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key.cpp
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// Copyright (c) 2009-2014 The Bitcoin Core developers
// Distributed under the MIT software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include "key.h"
#include "crypto/hmac_sha512.h"
#include "crypto/rfc6979_hmac_sha256.h"
#include "eccryptoverify.h"
#include "pubkey.h"
#include "random.h"
#include <secp256k1.h>
#include "ecwrapper.h"
//! anonymous namespace
namespace {
class CSecp256k1Init {
public:
CSecp256k1Init() {
secp256k1_start(SECP256K1_START_SIGN);
}
~CSecp256k1Init() {
secp256k1_stop();
}
};
static CSecp256k1Init instance_of_csecp256k1;
} // anon namespace
bool CKey::Check(const unsigned char *vch) {
return eccrypto::Check(vch);
}
void CKey::MakeNewKey(bool fCompressedIn) {
do {
GetRandBytes(vch, sizeof(vch));
} while (!Check(vch));
fValid = true;
fCompressed = fCompressedIn;
}
bool CKey::SetPrivKey(const CPrivKey &privkey, bool fCompressedIn) {
if (!secp256k1_ec_privkey_import((unsigned char*)begin(), &privkey[0], privkey.size()))
return false;
fCompressed = fCompressedIn;
fValid = true;
return true;
}
CPrivKey CKey::GetPrivKey() const {
assert(fValid);
CPrivKey privkey;
int privkeylen, ret;
privkey.resize(279);
privkeylen = 279;
ret = secp256k1_ec_privkey_export(begin(), (unsigned char*)&privkey[0], &privkeylen, fCompressed);
assert(ret);
privkey.resize(privkeylen);
return privkey;
}
CPubKey CKey::GetPubKey() const {
assert(fValid);
CPubKey result;
int clen = 65;
int ret = secp256k1_ec_pubkey_create((unsigned char*)result.begin(), &clen, begin(), fCompressed);
assert((int)result.size() == clen);
assert(ret);
assert(result.IsValid());
return result;
}
bool CKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig, uint32_t test_case) const {
if (!fValid)
return false;
vchSig.resize(72);
RFC6979_HMAC_SHA256 prng(begin(), 32, (unsigned char*)&hash, 32);
do {
uint256 nonce;
prng.Generate((unsigned char*)&nonce, 32);
nonce += test_case;
int nSigLen = 72;
int ret = secp256k1_ecdsa_sign((const unsigned char*)&hash, (unsigned char*)&vchSig[0], &nSigLen, begin(), (unsigned char*)&nonce);
nonce = 0;
if (ret) {
vchSig.resize(nSigLen);
return true;
}
} while(true);
}
bool CKey::VerifyPubKey(const CPubKey& pubkey) const {
if (pubkey.IsCompressed() != fCompressed) {
return false;
}
unsigned char rnd[8];
std::string str = "Bitcoin key verification\n";
GetRandBytes(rnd, sizeof(rnd));
uint256 hash;
CHash256().Write((unsigned char*)str.data(), str.size()).Write(rnd, sizeof(rnd)).Finalize((unsigned char*)&hash);
std::vector<unsigned char> vchSig;
Sign(hash, vchSig);
return pubkey.Verify(hash, vchSig);
}
bool CKey::SignCompact(const uint256 &hash, std::vector<unsigned char>& vchSig) const {
if (!fValid)
return false;
vchSig.resize(65);
int rec = -1;
RFC6979_HMAC_SHA256 prng(begin(), 32, (unsigned char*)&hash, 32);
do {
uint256 nonce;
prng.Generate((unsigned char*)&nonce, 32);
