elements/src/script/sign.h

// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2020 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 <coins.h>
#include <hash.h>
#include <pubkey.h>
#include <script/interpreter.h>
#include <script/keyorigin.h>
#include <span.h>
#include <streams.h>

class CKey;
class CKeyID;
class CScript;
class CScriptID;
class CTransaction;
class SigningProvider;

struct CMutableTransaction;

/** 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, unsigned int flags) const =0;
};

/** A signature creator for transactions. */
class MutableTransactionSignatureCreator : public BaseSignatureCreator {
    const CMutableTransaction* txTo;
    unsigned int nIn;
    int nHashType;
    CConfidentialValue amount;
    const MutableTransactionSignatureChecker checker;

public:
    MutableTransactionSignatureCreator(const CMutableTransaction* txToIn, unsigned int nInIn, const CConfidentialValue& 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, unsigned int flags) 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, std::pair<CPubKey, KeyOriginInfo>> misc_pubkeys;
    std::vector<CKeyID> missing_pubkeys; ///< KeyIDs of pubkeys which could not be found
    std::vector<CKeyID> missing_sigs; ///< KeyIDs of pubkeys for signatures which could not be found
    uint160 missing_redeem_script; ///< ScriptID of the missing redeemScript (if any)
    uint256 missing_witness_script; ///< SHA256 of the missing witnessScript (if any)

    SignatureData() {}
    explicit SignatureData(const CScript& script) : scriptSig(script) {}
    void MergeSignatureData(SignatureData sigdata);
};

// 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.GetVersion(), 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, KeyOriginInfo>& hd_keypaths)
{
    // Make sure that the key is the size of pubkey + 1
    if (key.size() != CPubKey::SIZE + 1 && key.size() != CPubKey::COMPRESSED_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);
    if (value_len % 4 || value_len == 0) {
        throw std::ios_base::failure("Invalid length for HD key path");
    }

    KeyOriginInfo keypath;
    s >> keypath.fingerprint;
    for (unsigned int i = 4; i < value_len; i += sizeof(uint32_t)) {
        uint32_t index;
        s >> index;
        keypath.path.push_back(index);
    }

    // Add to map
    hd_keypaths.emplace(pubkey, std::move(keypath));
}

// Serialize HD keypaths to a stream from a map
template<typename Stream>
void SerializeHDKeypaths(Stream& s, const std::map<CPubKey, KeyOriginInfo>& hd_keypaths, uint8_t type)
{
    for (auto keypath_pair : hd_keypaths) {
        if (!keypath_pair.first.IsValid()) {
            throw std::ios_base::failure("Invalid CPubKey being serialized");
        }
        SerializeToVector(s, type, MakeSpan(keypath_pair.first));
        WriteCompactSize(s, (keypath_pair.second.path.size() + 1) * sizeof(uint32_t));
        s << keypath_pair.second.fingerprint;
        for (const auto& path : keypath_pair.second.path) {
            s << path;
        }
    }
}

/** Produce a script signature using a generic signature creator. */
bool ProduceSignature(const SigningProvider& provider, const BaseSignatureCreator& creator, const CScript& scriptPubKey, SignatureData& sigdata, unsigned int additional_flags=0);

/** Produce a script signature for a transaction. */
bool SignSignature(const SigningProvider &provider, const CScript& fromPubKey, CMutableTransaction& txTo, unsigned int nIn, const CConfidentialValue& amount, int nHashType);
bool SignSignature(const SigningProvider &provider, const CTransaction& txFrom, CMutableTransaction& txTo, unsigned int nIn, int nHashType);

/** Extract signature data from a transaction input, and insert it. */
SignatureData DataFromTransaction(const CMutableTransaction& tx, unsigned int nIn, const CTxOut& txout);
void UpdateTransaction(CMutableTransaction& input, const size_t nIn, 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);

/** Check whether a scriptPubKey is known to be segwit. */
bool IsSegWitOutput(const SigningProvider& provider, const CScript& script);

/** Sign the CMutableTransaction */
bool SignTransaction(CMutableTransaction& mtx, const SigningProvider* provider, const std::map<COutPoint, Coin>& coins, int sighash, std::map<int, std::string>& input_errors);

#endif // BITCOIN_SCRIPT_SIGN_H