src/key.cpp

   1 // Copyright (c) 2009-2013 The Bitcoin developers
   2 // Distributed under the MIT/X11 software license, see the accompanying
   3 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
   4
   5 #include "key.h"
   6
   7 #include <openssl/bn.h>
   8 #include <openssl/ecdsa.h>
   9 #include <openssl/obj_mac.h>
  10 #include <openssl/rand.h>
  11
  12 // anonymous namespace with local implementation code (OpenSSL interaction)
  13 namespace {
  14
  15 // Generate a private key from just the secret parameter
  16 int EC_KEY_regenerate_key(EC_KEY *eckey, BIGNUM *priv_key)
  17 {
  18     int ok = 0;
  19     BN_CTX *ctx = NULL;
  20     EC_POINT *pub_key = NULL;
  21
  22     if (!eckey) return 0;
  23
  24     const EC_GROUP *group = EC_KEY_get0_group(eckey);
  25
  26     if ((ctx = BN_CTX_new()) == NULL)
  27         goto err;
  28
  29     pub_key = EC_POINT_new(group);
  30
  31     if (pub_key == NULL)
  32         goto err;
  33
  34     if (!EC_POINT_mul(group, pub_key, priv_key, NULL, NULL, ctx))
  35         goto err;
  36
  37     EC_KEY_set_private_key(eckey,priv_key);
  38     EC_KEY_set_public_key(eckey,pub_key);
  39
  40     ok = 1;
  41
  42 err:
  43
  44     if (pub_key)
  45         EC_POINT_free(pub_key);
  46     if (ctx != NULL)
  47         BN_CTX_free(ctx);
  48
  49     return(ok);
  50 }
  51
  52 // Perform ECDSA key recovery (see SEC1 4.1.6) for curves over (mod p)-fields
  53 // recid selects which key is recovered
  54 // if check is non-zero, additional checks are performed
  55 int ECDSA_SIG_recover_key_GFp(EC_KEY *eckey, ECDSA_SIG *ecsig, const unsigned char *msg, int msglen, int recid, int check)
  56 {
  57     if (!eckey) return 0;
  58
  59     int ret = 0;
  60     BN_CTX *ctx = NULL;
  61
  62     BIGNUM *x = NULL;
  63     BIGNUM *e = NULL;
  64     BIGNUM *order = NULL;
  65     BIGNUM *sor = NULL;
  66     BIGNUM *eor = NULL;
  67     BIGNUM *field = NULL;
  68     EC_POINT *R = NULL;
  69     EC_POINT *O = NULL;
  70     EC_POINT *Q = NULL;
  71     BIGNUM *rr = NULL;
  72     BIGNUM *zero = NULL;
  73     int n = 0;
  74     int i = recid / 2;
  75
  76     const EC_GROUP *group = EC_KEY_get0_group(eckey);
  77     if ((ctx = BN_CTX_new()) == NULL) { ret = -1; goto err; }
  78     BN_CTX_start(ctx);
  79     order = BN_CTX_get(ctx);
  80     if (!EC_GROUP_get_order(group, order, ctx)) { ret = -2; goto err; }
  81     x = BN_CTX_get(ctx);
  82     if (!BN_copy(x, order)) { ret=-1; goto err; }
  83     if (!BN_mul_word(x, i)) { ret=-1; goto err; }
  84     if (!BN_add(x, x, ecsig->r)) { ret=-1; goto err; }
  85     field = BN_CTX_get(ctx);
  86     if (!EC_GROUP_get_curve_GFp(group, field, NULL, NULL, ctx)) { ret=-2; goto err; }
  87     if (BN_cmp(x, field) >= 0) { ret=0; goto err; }
  88     if ((R = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
  89     if (!EC_POINT_set_compressed_coordinates_GFp(group, R, x, recid % 2, ctx)) { ret=0; goto err; }
  90     if (check)
  91     {
  92         if ((O = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
  93         if (!EC_POINT_mul(group, O, NULL, R, order, ctx)) { ret=-2; goto err; }
