src/pubkey.h

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2016 The Bitcoin Core developers
   3 // Copyright (c) 2017 The Zcash developers
   4 // Distributed under the MIT software license, see the accompanying
   5 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   6
   7 #ifndef BITCOIN_PUBKEY_H
   8 #define BITCOIN_PUBKEY_H
   9
  10 #include <hash.h>
  11 #include <serialize.h>
  12 #include <uint256.h>
  13
  14 #include <stdexcept>
  15 #include <vector>
  16
  17 const unsigned int BIP32_EXTKEY_SIZE = 74;
  18
  19 /** A reference to a CKey: the Hash160 of its serialized public key */
  20 class CKeyID : public uint160
  21 {
  22 public:
  23     CKeyID() : uint160() {}
  24     explicit CKeyID(const uint160& in) : uint160(in) {}
  25 };
  26
  27 typedef uint256 ChainCode;
  28
  29 /** An encapsulated public key. */
  30 class CPubKey
  31 {
  32 public:
  33     /**
  34      * secp256k1:
  35      */
  36     static const unsigned int PUBLIC_KEY_SIZE             = 65;
  37     static const unsigned int COMPRESSED_PUBLIC_KEY_SIZE  = 33;
  38     static const unsigned int SIGNATURE_SIZE              = 72;
  39     static const unsigned int COMPACT_SIGNATURE_SIZE      = 65;
  40     /**
  41      * see www.keylength.com
  42      * script supports up to 75 for single byte push
  43      */
  44     static_assert(
  45         PUBLIC_KEY_SIZE >= COMPRESSED_PUBLIC_KEY_SIZE,
  46         "COMPRESSED_PUBLIC_KEY_SIZE is larger than PUBLIC_KEY_SIZE");
  47
  48 private:
  49
  50     /**
  51      * Just store the serialized data.
  52      * Its length can very cheaply be computed from the first byte.
  53      */
  54     unsigned char vch[PUBLIC_KEY_SIZE];
  55
  56     //! Compute the length of a pubkey with a given first byte.
  57     unsigned int static GetLen(unsigned char chHeader)
  58     {
  59         if (chHeader == 2 || chHeader == 3)
  60             return COMPRESSED_PUBLIC_KEY_SIZE;
  61         if (chHeader == 4 || chHeader == 6 || chHeader == 7)
  62             return PUBLIC_KEY_SIZE;
  63         return 0;
  64     }
  65
  66     //! Set this key data to be invalid
  67     void Invalidate()
  68     {
  69         vch[0] = 0xFF;
  70     }
  71
  72 public:
  73     //! Construct an invalid public key.
  74     CPubKey()
  75     {
  76         Invalidate();
  77     }
  78
  79     //! Initialize a public key using begin/end iterators to byte data.
  80     template <typename T>
  81     void Set(const T pbegin, const T pend)
  82     {
  83         int len = pend == pbegin ? 0 : GetLen(pbegin[0]);
  84         if (len && len == (pend - pbegin))
  85             memcpy(vch, (unsigned char*)&pbegin[0], len);
  86         else
  87             Invalidate();
  88     }
  89
  90     //! Construct a public key using begin/end iterators to byte data.
  91     template <typename T>
  92     CPubKey(const T pbegin, const T pend)
  93     {
  94         Set(pbegin, pend);
  95     }
  96
  97     //! Construct a public key from a byte vector.
  98     explicit CPubKey(const std::vector<unsigned char>& _vch)
  99     {
 100         Set(_vch.begin(), _vch.end());
 101     }
 102
 103     //! Simple read-only vector-like interface to the pubkey data.
 104     unsigned int size() const { return GetLen(vch[0]); }
 105     const unsigned char* begin() const { return vch; }
 106     const unsigned char* end() const { return vch + size(); }
 107     const unsigned char& operator[](unsigned int pos) const { return vch[pos]; }
 108
 109     //! Comparator implementation.
 110     friend bool operator==(const CPubKey& a, const CPubKey& b)
 111     {
 112         return a.vch[0] == b.vch[0] &&
 113                memcmp(a.vch, b.vch, a.size()) == 0;
 114     }
 115     friend bool operator!=(const CPubKey& a, const CPubKey& b)
 116     {
 117         return !(a == b);
 118     }
 119     friend bool operator<(const CPubKey& a, const CPubKey& b)
 120     {
 121         return a.vch[0] < b.vch[0] ||
 122                (a.vch[0] == b.vch[0] && memcmp(a.vch, b.vch, a.size()) < 0);
 123     }
 124
 125     //! Implement serialization, as if this was a byte vector.
