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.
195 lines
6.4 KiB
195 lines
6.4 KiB
// Copyright (c) 2009-2014 The Bitcoin Core developers |
|
// Distributed under the MIT 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 { |
|
|
|
/** |
|
* 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::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::Verify(const uint256 &hash, const std::vector<unsigned char>& vchSig) { |
|
if (vchSig.empty()) |
|
return false; |
|
|
|
// New versions of OpenSSL will reject non-canonical DER signatures. de/re-serialize first. |
|
unsigned char *norm_der = NULL; |
|
ECDSA_SIG *norm_sig = ECDSA_SIG_new(); |
|
const unsigned char* sigptr = &vchSig[0]; |
|
assert(norm_sig); |
|
if (d2i_ECDSA_SIG(&norm_sig, &sigptr, vchSig.size()) == NULL) |
|
{ |
|
/* As of OpenSSL 1.0.0p d2i_ECDSA_SIG frees and nulls the pointer on |
|
* error. But OpenSSL's own use of this function redundantly frees the |
|
* result. As ECDSA_SIG_free(NULL) is a no-op, and in the absence of a |
|
* clear contract for the function behaving the same way is more |
|
* conservative. |
|
*/ |
|
ECDSA_SIG_free(norm_sig); |
|
return false; |
|
} |
|
int derlen = i2d_ECDSA_SIG(norm_sig, &norm_der); |
|
ECDSA_SIG_free(norm_sig); |
|
if (derlen <= 0) |
|
return false; |
|
|
|
// -1 = error, 0 = bad sig, 1 = good |
|
bool ret = ECDSA_verify(0, (unsigned char*)&hash, sizeof(hash), norm_der, derlen, pkey) == 1; |
|
OPENSSL_free(norm_der); |
|
return ret; |
|
} |
|
|
|
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::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; |
|
}
|
|
|