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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2012 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.
#ifndef BITCOIN_KEY_H
#define BITCOIN_KEY_H
#include <stdexcept>
#include <vector>
#include <openssl/ec.h>
#include <openssl/ecdsa.h>
#include <openssl/obj_mac.h>
#include "serialize.h"
#include "uint256.h"
// secp160k1
// const unsigned int PRIVATE_KEY_SIZE = 192;
// const unsigned int PUBLIC_KEY_SIZE = 41;
// const unsigned int SIGNATURE_SIZE = 48;
//
// secp192k1
// const unsigned int PRIVATE_KEY_SIZE = 222;
// const unsigned int PUBLIC_KEY_SIZE = 49;
// const unsigned int SIGNATURE_SIZE = 57;
//
// secp224k1
// const unsigned int PRIVATE_KEY_SIZE = 250;
// const unsigned int PUBLIC_KEY_SIZE = 57;
// const unsigned int SIGNATURE_SIZE = 66;
//
// 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
int extern EC_KEY_regenerate_key(EC_KEY *eckey, BIGNUM *priv_key);
int extern ECDSA_SIG_recover_key_GFp(EC_KEY *eckey, ECDSA_SIG *ecsig, const unsigned char *msg, int msglen, int recid, int check);
class key_error : public std::runtime_error
{
public:
explicit key_error(const std::string& str) : std::runtime_error(str) {}
};
// secure_allocator is defined in serialize.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;
class CKey
{
protected:
EC_KEY* pkey;
bool fSet;
bool fCompressedPubKey;
void SetCompressedPubKey()
{
EC_KEY_set_conv_form(pkey, POINT_CONVERSION_COMPRESSED);
fCompressedPubKey = true;
}
public:
void Reset()
{
fCompressedPubKey = false;
pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
if (pkey == NULL)
throw key_error("CKey::CKey() : EC_KEY_new_by_curve_name failed");
fSet = false;
}
CKey()
{
Reset();
}
CKey(const CKey& b)
{
pkey = EC_KEY_dup(b.pkey);
if (pkey == NULL)
throw key_error("CKey::CKey(const CKey&) : EC_KEY_dup failed");
fSet = b.fSet;
}
CKey& operator=(const CKey& b)
{
if (!EC_KEY_copy(pkey, b.pkey))
throw key_error("CKey::operator=(const CKey&) : EC_KEY_copy failed");
fSet = b.fSet;
return (*this);
}
~CKey()
{
EC_KEY_free(pkey);
}
bool IsNull() const
{
return !fSet;
}
bool IsCompressed() const
{
return fCompressedPubKey;
}
void MakeNewKey(bool fCompressed)
{
if (!EC_KEY_generate_key(pkey))
throw key_error("CKey::MakeNewKey() : EC_KEY_generate_key failed");
if (fCompressed)
SetCompressedPubKey();
fSet = true;
}
bool SetPrivKey(const CPrivKey& vchPrivKey)
{
const unsigned char* pbegin = &vchPrivKey[0];
if (!d2i_ECPrivateKey(&pkey, &pbegin, vchPrivKey.size()))
return false;
fSet = true;
return true;
}
bool SetSecret(const CSecret& vchSecret, bool fCompressed = false)
{
EC_KEY_free(pkey);
pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
if (pkey == NULL)
throw key_error("CKey::SetSecret() : EC_KEY_new_by_curve_name failed");
if (vchSecret.size() != 32)
throw key_error("CKey::SetSecret() : secret must be 32 bytes");
BIGNUM *bn = BN_bin2bn(&vchSecret[0],32,BN_new());
if (bn == NULL)
throw key_error("CKey::SetSecret() : BN_bin2bn failed");
if (!EC_KEY_regenerate_key(pkey,bn))
{
BN_clear_free(bn);
throw key_error("CKey::SetSecret() : EC_KEY_regenerate_key failed");
}
BN_clear_free(bn);
fSet = true;
if (fCompressed || fCompressedPubKey)
SetCompressedPubKey();
return true;
}
CSecret GetSecret(bool &fCompressed) const
{
CSecret vchRet;
vchRet.resize(32);
const BIGNUM *bn = EC_KEY_get0_private_key(pkey);
int nBytes = BN_num_bytes(bn);
if (bn == NULL)
throw key_error("CKey::GetSecret() : EC_KEY_get0_private_key failed");
int n=BN_bn2bin(bn,&vchRet[32 - nBytes]);
if (n != nBytes)
throw key_error("CKey::GetSecret(): BN_bn2bin failed");
fCompressed = fCompressedPubKey;
return vchRet;
}
CPrivKey GetPrivKey() const
{
unsigned int nSize = i2d_ECPrivateKey(pkey, NULL);
if (!nSize)