  94         if (!EC_POINT_is_at_infinity(group, O)) { ret = 0; goto err; }
  95     }
  96     if ((Q = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
  97     n = EC_GROUP_get_degree(group);
  98     e = BN_CTX_get(ctx);
  99     if (!BN_bin2bn(msg, msglen, e)) { ret=-1; goto err; }
 100     if (8*msglen > n) BN_rshift(e, e, 8-(n & 7));
 101     zero = BN_CTX_get(ctx);
 102     if (!BN_zero(zero)) { ret=-1; goto err; }
 103     if (!BN_mod_sub(e, zero, e, order, ctx)) { ret=-1; goto err; }
 104     rr = BN_CTX_get(ctx);
 105     if (!BN_mod_inverse(rr, ecsig->r, order, ctx)) { ret=-1; goto err; }
 106     sor = BN_CTX_get(ctx);
 107     if (!BN_mod_mul(sor, ecsig->s, rr, order, ctx)) { ret=-1; goto err; }
 108     eor = BN_CTX_get(ctx);
 109     if (!BN_mod_mul(eor, e, rr, order, ctx)) { ret=-1; goto err; }
 110     if (!EC_POINT_mul(group, Q, eor, R, sor, ctx)) { ret=-2; goto err; }
 111     if (!EC_KEY_set_public_key(eckey, Q)) { ret=-2; goto err; }
 112
 113     ret = 1;
 114
 115 err:
 116     if (ctx) {
 117         BN_CTX_end(ctx);
 118         BN_CTX_free(ctx);
 119     }
 120     if (R != NULL) EC_POINT_free(R);
 121     if (O != NULL) EC_POINT_free(O);
 122     if (Q != NULL) EC_POINT_free(Q);
 123     return ret;
 124 }
 125
 126 // RAII Wrapper around OpenSSL's EC_KEY
 127 class CECKey {
 128 private:
 129     EC_KEY *pkey;
 130
 131 public:
 132     CECKey() {
 133         pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
 134         assert(pkey != NULL);
 135     }
 136
 137     ~CECKey() {
 138         EC_KEY_free(pkey);
 139     }
 140
 141     void GetSecretBytes(unsigned char vch[32]) const {
 142         const BIGNUM *bn = EC_KEY_get0_private_key(pkey);
 143         assert(bn);
 144         int nBytes = BN_num_bytes(bn);
 145         int n=BN_bn2bin(bn,&vch[32 - nBytes]);
 146         assert(n == nBytes);
 147         memset(vch, 0, 32 - nBytes);
 148     }
 149
 150     void SetSecretBytes(const unsigned char vch[32]) {
 151         bool ret;
 152         BIGNUM bn;
 153         BN_init(&bn);
 154         ret = BN_bin2bn(vch, 32, &bn);
 155         assert(ret);
 156         ret = EC_KEY_regenerate_key(pkey, &bn);
 157         assert(ret);
 158         BN_clear_free(&bn);
 159     }
 160
 161     void GetPrivKey(CPrivKey &privkey, bool fCompressed) {
 162         EC_KEY_set_conv_form(pkey, fCompressed ? POINT_CONVERSION_COMPRESSED : POINT_CONVERSION_UNCOMPRESSED);
 163         int nSize = i2d_ECPrivateKey(pkey, NULL);
 164         assert(nSize);
 165         privkey.resize(nSize);
 166         unsigned char* pbegin = &privkey[0];
 167         int nSize2 = i2d_ECPrivateKey(pkey, &pbegin);
 168         assert(nSize == nSize2);
 169     }
 170
 171     bool SetPrivKey(const CPrivKey &privkey, bool fSkipCheck=false) {
 172         const unsigned char* pbegin = &privkey[0];
 173         if (d2i_ECPrivateKey(&pkey, &pbegin, privkey.size())) {
 174             if(fSkipCheck)
 175                 return true;
 176
 177             // d2i_ECPrivateKey returns true if parsing succeeds.
 178             // This doesn't necessarily mean the key is valid.
