src/pubkey.h

   1 // Copyright (c) 2009-2010 Satoshi Nakamoto
   2 // Copyright (c) 2009-2014 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 /** A reference to a CKey: the Hash160 of its serialized public key */
  27 class CKeyID : public uint160
  28 {
  29 public:
  30     CKeyID() : uint160() {}
  31     CKeyID(const uint160& in) : uint160(in) {}
  32 };
  33
  34 typedef uint256 ChainCode;
  35
  36 /** An encapsulated public key. */
  37 class CPubKey
  38 {
  39 private:
  40
  41     /**
  42      * Just store the serialized data.
  43      * Its length can very cheaply be computed from the first byte.
  44      */
  45     unsigned char vch[65];
  46
  47     //! Compute the length of a pubkey with a given first byte.
  48     unsigned int static GetLen(unsigned char chHeader)
  49     {
  50         if (chHeader == 2 || chHeader == 3)
  51             return 33;
  52         if (chHeader == 4 || chHeader == 6 || chHeader == 7)
  53             return 65;
  54         return 0;
  55     }
  56
  57     //! Set this key data to be invalid
  58     void Invalidate()
  59     {
  60         vch[0] = 0xFF;
  61     }
  62
  63 public:
  64     //! Construct an invalid public key.
  65     CPubKey()
  66     {
  67         Invalidate();
  68     }
  69
  70     //! Initialize a public key using begin/end iterators to byte data.
  71     template <typename T>
  72     void Set(const T pbegin, const T pend)
  73     {
  74         int len = pend == pbegin ? 0 : GetLen(pbegin[0]);
  75         if (len && len == (pend - pbegin))
  76             memcpy(vch, (unsigned char*)&pbegin[0], len);
  77         else
  78             Invalidate();
  79     }
  80
  81     //! Construct a public key using begin/end iterators to byte data.
  82     template <typename T>
  83     CPubKey(const T pbegin, const T pend)
  84     {
  85         Set(pbegin, pend);
  86     }
  87
  88     //! Construct a public key from a byte vector.
  89     CPubKey(const std::vector<unsigned char>& vch)
  90     {
  91         Set(vch.begin(), vch.end());
  92     }
  93
  94     //! Simple read-only vector-like interface to the pubkey data.
  95     unsigned int size() const { return GetLen(vch[0]); }
  96     const unsigned char* begin() const { return vch; }
  97     const unsigned char* end() const { return vch + size(); }
  98     const unsigned char& operator[](unsigned int pos) const { return vch[pos]; }
  99
 100     //! Comparator implementation.
 101     friend bool operator==(const CPubKey& a, const CPubKey& b)
 102     {
 103         return a.vch[0] == b.vch[0] &&
 104                memcmp(a.vch, b.vch, a.size()) == 0;
 105     }
 106     friend bool operator!=(const CPubKey& a, const CPubKey& b)
 107     {
 108         return !(a == b);
 109     }
 110     friend bool operator<(const CPubKey& a, const CPubKey& b)
 111     {
 112         return a.vch[0] < b.vch[0] ||
 113                (a.vch[0] == b.vch[0] && memcmp(a.vch, b.vch, a.size()) < 0);
 114     }
 115
 116     //! Implement serialization, as if this was a byte vector.
 117     unsigned int GetSerializeSize(int nType, int nVersion) const
 118     {
 119         return size() + 1;
 120     }
 121     template <typename Stream>
 122     void Serialize(Stream& s, int nType, int nVersion) const
 123     {
 124         unsigned int len = size();
 125         ::WriteCompactSize(s, len);
 126         s.write((char*)vch, len);
 127     }
 128     template <typename Stream>
 129     void Unserialize(Stream& s, int nType, int nVersion)
 130     {
 131         unsigned int len = ::ReadCompactSize(s);
 132         if (len <= 65) {
 133             s.read((char*)vch, len);
 134         } else {
 135             // invalid pubkey, skip available data
 136             char dummy;
 137             while (len--)
 138                 s.read(&dummy, 1);
 139             Invalidate();
 140         }
 141     }
 142
 143     //! Get the KeyID of this public key (hash of its serialization)
 144     CKeyID GetID() const
 145     {
 146         return CKeyID(Hash160(vch, vch + size()));
 147     }
 148
 149     //! Get the 256-bit hash of this public key.
 150     uint256 GetHash() const
 151     {
 152         return Hash(vch, vch + size());
 153     }
 154
 155     /*
 156      * Check syntactic correctness.
 157      *
 158      * Note that this is consensus critical as CheckSig() calls it!
 159      */
 160     bool IsValid() const
 161     {
 162         return size() > 0;
 163     }
 164
 165     //! fully validate whether this is a valid public key (more expensive than IsValid())
 166     bool IsFullyValid() const;
 167
 168     //! Check whether this is a compressed public key.
 169     bool IsCompressed() const
 170     {
 171         return size() == 33;
 172     }
 173
 174     /**
 175      * Verify a DER signature (~72 bytes).
 176      * If this public key is not fully valid, the return value will be false.
 177      */
 178     bool Verify(const uint256& hash, const std::vector<unsigned char>& vchSig) const;
 179
 180     //! Recover a public key from a compact signature.
 181     bool RecoverCompact(const uint256& hash, const std::vector<unsigned char>& vchSig);
 182
 183     //! Turn this public key into an uncompressed public key.
 184     bool Decompress();
 185
 186     //! Derive BIP32 child pubkey.
 187     bool Derive(CPubKey& pubkeyChild, ChainCode &ccChild, unsigned int nChild, const ChainCode& cc) const;
 188 };
 189
 190 struct CExtPubKey {
 191     unsigned char nDepth;
 192     unsigned char vchFingerprint[4];
 193     unsigned int nChild;
 194     ChainCode chaincode;
 195     CPubKey pubkey;
 196
 197     friend bool operator==(const CExtPubKey &a, const CExtPubKey &b)
 198     {
 199         return a.nDepth == b.nDepth && memcmp(&a.vchFingerprint[0], &b.vchFingerprint[0], 4) == 0 && a.nChild == b.nChild &&
 200                a.chaincode == b.chaincode && a.pubkey == b.pubkey;
 201     }
 202
 203     void Encode(unsigned char code[74]) const;
 204     void Decode(const unsigned char code[74]);
 205     bool Derive(CExtPubKey& out, unsigned int nChild) const;
 206 };
 207
 208 #endif // BITCOIN_PUBKEY_H