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// Copyright (c) 2009-2017 The Starwels developers
// Copyright (c) 2017 The Zcash 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 <arith_uint256.h>
#include <crypto/common.h>
#include <crypto/hmac_sha512.h>
#include <random.h>
#include <secp256k1.h>
#include <secp256k1_recovery.h>
static secp256k1_context* secp256k1_context_sign = nullptr;
/** These functions are taken from the libsecp256k1 distribution and are very ugly. */
6 years ago
/**
* This parses a format loosely based on a DER encoding of the ECPrivateKey type from
* section C.4 of SEC 1 <http://www.secg.org/sec1-v2.pdf>, with the following caveats:
*
* * The octet-length of the SEQUENCE must be encoded as 1 or 2 octets. It is not
* required to be encoded as one octet if it is less than 256, as DER would require.
* * The octet-length of the SEQUENCE must not be greater than the remaining
* length of the key encoding, but need not match it (i.e. the encoding may contain
* junk after the encoded SEQUENCE).
* * The privateKey OCTET STRING is zero-filled on the left to 32 octets.
* * Anything after the encoding of the privateKey OCTET STRING is ignored, whether
* or not it is validly encoded DER.
*
* out32 must point to an output buffer of length at least 32 bytes.
*/
static int ec_privkey_import_der(const secp256k1_context* ctx, unsigned char *out32, const unsigned char *privkey, size_t privkeylen) {
const unsigned char *end = privkey + privkeylen;
memset(out32, 0, 32);
/* sequence header */
if (end - privkey < 1 || *privkey != 0x30u) {
return 0;
}
privkey++;
/* sequence length constructor */
if (end - privkey < 1 || !(*privkey & 0x80u)) {
return 0;
}
size_t lenb = *privkey & ~0x80u; privkey++;
if (lenb < 1 || lenb > 2) {
return 0;
}
if (end - privkey < lenb) {
return 0;
}
/* sequence length */
size_t len = privkey[lenb-1] | (lenb > 1 ? privkey[lenb-2] << 8 : 0u);
privkey += lenb;
if (end - privkey < len) {
return 0;
}
/* sequence element 0: version number (=1) */
if (end - privkey < 3 || privkey[0] != 0x02u || privkey[1] != 0x01u || privkey[2] != 0x01u) {
return 0;
}
privkey += 3;
/* sequence element 1: octet string, up to 32 bytes */
if (end - privkey < 2 || privkey[0] != 0x04u) {
return 0;
}
size_t oslen = privkey[1];
privkey += 2;
if (oslen > 32 || end - privkey < oslen) {
return 0;
}
memcpy(out32 + (32 - oslen), privkey, oslen);
if (!secp256k1_ec_seckey_verify(ctx, out32)) {
memset(out32, 0, 32);
return 0;
}
return 1;
}
6 years ago
/**
* This serializes to a DER encoding of the ECPrivateKey type from section C.4 of SEC 1
* <http://www.secg.org/sec1-v2.pdf>. The optional parameters and publicKey fields are
* included.
*
* privkey must point to an output buffer of length at least CKey::PRIVATE_KEY_SIZE bytes.
* privkeylen must initially be set to the size of the privkey buffer. Upon return it
* will be set to the number of bytes used in the buffer.
6 years ago
* key32 must point to a 32-byte raw private key.
*/
static int ec_privkey_export_der(const secp256k1_context *ctx, unsigned char *privkey, size_t *privkeylen, const unsigned char *key32, int compressed) {
assert(*privkeylen >= CKey::PRIVATE_KEY_SIZE);
secp256k1_pubkey pubkey;
size_t pubkeylen = 0;
if (!secp256k1_ec_pubkey_create(ctx, &pubkey, key32)) {
*privkeylen = 0;
return 0;
}
if (compressed) {
static const unsigned char begin[] = {
0x30,0x81,0xD3,0x02,0x01,0x01,0x04,0x20
};
static const unsigned char middle[] = {
0xA0,0x81,0x85,0x30,0x81,0x82,0x02,0x01,0x01,0x30,0x2C,0x06,0x07,0x2A,0x86,0x48,
0xCE,0x3D,0x01,0x01,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F,0x30,0x06,0x04,0x01,0x00,0x04,0x01,0x07,0x04,
