text: // Copyright (c) 2009-2010 Satoshi Nakamoto
  // Copyright (c) 2009-2013 The Bitcoin developers
  // Distributed under the MIT/X11 software license, see the accompanying
  // file COPYING or http://www.opensource.org/licenses/mit-license.php.
  #ifndef BITCOIN_KEY_H
  #define BITCOIN_KEY_H
  
  #include <stdexcept>
  #include <vector>
  
  #include "allocators.h"
  #include "serialize.h"
  #include "uint256.h"
  #include "hash.h"
  #include "util.h"
  
  #include <openssl/ec.h> // for EC_KEY definition
  
  // secp256k1:
  // const unsigned int PRIVATE_KEY_SIZE = 279;
  // const unsigned int PUBLIC_KEY_SIZE  = 65;
  // const unsigned int SIGNATURE_SIZE   = 72;
  //
  // see www.keylength.com
  // script supports up to 75 for single byte push
  
  /** A reference to a CKey: the Hash160 of its serialized public key */
  class CKeyID : public uint160
  {
  public:
      CKeyID() : uint160(0) { }
      CKeyID(const uint160 &in) : uint160(in) { }
  };
  
  /** A reference to a CScript: the Hash160 of its serialization (see script.h) */
  class CScriptID : public uint160
  {
  public:
      CScriptID() : uint160(0) { }
      CScriptID(const uint160 &in) : uint160(in) { }
  };
  
  /** An encapsulated public key. */
  class CPubKey {
  private:
      // Just store the serialized data.
      // Its length can very cheaply be computed from the first byte.
      unsigned char vch[65];
  
      // Compute the length of a pubkey with a given first byte.
      unsigned int static GetLen(unsigned char chHeader) {
          if (chHeader == 2 || chHeader == 3)
              return 33;
          if (chHeader == 4 || chHeader == 6 || chHeader == 7)
              return 65;
          return 0;
      }
  
      // Set this key data to be invalid
      void Invalidate() {
          vch[0] = 0xFF;
      }
  
  public:
      // Construct an invalid public key.
      CPubKey() {
          Invalidate();
      }
  
      // Initialize a public key using begin/end iterators to byte data.
      template<typename T>
      void Set(const T pbegin, const T pend) {
          int len = pend == pbegin ? 0 : GetLen(pbegin[0]);
          if (len && len == (pend-pbegin))
              memcpy(vch, (unsigned char*)&pbegin[0], len);
          else
              Invalidate();
      }
  
      // Construct a public key using begin/end iterators to byte data.
      template<typename T>
      CPubKey(const T pbegin, const T pend) {
          Set(pbegin, pend);
      }
  
      // Construct a public key from a byte vector.
      CPubKey(const std::vector<unsigned char> &vch) {
          Set(vch.begin(), vch.end());
      }
  
      // Simple read-only vector-like interface to the pubkey data.
      unsigned int size() const { return GetLen(vch[0]); }
      const unsigned char *begin() const { return vch; }
      const unsigned char *end() const { return vch+size(); }
      const unsigned char &operator[](unsigned int pos) const { return vch[pos]; }
  
      // Comparator implementation.
      friend bool operator==(const CPubKey &a, const CPubKey &b) {
          return a.vch[0] == b.vch[0] &&
                 memcmp(a.vch, b.vch, a.size()) == 0;
      }
      friend bool operator!=(const CPubKey &a, const CPubKey &b) {
          return !(a == b);
      }
      friend bool operator<(const CPubKey &a, const CPubKey &b) {
          return a.vch[0] < b.vch[0] ||
                 (a.vch[0] == b.vch[0] && memcmp(a.vch, b.vch, a.size()) < 0);
      }
  
