You can not select more than 25 topics Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
 
 
 
 
 
 

395 lines
12 KiB

// Copyright (c) 2009-2012 The Bitcoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file COPYING or http://www.opensource.org/licenses/mit-license.php.
#include <openssl/ecdsa.h>
#include <openssl/rand.h>
#include <openssl/obj_mac.h>
#include "key.h"
// anonymous namespace with local implementation code (OpenSSL interaction)
namespace {
// Generate a private key from just the secret parameter
int EC_KEY_regenerate_key(EC_KEY *eckey, BIGNUM *priv_key)
{
int ok = 0;
BN_CTX *ctx = NULL;
EC_POINT *pub_key = NULL;
if (!eckey) return 0;
const EC_GROUP *group = EC_KEY_get0_group(eckey);
if ((ctx = BN_CTX_new()) == NULL)
goto err;
pub_key = EC_POINT_new(group);
if (pub_key == NULL)
goto err;
if (!EC_POINT_mul(group, pub_key, priv_key, NULL, NULL, ctx))
goto err;
EC_KEY_set_private_key(eckey,priv_key);
EC_KEY_set_public_key(eckey,pub_key);
ok = 1;
err:
if (pub_key)
EC_POINT_free(pub_key);
if (ctx != NULL)
BN_CTX_free(ctx);
return(ok);
}
// Perform ECDSA key recovery (see SEC1 4.1.6) for curves over (mod p)-fields
// recid selects which key is recovered
// if check is non-zero, additional checks are performed
int ECDSA_SIG_recover_key_GFp(EC_KEY *eckey, ECDSA_SIG *ecsig, const unsigned char *msg, int msglen, int recid, int check)
{
if (!eckey) return 0;
int ret = 0;
BN_CTX *ctx = NULL;
BIGNUM *x = NULL;
BIGNUM *e = NULL;
BIGNUM *order = NULL;
BIGNUM *sor = NULL;
BIGNUM *eor = NULL;
BIGNUM *field = NULL;
EC_POINT *R = NULL;
EC_POINT *O = NULL;
EC_POINT *Q = NULL;
BIGNUM *rr = NULL;
BIGNUM *zero = NULL;
int n = 0;
int i = recid / 2;
const EC_GROUP *group = EC_KEY_get0_group(eckey);
if ((ctx = BN_CTX_new()) == NULL) { ret = -1; goto err; }
BN_CTX_start(ctx);
order = BN_CTX_get(ctx);
if (!EC_GROUP_get_order(group, order, ctx)) { ret = -2; goto err; }
x = BN_CTX_get(ctx);
if (!BN_copy(x, order)) { ret=-1; goto err; }
if (!BN_mul_word(x, i)) { ret=-1; goto err; }
if (!BN_add(x, x, ecsig->r)) { ret=-1; goto err; }
field = BN_CTX_get(ctx);
if (!EC_GROUP_get_curve_GFp(group, field, NULL, NULL, ctx)) { ret=-2; goto err; }
if (BN_cmp(x, field) >= 0) { ret=0; goto err; }
if ((R = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
if (!EC_POINT_set_compressed_coordinates_GFp(group, R, x, recid % 2, ctx)) { ret=0; goto err; }
if (check)
{
if ((O = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
if (!EC_POINT_mul(group, O, NULL, R, order, ctx)) { ret=-2; goto err; }
if (!EC_POINT_is_at_infinity(group, O)) { ret = 0; goto err; }
}
if ((Q = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
n = EC_GROUP_get_degree(group);
e = BN_CTX_get(ctx);
if (!BN_bin2bn(msg, msglen, e)) { ret=-1; goto err; }
if (8*msglen > n) BN_rshift(e, e, 8-(n & 7));
zero = BN_CTX_get(ctx);
if (!BN_zero(zero)) { ret=-1; goto err; }
if (!BN_mod_sub(e, zero, e, order, ctx)) { ret=-1; goto err; }
rr = BN_CTX_get(ctx);
if (!BN_mod_inverse(rr, ecsig->r, order, ctx)) { ret=-1; goto err; }
sor = BN_CTX_get(ctx);
if (!BN_mod_mul(sor, ecsig->s, rr, order, ctx)) { ret=-1; goto err; }
eor = BN_CTX_get(ctx);
if (!BN_mod_mul(eor, e, rr, order, ctx)) { ret=-1; goto err; }
