src/pubkey.h

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2016 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_PUBKEY_H
   7 #define BITCOIN_PUBKEY_H
   8
   9 #include "hash.h"
  10 #include "serialize.h"
  11 #include "uint256.h"
  12
  13 #include <stdexcept>
  14 #include <vector>
  15
  16 /**
  17  * secp256k1:
  18  * const unsigned int PRIVATE_KEY_SIZE = 279;
  19  * const unsigned int PUBLIC_KEY_SIZE  = 65;
  20  * const unsigned int SIGNATURE_SIZE   = 72;
  21  *
  22  * see www.keylength.com
  23  * script supports up to 75 for single byte push
  24  */
  25
  26 const unsigned int BIP32_EXTKEY_SIZE = 74;
  27
  28 /** A reference to a CKey: the Hash160 of its serialized public key */
  29 class CKeyID : public uint160
  30 {
  31 public:
  32     CKeyID() : uint160() {}
  33     explicit CKeyID(const uint160& in) : uint160(in) {}
  34 };
  35
  36 typedef uint256 ChainCode;
  37
  38 /** An encapsulated public key. */
  39 class CPubKey
  40 {
  41 private:
  42
  43     /**
  44      * Just store the serialized data.
  45      * Its length can very cheaply be computed from the first byte.
  46      */
  47     unsigned char vch[65];
  48
  49     //! Compute the length of a pubkey with a given first byte.
  50     unsigned int static GetLen(unsigned char chHeader)
  51     {
  52         if (chHeader == 2 || chHeader == 3)
  53             return 33;
  54         if (chHeader == 4 || chHeader == 6 || chHeader == 7)
  55             return 65;
  56         return 0;
  57     }
  58
  59     //! Set this key data to be invalid
  60     void Invalidate()
  61     {
  62         vch[0] = 0xFF;
  63     }
  64
  65 public:
  66     //! Construct an invalid public key.
  67     CPubKey()
  68     {
  69         Invalidate();
  70     }
  71
  72     //! Initialize a public key using begin/end iterators to byte data.
  73     template <typename T>
  74     void Set(const T pbegin, const T pend)
  75     {
  76         int len = pend == pbegin ? 0 : GetLen(pbegin[0]);
  77         if (len && len == (pend - pbegin))
  78             memcpy(vch, (unsigned char*)&pbegin[0], len);
  79         else
  80             Invalidate();
  81     }
  82
  83     //! Construct a public key using begin/end iterators to byte data.
  84     template <typename T>
  85     CPubKey(const T pbegin, const T pend)
  86     {
  87         Set(pbegin, pend);
  88     }
  89
  90     //! Construct a public key from a byte vector.
  91     explicit CPubKey(const std::vector<unsigned char>& _vch)
  92     {
  93         Set(_vch.begin(), _vch.end());
  94     }
  95
  96     //! Simple read-only vector-like interface to the pubkey data.
  97     unsigned int size() const { return GetLen(vch[0]); }
  98     const unsigned char* begin() const { return vch; }
  99     const unsigned char* end() const { return vch + size(); }
 100     const unsigned char& operator[](unsigned int pos) const { return vch[pos]; }
 101
 102     //! Comparator implementation.
 103     friend bool operator==(const CPubKey& a, const CPubKey& b)
 104     {
 105         return a.vch[0] == b.vch[0] &&
 106                memcmp(a.vch, b.vch, a.size()) == 0;
 107     }
 108     friend bool operator!=(const CPubKey& a, const CPubKey& b)
 109     {
 110         return !(a == b);
 111     }
 112     friend bool operator<(const CPubKey& a, const CPubKey& b)
 113     {
 114         return a.vch[0] < b.vch[0] ||
 115                (a.vch[0] == b.vch[0] && memcmp(a.vch, b.vch, a.size()) < 0);
 116     }
 117
 118     //! Implement serialization, as if this was a byte vector.
 119     template <typename Stream>
 120     void Serialize(Stream& s) const
 121     {
 122         unsigned int len = size();
 123         ::WriteCompactSize(s, len);
 124         s.write((char*)vch, len);
 125     }
 126     template <typename Stream>
 127     void Unserialize(Stream& s)
 128     {
 129         unsigned int len = ::ReadCompactSize(s);
 130         if (len <= 65) {
 131             s.read((char*)vch, len);
 132         } else {
 133             // invalid pubkey, skip available data
 134             char dummy;
 135             while (len--)
 136                 s.read(&dummy, 1);
 137             Invalidate();
 138         }
 139     }
 140
 141     //! Get the KeyID of this public key (hash of its serialization)
 142     CKeyID GetID() const
 143     {
 144         return CKeyID(Hash160(vch, vch + size()));
 145     }
 146
 147     //! Get the 256-bit hash of this public key.
