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bitcoin-core/src/script/sign.h
Wladimir J. van der Laan 2115cba9c6
Merge #13666: Always create signatures with Low R values
e306be7429 Use 72 byte dummy signatures when watching only inputs may be used (Andrew Chow)
48b1473c89 Use 71 byte signature for DUMMY_SIGNATURE_CREATOR (Andrew Chow)
18dfea0dd0 Always create 70 byte signatures with low R values (Andrew Chow)

Pull request description:

  When creating signatures for transactions, always make one which has a 32 byte or smaller R and 32 byte or smaller S value. This results in signatures that are always less than 71 bytes (32 byte R + 32 byte S + 6 bytes DER + 1 byte sighash) with low R values. In most cases, the signature will be 71 bytes.

  Because R is not mutable in the same way that S is, a low R value can only be found by trying different nonces. RFC 6979 for deterministic nonce generation has the option to specify additional entropy, so we simply use that and add a uin32_t counter which we increment in order to try different nonces. Nonces are sill deterministically generated as the nonce used will the be the first one where the counter results in a nonce that results in a low R value. Because different nonces need to be tried, time to produce a signature does increase. On average, it takes twice as long to make a signature as two signatures need to be created, on average, to find one with a low R.

  Having a fixed size signature makes size calculations easier and also saves half a byte of transaction size, on average.

  DUMMY_SIGNATURE_CREATOR has been modified to produce 71 byte dummy signatures instead of 72 byte signatures.

Tree-SHA512: 3cd791505126ce92da7c631856a97ba0b59e87d9c132feff6e0eef1dc47768e81fbb38bfbe970371bedf9714b7f61a13a5fe9f30f962c81734092a4d19a4ef33
2018-08-13 12:07:20 +02:00

694 lines
27 KiB
C++

// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2018 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_SIGN_H
#define BITCOIN_SCRIPT_SIGN_H
#include <boost/optional.hpp>
#include <hash.h>
#include <pubkey.h>
#include <script/interpreter.h>
#include <streams.h>
class CKey;
class CKeyID;
class CScript;
class CScriptID;
class CTransaction;
struct CMutableTransaction;
/** An interface to be implemented by keystores that support signing. */
class SigningProvider
{
public:
virtual ~SigningProvider() {}
virtual bool GetCScript(const CScriptID &scriptid, CScript& script) const { return false; }
virtual bool GetPubKey(const CKeyID &address, CPubKey& pubkey) const { return false; }
virtual bool GetKey(const CKeyID &address, CKey& key) const { return false; }
};
extern const SigningProvider& DUMMY_SIGNING_PROVIDER;
class PublicOnlySigningProvider : public SigningProvider
{
private:
const SigningProvider* m_provider;
public:
PublicOnlySigningProvider(const SigningProvider* provider) : m_provider(provider) {}
bool GetCScript(const CScriptID &scriptid, CScript& script) const;
bool GetPubKey(const CKeyID &address, CPubKey& pubkey) const;
};
struct FlatSigningProvider final : public SigningProvider
{
std::map<CScriptID, CScript> scripts;
std::map<CKeyID, CPubKey> pubkeys;
std::map<CKeyID, CKey> keys;
bool GetCScript(const CScriptID& scriptid, CScript& script) const override;
bool GetPubKey(const CKeyID& keyid, CPubKey& pubkey) const override;
bool GetKey(const CKeyID& keyid, CKey& key) const override;
};
FlatSigningProvider Merge(const FlatSigningProvider& a, const FlatSigningProvider& b);
/** Interface for signature creators. */
class BaseSignatureCreator {
public:
virtual ~BaseSignatureCreator() {}
virtual const BaseSignatureChecker& Checker() const =0;
/** Create a singular (non-script) signature. */
virtual bool CreateSig(const SigningProvider& provider, std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const =0;
};
/** A signature creator for transactions. */
class MutableTransactionSignatureCreator : public BaseSignatureCreator {
const CMutableTransaction* txTo;
unsigned int nIn;
int nHashType;
CAmount amount;
const MutableTransactionSignatureChecker checker;
public:
MutableTransactionSignatureCreator(const CMutableTransaction* txToIn, unsigned int nInIn, const CAmount& amountIn, int nHashTypeIn = SIGHASH_ALL);
const BaseSignatureChecker& Checker() const override { return checker; }
bool CreateSig(const SigningProvider& provider, std::vector<unsigned char>& vchSig, const CKeyID& keyid, const CScript& scriptCode, SigVersion sigversion) const override;
};
/** A signature creator that just produces 71-byte empty signatures. */
extern const BaseSignatureCreator& DUMMY_SIGNATURE_CREATOR;
/** A signature creator that just produces 72-byte empty signatures. */
extern const BaseSignatureCreator& DUMMY_MAXIMUM_SIGNATURE_CREATOR;
typedef std::pair<CPubKey, std::vector<unsigned char>> SigPair;
// This struct contains information from a transaction input and also contains signatures for that input.