if (!EC_POINT_mul(group, Q, eor, R, sor, ctx)) { ret=-2; goto err; }
if (!EC_KEY_set_public_key(eckey, Q)) { ret=-2; goto err; }
ret = 1;
err:
if (ctx) {
BN_CTX_end(ctx);
BN_CTX_free(ctx);
}
if (R != NULL) EC_POINT_free(R);
if (O != NULL) EC_POINT_free(O);
if (Q != NULL) EC_POINT_free(Q);
return ret;
}
// RAII Wrapper around OpenSSL's EC_KEY
class CECKey {
private:
EC_KEY *pkey;
public:
CECKey() {
pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
assert(pkey != NULL);
}
~CECKey() {
EC_KEY_free(pkey);
}
void GetSecretBytes(unsigned char vch[32]) const {
const BIGNUM *bn = EC_KEY_get0_private_key(pkey);
assert(bn);
int nBytes = BN_num_bytes(bn);
int n=BN_bn2bin(bn,&vch[32 - nBytes]);
assert(n == nBytes);
memset(vch, 0, 32 - nBytes);
}
void SetSecretBytes(const unsigned char vch[32]) {
BIGNUM bn;
BN_init(&bn);
assert(BN_bin2bn(vch, 32, &bn));
assert(EC_KEY_regenerate_key(pkey, &bn));
BN_clear_free(&bn);
}
void GetPrivKey(CPrivKey &privkey) {
int nSize = i2d_ECPrivateKey(pkey, NULL);
assert(nSize);
privkey.resize(nSize);
unsigned char* pbegin = &privkey[0];
int nSize2 = i2d_ECPrivateKey(pkey, &pbegin);
assert(nSize == nSize2);
}
bool SetPrivKey(const CPrivKey &privkey) {
const unsigned char* pbegin = &privkey[0];
if (d2i_ECPrivateKey(&pkey, &pbegin, privkey.size())) {
// d2i_ECPrivateKey returns true if parsing succeeds.
// This doesn't necessarily mean the key is valid.
if (EC_KEY_check_key(pkey))
return true;
}
return false;
}
void GetPubKey(CPubKey &pubkey, bool fCompressed) {
EC_KEY_set_conv_form(pkey, fCompressed ? POINT_CONVERSION_COMPRESSED : POINT_CONVERSION_UNCOMPRESSED);
int nSize = i2o_ECPublicKey(pkey, NULL);
assert(nSize);
assert(nSize <= 65);
unsigned char c[65];
unsigned char *pbegin = c;
int nSize2 = i2o_ECPublicKey(pkey, &pbegin);
assert(nSize == nSize2);
pubkey.Set(&c[0], &c[nSize]);
}
bool SetPubKey(const CPubKey &pubkey) {
const unsigned char* pbegin = pubkey.begin();
return o2i_ECPublicKey(&pkey, &pbegin, pubkey.size());
}
bool Sign(const uint256 &hash, std::vector<unsigned char>& vchSig) {
unsigned int nSize = ECDSA_size(pkey);
vchSig.resize(nSize); // Make sure it is big enough
assert(ECDSA_sign(0, (unsigned char*)&hash, sizeof(hash), &vchSig[0], &nSize, pkey));
vchSig.resize(nSize); // Shrink to fit actual size
return true;
}
bool Verify(const 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;
}
bool SignCompact(const uint256 &hash, unsigned char *p64, int &rec) {
bool fOk = false;
ECDSA_SIG *sig = ECDSA_do_sign((unsigned char*)&hash, sizeof(hash), pkey);
if (sig==NULL)
return false;
memset(p64, 0, 64);
int nBitsR = BN_num_bits(sig->r);
int nBitsS = BN_num_bits(sig->s);
if (nBitsR <= 256 && nBitsS <= 256) {
CPubKey pubkey;
GetPubKey(pubkey, true);
for (int i=0; i<4; i++) {
CECKey keyRec;
if (ECDSA_SIG_recover_key_GFp(keyRec.pkey, sig, (unsigned char*)&hash, sizeof(hash), i, 1) == 1) {
CPubKey pubkeyRec;
keyRec.GetPubKey(pubkeyRec, true);
if (pubkeyRec == pubkey) {
rec = i;
fOk = true;
break;
}
}
}
assert(fOk);
BN_bn2bin(sig->r,&p64[32-(nBitsR+7)/8]);
BN_bn2bin(sig->s,&p64[64-(nBitsS+7)/8]);
}
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 Recover(const uint256 &hash, const unsigned char *p64, int rec)