 179             if (EC_KEY_check_key(pkey))
 180                 return true;
 181         }
 182         return false;
 183     }
 184
 185     void GetPubKey(CPubKey &pubkey, bool fCompressed) {
 186         EC_KEY_set_conv_form(pkey, fCompressed ? POINT_CONVERSION_COMPRESSED : POINT_CONVERSION_UNCOMPRESSED);
 187         int nSize = i2o_ECPublicKey(pkey, NULL);
 188         assert(nSize);
 189         assert(nSize <= 65);
 190         unsigned char c[65];
 191         unsigned char *pbegin = c;
 192         int nSize2 = i2o_ECPublicKey(pkey, &pbegin);
 193         assert(nSize == nSize2);
 194         pubkey.Set(&c[0], &c[nSize]);
 195     }
 196
 197     bool SetPubKey(const CPubKey &pubkey) {
 198         const unsigned char* pbegin = pubkey.begin();
 199         return o2i_ECPublicKey(&pkey, &pbegin, pubkey.size());
 200     }
 201
 202     bool Sign(const uint256 &hash, std::vector<unsigned char>& vchSig) {
 203         vchSig.clear();
 204         ECDSA_SIG *sig = ECDSA_do_sign((unsigned char*)&hash, sizeof(hash), pkey);
 205         if (sig == NULL)
 206             return false;
 207         BN_CTX *ctx = BN_CTX_new();
 208         BN_CTX_start(ctx);
 209         const EC_GROUP *group = EC_KEY_get0_group(pkey);
 210         BIGNUM *order = BN_CTX_get(ctx);
 211         BIGNUM *halforder = BN_CTX_get(ctx);
 212         EC_GROUP_get_order(group, order, ctx);
 213         BN_rshift1(halforder, order);
 214         if (BN_cmp(sig->s, halforder) > 0) {
 215             // enforce low S values, by negating the value (modulo the order) if above order/2.
 216             BN_sub(sig->s, order, sig->s);
 217         }
 218         BN_CTX_end(ctx);
 219         BN_CTX_free(ctx);
 220         unsigned int nSize = ECDSA_size(pkey);
 221         vchSig.resize(nSize); // Make sure it is big enough
 222         unsigned char *pos = &vchSig[0];
 223         nSize = i2d_ECDSA_SIG(sig, &pos);
 224         ECDSA_SIG_free(sig);
 225         vchSig.resize(nSize); // Shrink to fit actual size
 226         return true;
 227     }
 228
 229     bool Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) {
 230         // -1 = error, 0 = bad sig, 1 = good
 231         if (ECDSA_verify(0, (unsigned char*)&hash, sizeof(hash), &vchSig[0], vchSig.size(), pkey) != 1)
 232             return false;
 233         return true;
 234     }
 235
 236     bool SignCompact(const uint256 &hash, unsigned char *p64, int &rec) {
 237         bool fOk = false;
 238         ECDSA_SIG *sig = ECDSA_do_sign((unsigned char*)&hash, sizeof(hash), pkey);
 239         if (sig==NULL)
 240             return false;
 241         memset(p64, 0, 64);
 242         int nBitsR = BN_num_bits(sig->r);
 243         int nBitsS = BN_num_bits(sig->s);
 244         if (nBitsR <= 256 && nBitsS <= 256) {
 245             CPubKey pubkey;
 246             GetPubKey(pubkey, true);
 247             for (int i=0; i<4; i++) {
 248                 CECKey keyRec;
 249                 if (ECDSA_SIG_recover_key_GFp(keyRec.pkey, sig, (unsigned char*)&hash, sizeof(hash), i, 1) == 1) {
 250                     CPubKey pubkeyRec;
 251                     keyRec.GetPubKey(pubkeyRec, true);
 252                     if (pubkeyRec == pubkey) {
 253                         rec = i;
 254                         fOk = true;
 255                         break;
 256                     }
 257                 }
 258             }
 259             assert(fOk);
 260             BN_bn2bin(sig->r,&p64[32-(nBitsR+7)/8]);
 261             BN_bn2bin(sig->s,&p64[64-(nBitsS+7)/8]);
 262         }
 263         ECDSA_SIG_free(sig);
 264         return fOk;
 265     }
 266
 267     // reconstruct public key from a compact signature
 268     // This is only slightly more CPU intensive than just verifying it.