 126     template <typename Stream>
 127     void Serialize(Stream& s) const
 128     {
 129         unsigned int len = size();
 130         ::WriteCompactSize(s, len);
 131         s.write((char*)vch, len);
 132     }
 133     template <typename Stream>
 134     void Unserialize(Stream& s)
 135     {
 136         unsigned int len = ::ReadCompactSize(s);
 137         if (len <= PUBLIC_KEY_SIZE) {
 138             s.read((char*)vch, len);
 139         } else {
 140             // invalid pubkey, skip available data
 141             char dummy;
 142             while (len--)
 143                 s.read(&dummy, 1);
 144             Invalidate();
 145         }
 146     }
 147
 148     //! Get the KeyID of this public key (hash of its serialization)
 149     CKeyID GetID() const
 150     {
 151         return CKeyID(Hash160(vch, vch + size()));
 152     }
 153
 154     //! Get the 256-bit hash of this public key.
 155     uint256 GetHash() const
 156     {
 157         return Hash(vch, vch + size());
 158     }
 159
 160     /*
 161      * Check syntactic correctness.
 162      *
 163      * Note that this is consensus critical as CheckSig() calls it!
 164      */
 165     bool IsValid() const
 166     {
 167         return size() > 0;
 168     }
 169
 170     //! fully validate whether this is a valid public key (more expensive than IsValid())
 171     bool IsFullyValid() const;
 172
 173     //! Check whether this is a compressed public key.
 174     bool IsCompressed() const
 175     {
 176         return size() == COMPRESSED_PUBLIC_KEY_SIZE;
 177     }
 178
 179     /**
 180      * Verify a DER signature (~72 bytes).
 181      * If this public key is not fully valid, the return value will be false.
 182      */
 183     bool Verify(const uint256& hash, const std::vector<unsigned char>& vchSig) const;
 184
 185     /**
 186      * Check whether a signature is normalized (lower-S).
 187      */
 188     static bool CheckLowS(const std::vector<unsigned char>& vchSig);
 189
 190     //! Recover a public key from a compact signature.
 191     bool RecoverCompact(const uint256& hash, const std::vector<unsigned char>& vchSig);
 192
 193     //! Turn this public key into an uncompressed public key.
 194     bool Decompress();
 195
 196     //! Derive BIP32 child pubkey.
 197     bool Derive(CPubKey& pubkeyChild, ChainCode &ccChild, unsigned int nChild, const ChainCode& cc) const;
 198 };
 199
 200 struct CExtPubKey {
 201     unsigned char nDepth;
 202     unsigned char vchFingerprint[4];
 203     unsigned int nChild;
 204     ChainCode chaincode;
 205     CPubKey pubkey;
 206
 207     friend bool operator==(const CExtPubKey &a, const CExtPubKey &b)
 208     {
 209         return a.nDepth == b.nDepth &&
 210             memcmp(&a.vchFingerprint[0], &b.vchFingerprint[0], sizeof(vchFingerprint)) == 0 &&
 211             a.nChild == b.nChild &&
 212             a.chaincode == b.chaincode &&
 213             a.pubkey == b.pubkey;
 214     }
 215
 216     void Encode(unsigned char code[BIP32_EXTKEY_SIZE]) const;
 217     void Decode(const unsigned char code[BIP32_EXTKEY_SIZE]);
 218     bool Derive(CExtPubKey& out, unsigned int nChild) const;
 219
 220     void Serialize(CSizeComputer& s) const
 221     {
 222         // Optimized implementation for ::GetSerializeSize that avoids copying.
 223         s.seek(BIP32_EXTKEY_SIZE + 1); // add one byte for the size (compact int)
 224     }
 225     template <typename Stream>
 226     void Serialize(Stream& s) const
 227     {
 228         unsigned int len = BIP32_EXTKEY_SIZE;
 229         ::WriteCompactSize(s, len);
 230         unsigned char code[BIP32_EXTKEY_SIZE];
 231         Encode(code);
 232         s.write((const char *)&code[0], len);
 233     }
 234     template <typename Stream>
 235     void Unserialize(Stream& s)
 236     {
 237         unsigned int len = ::ReadCompactSize(s);
 238         unsigned char code[BIP32_EXTKEY_SIZE];
 239         if (len != BIP32_EXTKEY_SIZE)
 240             throw std::runtime_error("Invalid extended key size\n");
 241         s.read((char *)&code[0], len);
 242         Decode(code);
 243     }
 244 };
 245
 246 /** Users of this module must hold an ECCVerifyHandle. The constructor and
 247  *  destructor of these are not allowed to run in parallel, though. */
 248 class ECCVerifyHandle
 249 {
 250     static int refcount;
 251
 252 public:
 253     ECCVerifyHandle();
 254     ~ECCVerifyHandle();
 255 };
 256
 257 #endif // BITCOIN_PUBKEY_H