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BIP32 derivation implementation
This commit is contained in:
Pieter Wuille
parent
8388289eb6
commit
eb2c999050
26
src/base58.h
26
src/base58.h
@ -390,4 +390,30 @@ public:
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}
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};
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template<typename K, int Size, CChainParams::Base58Type Type> class CBitcoinExtKeyBase : public CBase58Data
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{
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public:
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void SetKey(const K &key) {
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unsigned char vch[Size];
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key.Encode(vch);
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SetData(Params().Base58Prefix(Type), vch, vch+Size);
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}
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K GetKey() {
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K ret;
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ret.Decode(&vchData[0], &vchData[Size]);
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return ret;
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}
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CBitcoinExtKeyBase(const K &key) {
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SetKey(key);
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}
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CBitcoinExtKeyBase() {}
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};
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typedef CBitcoinExtKeyBase<CExtKey, 74, CChainParams::EXT_SECRET_KEY> CBitcoinExtKey;
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typedef CBitcoinExtKeyBase<CExtPubKey, 74, CChainParams::EXT_PUBLIC_KEY> CBitcoinExtPubKey;
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#endif // BITCOIN_BASE58_H
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@ -147,6 +147,8 @@ public:
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base58Prefixes[PUBKEY_ADDRESS] = list_of(0);
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base58Prefixes[SCRIPT_ADDRESS] = list_of(5);
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base58Prefixes[SECRET_KEY] = list_of(128);
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base58Prefixes[EXT_PUBLIC_KEY] = list_of(0x04)(0x88)(0xB2)(0x1E);
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base58Prefixes[EXT_SECRET_KEY] = list_of(0x04)(0x88)(0xAD)(0xE4);
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// Convert the pnSeeds array into usable address objects.
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for (unsigned int i = 0; i < ARRAYLEN(pnSeed); i++)
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@ -209,6 +211,8 @@ public:
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base58Prefixes[PUBKEY_ADDRESS] = list_of(111);
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base58Prefixes[SCRIPT_ADDRESS] = list_of(196);
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base58Prefixes[SECRET_KEY] = list_of(239);
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base58Prefixes[EXT_PUBLIC_KEY] = list_of(0x04)(0x35)(0x87)(0xCF);
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base58Prefixes[EXT_SECRET_KEY] = list_of(0x04)(0x35)(0x83)(0x94);
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}
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virtual Network NetworkID() const { return CChainParams::TESTNET; }
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};
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@ -45,6 +45,8 @@ public:
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PUBKEY_ADDRESS,
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SCRIPT_ADDRESS,
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SECRET_KEY,
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EXT_PUBLIC_KEY,
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EXT_SECRET_KEY,
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MAX_BASE58_TYPES
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};
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180
src/key.cpp
180
src/key.cpp
@ -2,6 +2,7 @@
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// Distributed under the MIT/X11 software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#include <openssl/bn.h>
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#include <openssl/ecdsa.h>
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#include <openssl/rand.h>
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#include <openssl/obj_mac.h>
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@ -253,6 +254,57 @@ public:
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ECDSA_SIG_free(sig);
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return ret;
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}
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static bool TweakSecret(unsigned char vchSecretOut[32], const unsigned char vchSecretIn[32], const unsigned char vchTweak[32])
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{
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bool ret = true;
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BN_CTX *ctx = BN_CTX_new();
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BN_CTX_start(ctx);
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BIGNUM *bnSecret = BN_CTX_get(ctx);
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BIGNUM *bnTweak = BN_CTX_get(ctx);
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BIGNUM *bnOrder = BN_CTX_get(ctx);
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EC_GROUP *group = EC_GROUP_new_by_curve_name(NID_secp256k1);
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EC_GROUP_get_order(group, bnOrder, ctx); // what a grossly inefficient way to get the (constant) group order...
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BN_bin2bn(vchTweak, 32, bnTweak);
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if (BN_cmp(bnTweak, bnOrder) >= 0)
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ret = false; // extremely unlikely
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BN_bin2bn(vchSecretIn, 32, bnSecret);
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BN_add(bnSecret, bnSecret, bnTweak);
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BN_nnmod(bnSecret, bnSecret, bnOrder, ctx);
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if (BN_is_zero(bnSecret))
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ret = false; // ridiculously unlikely
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int nBits = BN_num_bits(bnSecret);
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memset(vchSecretOut, 0, 32);
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BN_bn2bin(bnSecret, &vchSecretOut[32-(nBits+7)/8]);
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EC_GROUP_free(group);
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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return ret;
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}
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bool TweakPublic(const unsigned char vchTweak[32]) {
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bool ret = true;
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BN_CTX *ctx = BN_CTX_new();
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BN_CTX_start(ctx);
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BIGNUM *bnTweak = BN_CTX_get(ctx);
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BIGNUM *bnOrder = BN_CTX_get(ctx);
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BIGNUM *bnOne = BN_CTX_get(ctx);
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const EC_GROUP *group = EC_KEY_get0_group(pkey);
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EC_GROUP_get_order(group, bnOrder, ctx); // what a grossly inefficient way to get the (constant) group order...