 269     // If this function succeeds, the recovered public key is guaranteed to be valid
 270     // (the signature is a valid signature of the given data for that key)
 271     bool Recover(const uint256 &hash, const unsigned char *p64, int rec)
 272     {
 273         if (rec<0 || rec>=3)
 274             return false;
 275         ECDSA_SIG *sig = ECDSA_SIG_new();
 276         BN_bin2bn(&p64[0],  32, sig->r);
 277         BN_bin2bn(&p64[32], 32, sig->s);
 278         bool ret = ECDSA_SIG_recover_key_GFp(pkey, sig, (unsigned char*)&hash, sizeof(hash), rec, 0) == 1;
 279         ECDSA_SIG_free(sig);
 280         return ret;
 281     }
 282
 283     static bool TweakSecret(unsigned char vchSecretOut[32], const unsigned char vchSecretIn[32], const unsigned char vchTweak[32])
 284     {
 285         bool ret = true;
 286         BN_CTX *ctx = BN_CTX_new();
 287         BN_CTX_start(ctx);
 288         BIGNUM *bnSecret = BN_CTX_get(ctx);
 289         BIGNUM *bnTweak = BN_CTX_get(ctx);
 290         BIGNUM *bnOrder = BN_CTX_get(ctx);
 291         EC_GROUP *group = EC_GROUP_new_by_curve_name(NID_secp256k1);
 292         EC_GROUP_get_order(group, bnOrder, ctx); // what a grossly inefficient way to get the (constant) group order...
 293         BN_bin2bn(vchTweak, 32, bnTweak);
 294         if (BN_cmp(bnTweak, bnOrder) >= 0)
 295             ret = false; // extremely unlikely
 296         BN_bin2bn(vchSecretIn, 32, bnSecret);
 297         BN_add(bnSecret, bnSecret, bnTweak);
 298         BN_nnmod(bnSecret, bnSecret, bnOrder, ctx);
 299         if (BN_is_zero(bnSecret))
 300             ret = false; // ridiculously unlikely
 301         int nBits = BN_num_bits(bnSecret);
 302         memset(vchSecretOut, 0, 32);
 303         BN_bn2bin(bnSecret, &vchSecretOut[32-(nBits+7)/8]);
 304         EC_GROUP_free(group);
 305         BN_CTX_end(ctx);
 306         BN_CTX_free(ctx);
 307         return ret;
 308     }
 309
 310     bool TweakPublic(const unsigned char vchTweak[32]) {
 311         bool ret = true;
 312         BN_CTX *ctx = BN_CTX_new();
 313         BN_CTX_start(ctx);
 314         BIGNUM *bnTweak = BN_CTX_get(ctx);
 315         BIGNUM *bnOrder = BN_CTX_get(ctx);
 316         BIGNUM *bnOne = BN_CTX_get(ctx);
 317         const EC_GROUP *group = EC_KEY_get0_group(pkey);
 318         EC_GROUP_get_order(group, bnOrder, ctx); // what a grossly inefficient way to get the (constant) group order...
 319         BN_bin2bn(vchTweak, 32, bnTweak);
 320         if (BN_cmp(bnTweak, bnOrder) >= 0)
 321             ret = false; // extremely unlikely
 322         EC_POINT *point = EC_POINT_dup(EC_KEY_get0_public_key(pkey), group);
 323         BN_one(bnOne);
 324         EC_POINT_mul(group, point, bnTweak, point, bnOne, ctx);
 325         if (EC_POINT_is_at_infinity(group, point))
 326             ret = false; // ridiculously unlikely
 327         EC_KEY_set_public_key(pkey, point);
 328         EC_POINT_free(point);
 329         BN_CTX_end(ctx);
 330         BN_CTX_free(ctx);
 331         return ret;
 332     }
 333 };
 334
 335 }; // end of anonymous namespace
 336
 337 bool CKey::Check(const unsigned char *vch) {
 338     // Do not convert to OpenSSL's data structures for range-checking keys,
 339     // it's easy enough to do directly.