int ret = secp256k1_ecdsa_sign_compact((const unsigned char*)&hash, &vchSig[1], begin(), (unsigned char*)&nonce, &rec);
nonce = 0;
if (ret)
break;
} while(true);
assert(rec != -1);
vchSig[0] = 27 + rec + (fCompressed ? 4 : 0);
return true;
}
bool CKey::Load(CPrivKey &privkey, CPubKey &vchPubKey, bool fSkipCheck=false) {
if (!secp256k1_ec_privkey_import((unsigned char*)begin(), &privkey[0], privkey.size()))
return false;
fCompressed = vchPubKey.IsCompressed();
fValid = true;
if (fSkipCheck)
return true;
return VerifyPubKey(vchPubKey);
}
bool CKey::Derive(CKey& keyChild, unsigned char ccChild[32], unsigned int nChild, const unsigned char cc[32]) const {
assert(IsValid());
assert(IsCompressed());
unsigned char out[64];
LockObject(out);
if ((nChild >> 31) == 0) {
CPubKey pubkey = GetPubKey();
assert(pubkey.begin() + 33 == pubkey.end());
BIP32Hash(cc, nChild, *pubkey.begin(), pubkey.begin()+1, out);
} else {
assert(begin() + 32 == end());
BIP32Hash(cc, nChild, 0, begin(), out);
}
memcpy(ccChild, out+32, 32);
memcpy((unsigned char*)keyChild.begin(), begin(), 32);
bool ret = secp256k1_ec_privkey_tweak_add((unsigned char*)keyChild.begin(), out);
UnlockObject(out);
keyChild.fCompressed = true;
keyChild.fValid = ret;
return ret;
}
bool CExtKey::Derive(CExtKey &out, unsigned int nChild) const {
out.nDepth = nDepth + 1;
CKeyID id = key.GetPubKey().GetID();
memcpy(&out.vchFingerprint[0], &id, 4);
out.nChild = nChild;
return key.Derive(out.key, out.vchChainCode, nChild, vchChainCode);
}
void CExtKey::SetMaster(const unsigned char *seed, unsigned int nSeedLen) {
static const unsigned char hashkey[] = {'B','i','t','c','o','i','n',' ','s','e','e','d'};
unsigned char out[64];
LockObject(out);
CHMAC_SHA512(hashkey, sizeof(hashkey)).Write(seed, nSeedLen).Finalize(out);
key.Set(&out[0], &out[32], true);
memcpy(vchChainCode, &out[32], 32);
UnlockObject(out);
nDepth = 0;
nChild = 0;
memset(vchFingerprint, 0, sizeof(vchFingerprint));
}
CExtPubKey CExtKey::Neuter() const {
CExtPubKey ret;
ret.nDepth = nDepth;
memcpy(&ret.vchFingerprint[0], &vchFingerprint[0], 4);
ret.nChild = nChild;
ret.pubkey = key.GetPubKey();
memcpy(&ret.vchChainCode[0], &vchChainCode[0], 32);
return ret;
}
void CExtKey::Encode(unsigned char code[74]) const {
code[0] = nDepth;
memcpy(code+1, vchFingerprint, 4);
code[5] = (nChild >> 24) & 0xFF; code[6] = (nChild >> 16) & 0xFF;
code[7] = (nChild >> 8) & 0xFF; code[8] = (nChild >> 0) & 0xFF;
memcpy(code+9, vchChainCode, 32);
code[41] = 0;
assert(key.size() == 32);
memcpy(code+42, key.begin(), 32);
}
void CExtKey::Decode(const unsigned char code[74]) {
nDepth = code[0];
memcpy(vchFingerprint, code+1, 4);
nChild = (code[5] << 24) | (code[6] << 16) | (code[7] << 8) | code[8];
memcpy(vchChainCode, code+9, 32);
key.Set(code+42, code+74, true);
}
bool ECC_InitSanityCheck() {
#if !defined(USE_SECP256K1)
if (!CECKey::SanityCheck()) {
return false;
}
#endif
CKey key;
key.MakeNewKey(true);
CPubKey pubkey = key.GetPubKey();
return key.VerifyPubKey(pubkey);
}

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