// The information contained here can be used to create a signature and is also filled by ProduceSignature
// in order to construct final scriptSigs and scriptWitnesses.
struct SignatureData {
bool complete = false; ///< Stores whether the scriptSig and scriptWitness are complete
bool witness = false; ///< Stores whether the input this SigData corresponds to is a witness input
CScript scriptSig; ///< The scriptSig of an input. Contains complete signatures or the traditional partial signatures format
CScript redeem_script; ///< The redeemScript (if any) for the input
CScript witness_script; ///< The witnessScript (if any) for the input. witnessScripts are used in P2WSH outputs.
CScriptWitness scriptWitness; ///< The scriptWitness of an input. Contains complete signatures or the traditional partial signatures format. scriptWitness is part of a transaction input per BIP 144.
std::map<CKeyID, SigPair> signatures; ///< BIP 174 style partial signatures for the input. May contain all signatures necessary for producing a final scriptSig or scriptWitness.
std::map<CKeyID, CPubKey> misc_pubkeys;
SignatureData() {}
explicit SignatureData(const CScript& script) : scriptSig(script) {}
void MergeSignatureData(SignatureData sigdata);
};
// Magic bytes
static constexpr uint8_t PSBT_MAGIC_BYTES[5] = {'p', 's', 'b', 't', 0xff};
// Global types
static constexpr uint8_t PSBT_GLOBAL_UNSIGNED_TX = 0x00;
// Input types
static constexpr uint8_t PSBT_IN_NON_WITNESS_UTXO = 0x00;
static constexpr uint8_t PSBT_IN_WITNESS_UTXO = 0x01;
static constexpr uint8_t PSBT_IN_PARTIAL_SIG = 0x02;
static constexpr uint8_t PSBT_IN_SIGHASH = 0x03;
static constexpr uint8_t PSBT_IN_REDEEMSCRIPT = 0x04;
static constexpr uint8_t PSBT_IN_WITNESSSCRIPT = 0x05;
static constexpr uint8_t PSBT_IN_BIP32_DERIVATION = 0x06;
static constexpr uint8_t PSBT_IN_SCRIPTSIG = 0x07;
static constexpr uint8_t PSBT_IN_SCRIPTWITNESS = 0x08;
// Output types
static constexpr uint8_t PSBT_OUT_REDEEMSCRIPT = 0x00;
static constexpr uint8_t PSBT_OUT_WITNESSSCRIPT = 0x01;
static constexpr uint8_t PSBT_OUT_BIP32_DERIVATION = 0x02;
// The separator is 0x00. Reading this in means that the unserializer can interpret it
// as a 0 length key which indicates that this is the separator. The separator has no value.
static constexpr uint8_t PSBT_SEPARATOR = 0x00;
// Takes a stream and multiple arguments and serializes them as if first serialized into a vector and then into the stream
// The resulting output into the stream has the total serialized length of all of the objects followed by all objects concatenated with each other.