0x21,0x02,0x79,0xBE,0x66,0x7E,0xF9,0xDC,0xBB,0xAC,0x55,0xA0,0x62,0x95,0xCE,0x87,
0x0B,0x07,0x02,0x9B,0xFC,0xDB,0x2D,0xCE,0x28,0xD9,0x59,0xF2,0x81,0x5B,0x16,0xF8,
0x17,0x98,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
0xFF,0xFF,0xFF,0xFF,0xFE,0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,0xBF,0xD2,0x5E,
0x8C,0xD0,0x36,0x41,0x41,0x02,0x01,0x01,0xA1,0x24,0x03,0x22,0x00
};
unsigned char *ptr = privkey;
memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin);
memcpy(ptr, key32, 32); ptr += 32;
memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle);
pubkeylen = CPubKey::COMPRESSED_PUBLIC_KEY_SIZE;
secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_COMPRESSED);
ptr += pubkeylen;
*privkeylen = ptr - privkey;
assert(*privkeylen == CKey::COMPRESSED_PRIVATE_KEY_SIZE);
} else {
static const unsigned char begin[] = {
0x30,0x82,0x01,0x13,0x02,0x01,0x01,0x04,0x20
};
static const unsigned char middle[] = {
0xA0,0x81,0xA5,0x30,0x81,0xA2,0x02,0x01,0x01,0x30,0x2C,0x06,0x07,0x2A,0x86,0x48,
0xCE,0x3D,0x01,0x01,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
0xFF,0xFF,0xFE,0xFF,0xFF,0xFC,0x2F,0x30,0x06,0x04,0x01,0x00,0x04,0x01,0x07,0x04,
0x41,0x04,0x79,0xBE,0x66,0x7E,0xF9,0xDC,0xBB,0xAC,0x55,0xA0,0x62,0x95,0xCE,0x87,
0x0B,0x07,0x02,0x9B,0xFC,0xDB,0x2D,0xCE,0x28,0xD9,0x59,0xF2,0x81,0x5B,0x16,0xF8,
0x17,0x98,0x48,0x3A,0xDA,0x77,0x26,0xA3,0xC4,0x65,0x5D,0xA4,0xFB,0xFC,0x0E,0x11,
0x08,0xA8,0xFD,0x17,0xB4,0x48,0xA6,0x85,0x54,0x19,0x9C,0x47,0xD0,0x8F,0xFB,0x10,
0xD4,0xB8,0x02,0x21,0x00,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
0xFF,0xFF,0xFF,0xFF,0xFE,0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,0xBF,0xD2,0x5E,
0x8C,0xD0,0x36,0x41,0x41,0x02,0x01,0x01,0xA1,0x44,0x03,0x42,0x00
};
unsigned char *ptr = privkey;
memcpy(ptr, begin, sizeof(begin)); ptr += sizeof(begin);
memcpy(ptr, key32, 32); ptr += 32;
memcpy(ptr, middle, sizeof(middle)); ptr += sizeof(middle);
pubkeylen = CPubKey::PUBLIC_KEY_SIZE;
secp256k1_ec_pubkey_serialize(ctx, ptr, &pubkeylen, &pubkey, SECP256K1_EC_UNCOMPRESSED);
ptr += pubkeylen;
*privkeylen = ptr - privkey;
assert(*privkeylen == CKey::PRIVATE_KEY_SIZE);
}
return 1;
}
bool CKey::Check(const unsigned char *vch) {
return secp256k1_ec_seckey_verify(secp256k1_context_sign, vch);
}
void CKey::MakeNewKey(bool fCompressedIn) {
do {
GetStrongRandBytes(keydata.data(), keydata.size());
} while (!Check(keydata.data()));
fValid = true;
fCompressed = fCompressedIn;
}
CPrivKey CKey::GetPrivKey() const {
assert(fValid);
CPrivKey privkey;
int ret;
size_t privkeylen;
privkey.resize(PRIVATE_KEY_SIZE);
privkeylen = PRIVATE_KEY_SIZE;
ret = ec_privkey_export_der(secp256k1_context_sign, (unsigned char*) privkey.data(), &privkeylen, begin(), fCompressed ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED);
assert(ret);
privkey.resize(privkeylen);
return privkey;
}
CPubKey CKey::GetPubKey() const {
assert(fValid);
secp256k1_pubkey pubkey;
size_t clen = CPubKey::PUBLIC_KEY_SIZE;
CPubKey result;
int ret = secp256k1_ec_pubkey_create(secp256k1_context_sign, &pubkey, begin());
assert(ret);
secp256k1_ec_pubkey_serialize(secp256k1_context_sign, (unsigned char*)result.begin(), &clen, &pubkey, fCompressed ? SECP256K1_EC_COMPRESSED : SECP256K1_EC_UNCOMPRESSED);
assert(result.size() == clen);
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(CPubKey::SIGNATURE_SIZE);
size_t nSigLen = CPubKey::SIGNATURE_SIZE;
unsigned char extra_entropy[32] = {0};
WriteLE32(extra_entropy, test_case);
secp256k1_ecdsa_signature sig;
int ret = secp256k1_ecdsa_sign(secp256k1_context_sign, &sig, hash.begin(), begin(), secp256k1_nonce_function_rfc6979, test_case ? extra_entropy : nullptr);
assert(ret);