throw key_error("CKey::GetPrivKey() : i2d_ECPrivateKey failed");
CPrivKey vchPrivKey(nSize, 0);
unsigned char* pbegin = &vchPrivKey[0];
if (i2d_ECPrivateKey(pkey, &pbegin) != nSize)
throw key_error("CKey::GetPrivKey() : i2d_ECPrivateKey returned unexpected size");
return vchPrivKey;
}
bool SetPubKey(const std::vector<unsigned char>& vchPubKey)
{
const unsigned char* pbegin = &vchPubKey[0];
if (!o2i_ECPublicKey(&pkey, &pbegin, vchPubKey.size()))
return false;
fSet = true;
if (vchPubKey.size() == 33)
SetCompressedPubKey();
return true;
}
std::vector<unsigned char> GetPubKey() const
{
unsigned int nSize = i2o_ECPublicKey(pkey, NULL);
if (!nSize)
throw key_error("CKey::GetPubKey() : i2o_ECPublicKey failed");
std::vector<unsigned char> vchPubKey(nSize, 0);
unsigned char* pbegin = &vchPubKey[0];
if (i2o_ECPublicKey(pkey, &pbegin) != nSize)
throw key_error("CKey::GetPubKey() : i2o_ECPublicKey returned unexpected size");
return vchPubKey;
}
bool Sign(uint256 hash, std::vector<unsigned char>& vchSig)
{
unsigned int nSize = ECDSA_size(pkey);
vchSig.resize(nSize); // Make sure it is big enough
if (!ECDSA_sign(0, (unsigned char*)&hash, sizeof(hash), &vchSig[0], &nSize, pkey))
{
vchSig.clear();
return false;
}
vchSig.resize(nSize); // Shrink to fit actual size
return true;
}
// 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
bool SignCompact(uint256 hash, std::vector<unsigned char>& vchSig)
{
bool fOk = false;
ECDSA_SIG *sig = ECDSA_do_sign((unsigned char*)&hash, sizeof(hash), pkey);
if (sig==NULL)
return false;
vchSig.clear();
vchSig.resize(65,0);
int nBitsR = BN_num_bits(sig->r);
int nBitsS = BN_num_bits(sig->s);
if (nBitsR <= 256 && nBitsS <= 256)
{
int nRecId = -1;
for (int i=0; i<4; i++)
{
CKey keyRec;
keyRec.fSet = true;
if (fCompressedPubKey)
keyRec.SetCompressedPubKey();
if (ECDSA_SIG_recover_key_GFp(keyRec.pkey, sig, (unsigned char*)&hash, sizeof(hash), i, 1) == 1)
if (keyRec.GetPubKey() == this->GetPubKey())
{
nRecId = i;
break;
}
}
if (nRecId == -1)
throw key_error("CKey::SignCompact() : unable to construct recoverable key");
vchSig[0] = nRecId+27+(fCompressedPubKey ? 4 : 0);
BN_bn2bin(sig->r,&vchSig[33-(nBitsR+7)/8]);
BN_bn2bin(sig->s,&vchSig[65-(nBitsS+7)/8]);
fOk = true;
}
ECDSA_SIG_free(sig);
return fOk;
}
// reconstruct public key from a compact signature
// This is only slightly more CPU intensive than just verifying it.
// If this function succeeds, the recovered public key is guaranteed to be valid
// (the signature is a valid signature of the given data for that key)
bool SetCompactSignature(uint256 hash, const std::vector<unsigned char>& vchSig)
{
if (vchSig.size() != 65)
return false;
int nV = vchSig[0];
if (nV<27 || nV>=35)
return false;
ECDSA_SIG *sig = ECDSA_SIG_new();
BN_bin2bn(&vchSig[1],32,sig->r);
BN_bin2bn(&vchSig[33],32,sig->s);
EC_KEY_free(pkey);
pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
if (nV >= 31)
{
SetCompressedPubKey();
nV -= 4;
}
if (ECDSA_SIG_recover_key_GFp(pkey, sig, (unsigned char*)&hash, sizeof(hash), nV - 27, 0) == 1)
{
fSet = true;
ECDSA_SIG_free(sig);
return true;
}
return false;
}
bool Verify(uint256 hash, const std::vector<unsigned char>& vchSig)
{
// -1 = error, 0 = bad sig, 1 = good
if (ECDSA_verify(0, (unsigned char*)&hash, sizeof(hash), &vchSig[0], vchSig.size(), pkey) != 1)
return false;
return true;
}
// Verify a compact signature
bool VerifyCompact(uint256 hash, const std::vector<unsigned char>& vchSig)
{
CKey key;
if (!key.SetCompactSignature(hash, vchSig))
return false;
if (GetPubKey() != key.GetPubKey())
return false;
return true;
}
bool IsValid()
{
if (!fSet)
return false;
bool fCompr;
CSecret secret = GetSecret(fCompr);
CKey key2;
key2.SetSecret(secret, fCompr);
return GetPubKey() == key2.GetPubKey();
}
};
#endif