template<typename Stream, typename... X>
void SerializeToVector(Stream& s, const X&... args)
{
WriteCompactSize(s, GetSerializeSizeMany(s, args...));
SerializeMany(s, args...);
}
// Takes a stream and multiple arguments and unserializes them first as a vector then each object individually in the order provided in the arguments
template<typename Stream, typename... X>
void UnserializeFromVector(Stream& s, X&... args)
{
size_t expected_size = ReadCompactSize(s);
size_t remaining_before = s.size();
UnserializeMany(s, args...);
size_t remaining_after = s.size();
if (remaining_after + expected_size != remaining_before) {
throw std::ios_base::failure("Size of value was not the stated size");
}
}
// Deserialize HD keypaths into a map
template<typename Stream>
void DeserializeHDKeypaths(Stream& s, const std::vector<unsigned char>& key, std::map<CPubKey, std::vector<uint32_t>>& hd_keypaths)
{
// Make sure that the key is the size of pubkey + 1
if (key.size() != CPubKey::PUBLIC_KEY_SIZE + 1 && key.size() != CPubKey::COMPRESSED_PUBLIC_KEY_SIZE + 1) {
throw std::ios_base::failure("Size of key was not the expected size for the type BIP32 keypath");
}
// Read in the pubkey from key
CPubKey pubkey(key.begin() + 1, key.end());
if (!pubkey.IsFullyValid()) {
throw std::ios_base::failure("Invalid pubkey");
}
if (hd_keypaths.count(pubkey) > 0) {
throw std::ios_base::failure("Duplicate Key, pubkey derivation path already provided");
}
// Read in key path
uint64_t value_len = ReadCompactSize(s);
std::vector<uint32_t> keypath;
for (unsigned int i = 0; i < value_len; i += sizeof(uint32_t)) {
uint32_t index;
s >> index;
keypath.push_back(index);
}
// Add to map
hd_keypaths.emplace(pubkey, keypath);
}
// Serialize HD keypaths to a stream from a map
template<typename Stream>
void SerializeHDKeypaths(Stream& s, const std::map<CPubKey, std::vector<uint32_t>>& hd_keypaths, uint8_t type)
{
for (auto keypath_pair : hd_keypaths) {
SerializeToVector(s, type, MakeSpan(keypath_pair.first));
WriteCompactSize(s, keypath_pair.second.size() * sizeof(uint32_t));
for (auto& path : keypath_pair.second) {
s << path;
}
}
}
/** A structure for PSBTs which contain per-input information */
struct PSBTInput
{
CTransactionRef non_witness_utxo;
CTxOut witness_utxo;
CScript redeem_script;
CScript witness_script;
CScript final_script_sig;
CScriptWitness final_script_witness;
std::map<CPubKey, std::vector<uint32_t>> hd_keypaths;
std::map<CKeyID, SigPair> partial_sigs;
std::map<std::vector<unsigned char>, std::vector<unsigned char>> unknown;
int sighash_type = 0;
bool IsNull() const;
void FillSignatureData(SignatureData& sigdata) const;
void FromSignatureData(const SignatureData& sigdata);
void Merge(const PSBTInput& input);
bool IsSane() const;
PSBTInput() {}
template <typename Stream>
inline void Serialize(Stream& s) const {
// Write the utxo
// If there is a non-witness utxo, then don't add the witness one.
if (non_witness_utxo) {
SerializeToVector(s, PSBT_IN_NON_WITNESS_UTXO);
SerializeToVector(s, non_witness_utxo);
} else if (!witness_utxo.IsNull()) {
SerializeToVector(s, PSBT_IN_WITNESS_UTXO);
SerializeToVector(s, witness_utxo);
}
if (final_script_sig.empty() && final_script_witness.IsNull()) {
// Write any partial signatures
for (auto sig_pair : partial_sigs) {
SerializeToVector(s, PSBT_IN_PARTIAL_SIG, MakeSpan(sig_pair.second.first));
s << sig_pair.second.second;
}
// Write the sighash type
if (sighash_type > 0) {
SerializeToVector(s, PSBT_IN_SIGHASH);
SerializeToVector(s, sighash_type);
}
// Write the redeem script
if (!redeem_script.empty()) {
SerializeToVector(s, PSBT_IN_REDEEMSCRIPT);
s << redeem_script;
}
// Write the witness script
if (!witness_script.empty()) {
SerializeToVector(s, PSBT_IN_WITNESSSCRIPT);
s << witness_script;
}
// Write any hd keypaths
SerializeHDKeypaths(s, hd_keypaths, PSBT_IN_BIP32_DERIVATION);
}
// Write script sig
if (!final_script_sig.empty()) {
SerializeToVector(s, PSBT_IN_SCRIPTSIG);
s << final_script_sig;
}