 340     static const unsigned char vchMax[32] = {
 341         0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,
 342         0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFF,0xFE,
 343         0xBA,0xAE,0xDC,0xE6,0xAF,0x48,0xA0,0x3B,
 344         0xBF,0xD2,0x5E,0x8C,0xD0,0x36,0x41,0x40
 345     };
 346     bool fIsZero = true;
 347     for (int i=0; i<32 && fIsZero; i++)
 348         if (vch[i] != 0)
 349             fIsZero = false;
 350     if (fIsZero)
 351         return false;
 352     for (int i=0; i<32; i++) {
 353         if (vch[i] < vchMax[i])
 354             return true;
 355         if (vch[i] > vchMax[i])
 356             return false;
 357     }
 358     return true;
 359 }
 360
 361 void CKey::MakeNewKey(bool fCompressedIn) {
 362     do {
 363         RAND_bytes(vch, sizeof(vch));
 364     } while (!Check(vch));
 365     fValid = true;
 366     fCompressed = fCompressedIn;
 367 }
 368
 369 bool CKey::SetPrivKey(const CPrivKey &privkey, bool fCompressedIn) {
 370     CECKey key;
 371     if (!key.SetPrivKey(privkey))
 372         return false;
 373     key.GetSecretBytes(vch);
 374     fCompressed = fCompressedIn;
 375     fValid = true;
 376     return true;
 377 }
 378
 379 CPrivKey CKey::GetPrivKey() const {
 380     assert(fValid);
 381     CECKey key;
 382     key.SetSecretBytes(vch);
 383     CPrivKey privkey;
 384     key.GetPrivKey(privkey, fCompressed);
 385     return privkey;
 386 }
 387
 388 CPubKey CKey::GetPubKey() const {
 389     assert(fValid);
 390     CECKey key;
 391     key.SetSecretBytes(vch);
 392     CPubKey pubkey;
 393     key.GetPubKey(pubkey, fCompressed);
 394     return pubkey;
 395 }
 396
 397 bool CKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig) const {
 398     if (!fValid)
 399         return false;
 400     CECKey key;
 401     key.SetSecretBytes(vch);
 402     return key.Sign(hash, vchSig);
 403 }
 404
 405 bool CKey::SignCompact(const uint256 &hash, std::vector<unsigned char>& vchSig) const {
 406     if (!fValid)
 407         return false;
 408     CECKey key;
 409     key.SetSecretBytes(vch);
 410     vchSig.resize(65);
 411     int rec = -1;
 412     if (!key.SignCompact(hash, &vchSig[1], rec))
 413         return false;
 414     assert(rec != -1);
 415     vchSig[0] = 27 + rec + (fCompressed ? 4 : 0);
 416     return true;
 417 }
 418
 419 bool CKey::Load(CPrivKey &privkey, CPubKey &vchPubKey, bool fSkipCheck=false) {
 420     CECKey key;
 421     if (!key.SetPrivKey(privkey, fSkipCheck))
 422         return false;
 423
 424     key.GetSecretBytes(vch);
 425     fCompressed = vchPubKey.IsCompressed();
 426     fValid = true;
 427
 428     if (fSkipCheck)
 429         return true;
 430
 431     if (GetPubKey() != vchPubKey)
 432         return false;
 433
 434     return true;
 435 }
 436
 437 bool CPubKey::Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) const {
 438     if (!IsValid())
 439         return false;
 440     CECKey key;
 441     if (!key.SetPubKey(*this))
 442         return false;
 443     if (!key.Verify(hash, vchSig))
 444         return false;
 445     return true;
 446 }
 447