{
if (rec<0 || rec>=3)
return false;
ECDSA_SIG *sig = ECDSA_SIG_new();
BN_bin2bn(&p64[0], 32, sig->r);
BN_bin2bn(&p64[32], 32, sig->s);
bool ret = ECDSA_SIG_recover_key_GFp(pkey, sig, (unsigned char*)&hash, sizeof(hash), rec, 0) == 1;
ECDSA_SIG_free(sig);
return ret;
}
};
}; // end of anonymous namespace
bool CKey::Check(const unsigned char *vch) {
// Do not convert to OpenSSL's data structures for range-checking keys,
// it's easy enough to do directly.
static const unsigned char vchMax[32] = {
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,0xD0,0x36,0x41,0x40
};
bool fIsZero = true;
for (int i=0; i<32 && fIsZero; i++)
if (vch[i] != 0)
fIsZero = false;
if (fIsZero)
return false;
for (int i=0; i<32; i++) {
if (vch[i] < vchMax[i])
return true;
if (vch[i] > vchMax[i])
return false;
}
return true;
}
void CKey::MakeNewKey(bool fCompressedIn) {
do {
RAND_bytes(vch, sizeof(vch));
} while (!Check(vch));
fValid = true;
fCompressed = fCompressedIn;
}
bool CKey::SetPrivKey(const CPrivKey &privkey, bool fCompressedIn) {
CECKey key;
if (!key.SetPrivKey(privkey))
return false;
key.GetSecretBytes(vch);
fCompressed = fCompressedIn;
fValid = true;
return true;
}
CPrivKey CKey::GetPrivKey() const {
assert(fValid);
CECKey key;
key.SetSecretBytes(vch);
CPrivKey privkey;
key.GetPrivKey(privkey);
return privkey;
}
CPubKey CKey::GetPubKey() const {
assert(fValid);
CECKey key;
key.SetSecretBytes(vch);
CPubKey pubkey;
key.GetPubKey(pubkey, fCompressed);
return pubkey;
}
bool CKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig) const {
if (!fValid)
return false;
CECKey key;
key.SetSecretBytes(vch);
return key.Sign(hash, vchSig);
}
bool CKey::SignCompact(const uint256 &hash, std::vector<unsigned char>& vchSig) const {
if (!fValid)
return false;
CECKey key;
key.SetSecretBytes(vch);
vchSig.resize(65);
int rec = -1;
if (!key.SignCompact(hash, &vchSig[1], rec))
return false;
assert(rec != -1);
vchSig[0] = 27 + rec + (fCompressed ? 4 : 0);
return true;
}
bool CPubKey::Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) const {
if (!IsValid())
return false;
CECKey key;
if (!key.SetPubKey(*this))
return false;
if (!key.Verify(hash, vchSig))
return false;
return true;
}
bool CPubKey::RecoverCompact(const uint256 &hash, const std::vector<unsigned char>& vchSig) {
if (vchSig.size() != 65)
return false;
CECKey key;
if (!key.Recover(hash, &vchSig[1], (vchSig[0] - 27) & ~4))
return false;
key.GetPubKey(*this, (vchSig[0] - 27) & 4);
return true;
}
bool CPubKey::VerifyCompact(const uint256 &hash, const std::vector<unsigned char>& vchSig) const {
if (!IsValid())
return false;
if (vchSig.size() != 65)
return false;
CECKey key;
if (!key.Recover(hash, &vchSig[1], (vchSig[0] - 27) & ~4))
return false;
CPubKey pubkeyRec;
key.GetPubKey(pubkeyRec, IsCompressed());
if (*this != pubkeyRec)
return false;
return true;
}
bool CPubKey::IsFullyValid() const {
if (!IsValid())
return false;
CECKey key;
if (!key.SetPubKey(*this))
return false;
return true;
}
bool CPubKey::Decompress() {
if (!IsValid())
return false;
CECKey key;
if (!key.SetPubKey(*this))
return false;
key.GetPubKey(*this, false);
return true;
}