      // Implement serialization, as if this was a byte vector.
      unsigned int GetSerializeSize(int nType, int nVersion) const {
          return size() + 1;
      }
      template<typename Stream> void Serialize(Stream &s, int nType, int nVersion) const {
          unsigned int len = size();
          ::WriteCompactSize(s, len);
          s.write((char*)vch, len);
      }
      template<typename Stream> void Unserialize(Stream &s, int nType, int nVersion) {
          unsigned int len = ::ReadCompactSize(s);
          if (len <= 65) {
              s.read((char*)vch, len);
          } else {
              // invalid pubkey, skip available data
              char dummy;
              while (len--)
                  s.read(&dummy, 1);
              Invalidate();
          }
      }
  
      // Get the KeyID of this public key (hash of its serialization)
      CKeyID GetID() const {
          return CKeyID(Hash160(vch, vch+size()));
      }
  
      // Get the 256-bit hash of this public key.
      uint256 GetHash() const {
          return Hash(vch, vch+size());
      }
  
      // Check syntactic correctness.
      //
      // Note that this is consensus critical as CheckSig() calls it!
      bool IsValid() const {
          return size() > 0;
      }
  
      // fully validate whether this is a valid public key (more expensive than IsValid())
      bool IsFullyValid() const;
  
      // Check whether this is a compressed public key.
      bool IsCompressed() const {
          return size() == 33;
      }
  
      // Verify a DER signature (~72 bytes).
      // If this public key is not fully valid, the return value will be false.
      bool Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) const;
  
      // Verify a compact signature (~65 bytes).
      // See CKey::SignCompact.
      bool VerifyCompact(const uint256 &hash, const std::vector<unsigned char>& vchSig) const;
  
      // Recover a public key from a compact signature.
      bool RecoverCompact(const uint256 &hash, const std::vector<unsigned char>& vchSig);
  
      // Turn this public key into an uncompressed public key.
      bool Decompress();
  
      // Derive BIP32 child pubkey.
      bool Derive(CPubKey& pubkeyChild, unsigned char ccChild[32], unsigned int nChild, const unsigned char cc[32]) const;
  
      // Raw for stealth address
      std::vector<unsigned char> Raw() const {
  	std::vector<unsigned char> r;
          r.insert(r.end(), vch, vch+size());
  	return r;
      }
  };
  
  
  // secure_allocator is defined in allocators.h
  // CPrivKey is a serialized private key, with all parameters included (279 bytes)
  typedef std::vector<unsigned char, secure_allocator<unsigned char> > CPrivKey;
  // CSecret is a serialization of just the secret parameter (32 bytes)
  typedef std::vector<unsigned char, secure_allocator<unsigned char> > CSecret;
  
  /** An encapsulated private key. */
  class CKey {
  private:
      // Whether this private key is valid. We check for correctness when modifying the key
      // data, so fValid should always correspond to the actual state.
      bool fValid;
  
      // Whether the public key corresponding to this private key is (to be) compressed.
      bool fCompressed;
  
      // The actual byte data
      unsigned char vch[32];
  
      // Check whether the 32-byte array pointed to be vch is valid keydata.
      bool static Check(const unsigned char *vch);
  public:
  
      // Construct an invalid private key.
      CKey() : fValid(false) {
          LockObject(vch);
      }
  
      // Copy constructor. This is necessary because of memlocking.
      CKey(const CKey &secret) : fValid(secret.fValid), fCompressed(secret.fCompressed) {
          LockObject(vch);
          memcpy(vch, secret.vch, sizeof(vch));
      }
  
      // Destructor (again necessary because of memlocking).
      ~CKey() {
          UnlockObject(vch);
      }
  
      friend bool operator==(const CKey &a, const CKey &b) {
          return a.fCompressed == b.fCompressed && a.size() == b.size() &&
                 memcmp(&a.vch[0], &b.vch[0], a.size()) == 0;
      }
  
      // Initialize using begin and end iterators to byte data.
      template<typename T>
      void Set(const T pbegin, const T pend, bool fCompressedIn) {
          if (pend - pbegin != 32) {
              fValid = false;
              return;
          }
          if (Check(&pbegin[0])) {
              memcpy(vch, (unsigned char*)&pbegin[0], 32);
              fValid = true;
              fCompressed = fCompressedIn;
          } else {
              fValid = false;
          }
      }
  
