boost: code movement only: split CECKey into separate files

1 files changed, 333 insertions, 0 deletions

diff --git a/src/ecwrapper.cpp b/src/ecwrapper.cpp
new file mode 100644
index 0000000000..e5db670927
--- /dev/null
+++ b/src/ecwrapper.cpp
@@ -0,0 +1,333 @@
+// Copyright (c) 2009-2014 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 "ecwrapper.h"
+
+#include "serialize.h"
+#include "uint256.h"
+
+#include <openssl/bn.h>
+#include <openssl/ecdsa.h>
+#include <openssl/obj_mac.h>
+
+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;
+}
+
+} // anon namespace
+
+CECKey::CECKey() {
+    pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
+    assert(pkey != NULL);
+}
+
+CECKey::~CECKey() {
+    EC_KEY_free(pkey);
+}
+
+void CECKey::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 CECKey::SetSecretBytes(const unsigned char vch[32]) {
+    bool ret;
+    BIGNUM bn;
+    BN_init(&bn);
+    ret = BN_bin2bn(vch, 32, &bn) != NULL;
+    assert(ret);
+    ret = EC_KEY_regenerate_key(pkey, &bn) != 0;
+    assert(ret);
+    BN_clear_free(&bn);
+}
+
+int CECKey::GetPrivKeySize(bool fCompressed) {
+    EC_KEY_set_conv_form(pkey, fCompressed ? POINT_CONVERSION_COMPRESSED : POINT_CONVERSION_UNCOMPRESSED);
+    return i2d_ECPrivateKey(pkey, NULL);
+}
+int CECKey::GetPrivKey(unsigned char* privkey, bool fCompressed) {
+    EC_KEY_set_conv_form(pkey, fCompressed ? POINT_CONVERSION_COMPRESSED : POINT_CONVERSION_UNCOMPRESSED);
+    return i2d_ECPrivateKey(pkey, &privkey);
+}
+
+bool CECKey::SetPrivKey(const unsigned char* privkey, size_t size, bool fSkipCheck) {
+    if (d2i_ECPrivateKey(&pkey, &privkey, size)) {
+        if(fSkipCheck)
+            return true;
+
+        // 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 CECKey::GetPubKey(std::vector<unsigned char> &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);
+    pubkey.clear();
+    pubkey.resize(nSize);
+    unsigned char *pbegin(begin_ptr(pubkey));
+    int nSize2 = i2o_ECPublicKey(pkey, &pbegin);
+    assert(nSize == nSize2);
+}
+
+bool CECKey::SetPubKey(const unsigned char* pubkey, size_t size) {
+    return o2i_ECPublicKey(&pkey, &pubkey, size) != NULL;
+}
+
+bool CECKey::Sign(const uint256 &hash, std::vector<unsigned char>& vchSig, bool lowS) {
+    vchSig.clear();
+    ECDSA_SIG *sig = ECDSA_do_sign((unsigned char*)&hash, sizeof(hash), pkey);
+    if (sig == NULL)
+        return false;
+    BN_CTX *ctx = BN_CTX_new();
+    BN_CTX_start(ctx);
+    const EC_GROUP *group = EC_KEY_get0_group(pkey);
+    BIGNUM *order = BN_CTX_get(ctx);
+    BIGNUM *halforder = BN_CTX_get(ctx);
+    EC_GROUP_get_order(group, order, ctx);
+    BN_rshift1(halforder, order);
+    if (lowS && BN_cmp(sig->s, halforder) > 0) {
+        // enforce low S values, by negating the value (modulo the order) if above order/2.
+        BN_sub(sig->s, order, sig->s);
+    }
+    BN_CTX_end(ctx);
+    BN_CTX_free(ctx);
+    unsigned int nSize = ECDSA_size(pkey);
+    vchSig.resize(nSize); // Make sure it is big enough
+    unsigned char *pos = &vchSig[0];
+    nSize = i2d_ECDSA_SIG(sig, &pos);
+    ECDSA_SIG_free(sig);
+    vchSig.resize(nSize); // Shrink to fit actual size
+    return true;
+}
+
+bool CECKey::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 CECKey::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) {
+        std::vector<unsigned char> 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) {
+                std::vector<unsigned char> 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;
+}
+
+bool CECKey::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;
+}
+
+bool CECKey::TweakSecret(unsigned char vchSecretOut[32], const unsigned char vchSecretIn[32], const unsigned char vchTweak[32])
+{
+    bool ret = true;
+    BN_CTX *ctx = BN_CTX_new();
+    BN_CTX_start(ctx);
+    BIGNUM *bnSecret = BN_CTX_get(ctx);
+    BIGNUM *bnTweak = BN_CTX_get(ctx);
+    BIGNUM *bnOrder = BN_CTX_get(ctx);
+    EC_GROUP *group = EC_GROUP_new_by_curve_name(NID_secp256k1);
+    EC_GROUP_get_order(group, bnOrder, ctx); // what a grossly inefficient way to get the (constant) group order...
+    BN_bin2bn(vchTweak, 32, bnTweak);
+    if (BN_cmp(bnTweak, bnOrder) >= 0)
+        ret = false; // extremely unlikely
+    BN_bin2bn(vchSecretIn, 32, bnSecret);
+    BN_add(bnSecret, bnSecret, bnTweak);
+    BN_nnmod(bnSecret, bnSecret, bnOrder, ctx);
+    if (BN_is_zero(bnSecret))
+        ret = false; // ridiculously unlikely
+    int nBits = BN_num_bits(bnSecret);
+    memset(vchSecretOut, 0, 32);
+    BN_bn2bin(bnSecret, &vchSecretOut[32-(nBits+7)/8]);
+    EC_GROUP_free(group);
+    BN_CTX_end(ctx);
+    BN_CTX_free(ctx);
+    return ret;
+}
+
+bool CECKey::TweakPublic(const unsigned char vchTweak[32]) {
+    bool ret = true;
+    BN_CTX *ctx = BN_CTX_new();
+    BN_CTX_start(ctx);
+    BIGNUM *bnTweak = BN_CTX_get(ctx);
+    BIGNUM *bnOrder = BN_CTX_get(ctx);
+    BIGNUM *bnOne = BN_CTX_get(ctx);
+    const EC_GROUP *group = EC_KEY_get0_group(pkey);
+    EC_GROUP_get_order(group, bnOrder, ctx); // what a grossly inefficient way to get the (constant) group order...
+    BN_bin2bn(vchTweak, 32, bnTweak);
+    if (BN_cmp(bnTweak, bnOrder) >= 0)
+        ret = false; // extremely unlikely
+    EC_POINT *point = EC_POINT_dup(EC_KEY_get0_public_key(pkey), group);
+    BN_one(bnOne);
+    EC_POINT_mul(group, point, bnTweak, point, bnOne, ctx);
+    if (EC_POINT_is_at_infinity(group, point))
+        ret = false; // ridiculously unlikely
+    EC_KEY_set_public_key(pkey, point);
+    EC_POINT_free(point);
+    BN_CTX_end(ctx);
+    BN_CTX_free(ctx);
+    return ret;
+}
+
+bool CECKey::SanityCheck()
+{
+    EC_KEY *pkey = EC_KEY_new_by_curve_name(NID_secp256k1);
+    if(pkey == NULL)
+        return false;
+    EC_KEY_free(pkey);
+
+    // TODO Is there more EC functionality that could be missing?
+    return true;
+}