules. It is automatic there and does not depend on this flag.
116 : : SCRIPT_VERIFY_MINIMALIF = (1U << 13),
117 : :
118 : : // Signature(s) must be empty vector if a CHECK(MULTI)SIG operation failed
119 : : //
120 : : SCRIPT_VERIFY_NULLFAIL = (1U << 14),
121 : :
122 : : // Public keys in segregated witness scripts must be compressed
123 : : //
124 : : SCRIPT_VERIFY_WITNESS_PUBKEYTYPE = (1U << 15),
125 : :
126 : : // Making OP_CODESEPARATOR and FindAndDelete fail any non-segwit scripts
127 : : //
128 : : SCRIPT_VERIFY_CONST_SCRIPTCODE = (1U << 16),
129 : :
130 : : // Taproot/Tapscript validation (BIPs 341 & 342)
131 : : //
132 : : SCRIPT_VERIFY_TAPROOT = (1U << 17),
133 : :
134 : : // Making unknown Taproot leaf versions non-standard
135 : : //
136 : : SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_TAPROOT_VERSION = (1U << 18),
137 : :
138 : : // Making unknown OP_SUCCESS non-standard
139 : : SCRIPT_VERIFY_DISCOURAGE_OP_SUCCESS = (1U << 19),
140 : :
141 : : // Making unknown public key versions (in BIP 342 scripts) non-standard
142 : : SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_PUBKEYTYPE = (1U << 20),
143 : :
144 : : // Constants to point to the highest flag in use. Add new flags above this line.
145 : : //
146 : : SCRIPT_VERIFY_END_MARKER
147 : : };
148 : :
149 : : bool CheckSignatureEncoding(const std::vector<unsigned char> &vchSig, unsigned int flags, ScriptError* serror);
150 : :
151 : 0 : struct PrecomputedTransactionData
152 : : {
153 : : // BIP341 precomputed data.
154 : : // These are single-SHA256, see https://github.com/bitcoin/bips/blob/master/bip-0341.mediawiki#cite_note-16.
155 : : uint256 m_prevouts_single_hash;
156 : : uint256 m_sequences_single_hash;
157 : : uint256 m_outputs_single_hash;
158 : : uint256 m_spent_amounts_single_hash;
159 : : uint256 m_spent_scripts_single_hash;
160 : : //! Whether the 5 fields above are initialized.
161 : 400 : bool m_bip341_taproot_ready = false;
162 : :
163 : : // BIP143 precomputed data (double-SHA256).
164 : : uint256 hashPrevouts, hashSequence, hashOutputs;
165 : : //! Whether the 3 fields above are initialized.
166 : 400 : bool m_bip143_segwit_ready = false;
167 : :
168 : : std::vector<CTxOut> m_spent_outputs;
169 : : //! Whether m_spent_outputs is initialized.
170 : 400 : bool m_spent_outputs_ready = false;
171 : :
172 : 1600 : PrecomputedTransactionData() = default;
173 : :
174 : : /** Initialize this PrecomputedTransactionData with transaction data.
175 : : *
176 : : * @param[in] tx The transaction for which data is being precomputed.
177 : : * @param[in] spent_outputs The CTxOuts being spent, one for each tx.vin, in order.
178 : : * @param[in] force Whether to precompute data for all optional features,
179 : : * regardless of what is in the inputs (used at signing
180 : : * time, when the inputs aren't filled in yet). */
181 : : template <class T>
182 : : void Init(const T& tx, std::vector<CTxOut>&& spent_outputs, bool force = false);
183 : :
184 : : template <class T>
185 : : explicit PrecomputedTransactionData(const T& tx);
186 : : };
187 : :
188 : : enum class SigVersion
189 : : {
190 : : BASE = 0, //!< Bare scripts and BIP16 P2SH-wrapped redeemscripts
191 : : WITNESS_V0 = 1, //!< Witness v0 (P2WPKH and P2WSH); see BIP 141
192 : : TAPROOT = 2, //!< Witness v1 with 32-byte program, not BIP16 P2SH-wrapped, key path spending; see BIP 341
193 : : TAPSCRIPT = 3, //!< Witness v1 with 32-byte program, not BIP16 P2SH-wrapped, script path spending, leaf version 0xc0; see BIP 342
194 : : };
195 : :
196 : 0 : struct ScriptExecutionData
197 : : {
198 : : //! Whether m_tapleaf_hash is initialized.
199 : 0 : bool m_tapleaf_hash_init = false;
200 : : //! The tapleaf hash.
201 : : uint256 m_tapleaf_hash;
202 : :
203 : : //! Whether m_codeseparator_pos is initialized.
