raw
genesis                 1 // Copyright (c) 2009-2010 Satoshi Nakamoto
genesis                 2 // Copyright (c) 2009-2012 The Bitcoin developers
genesis                 3 // Distributed under the MIT/X11 software license, see the accompanying
genesis                 4 // file license.txt or http://www.opensource.org/licenses/mit-license.php.
genesis                 5 #ifndef BITCOIN_KEY_H
genesis                 6 #define BITCOIN_KEY_H
genesis                 7 
genesis                 8 #include <stdexcept>
genesis                 9 #include <vector>
genesis                10 
genesis                11 #include <openssl/ec.h>
genesis                12 #include <openssl/ecdsa.h>
genesis                13 #include <openssl/obj_mac.h>
genesis                14 
genesis                15 #include "serialize.h"
genesis                16 #include "uint256.h"
genesis                17 
genesis                18 // secp160k1
genesis                19 // const unsigned int PRIVATE_KEY_SIZE = 192;
genesis                20 // const unsigned int PUBLIC_KEY_SIZE  = 41;
genesis                21 // const unsigned int SIGNATURE_SIZE   = 48;
genesis                22 //
genesis                23 // secp192k1
genesis                24 // const unsigned int PRIVATE_KEY_SIZE = 222;
genesis                25 // const unsigned int PUBLIC_KEY_SIZE  = 49;
genesis                26 // const unsigned int SIGNATURE_SIZE   = 57;
genesis                27 //
genesis                28 // secp224k1
genesis                29 // const unsigned int PRIVATE_KEY_SIZE = 250;
genesis                30 // const unsigned int PUBLIC_KEY_SIZE  = 57;
genesis                31 // const unsigned int SIGNATURE_SIZE   = 66;
genesis                32 //
genesis                33 // secp256k1:
genesis                34 // const unsigned int PRIVATE_KEY_SIZE = 279;
genesis                35 // const unsigned int PUBLIC_KEY_SIZE  = 65;
genesis                36 // const unsigned int SIGNATURE_SIZE   = 72;
genesis                37 //
genesis                38 // see www.keylength.com
genesis                39 // script supports up to 75 for single byte push
genesis                40 
genesis                41 // Generate a private key from just the secret parameter
genesis                42 int static inline EC_KEY_regenerate_key(EC_KEY *eckey, BIGNUM *priv_key)
genesis                43 {
genesis                44     int ok = 0;
genesis                45     BN_CTX *ctx = NULL;
genesis                46     EC_POINT *pub_key = NULL;
genesis                47 
genesis                48     if (!eckey) return 0;
genesis                49 
genesis                50     const EC_GROUP *group = EC_KEY_get0_group(eckey);
genesis                51 
genesis                52     if ((ctx = BN_CTX_new()) == NULL)
genesis                53         goto err;
genesis                54 
genesis                55     pub_key = EC_POINT_new(group);
genesis                56 
genesis                57     if (pub_key == NULL)
genesis                58         goto err;
genesis                59 
genesis                60     if (!EC_POINT_mul(group, pub_key, priv_key, NULL, NULL, ctx))
genesis                61         goto err;
genesis                62 
genesis                63     EC_KEY_set_private_key(eckey,priv_key);
genesis                64     EC_KEY_set_public_key(eckey,pub_key);
genesis                65 
genesis                66     ok = 1;
genesis                67 
genesis                68 err:
genesis                69 
genesis                70     if (pub_key)
genesis                71         EC_POINT_free(pub_key);
genesis                72     if (ctx != NULL)
genesis                73         BN_CTX_free(ctx);
genesis                74 
genesis                75     return(ok);
genesis                76 }
genesis                77 
genesis                78 // Perform ECDSA key recovery (see SEC1 4.1.6) for curves over (mod p)-fields
genesis                79 // recid selects which key is recovered
genesis                80 // if check is nonzero, additional checks are performed
genesis                81 int static inline ECDSA_SIG_recover_key_GFp(EC_KEY *eckey, ECDSA_SIG *ecsig, const unsigned char *msg, int msglen, int recid, int check)
genesis                82 {