// write script witness
if (!final_script_witness.IsNull()) {
SerializeToVector(s, PSBT_IN_SCRIPTWITNESS);
SerializeToVector(s, final_script_witness.stack);
}
// Write unknown things
for (auto& entry : unknown) {
s << entry.first;
s << entry.second;
}
s << PSBT_SEPARATOR;
}
template <typename Stream>
inline void Unserialize(Stream& s) {
// Read loop
while(!s.empty()) {
// Read
std::vector<unsigned char> key;
s >> key;
// the key is empty if that was actually a separator byte
// This is a special case for key lengths 0 as those are not allowed (except for separator)
if (key.empty()) return;
// First byte of key is the type
unsigned char type = key[0];
// Do stuff based on type
switch(type) {
case PSBT_IN_NON_WITNESS_UTXO:
if (non_witness_utxo) {
throw std::ios_base::failure("Duplicate Key, input non-witness utxo already provided");
} else if (key.size() != 1) {
throw std::ios_base::failure("Non-witness utxo key is more than one byte type");
}
UnserializeFromVector(s, non_witness_utxo);
break;
case PSBT_IN_WITNESS_UTXO:
if (!witness_utxo.IsNull()) {
throw std::ios_base::failure("Duplicate Key, input witness utxo already provided");
} else if (key.size() != 1) {
throw std::ios_base::failure("Witness utxo key is more than one byte type");
}
UnserializeFromVector(s, witness_utxo);
break;
case PSBT_IN_PARTIAL_SIG:
{
// Make sure that the key is the size of pubkey + 1
if (key.size() != CPubKey::PUBLIC_KEY_SIZE + 1 && key.size() != CPubKey::COMPRESSED_PUBLIC_KEY_SIZE + 1) {
throw std::ios_base::failure("Size of key was not the expected size for the type partial signature pubkey");
}
// Read in the pubkey from key
CPubKey pubkey(key.begin() + 1, key.end());
if (!pubkey.IsFullyValid()) {
throw std::ios_base::failure("Invalid pubkey");
}
if (partial_sigs.count(pubkey.GetID()) > 0) {
throw std::ios_base::failure("Duplicate Key, input partial signature for pubkey already provided");
}
// Read in the signature from value
std::vector<unsigned char> sig;
s >> sig;
// Add to list
partial_sigs.emplace(pubkey.GetID(), SigPair(pubkey, std::move(sig)));
break;
}
case PSBT_IN_SIGHASH:
if (sighash_type > 0) {
throw std::ios_base::failure("Duplicate Key, input sighash type already provided");
} else if (key.size() != 1) {
throw std::ios_base::failure("Sighash type key is more than one byte type");
}
UnserializeFromVector(s, sighash_type);
break;
case PSBT_IN_REDEEMSCRIPT:
{
if (!redeem_script.empty()) {
throw std::ios_base::failure("Duplicate Key, input redeemScript already provided");
} else if (key.size() != 1) {
throw std::ios_base::failure("Input redeemScript key is more than one byte type");
}
s >> redeem_script;
break;
}
case PSBT_IN_WITNESSSCRIPT:
{
if (!witness_script.empty()) {
throw std::ios_base::failure("Duplicate Key, input witnessScript already provided");
} else if (key.size() != 1) {
throw std::ios_base::failure("Input witnessScript key is more than one byte type");
}
s >> witness_script;
break;
}
case PSBT_IN_BIP32_DERIVATION:
{
DeserializeHDKeypaths(s, key, hd_keypaths);
break;
}
case PSBT_IN_SCRIPTSIG:
{
if (!final_script_sig.empty()) {
throw std::ios_base::failure("Duplicate Key, input final scriptSig already provided");
} else if (key.size() != 1) {
throw std::ios_base::failure("Final scriptSig key is more than one byte type");
}
s >> final_script_sig;
break;
}
case PSBT_IN_SCRIPTWITNESS:
{
if (!final_script_witness.IsNull()) {
throw std::ios_base::failure("Duplicate Key, input final scriptWitness already provided");
} else if (key.size() != 1) {
throw std::ios_base::failure("Final scriptWitness key is more than one byte type");
}
UnserializeFromVector(s, final_script_witness.stack);
break;
}
// Unknown stuff
default:
if (unknown.count(key) > 0) {
throw std::ios_base::failure("Duplicate Key, key for unknown value already provided");
}
// Read in the value
std::vector<unsigned char> val_bytes;
s >> val_bytes;
unknown.emplace(std::move(key), std::move(val_bytes));
break;
}
}
}
template <typename Stream>