 448 bool CPubKey::RecoverCompact(const uint256 &hash, const std::vector<unsigned char>& vchSig) {
 449     if (vchSig.size() != 65)
 450         return false;
 451     CECKey key;
 452     if (!key.Recover(hash, &vchSig[1], (vchSig[0] - 27) & ~4))
 453         return false;
 454     key.GetPubKey(*this, (vchSig[0] - 27) & 4);
 455     return true;
 456 }
 457
 458 bool CPubKey::VerifyCompact(const uint256 &hash, const std::vector<unsigned char>& vchSig) const {
 459     if (!IsValid())
 460         return false;
 461     if (vchSig.size() != 65)
 462         return false;
 463     CECKey key;
 464     if (!key.Recover(hash, &vchSig[1], (vchSig[0] - 27) & ~4))
 465         return false;
 466     CPubKey pubkeyRec;
 467     key.GetPubKey(pubkeyRec, IsCompressed());
 468     if (*this != pubkeyRec)
 469         return false;
 470     return true;
 471 }
 472
 473 bool CPubKey::IsFullyValid() const {
 474     if (!IsValid())
 475         return false;
 476     CECKey key;
 477     if (!key.SetPubKey(*this))
 478         return false;
 479     return true;
 480 }
 481
 482 bool CPubKey::Decompress() {
 483     if (!IsValid())
 484         return false;
 485     CECKey key;
 486     if (!key.SetPubKey(*this))
 487         return false;
 488     key.GetPubKey(*this, false);
 489     return true;
 490 }
 491
 492 void static BIP32Hash(const unsigned char chainCode[32], unsigned int nChild, unsigned char header, const unsigned char data[32], unsigned char output[64]) {
 493     unsigned char num[4];
 494     num[0] = (nChild >> 24) & 0xFF;
 495     num[1] = (nChild >> 16) & 0xFF;
 496     num[2] = (nChild >>  8) & 0xFF;
 497     num[3] = (nChild >>  0) & 0xFF;
 498     HMAC_SHA512_CTX ctx;
 499     HMAC_SHA512_Init(&ctx, chainCode, 32);
 500     HMAC_SHA512_Update(&ctx, &header, 1);
 501     HMAC_SHA512_Update(&ctx, data, 32);
 502     HMAC_SHA512_Update(&ctx, num, 4);
 503     HMAC_SHA512_Final(output, &ctx);
 504 }
 505
 506 bool CKey::Derive(CKey& keyChild, unsigned char ccChild[32], unsigned int nChild, const unsigned char cc[32]) const {
 507     assert(IsValid());
 508     assert(IsCompressed());
 509     unsigned char out[64];
 510     LockObject(out);
 511     if ((nChild >> 31) == 0) {
 512         CPubKey pubkey = GetPubKey();
 513         assert(pubkey.begin() + 33 == pubkey.end());
 514         BIP32Hash(cc, nChild, *pubkey.begin(), pubkey.begin()+1, out);
 515     } else {
 516         assert(begin() + 32 == end());
 517         BIP32Hash(cc, nChild, 0, begin(), out);
 518     }
 519     memcpy(ccChild, out+32, 32);
 520     bool ret = CECKey::TweakSecret((unsigned char*)keyChild.begin(), begin(), out);
 521     UnlockObject(out);
 522     keyChild.fCompressed = true;
 523     keyChild.fValid = ret;
 524     return ret;
 525 }
 526
 527 bool CPubKey::Derive(CPubKey& pubkeyChild, unsigned char ccChild[32], unsigned int nChild, const unsigned char cc[32]) const {
 528     assert(IsValid());
 529     assert((nChild >> 31) == 0);
 530     assert(begin() + 33 == end());
 531     unsigned char out[64];
 532     BIP32Hash(cc, nChild, *begin(), begin()+1, out);
 533     memcpy(ccChild, out+32, 32);
 534     CECKey key;
 535     bool ret = key.SetPubKey(*this);