genesis                83     if (!eckey) return 0;
genesis                84 
genesis                85     int ret = 0;
genesis                86     BN_CTX *ctx = NULL;
genesis                87 
genesis                88     BIGNUM *x = NULL;
genesis                89     BIGNUM *e = NULL;
genesis                90     BIGNUM *order = NULL;
genesis                91     BIGNUM *sor = NULL;
genesis                92     BIGNUM *eor = NULL;
genesis                93     BIGNUM *field = NULL;
genesis                94     EC_POINT *R = NULL;
genesis                95     EC_POINT *O = NULL;
genesis                96     EC_POINT *Q = NULL;
genesis                97     BIGNUM *rr = NULL;
genesis                98     BIGNUM *zero = NULL;
genesis                99     int n = 0;
genesis               100     int i = recid / 2;
genesis               101 
genesis               102     const EC_GROUP *group = EC_KEY_get0_group(eckey);
genesis               103     if ((ctx = BN_CTX_new()) == NULL) { ret = -1; goto err; }
genesis               104     BN_CTX_start(ctx);
genesis               105     order = BN_CTX_get(ctx);
genesis               106     if (!EC_GROUP_get_order(group, order, ctx)) { ret = -2; goto err; }
genesis               107     x = BN_CTX_get(ctx);
genesis               108     if (!BN_copy(x, order)) { ret=-1; goto err; }
genesis               109     if (!BN_mul_word(x, i)) { ret=-1; goto err; }
genesis               110     if (!BN_add(x, x, ecsig->r)) { ret=-1; goto err; }
genesis               111     field = BN_CTX_get(ctx);
genesis               112     if (!EC_GROUP_get_curve_GFp(group, field, NULL, NULL, ctx)) { ret=-2; goto err; }
genesis               113     if (BN_cmp(x, field) >= 0) { ret=0; goto err; }
genesis               114     if ((R = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
genesis               115     if (!EC_POINT_set_compressed_coordinates_GFp(group, R, x, recid % 2, ctx)) { ret=0; goto err; }
genesis               116     if (check)
genesis               117     {
genesis               118         if ((O = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
genesis               119         if (!EC_POINT_mul(group, O, NULL, R, order, ctx)) { ret=-2; goto err; }
genesis               120         if (!EC_POINT_is_at_infinity(group, O)) { ret = 0; goto err; }
genesis               121     }
genesis               122     if ((Q = EC_POINT_new(group)) == NULL) { ret = -2; goto err; }
genesis               123     n = EC_GROUP_get_degree(group);
genesis               124     e = BN_CTX_get(ctx);
genesis               125     if (!BN_bin2bn(msg, msglen, e)) { ret=-1; goto err; }
genesis               126     if (8*msglen > n) BN_rshift(e, e, 8-(n & 7));
genesis               127     zero = BN_CTX_get(ctx);
genesis               128     if (!BN_zero(zero)) { ret=-1; goto err; }
genesis               129     if (!BN_mod_sub(e, zero, e, order, ctx)) { ret=-1; goto err; }
genesis               130     rr = BN_CTX_get(ctx);
genesis               131     if (!BN_mod_inverse(rr, ecsig->r, order, ctx)) { ret=-1; goto err; }
genesis               132     sor = BN_CTX_get(ctx);
genesis               133     if (!BN_mod_mul(sor, ecsig->s, rr, order, ctx)) { ret=-1; goto err; }
genesis               134     eor = BN_CTX_get(ctx);
genesis               135     if (!BN_mod_mul(eor, e, rr, order, ctx)) { ret=-1; goto err; }
genesis               136     if (!EC_POINT_mul(group, Q, eor, R, sor, ctx)) { ret=-2; goto err; }
genesis               137     if (!EC_KEY_set_public_key(eckey, Q)) { ret=-2; goto err; }
genesis               138 
genesis               139     ret = 1;
genesis               140 
genesis               141 err:
genesis               142     if (ctx) {
genesis               143         BN_CTX_end(ctx);
genesis               144         BN_CTX_free(ctx);
genesis               145     }
genesis               146     if (R != NULL) EC_POINT_free(R);
genesis               147     if (O != NULL) EC_POINT_free(O);
genesis               148     if (Q != NULL) EC_POINT_free(Q);
genesis               149     return ret;
genesis               150 }
genesis               151 
genesis               152 class key_error : public std::runtime_error
genesis               153 {
