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6ef405ddb1
Instead of storing the key material as an std::vector (with secure allocator), use a secure_unique_ptr to a 32-byte array, and use nullptr for invalid keys. This means a smaller CKey type, and no secure/dynamic memory usage for invalid keys.
240 lines
8.5 KiB
C++
240 lines
8.5 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2022 The Bitcoin Core developers
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// Copyright (c) 2017 The Zcash developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_KEY_H
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#define BITCOIN_KEY_H
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#include <pubkey.h>
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#include <serialize.h>
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#include <support/allocators/secure.h>
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#include <uint256.h>
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#include <stdexcept>
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#include <vector>
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/**
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* CPrivKey is a serialized private key, with all parameters included
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* (SIZE bytes)
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*/
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typedef std::vector<unsigned char, secure_allocator<unsigned char> > CPrivKey;
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/** Size of ECDH shared secrets. */
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constexpr static size_t ECDH_SECRET_SIZE = CSHA256::OUTPUT_SIZE;
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// Used to represent ECDH shared secret (ECDH_SECRET_SIZE bytes)
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using ECDHSecret = std::array<std::byte, ECDH_SECRET_SIZE>;
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/** An encapsulated private key. */
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class CKey
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{
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public:
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/**
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* secp256k1:
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*/
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static const unsigned int SIZE = 279;
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static const unsigned int COMPRESSED_SIZE = 214;
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/**
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* see www.keylength.com
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* script supports up to 75 for single byte push
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*/
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static_assert(
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SIZE >= COMPRESSED_SIZE,
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"COMPRESSED_SIZE is larger than SIZE");
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private:
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/** Internal data container for private key material. */
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using KeyType = std::array<unsigned char, 32>;
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//! Whether the public key corresponding to this private key is (to be) compressed.
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bool fCompressed{false};
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//! The actual byte data. nullptr for invalid keys.
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secure_unique_ptr<KeyType> keydata;
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//! Check whether the 32-byte array pointed to by vch is valid keydata.
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bool static Check(const unsigned char* vch);
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void MakeKeyData()
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{
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if (!keydata) keydata = make_secure_unique<KeyType>();
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}
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void ClearKeyData()
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{
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keydata.reset();
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}
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public:
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CKey() noexcept = default;
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CKey(CKey&&) noexcept = default;
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CKey& operator=(CKey&&) noexcept = default;
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CKey& operator=(const CKey& other)
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{
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if (other.keydata) {
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MakeKeyData();
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*keydata = *other.keydata;
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} else {
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ClearKeyData();
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}
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fCompressed = other.fCompressed;
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return *this;
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}
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CKey(const CKey& other) { *this = other; }
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friend bool operator==(const CKey& a, const CKey& b)
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{
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return a.fCompressed == b.fCompressed &&
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a.size() == b.size() &&
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memcmp(a.data(), b.data(), a.size()) == 0;
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}
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//! Initialize using begin and end iterators to byte data.
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template <typename T>
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void Set(const T pbegin, const T pend, bool fCompressedIn)
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{
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if (size_t(pend - pbegin) != std::tuple_size_v<KeyType>) {
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ClearKeyData();
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} else if (Check(&pbegin[0])) {
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MakeKeyData();
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memcpy(keydata->data(), (unsigned char*)&pbegin[0], keydata->size());
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fCompressed = fCompressedIn;
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} else {
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ClearKeyData();
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}
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}
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//! Simple read-only vector-like interface.
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unsigned int size() const { return keydata ? keydata->size() : 0; }
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const std::byte* data() const { return keydata ? reinterpret_cast<const std::byte*>(keydata->data()) : nullptr; }
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const unsigned char* begin() const { return keydata ? keydata->data() : nullptr; }
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const unsigned char* end() const { return begin() + size(); }
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//! Check whether this private key is valid.
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bool IsValid() const { return !!keydata; }
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//! Check whether the public key corresponding to this private key is (to be) compressed.
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bool IsCompressed() const { return fCompressed; }
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//! Generate a new private key using a cryptographic PRNG.
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void MakeNewKey(bool fCompressed);
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//! Negate private key
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bool Negate();
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/**
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* Convert the private key to a CPrivKey (serialized OpenSSL private key data).
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* This is expensive.
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*/
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CPrivKey GetPrivKey() const;
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/**
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* Compute the public key from a private key.
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* This is expensive.
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*/
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CPubKey GetPubKey() const;
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/**
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* Create a DER-serialized signature.