 536     ret &= key.TweakPublic(out);
 537     key.GetPubKey(pubkeyChild, true);
 538     return ret;
 539 }
 540
 541 bool CExtKey::Derive(CExtKey &out, unsigned int nChild) const {
 542     out.nDepth = nDepth + 1;
 543     CKeyID id = key.GetPubKey().GetID();
 544     memcpy(&out.vchFingerprint[0], &id, 4);
 545     out.nChild = nChild;
 546     return key.Derive(out.key, out.vchChainCode, nChild, vchChainCode);
 547 }
 548
 549 void CExtKey::SetMaster(const unsigned char *seed, unsigned int nSeedLen) {
 550     static const char hashkey[] = {'B','i','t','c','o','i','n',' ','s','e','e','d'};
 551     HMAC_SHA512_CTX ctx;
 552     HMAC_SHA512_Init(&ctx, hashkey, sizeof(hashkey));
 553     HMAC_SHA512_Update(&ctx, seed, nSeedLen);
 554     unsigned char out[64];
 555     LockObject(out);
 556     HMAC_SHA512_Final(out, &ctx);
 557     key.Set(&out[0], &out[32], true);
 558     memcpy(vchChainCode, &out[32], 32);
 559     UnlockObject(out);
 560     nDepth = 0;
 561     nChild = 0;
 562     memset(vchFingerprint, 0, sizeof(vchFingerprint));
 563 }
 564
 565 CExtPubKey CExtKey::Neuter() const {
 566     CExtPubKey ret;
 567     ret.nDepth = nDepth;
 568     memcpy(&ret.vchFingerprint[0], &vchFingerprint[0], 4);
 569     ret.nChild = nChild;
 570     ret.pubkey = key.GetPubKey();
 571     memcpy(&ret.vchChainCode[0], &vchChainCode[0], 32);
 572     return ret;
 573 }
 574
 575 void CExtKey::Encode(unsigned char code[74]) const {
 576     code[0] = nDepth;
 577     memcpy(code+1, vchFingerprint, 4);
 578     code[5] = (nChild >> 24) & 0xFF; code[6] = (nChild >> 16) & 0xFF;
 579     code[7] = (nChild >>  8) & 0xFF; code[8] = (nChild >>  0) & 0xFF;
 580     memcpy(code+9, vchChainCode, 32);
 581     code[41] = 0;
 582     assert(key.size() == 32);
 583     memcpy(code+42, key.begin(), 32);
 584 }
 585
 586 void CExtKey::Decode(const unsigned char code[74]) {
 587     nDepth = code[0];
 588     memcpy(vchFingerprint, code+1, 4);
 589     nChild = (code[5] << 24) | (code[6] << 16) | (code[7] << 8) | code[8];
 590     memcpy(vchChainCode, code+9, 32);
 591     key.Set(code+42, code+74, true);
 592 }
 593
 594 void CExtPubKey::Encode(unsigned char code[74]) const {
 595     code[0] = nDepth;
 596     memcpy(code+1, vchFingerprint, 4);
 597     code[5] = (nChild >> 24) & 0xFF; code[6] = (nChild >> 16) & 0xFF;
 598     code[7] = (nChild >>  8) & 0xFF; code[8] = (nChild >>  0) & 0xFF;
 599     memcpy(code+9, vchChainCode, 32);
 600     assert(pubkey.size() == 33);
 601     memcpy(code+41, pubkey.begin(), 33);
 602 }
 603
 604 void CExtPubKey::Decode(const unsigned char code[74]) {
 605     nDepth = code[0];
 606     memcpy(vchFingerprint, code+1, 4);
 607     nChild = (code[5] << 24) | (code[6] << 16) | (code[7] << 8) | code[8];
 608     memcpy(vchChainCode, code+9, 32);
 609     pubkey.Set(code+41, code+74);
 610 }
 611
 612 bool CExtPubKey::Derive(CExtPubKey &out, unsigned int nChild) const {
 613     out.nDepth = nDepth + 1;
 614     CKeyID id = pubkey.GetID();
 615     memcpy(&out.vchFingerprint[0], &id, 4);
 616     out.nChild = nChild;
 617     return pubkey.Derive(out.pubkey, out.vchChainCode, nChild, vchChainCode);
 618 }