PSBTInput(deserialize_type, Stream& s) {
Unserialize(s);
}
};
/** A structure for PSBTs which contains per output information */
struct PSBTOutput
{
CScript redeem_script;
CScript witness_script;
std::map<CPubKey, std::vector<uint32_t>> hd_keypaths;
std::map<std::vector<unsigned char>, std::vector<unsigned char>> unknown;
bool IsNull() const;
void FillSignatureData(SignatureData& sigdata) const;
void FromSignatureData(const SignatureData& sigdata);
void Merge(const PSBTOutput& output);
bool IsSane() const;
PSBTOutput() {}
template <typename Stream>
inline void Serialize(Stream& s) const {
// Write the redeem script
if (!redeem_script.empty()) {
SerializeToVector(s, PSBT_OUT_REDEEMSCRIPT);
s << redeem_script;
}
// Write the witness script
if (!witness_script.empty()) {
SerializeToVector(s, PSBT_OUT_WITNESSSCRIPT);
s << witness_script;
}
// Write any hd keypaths
SerializeHDKeypaths(s, hd_keypaths, PSBT_OUT_BIP32_DERIVATION);
// Write unknown things
for (auto& entry : unknown) {
s << entry.first;
s << entry.second;
}
s << PSBT_SEPARATOR;
}
template <typename Stream>
inline void Unserialize(Stream& s) {
// Read loop
while(!s.empty()) {
// Read
std::vector<unsigned char> key;
s >> key;
// the key is empty if that was actually a separator byte
// This is a special case for key lengths 0 as those are not allowed (except for separator)
if (key.empty()) return;
// First byte of key is the type
unsigned char type = key[0];
// Do stuff based on type
switch(type) {
case PSBT_OUT_REDEEMSCRIPT:
{
if (!redeem_script.empty()) {
throw std::ios_base::failure("Duplicate Key, output redeemScript already provided");
} else if (key.size() != 1) {
throw std::ios_base::failure("Output redeemScript key is more than one byte type");
}
s >> redeem_script;
break;
}
case PSBT_OUT_WITNESSSCRIPT:
{
if (!witness_script.empty()) {
throw std::ios_base::failure("Duplicate Key, output witnessScript already provided");
} else if (key.size() != 1) {
throw std::ios_base::failure("Output witnessScript key is more than one byte type");
}
s >> witness_script;
break;
}
case PSBT_OUT_BIP32_DERIVATION:
{
DeserializeHDKeypaths(s, key, hd_keypaths);
break;
}
// Unknown stuff
default: {
if (unknown.count(key) > 0) {
throw std::ios_base::failure("Duplicate Key, key for unknown value already provided");
}
// Read in the value
std::vector<unsigned char> val_bytes;
s >> val_bytes;
unknown.emplace(std::move(key), std::move(val_bytes));
break;
}
}
}
}
template <typename Stream>
PSBTOutput(deserialize_type, Stream& s) {
Unserialize(s);
}
};
/** A version of CTransaction with the PSBT format*/
struct PartiallySignedTransaction
{
boost::optional<CMutableTransaction> tx;
std::vector<PSBTInput> inputs;
std::vector<PSBTOutput> outputs;
std::map<std::vector<unsigned char>, std::vector<unsigned char>> unknown;
bool IsNull() const;
void Merge(const PartiallySignedTransaction& psbt);
bool IsSane() const;
PartiallySignedTransaction() {}
PartiallySignedTransaction(const PartiallySignedTransaction& psbt_in) : tx(psbt_in.tx), inputs(psbt_in.inputs), outputs(psbt_in.outputs), unknown(psbt_in.unknown) {}
// Only checks if they refer to the same transaction
friend bool operator==(const PartiallySignedTransaction& a, const PartiallySignedTransaction &b)
{
return a.tx->GetHash() == b.tx->GetHash();
}
friend bool operator!=(const PartiallySignedTransaction& a, const PartiallySignedTransaction &b)
{
return !(a == b);
}
template <typename Stream>
inline void Serialize(Stream& s) const {
// magic bytes
s << PSBT_MAGIC_BYTES;
// unsigned tx flag
SerializeToVector(s, PSBT_GLOBAL_UNSIGNED_TX);
// Write serialized tx to a stream
SerializeToVector(s, *tx);
// Write the unknown things
for (auto& entry : unknown) {
s << entry.first;
s << entry.second;
}
// Separator
s << PSBT_SEPARATOR;
// Write inputs
for (const PSBTInput& input : inputs) {
s << input;
}
// Write outputs
for (const PSBTOutput& output : outputs) {
s << output;
}
}
template <typename Stream>
inline void Unserialize(Stream& s) {
// Read the magic bytes