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BN_bin2bn(vchTweak, 32, bnTweak);
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if (BN_cmp(bnTweak, bnOrder) >= 0)
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ret = false; // extremely unlikely
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EC_POINT *point = EC_POINT_dup(EC_KEY_get0_public_key(pkey), group);
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BN_one(bnOne);
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EC_POINT_mul(group, point, bnTweak, point, bnOne, ctx);
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if (EC_POINT_is_at_infinity(group, point))
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ret = false; // ridiculously unlikely
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EC_KEY_set_public_key(pkey, point);
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EC_POINT_free(point);
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BN_CTX_end(ctx);
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BN_CTX_free(ctx);
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return ret;
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}
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};
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}; // end of anonymous namespace
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@ -393,3 +445,131 @@ bool CPubKey::Decompress() {
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key.GetPubKey(*this, false);
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return true;
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}
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void static BIP32Hash(const unsigned char chainCode[32], unsigned int nChild, unsigned char header, const unsigned char data[32], unsigned char output[64]) {
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unsigned char num[4];
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num[0] = (nChild >> 24) & 0xFF;
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num[1] = (nChild >> 16) & 0xFF;
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num[2] = (nChild >> 8) & 0xFF;
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num[3] = (nChild >> 0) & 0xFF;
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HMAC_SHA512_CTX ctx;
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HMAC_SHA512_Init(&ctx, chainCode, 32);
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HMAC_SHA512_Update(&ctx, &header, 1);
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HMAC_SHA512_Update(&ctx, data, 32);
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HMAC_SHA512_Update(&ctx, num, 4);
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HMAC_SHA512_Final(output, &ctx);
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}
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bool CKey::Derive(CKey& keyChild, unsigned char ccChild[32], unsigned int nChild, const unsigned char cc[32]) const {
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assert(IsValid());
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assert(IsCompressed());
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unsigned char out[64];
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LockObject(out);
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if ((nChild >> 31) == 0) {
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CPubKey pubkey = GetPubKey();
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assert(pubkey.begin() + 33 == pubkey.end());
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BIP32Hash(cc, nChild, *pubkey.begin(), pubkey.begin()+1, out);
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} else {
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assert(begin() + 32 == end());
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BIP32Hash(cc, nChild, 0, begin(), out);
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}
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memcpy(ccChild, out+32, 32);
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bool ret = CECKey::TweakSecret((unsigned char*)keyChild.begin(), begin(), out);
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UnlockObject(out);
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keyChild.fCompressed = true;
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keyChild.fValid = ret;
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return ret;
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}
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bool CPubKey::Derive(CPubKey& pubkeyChild, unsigned char ccChild[32], unsigned int nChild, const unsigned char cc[32]) const {
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assert(IsValid());
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assert((nChild >> 31) == 0);
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assert(begin() + 33 == end());
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unsigned char out[64];
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BIP32Hash(cc, nChild, *begin(), begin()+1, out);
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memcpy(ccChild, out+32, 32);
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CECKey key;
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bool ret = key.SetPubKey(*this);
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ret &= key.TweakPublic(out);
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key.GetPubKey(pubkeyChild, true);
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return ret;
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}
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bool CExtKey::Derive(CExtKey &out, unsigned int nChild) const {
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out.nDepth = nDepth + 1;
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CKeyID id = key.GetPubKey().GetID();
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memcpy(&out.vchFingerprint[0], &id, 4);
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out.nChild = nChild;
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return key.Derive(out.key, out.vchChainCode, nChild, vchChainCode);
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}
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void CExtKey::SetMaster(const unsigned char *seed, unsigned int nSeedLen) {
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static const char hashkey[] = {'B','i','t','c','o','i','n',' ','s','e','e','d'};
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HMAC_SHA512_CTX ctx;
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HMAC_SHA512_Init(&ctx, hashkey, sizeof(hashkey));
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HMAC_SHA512_Update(&ctx, seed, nSeedLen);
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unsigned char out[64];
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LockObject(out);
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HMAC_SHA512_Final(out, &ctx);
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key.Set(&out[0], &out[32], true);
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memcpy(vchChainCode, &out[32], 32);
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UnlockObject(out);
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nDepth = 0;
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nChild = 0;
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memset(vchFingerprint, 0, sizeof(vchFingerprint));
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}
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CExtPubKey CExtKey::Neuter() const {
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CExtPubKey ret;
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ret.nDepth = nDepth;
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memcpy(&ret.vchFingerprint[0], &vchFingerprint[0], 4);
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ret.nChild = nChild;
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ret.pubkey = key.GetPubKey();
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memcpy(&ret.vchChainCode[0], &vchChainCode[0], 32);
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return ret;
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}
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void CExtKey::Encode(unsigned char code[74]) const {