 148     uint256 GetHash() const
 149     {
 150         return Hash(vch, vch + size());
 151     }
 152
 153     /*
 154      * Check syntactic correctness.
 155      *
 156      * Note that this is consensus critical as CheckSig() calls it!
 157      */
 158     bool IsValid() const
 159     {
 160         return size() > 0;
 161     }
 162
 163     //! fully validate whether this is a valid public key (more expensive than IsValid())
 164     bool IsFullyValid() const;
 165
 166     //! Check whether this is a compressed public key.
 167     bool IsCompressed() const
 168     {
 169         return size() == 33;
 170     }
 171
 172     /**
 173      * Verify a DER signature (~72 bytes).
 174      * If this public key is not fully valid, the return value will be false.
 175      */
 176     bool Verify(const uint256& hash, const std::vector<unsigned char>& vchSig) const;
 177
 178     /**
 179      * Check whether a signature is normalized (lower-S).
 180      */
 181     static bool CheckLowS(const std::vector<unsigned char>& vchSig);
 182
 183     //! Recover a public key from a compact signature.
 184     bool RecoverCompact(const uint256& hash, const std::vector<unsigned char>& vchSig);
 185
 186     //! Turn this public key into an uncompressed public key.
 187     bool Decompress();
 188
 189     //! Derive BIP32 child pubkey.
 190     bool Derive(CPubKey& pubkeyChild, ChainCode &ccChild, unsigned int nChild, const ChainCode& cc) const;
 191 };
 192
 193 struct CExtPubKey {
 194     unsigned char nDepth;
 195     unsigned char vchFingerprint[4];
 196     unsigned int nChild;
 197     ChainCode chaincode;
 198     CPubKey pubkey;
 199
 200     friend bool operator==(const CExtPubKey &a, const CExtPubKey &b)
 201     {
 202         return a.nDepth == b.nDepth &&
 203             memcmp(&a.vchFingerprint[0], &b.vchFingerprint[0], sizeof(vchFingerprint)) == 0 &&
 204             a.nChild == b.nChild &&
 205             a.chaincode == b.chaincode &&
 206             a.pubkey == b.pubkey;
 207     }
 208
 209     void Encode(unsigned char code[BIP32_EXTKEY_SIZE]) const;
 210     void Decode(const unsigned char code[BIP32_EXTKEY_SIZE]);
 211     bool Derive(CExtPubKey& out, unsigned int nChild) const;
 212
 213     void Serialize(CSizeComputer& s) const
 214     {
 215         // Optimized implementation for ::GetSerializeSize that avoids copying.
 216         s.seek(BIP32_EXTKEY_SIZE + 1); // add one byte for the size (compact int)
 217     }
 218     template <typename Stream>
 219     void Serialize(Stream& s) const
 220     {
 221         unsigned int len = BIP32_EXTKEY_SIZE;
 222         ::WriteCompactSize(s, len);
 223         unsigned char code[BIP32_EXTKEY_SIZE];
 224         Encode(code);
 225         s.write((const char *)&code[0], len);
 226     }
 227     template <typename Stream>
 228     void Unserialize(Stream& s)
 229     {
 230         unsigned int len = ::ReadCompactSize(s);
 231         unsigned char code[BIP32_EXTKEY_SIZE];
 232         if (len != BIP32_EXTKEY_SIZE)
 233             throw std::runtime_error("Invalid extended key size\n");
 234         s.read((char *)&code[0], len);
 235         Decode(code);
 236     }
 237 };
 238
 239 /** Users of this module must hold an ECCVerifyHandle. The constructor and
 240  *  destructor of these are not allowed to run in parallel, though. */
 241 class ECCVerifyHandle
 242 {
 243     static int refcount;
 244
 245 public:
 246     ECCVerifyHandle();
 247     ~ECCVerifyHandle();
 248 };
 249
 250 #endif // BITCOIN_PUBKEY_H