genesis               154 public:
genesis               155     explicit key_error(const std::string& str) : std::runtime_error(str) {}
genesis               156 };
genesis               157 
genesis               158 
genesis               159 // secure_allocator is defined in serialize.h
genesis               160 // CPrivKey is a serialized private key, with all parameters included (279 bytes)
genesis               161 typedef std::vector<unsigned char, secure_allocator<unsigned char> > CPrivKey;
genesis               162 // CSecret is a serialization of just the secret parameter (32 bytes)
genesis               163 typedef std::vector<unsigned char, secure_allocator<unsigned char> > CSecret;
genesis               164 
genesis               165 class CKey
genesis               166 {
genesis               167 protected:
genesis               168     EC_KEY* pkey;
genesis               169     bool fSet;
genesis               170 
genesis               171 public:
genesis               172     CKey()
genesis               173     {
genesis               174         pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
genesis               175         if (pkey == NULL)
genesis               176             throw key_error("CKey::CKey() : EC_KEY_new_by_curve_name failed");
genesis               177         fSet = false;
genesis               178     }
genesis               179 
genesis               180     CKey(const CKey& b)
genesis               181     {
genesis               182         pkey = EC_KEY_dup(b.pkey);
genesis               183         if (pkey == NULL)
genesis               184             throw key_error("CKey::CKey(const CKey&) : EC_KEY_dup failed");
genesis               185         fSet = b.fSet;
genesis               186     }
genesis               187 
genesis               188     CKey& operator=(const CKey& b)
genesis               189     {
genesis               190         if (!EC_KEY_copy(pkey, b.pkey))
genesis               191             throw key_error("CKey::operator=(const CKey&) : EC_KEY_copy failed");
genesis               192         fSet = b.fSet;
genesis               193         return (*this);
genesis               194     }
genesis               195 
genesis               196     ~CKey()
genesis               197     {
genesis               198         EC_KEY_free(pkey);
genesis               199     }
genesis               200 
genesis               201     bool IsNull() const
genesis               202     {
genesis               203         return !fSet;
genesis               204     }
genesis               205 
genesis               206     void MakeNewKey()
genesis               207     {
genesis               208         if (!EC_KEY_generate_key(pkey))
genesis               209             throw key_error("CKey::MakeNewKey() : EC_KEY_generate_key failed");
genesis               210         fSet = true;
genesis               211     }
genesis               212 
genesis               213     bool SetPrivKey(const CPrivKey& vchPrivKey)
genesis               214     {
genesis               215         const unsigned char* pbegin = &vchPrivKey[0];
genesis               216         if (!d2i_ECPrivateKey(&pkey, &pbegin, vchPrivKey.size()))
genesis               217             return false;
genesis               218         fSet = true;
genesis               219         return true;
genesis               220     }
genesis               221 
genesis               222     bool SetSecret(const CSecret& vchSecret)
genesis               223     {
genesis               224         EC_KEY_free(pkey);
genesis               225         pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
genesis               226         if (pkey == NULL)
genesis               227             throw key_error("CKey::SetSecret() : EC_KEY_new_by_curve_name failed");
genesis               228         if (vchSecret.size() != 32)
genesis               229             throw key_error("CKey::SetSecret() : secret must be 32 bytes");
genesis               230         BIGNUM *bn = BN_bin2bn(&vchSecret[0],32,BN_new());
genesis               231         if (bn == NULL)
genesis               232             throw key_error("CKey::SetSecret() : BN_bin2bn failed");
genesis               233         if (!EC_KEY_regenerate_key(pkey,bn))