      // Simple read-only vector-like interface.
      unsigned int size() const { return (fValid ? 32 : 0); }
      const unsigned char *begin() const { return vch; }
      const unsigned char *end() const { return vch + size(); }
  
      // Check whether this private key is valid.
      bool IsValid() const { return fValid; }
  
      // Check whether the public key corresponding to this private key is (to be) compressed.
      bool IsCompressed() const { return fCompressed; }
  
      // Initialize from a CPrivKey (serialized OpenSSL private key data).
      bool SetPrivKey(const CPrivKey &vchPrivKey, bool fCompressed);
  
      // Generate a new private key using a cryptographic PRNG.
      void MakeNewKey(bool fCompressed);
  
      // Convert the private key to a CPrivKey (serialized OpenSSL private key data).
      // This is expensive.
      CPrivKey GetPrivKey() const;
  
      // Compute the public key from a private key.
      // This is expensive.
      CPubKey GetPubKey() const;
  
      // Create a DER-serialized signature.
      bool Sign(const uint256 &hash, std::vector<unsigned char>& vchSig) const;
  
      // Create a compact signature (65 bytes), which allows reconstructing the used public key.
      // The format is one header byte, followed by two times 32 bytes for the serialized r and s values.
      // The header byte: 0x1B = first key with even y, 0x1C = first key with odd y,
      //                  0x1D = second key with even y, 0x1E = second key with odd y,
      //                  add 0x04 for compressed keys.
      bool SignCompact(const uint256 &hash, std::vector<unsigned char>& vchSig) const;
  
      // Derive BIP32 child key.
      bool Derive(CKey& keyChild, unsigned char ccChild[32], unsigned int nChild, const unsigned char cc[32]) const;
  
      // Load private key and check that public key matches.
      bool Load(CPrivKey &privkey, CPubKey &vchPubKey, bool fSkipCheck);
  
      // Check whether an element of a signature (r or s) is valid.
      static bool CheckSignatureElement(const unsigned char *vch, int len, bool half);
  
      // Ensure that signature is DER-encoded
      static bool ReserealizeSignature(std::vector<unsigned char>& vchSig);
  };
  
  struct CExtPubKey {
      unsigned char nDepth;
      unsigned char vchFingerprint[4];
      unsigned int nChild;
      unsigned char vchChainCode[32];
      CPubKey pubkey;
  
      friend bool operator==(const CExtPubKey &a, const CExtPubKey &b) {
          return a.nDepth == b.nDepth && memcmp(&a.vchFingerprint[0], &b.vchFingerprint[0], 4) == 0 && a.nChild == b.nChild &&
                 memcmp(&a.vchChainCode[0], &b.vchChainCode[0], 32) == 0 && a.pubkey == b.pubkey;
      }
  
      void Encode(unsigned char code[74]) const;
      void Decode(const unsigned char code[74]);
      bool Derive(CExtPubKey &out, unsigned int nChild) const;
  };
  
  struct CExtKey {
      unsigned char nDepth;
      unsigned char vchFingerprint[4];
      unsigned int nChild;
      unsigned char vchChainCode[32];
      CKey key;
  
      friend bool operator==(const CExtKey &a, const CExtKey &b) {
          return a.nDepth == b.nDepth && memcmp(&a.vchFingerprint[0], &b.vchFingerprint[0], 4) == 0 && a.nChild == b.nChild &&
                 memcmp(&a.vchChainCode[0], &b.vchChainCode[0], 32) == 0 && a.key == b.key;
      }
  
      void Encode(unsigned char code[74]) const;
      void Decode(const unsigned char code[74]);
      bool Derive(CExtKey &out, unsigned int nChild) const;
      CExtPubKey Neuter() const;
      void SetMaster(const unsigned char *seed, unsigned int nSeedLen);
  };
  
  /** Check that required EC support is available at runtime */
  bool ECC_InitSanityCheck(void);
  
  #endif
  