204 : 0 : bool m_codeseparator_pos_init = false;
205 : : //! Opcode position of the last executed OP_CODESEPARATOR (or 0xFFFFFFFF if none executed).
206 : : uint32_t m_codeseparator_pos;
207 : :
208 : : //! Whether m_annex_present and (when needed) m_annex_hash are initialized.
209 : 0 : bool m_annex_init = false;
210 : : //! Whether an annex is present.
211 : : bool m_annex_present;
212 : : //! Hash of the annex data.
213 : : uint256 m_annex_hash;
214 : :
215 : : //! Whether m_validation_weight_left is initialized.
216 : 0 : bool m_validation_weight_left_init = false;
217 : : //! How much validation weight is left (decremented for every successful non-empty signature check).
218 : : int64_t m_validation_weight_left;
219 : :
220 : : //! The hash of the corresponding output
221 : : std::optional<uint256> m_output_hash;
222 : : };
223 : :
224 : : /** Signature hash sizes */
225 : : static constexpr size_t WITNESS_V0_SCRIPTHASH_SIZE = 32;
226 : : static constexpr size_t WITNESS_V0_KEYHASH_SIZE = 20;
227 : : static constexpr size_t WITNESS_V1_TAPROOT_SIZE = 32;
228 : :
229 : : static constexpr uint8_t TAPROOT_LEAF_MASK = 0xfe;
230 : : static constexpr uint8_t TAPROOT_LEAF_TAPSCRIPT = 0xc0;
231 : : static constexpr size_t TAPROOT_CONTROL_BASE_SIZE = 33;
232 : : static constexpr size_t TAPROOT_CONTROL_NODE_SIZE = 32;
233 : : static constexpr size_t TAPROOT_CONTROL_MAX_NODE_COUNT = 128;
234 : : static constexpr size_t TAPROOT_CONTROL_MAX_SIZE = TAPROOT_CONTROL_BASE_SIZE + TAPROOT_CONTROL_NODE_SIZE * TAPROOT_CONTROL_MAX_NODE_COUNT;
235 : :
236 : : extern const HashWriter HASHER_TAPSIGHASH; //!< Hasher with tag "TapSighash" pre-fed to it.
237 : : extern const HashWriter HASHER_TAPLEAF; //!< Hasher with tag "TapLeaf" pre-fed to it.
238 : : extern const HashWriter HASHER_TAPBRANCH; //!< Hasher with tag "TapBranch" pre-fed to it.
239 : :
240 : : template <class T>
241 : : uint256 SignatureHash(const CScript& scriptCode, const T& txTo, unsigned int nIn, int nHashType, const CAmount& amount, SigVersion sigversion, const PrecomputedTransactionData* cache = nullptr);
242 : :
243 : 0 : class BaseSignatureChecker
244 : : {
245 : : public:
246 : 0 : virtual bool CheckECDSASignature(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const
247 : : {
248 : 0 : return false;
249 : : }
250 : :
251 : 0 : virtual bool CheckSchnorrSignature(Span<const unsigned char> sig, Span<const unsigned char> pubkey, SigVersion sigversion, ScriptExecutionData& execdata, ScriptError* serror = nullptr) const
252 : : {
253 : 0 : return false;
254 : : }
255 : :
256 : 0 : virtual bool CheckLockTime(const CScriptNum& nLockTime) const
257 : : {
258 : 0 : return false;
259 : : }
260 : :
261 : 0 : virtual bool CheckSequence(const CScriptNum& nSequence) const
262 : : {
263 : 0 : return false;
264 : : }
265 : :
266 : 4 : virtual ~BaseSignatureChecker() {}
267 : : };
268 : :
269 : : /** Enum to specify what *TransactionSignatureChecker's behavior should be
270 : : * when dealing with missing transaction data.