genesis               234         {
genesis               235             BN_clear_free(bn);
genesis               236             throw key_error("CKey::SetSecret() : EC_KEY_regenerate_key failed");
genesis               237         }
genesis               238         BN_clear_free(bn);
genesis               239         fSet = true;
genesis               240         return true;
genesis               241     }
genesis               242 
genesis               243     CSecret GetSecret() const
genesis               244     {
genesis               245         CSecret vchRet;
genesis               246         vchRet.resize(32);
genesis               247         const BIGNUM *bn = EC_KEY_get0_private_key(pkey);
genesis               248         int nBytes = BN_num_bytes(bn);
genesis               249         if (bn == NULL)
genesis               250             throw key_error("CKey::GetSecret() : EC_KEY_get0_private_key failed");
genesis               251         int n=BN_bn2bin(bn,&vchRet[32 - nBytes]);
genesis               252         if (n != nBytes) 
genesis               253             throw key_error("CKey::GetSecret(): BN_bn2bin failed");
genesis               254         return vchRet;
genesis               255     }
genesis               256 
genesis               257     CPrivKey GetPrivKey() const
genesis               258     {
genesis               259         unsigned int nSize = i2d_ECPrivateKey(pkey, NULL);
genesis               260         if (!nSize)
genesis               261             throw key_error("CKey::GetPrivKey() : i2d_ECPrivateKey failed");
genesis               262         CPrivKey vchPrivKey(nSize, 0);
genesis               263         unsigned char* pbegin = &vchPrivKey[0];
genesis               264         if (i2d_ECPrivateKey(pkey, &pbegin) != nSize)
genesis               265             throw key_error("CKey::GetPrivKey() : i2d_ECPrivateKey returned unexpected size");
genesis               266         return vchPrivKey;
genesis               267     }
genesis               268 
genesis               269     bool SetPubKey(const std::vector<unsigned char>& vchPubKey)
genesis               270     {
genesis               271         const unsigned char* pbegin = &vchPubKey[0];
genesis               272         if (!o2i_ECPublicKey(&pkey, &pbegin, vchPubKey.size()))
genesis               273             return false;
genesis               274         fSet = true;
genesis               275         return true;
genesis               276     }
genesis               277 
genesis               278     std::vector<unsigned char> GetPubKey() const
genesis               279     {
genesis               280         unsigned int nSize = i2o_ECPublicKey(pkey, NULL);
genesis               281         if (!nSize)
genesis               282             throw key_error("CKey::GetPubKey() : i2o_ECPublicKey failed");
genesis               283         std::vector<unsigned char> vchPubKey(nSize, 0);
genesis               284         unsigned char* pbegin = &vchPubKey[0];
genesis               285         if (i2o_ECPublicKey(pkey, &pbegin) != nSize)
genesis               286             throw key_error("CKey::GetPubKey() : i2o_ECPublicKey returned unexpected size");
genesis               287         return vchPubKey;
genesis               288     }
genesis               289 
genesis               290     bool Sign(uint256 hash, std::vector<unsigned char>& vchSig)
genesis               291     {
genesis               292         vchSig.clear();
genesis               293         unsigned char pchSig[10000];
genesis               294         unsigned int nSize = 0;
genesis               295         if (!ECDSA_sign(0, (unsigned char*)&hash, sizeof(hash), pchSig, &nSize, pkey))
genesis               296             return false;
genesis               297         vchSig.resize(nSize);
genesis               298         memcpy(&vchSig[0], pchSig, nSize);
genesis               299         return true;
genesis               300     }
genesis               301 
genesis               302     // create a compact signature (65 bytes), which allows reconstructing the used public key
genesis               303     // The format is one header byte, followed by two times 32 bytes for the serialized r and s values.