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code[0] = nDepth;
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memcpy(code+1, vchFingerprint, 4);
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code[5] = (nChild >> 24) & 0xFF; code[6] = (nChild >> 16) & 0xFF;
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code[7] = (nChild >> 8) & 0xFF; code[8] = (nChild >> 0) & 0xFF;
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memcpy(code+9, vchChainCode, 32);
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code[41] = 0;
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assert(key.size() == 32);
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memcpy(code+42, key.begin(), 32);
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}
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void CExtKey::Decode(const unsigned char code[74]) {
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nDepth = code[0];
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memcpy(vchFingerprint, code+1, 4);
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nChild = (code[5] << 24) | (code[6] << 16) | (code[7] << 8) | code[8];
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memcpy(vchChainCode, code+9, 32);
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key.Set(code+42, code+74, true);
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}
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void CExtPubKey::Encode(unsigned char code[74]) const {
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code[0] = nDepth;
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memcpy(code+1, vchFingerprint, 4);
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code[5] = (nChild >> 24) & 0xFF; code[6] = (nChild >> 16) & 0xFF;
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code[7] = (nChild >> 8) & 0xFF; code[8] = (nChild >> 0) & 0xFF;
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memcpy(code+9, vchChainCode, 32);
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assert(pubkey.size() == 33);
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memcpy(code+41, pubkey.begin(), 33);
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}
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void CExtPubKey::Decode(const unsigned char code[74]) {
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nDepth = code[0];
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memcpy(vchFingerprint, code+1, 4);
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nChild = (code[5] << 24) | (code[6] << 16) | (code[7] << 8) | code[8];
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memcpy(vchChainCode, code+9, 32);
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pubkey.Set(code+41, code+74);
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}
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bool CExtPubKey::Derive(CExtPubKey &out, unsigned int nChild) const {
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out.nDepth = nDepth + 1;
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CKeyID id = pubkey.GetID();
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memcpy(&out.vchFingerprint[0], &id, 4);
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out.nChild = nChild;
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return pubkey.Derive(out.pubkey, out.vchChainCode, nChild, vchChainCode);
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}
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46
src/key.h
46
src/key.h
@ -161,6 +161,9 @@ public:
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// Turn this public key into an uncompressed public key.
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bool Decompress();
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// Derive BIP32 child pubkey.
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bool Derive(CPubKey& pubkeyChild, unsigned char ccChild[32], unsigned int nChild, const unsigned char cc[32]) const;
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};
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@ -201,6 +204,10 @@ public:
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UnlockObject(vch);
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}
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friend bool operator==(const CKey &a, const CKey &b) {
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return a.fCompressed == b.fCompressed && memcmp(&a.vch[0], &b.vch[0], 32);
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}
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// Initialize using begin and end iterators to byte data.
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template<typename T>
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void Set(const T pbegin, const T pend, bool fCompressedIn) {
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@ -251,6 +258,45 @@ public:
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// 0x1D = second key with even y, 0x1E = second key with odd y,
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// add 0x04 for compressed keys.
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bool SignCompact(const uint256 &hash, std::vector<unsigned char>& vchSig) const;
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// Derive BIP32 child key.
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bool Derive(CKey& keyChild, unsigned char ccChild[32], unsigned int nChild, const unsigned char cc[32]) const;
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};
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struct CExtPubKey {
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unsigned char nDepth;
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unsigned char vchFingerprint[4];
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unsigned int nChild;
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unsigned char vchChainCode[32];
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CPubKey pubkey;
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friend bool operator==(const CExtPubKey &a, const CExtPubKey &b) {
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return a.nDepth == b.nDepth && memcmp(&a.vchFingerprint[0], &b.vchFingerprint[0], 4) == 0 && a.nChild == b.nChild &&
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memcmp(&a.vchChainCode[0], &b.vchChainCode[0], 32) == 0 && a.pubkey == b.pubkey;
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}
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void Encode(unsigned char code[74]) const;
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void Decode(const unsigned char code[74]);
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bool Derive(CExtPubKey &out, unsigned int nChild) const;
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};
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struct CExtKey {
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unsigned char nDepth;
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unsigned char vchFingerprint[4];
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unsigned int nChild;
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unsigned char vchChainCode[32];
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CKey key;
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friend bool operator==(const CExtKey &a, const CExtKey &b) {
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return a.nDepth == b.nDepth && memcmp(&a.vchFingerprint[0], &b.vchFingerprint[0], 4) == 0 && a.nChild == b.nChild &&
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memcmp(&a.vchChainCode[0], &b.vchChainCode[0], 32) == 0 && a.key == b.key;
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}
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void Encode(unsigned char code[74]) const;
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void Decode(const unsigned char code[74]);
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bool Derive(CExtKey &out, unsigned int nChild) const;
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CExtPubKey Neuter() const;
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void SetMaster(const unsigned char *seed, unsigned int nSeedLen);
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};
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#endif
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