secp256k1_ecdsa_signature_serialize_der(secp256k1_context_sign, (unsigned char*)vchSig.data(), &nSigLen, &sig);
vchSig.resize(nSigLen);
return true;
}
bool CKey::VerifyPubKey(const CPubKey& pubkey) const {
if (pubkey.IsCompressed() != fCompressed) {
return false;
}
unsigned char rnd[8];
std::string str = "Starwels key verification\n";
GetRandBytes(rnd, sizeof(rnd));
uint256 hash;
CHash256().Write((unsigned char*)str.data(), str.size()).Write(rnd, sizeof(rnd)).Finalize(hash.begin());
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(CPubKey::COMPACT_SIGNATURE_SIZE);
int rec = -1;
secp256k1_ecdsa_recoverable_signature sig;
int ret = secp256k1_ecdsa_sign_recoverable(secp256k1_context_sign, &sig, hash.begin(), begin(), secp256k1_nonce_function_rfc6979, nullptr);
assert(ret);
secp256k1_ecdsa_recoverable_signature_serialize_compact(secp256k1_context_sign, (unsigned char*)&vchSig[1], &rec, &sig);
assert(ret);
assert(rec != -1);
vchSig[0] = 27 + rec + (fCompressed ? 4 : 0);
return true;
}
bool CKey::Load(const CPrivKey &privkey, const CPubKey &vchPubKey, bool fSkipCheck=false) {
if (!ec_privkey_import_der(secp256k1_context_sign, (unsigned char*)begin(), privkey.data(), privkey.size()))
return false;
fCompressed = vchPubKey.IsCompressed();
fValid = true;
if (fSkipCheck)
return true;
return VerifyPubKey(vchPubKey);
}
bool CKey::Derive(CKey& keyChild, ChainCode &ccChild, unsigned int nChild, const ChainCode& cc) const {
assert(IsValid());
assert(IsCompressed());
std::vector<unsigned char, secure_allocator<unsigned char>> vout(64);
if ((nChild >> 31) == 0) {
CPubKey pubkey = GetPubKey();
assert(pubkey.size() == CPubKey::COMPRESSED_PUBLIC_KEY_SIZE);
BIP32Hash(cc, nChild, *pubkey.begin(), pubkey.begin()+1, vout.data());
} else {
assert(size() == 32);
BIP32Hash(cc, nChild, 0, begin(), vout.data());
}
memcpy(ccChild.begin(), vout.data()+32, 32);
memcpy((unsigned char*)keyChild.begin(), begin(), 32);
bool ret = secp256k1_ec_privkey_tweak_add(secp256k1_context_sign, (unsigned char*)keyChild.begin(), vout.data());
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.chaincode, _nChild, chaincode);
}
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'};
std::vector<unsigned char, secure_allocator<unsigned char>> vout(64);
CHMAC_SHA512(hashkey, sizeof(hashkey)).Write(seed, nSeedLen).Finalize(vout.data());
key.Set(vout.data(), vout.data() + 32, true);
memcpy(chaincode.begin(), vout.data() + 32, 32);
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();
ret.chaincode = chaincode;
return ret;
}
void CExtKey::Encode(unsigned char code[BIP32_EXTKEY_SIZE]) 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, chaincode.begin(), 32);
code[41] = 0;
assert(key.size() == 32);
memcpy(code+42, key.begin(), 32);
}
void CExtKey::Decode(const unsigned char code[BIP32_EXTKEY_SIZE]) {
nDepth = code[0];
memcpy(vchFingerprint, code+1, 4);
nChild = (code[5] << 24) | (code[6] << 16) | (code[7] << 8) | code[8];
memcpy(chaincode.begin(), code+9, 32);
key.Set(code+42, code+BIP32_EXTKEY_SIZE, true);
}
bool ECC_InitSanityCheck() {
CKey key;
key.MakeNewKey(true);
CPubKey pubkey = key.GetPubKey();
return key.VerifyPubKey(pubkey);
}
void ECC_Start() {
assert(secp256k1_context_sign == nullptr);
secp256k1_context *ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN);
assert(ctx != nullptr);
{
// Pass in a random blinding seed to the secp256k1 context.
std::vector<unsigned char, secure_allocator<unsigned char>> vseed(32);
GetRandBytes(vseed.data(), 32);
bool ret = secp256k1_context_randomize(ctx, vseed.data());
assert(ret);
}
secp256k1_context_sign = ctx;
}
void ECC_Stop() {
secp256k1_context *ctx = secp256k1_context_sign;
secp256k1_context_sign = nullptr;
if (ctx) {
secp256k1_context_destroy(ctx);
}
}