genesis               304     // The header byte: 0x1B = first key with even y, 0x1C = first key with odd y,
genesis               305     //                  0x1D = second key with even y, 0x1E = second key with odd y
genesis               306     bool SignCompact(uint256 hash, std::vector<unsigned char>& vchSig)
genesis               307     {
genesis               308         bool fOk = false;
genesis               309         ECDSA_SIG *sig = ECDSA_do_sign((unsigned char*)&hash, sizeof(hash), pkey);
genesis               310         if (sig==NULL)
genesis               311             return false;
genesis               312         vchSig.clear();
genesis               313         vchSig.resize(65,0);
genesis               314         int nBitsR = BN_num_bits(sig->r);
genesis               315         int nBitsS = BN_num_bits(sig->s);
genesis               316         if (nBitsR <= 256 && nBitsS <= 256)
genesis               317         {
genesis               318             int nRecId = -1;
genesis               319             for (int i=0; i<4; i++)
genesis               320             {
genesis               321                 CKey keyRec;
genesis               322                 keyRec.fSet = true;
genesis               323                 if (ECDSA_SIG_recover_key_GFp(keyRec.pkey, sig, (unsigned char*)&hash, sizeof(hash), i, 1) == 1)
genesis               324                     if (keyRec.GetPubKey() == this->GetPubKey())
genesis               325                     {
genesis               326                         nRecId = i;
genesis               327                         break;
genesis               328                     }
genesis               329             }
genesis               330 
genesis               331             if (nRecId == -1)
genesis               332                 throw key_error("CKey::SignCompact() : unable to construct recoverable key");
genesis               333 
genesis               334             vchSig[0] = nRecId+27;
genesis               335             BN_bn2bin(sig->r,&vchSig[33-(nBitsR+7)/8]);
genesis               336             BN_bn2bin(sig->s,&vchSig[65-(nBitsS+7)/8]);
genesis               337             fOk = true;
genesis               338         }
genesis               339         ECDSA_SIG_free(sig);
genesis               340         return fOk;
genesis               341     }
genesis               342 
genesis               343     // reconstruct public key from a compact signature
genesis               344     // This is only slightly more CPU intensive than just verifying it.
genesis               345     // If this function succeeds, the recovered public key is guaranteed to be valid
genesis               346     // (the signature is a valid signature of the given data for that key)
genesis               347     bool SetCompactSignature(uint256 hash, const std::vector<unsigned char>& vchSig)
genesis               348     {
genesis               349         if (vchSig.size() != 65)
genesis               350             return false;
genesis               351         if (vchSig[0]<27 || vchSig[0]>=31)
genesis               352             return false;
genesis               353         ECDSA_SIG *sig = ECDSA_SIG_new();
genesis               354         BN_bin2bn(&vchSig[1],32,sig->r);
genesis               355         BN_bin2bn(&vchSig[33],32,sig->s);
genesis               356 
genesis               357         EC_KEY_free(pkey);
genesis               358         pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
genesis               359         if (ECDSA_SIG_recover_key_GFp(pkey, sig, (unsigned char*)&hash, sizeof(hash), vchSig[0] - 27, 0) == 1)
genesis               360         {
genesis               361             fSet = true;
genesis               362             ECDSA_SIG_free(sig);
genesis               363             return true;
genesis               364         }
genesis               365         return false;
genesis               366     }
genesis               367 
genesis               368     bool Verify(uint256 hash, const std::vector<unsigned char>& vchSig)
genesis               369     {
genesis               370         // -1 = error, 0 = bad sig, 1 = good
genesis               371         if (ECDSA_verify(0, (unsigned char*)&hash, sizeof(hash), &vchSig[0], vchSig.size(), pkey) != 1)
genesis               372             return false;
genesis               373         return true;
genesis               374     }
genesis               375 
genesis               376     // Verify a compact signature
genesis               377     bool VerifyCompact(uint256 hash, const std::vector<unsigned char>& vchSig)
genesis               378     {
genesis               379         CKey key;
genesis               380         if (!key.SetCompactSignature(hash, vchSig))
genesis               381             return false;
genesis               382         if (GetPubKey() != key.GetPubKey())
genesis               383             return false;
genesis               384         return true;
genesis               385     }
genesis               386 
genesis               387     bool IsValid()
genesis               388     {
genesis               389         if (!fSet)
genesis               390             return false;
genesis               391 
genesis               392         CSecret secret = GetSecret();
genesis               393         CKey key2;
genesis               394         key2.SetSecret(secret);
genesis               395         return GetPubKey() == key2.GetPubKey();
genesis               396     }
genesis               397 };
genesis               398 
genesis               399 #endif