uint8_t magic[5];
s >> magic;
if (!std::equal(magic, magic + 5, PSBT_MAGIC_BYTES)) {
throw std::ios_base::failure("Invalid PSBT magic bytes");
}
// Read global data
while(!s.empty()) {
// Read
std::vector<unsigned char> key;
s >> key;
// the key is empty if that was actually a separator byte
// This is a special case for key lengths 0 as those are not allowed (except for separator)
if (key.empty()) break;
// First byte of key is the type
unsigned char type = key[0];
// Do stuff based on type
switch(type) {
case PSBT_GLOBAL_UNSIGNED_TX:
{
if (tx) {
throw std::ios_base::failure("Duplicate Key, unsigned tx already provided");
} else if (key.size() != 1) {
throw std::ios_base::failure("Global unsigned tx key is more than one byte type");
}
CMutableTransaction mtx;
UnserializeFromVector(s, mtx);
tx = std::move(mtx);
// Make sure that all scriptSigs and scriptWitnesses are empty
for (const CTxIn& txin : tx->vin) {
if (!txin.scriptSig.empty() || !txin.scriptWitness.IsNull()) {
throw std::ios_base::failure("Unsigned tx does not have empty scriptSigs and scriptWitnesses.");
}
}
break;
}
// Unknown stuff
default: {
if (unknown.count(key) > 0) {
throw std::ios_base::failure("Duplicate Key, key for unknown value already provided");
}
// Read in the value
std::vector<unsigned char> val_bytes;
s >> val_bytes;
unknown.emplace(std::move(key), std::move(val_bytes));
}
}
}
// Make sure that we got an unsigned tx
if (!tx) {
throw std::ios_base::failure("No unsigned transcation was provided");
}
// Read input data
unsigned int i = 0;
while (!s.empty() && i < tx->vin.size()) {
PSBTInput input;
s >> input;
inputs.push_back(input);
// Make sure the non-witness utxo matches the outpoint
if (input.non_witness_utxo && input.non_witness_utxo->GetHash() != tx->vin[i].prevout.hash) {
throw std::ios_base::failure("Non-witness UTXO does not match outpoint hash");
}
++i;
}
// Make sure that the number of inputs matches the number of inputs in the transaction
if (inputs.size() != tx->vin.size()) {
throw std::ios_base::failure("Inputs provided does not match the number of inputs in transaction.");
}
// Read output data
i = 0;
while (!s.empty() && i < tx->vout.size()) {
PSBTOutput output;
s >> output;
outputs.push_back(output);
++i;
}
// Make sure that the number of outputs matches the number of outputs in the transaction
if (outputs.size() != tx->vout.size()) {
throw std::ios_base::failure("Outputs provided does not match the number of outputs in transaction.");
}
// Sanity check
if (!IsSane()) {
throw std::ios_base::failure("PSBT is not sane.");
}
}
template <typename Stream>
PartiallySignedTransaction(deserialize_type, Stream& s) {
Unserialize(s);
}
};
/** Produce a script signature using a generic signature creator. */
bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreator& creator, const CScript& scriptPubKey, SignatureData& sigdata);
/** Produce a script signature for a transaction. */
bool SignSignature(const SigningProvider &provider, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, const CAmount& amount, int nHashType);
bool SignSignature(const SigningProvider &provider, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType);
/** Signs a PSBTInput */
bool SignPSBTInput(const SigningProvider& provider, const CMutableTransaction& tx, PSBTInput& input, SignatureData& sigdata, int index, int sighash = 1);
/** Extract signature data from a transaction input, and insert it. */
SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn, const CTxOut& txout);
void UpdateInput(CTxIn& input, const SignatureData& data);
/* Check whether we know how to sign for an output like this, assuming we
* have all private keys. While this function does not need private keys, the passed
* provider is used to look up public keys and redeemscripts by hash.
* Solvability is unrelated to whether we consider this output to be ours. */
bool IsSolvable(const SigningProvider& provider, const CScript& script);
#endif // BITCOIN_SCRIPT_SIGN_H