271 : : */
272 : : enum class MissingDataBehavior
273 : : {
274 : : ASSERT_FAIL, //!< Abort execution through assertion failure (for consensus code)
275 : : FAIL, //!< Just act as if the signature was invalid
276 : : };
277 : :
278 : : template<typename T>
279 : : bool SignatureHashSchnorr(uint256& hash_out, ScriptExecutionData& execdata, const T& tx_to, uint32_t in_pos, uint8_t hash_type, SigVersion sigversion, const PrecomputedTransactionData& cache, MissingDataBehavior mdb);
280 : :
281 : : template <class T>
282 : 0 : class GenericTransactionSignatureChecker : public BaseSignatureChecker
283 : : {
284 : : private:
285 : : const T* txTo;
286 : : const MissingDataBehavior m_mdb;
287 : : unsigned int nIn;
288 : : const CAmount amount;
289 : : const PrecomputedTransactionData* txdata;
290 : :
291 : : protected:
292 : : virtual bool VerifyECDSASignature(const std::vector<unsigned char>& vchSig, const CPubKey& vchPubKey, const uint256& sighash) const;
293 : : virtual bool VerifySchnorrSignature(Span<const unsigned char> sig, const XOnlyPubKey& pubkey, const uint256& sighash) const;
294 : :
295 : : public:
296 : 0 : GenericTransactionSignatureChecker(const T* txToIn, unsigned int nInIn, const CAmount& amountIn, MissingDataBehavior mdb) : txTo(txToIn), m_mdb(mdb), nIn(nInIn), amount(amountIn), txdata(nullptr) {}
297 : 0 : GenericTransactionSignatureChecker(const T* txToIn, unsigned int nInIn, const CAmount& amountIn, const PrecomputedTransactionData& txdataIn, MissingDataBehavior mdb) : txTo(txToIn), m_mdb(mdb), nIn(nInIn), amount(amountIn), txdata(&txdataIn) {}
298 : : bool CheckECDSASignature(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const override;
299 : : bool CheckSchnorrSignature(Span<const unsigned char> sig, Span<const unsigned char> pubkey, SigVersion sigversion, ScriptExecutionData& execdata, ScriptError* serror = nullptr) const override;
300 : : bool CheckLockTime(const CScriptNum& nLockTime) const override;
301 : : bool CheckSequence(const CScriptNum& nSequence) const override;
302 : : };
303 : :
304 : : using TransactionSignatureChecker = GenericTransactionSignatureChecker<CTransaction>;
305 : : using MutableTransactionSignatureChecker = GenericTransactionSignatureChecker<CMutableTransaction>;
306 : :
307 : 0 : class DeferringSignatureChecker : public BaseSignatureChecker
308 : : {
309 : : protected:
310 : : const BaseSignatureChecker& m_checker;
311 : :
312 : : public:
313 : 0 : DeferringSignatureChecker(const BaseSignatureChecker& checker) : m_checker(checker) {}
314 : :
315 : 0 : bool CheckECDSASignature(const std::vector<unsigned char>& scriptSig, const std::vector<unsigned char>& vchPubKey, const CScript& scriptCode, SigVersion sigversion) const override
316 : : {
317 : 0 : return m_checker.CheckECDSASignature(scriptSig, vchPubKey, scriptCode, sigversion);
318 : : }
319 : :
320 : 0 : bool CheckSchnorrSignature(Span<const unsigned char> sig, Span<const unsigned char> pubkey, SigVersion sigversion, ScriptExecutionData& execdata, ScriptError* serror = nullptr) const override
321 : : {
322 : 0 : return m_checker.CheckSchnorrSignature(sig, pubkey, sigversion, execdata, serror);
323 : : }
324 : :
325 : 0 : bool CheckLockTime(const CScriptNum& nLockTime) const override
326 : : {
327 : 0 : return m_checker.CheckLockTime(nLockTime);
328 : : }
329 : 0 : bool CheckSequence(const CScriptNum& nSequence) const override
330 : : {
331 : 0 : return m_checker.CheckSequence(nSequence);
332 : : }
333 : : };
334 : :
335 : : /** Compute the BIP341 tapleaf hash from leaf version & script. */
336 : : uint256 ComputeTapleafHash(uint8_t leaf_version, Span<const unsigned char> script);
337 : : /** Compute the BIP341 tapbranch hash from two branches.
338 : : * Spans must be 32 bytes each. */
339 : : uint256 ComputeTapbranchHash(Span<const unsigned char> a, Span<const unsigned char> b);
340 : : /** Compute the BIP341 taproot script tree Merkle root from control block and leaf hash.
341 : : * Requires control block to have valid length (33 + k*32, with k in {0,1,..,128}). */
342 : : uint256 ComputeTaprootMerkleRoot(Span<const unsigned char> control, const uint256& tapleaf_hash);
343 : :
344 : : bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptExecutionData& execdata, ScriptError* error = nullptr);
345 : : bool EvalScript(std::vector<std::vector<unsigned char> >& stack, const CScript& script, unsigned int flags, const BaseSignatureChecker& checker, SigVersion sigversion, ScriptError* error = nullptr);
346 : : bool VerifyScript(const CScript& scriptSig, const CScript& scriptPubKey, const CScriptWitness* witness, unsigned int flags, const BaseSignatureChecker& checker, ScriptError* serror = nullptr);
347 : :
348 : : size_t CountWitnessSigOps(const CScript& scriptSig, const CScript& scriptPubKey, const CScriptWitness* witness, unsigned int flags);
349 : :
350 : : int FindAndDelete(CScript& script, const CScript& b);
351 : :
352 : : #endif // BITCOIN_SCRIPT_INTERPRETER_H
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