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* The test_case parameter tweaks the deterministic nonce.
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*/
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bool Sign(const uint256& hash, std::vector<unsigned char>& vchSig, bool grind = true, uint32_t test_case = 0) const;
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/**
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* Create a compact signature (65 bytes), which allows reconstructing the used public key.
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* The format is one header byte, followed by two times 32 bytes for the serialized r and s values.
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* The header byte: 0x1B = first key with even y, 0x1C = first key with odd y,
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* 0x1D = second key with even y, 0x1E = second key with odd y,
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* add 0x04 for compressed keys.
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*/
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bool SignCompact(const uint256& hash, std::vector<unsigned char>& vchSig) const;
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/**
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* Create a BIP-340 Schnorr signature, for the xonly-pubkey corresponding to *this,
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* optionally tweaked by *merkle_root. Additional nonce entropy is provided through
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* aux.
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*
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* merkle_root is used to optionally perform tweaking of the private key, as specified
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* in BIP341:
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* - If merkle_root == nullptr: no tweaking is done, sign with key directly (this is
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* used for signatures in BIP342 script).
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* - If merkle_root->IsNull(): sign with key + H_TapTweak(pubkey) (this is used for
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* key path spending when no scripts are present).
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* - Otherwise: sign with key + H_TapTweak(pubkey || *merkle_root)
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* (this is used for key path spending, with specific
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* Merkle root of the script tree).
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*/
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bool SignSchnorr(const uint256& hash, Span<unsigned char> sig, const uint256* merkle_root, const uint256& aux) const;
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//! Derive BIP32 child key.
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[[nodiscard]] bool Derive(CKey& keyChild, ChainCode &ccChild, unsigned int nChild, const ChainCode& cc) const;
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/**
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* Verify thoroughly whether a private key and a public key match.
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* This is done using a different mechanism than just regenerating it.
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*/
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bool VerifyPubKey(const CPubKey& vchPubKey) const;
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//! Load private key and check that public key matches.
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bool Load(const CPrivKey& privkey, const CPubKey& vchPubKey, bool fSkipCheck);
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/** Create an ellswift-encoded public key for this key, with specified entropy.
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*
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* entropy must be a 32-byte span with additional entropy to use in the encoding. Every
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* public key has ~2^256 different encodings, and this function will deterministically pick
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* one of them, based on entropy. Note that even without truly random entropy, the
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* resulting encoding will be indistinguishable from uniform to any adversary who does not
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* know the private key (because the private key itself is always used as entropy as well).
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*/
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EllSwiftPubKey EllSwiftCreate(Span<const std::byte> entropy) const;
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/** Compute a BIP324-style ECDH shared secret.
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*
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* - their_ellswift: EllSwiftPubKey that was received from the other side.
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* - our_ellswift: EllSwiftPubKey that was sent to the other side (must have been generated
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* from *this using EllSwiftCreate()).
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* - initiating: whether we are the initiating party (true) or responding party (false).
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*/
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ECDHSecret ComputeBIP324ECDHSecret(const EllSwiftPubKey& their_ellswift,
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const EllSwiftPubKey& our_ellswift,
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bool initiating) const;
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};
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struct CExtKey {
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unsigned char nDepth;
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unsigned char vchFingerprint[4];
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unsigned int nChild;
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ChainCode chaincode;
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CKey key;
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friend bool operator==(const CExtKey& a, const CExtKey& b)
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{
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return a.nDepth == b.nDepth &&
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memcmp(a.vchFingerprint, b.vchFingerprint, sizeof(vchFingerprint)) == 0 &&
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a.nChild == b.nChild &&
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a.chaincode == b.chaincode &&
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a.key == b.key;
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}
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void Encode(unsigned char code[BIP32_EXTKEY_SIZE]) const;
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void Decode(const unsigned char code[BIP32_EXTKEY_SIZE]);
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[[nodiscard]] bool Derive(CExtKey& out, unsigned int nChild) const;
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CExtPubKey Neuter() const;
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void SetSeed(Span<const std::byte> seed);
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};
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/** Initialize the elliptic curve support. May not be called twice without calling ECC_Stop first. */
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void ECC_Start();
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/** Deinitialize the elliptic curve support. No-op if ECC_Start wasn't called first. */
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void ECC_Stop();
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/** Check that required EC support is available at runtime. */
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bool ECC_InitSanityCheck();
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#endif // BITCOIN_KEY_H
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