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ringsig.cpp
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ringsig.cpp
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// Copyright (c) 2014 The ShadowCoin developers
// Distributed under the MIT/X11 software license, see the accompanying
// file license.txt or http://www.opensource.org/licenses/mit-license.php.
#include "ringsig.h"
#include "base58.h"
#include "key.h"
#include "main.h"
#include "chainparams.h"
#include <openssl/err.h>
#include <openssl/rand.h>
#include <openssl/ec.h>
#include <openssl/bn.h>
#include <openssl/ecdsa.h>
#include <openssl/obj_mac.h>
static EC_GROUP *ecGrp = NULL;
static BN_CTX *bnCtx = NULL;
static BIGNUM *bnOrder = NULL;
int initialiseRingSigs()
{
int rv = 0;
if (fDebugRingSig)
LogPrintf("initialiseRingSigs()\n");
if (!(ecGrp = EC_GROUP_new_by_curve_name(NID_secp256k1)))
return errorN(1, "initialiseRingSigs(): EC_GROUP_new_by_curve_name failed.");
if (!(bnCtx = BN_CTX_new()))
return errorN(1, "initialiseRingSigs(): BN_CTX_new failed.");
BN_CTX_start(bnCtx);
// get order and cofactor
bnOrder = BN_new();
if (!EC_GROUP_get_order(ecGrp, bnOrder, bnCtx))
return errorN(1, "initialiseRingSigs(): EC_GROUP_get_order failed.");
BN_CTX_end(bnCtx);
return rv;
}
int finaliseRingSigs()
{
if (fDebugRingSig)
LogPrintf("finaliseRingSigs()\n");
BN_free(bnOrder);
BN_CTX_free(bnCtx);
EC_GROUP_clear_free(ecGrp);
ecGrp = NULL;
bnCtx = NULL;
bnOrder = NULL;
return 0;
}
int splitAmount(int64_t nValue, std::vector<int64_t>& vOut)
{
// - split amounts into 1, 3, 4, 5
int64_t nTest = 1;
int i;
while (nValue >= nTest)
{
i = (nValue / nTest) % 10;
switch (i)
{
case 0:
break;
case 2:
vOut.push_back(1*nTest);
vOut.push_back(1*nTest);
break;
case 6:
vOut.push_back(5*nTest);
vOut.push_back(1*nTest);
break;
case 7:
vOut.push_back(3*nTest);
vOut.push_back(4*nTest);
break;
case 8:
vOut.push_back(5*nTest);
vOut.push_back(3*nTest);
break;
case 9:
vOut.push_back(5*nTest);
vOut.push_back(4*nTest);
break;
default:
vOut.push_back(i*nTest);
}
nTest *= 10;
}
return 0;
}
int getOldKeyImage(CPubKey &publicKey, ec_point &keyImage)
{
// - PublicKey * Hash(PublicKey)
if (publicKey.size() != EC_COMPRESSED_SIZE)
return errorN(1, "%s: Invalid publicKey.", __func__);
int rv = 0;
uint256 pkHash = publicKey.GetHash();
BN_CTX_start(bnCtx);
BIGNUM *bnTmp = BN_CTX_get(bnCtx);
EC_POINT *ptPk = NULL;
// Hash to BIGNUM
if (!BN_bin2bn(pkHash.begin(), EC_SECRET_SIZE, bnTmp)
&& (rv = errorN(1, "%s: BN_bin2bn failed.", __func__)))
goto End;
// PublicKey point
if (!(ptPk = EC_POINT_new(ecGrp))
&& (rv = errorN(1, "%s: EC_POINT_new failed.", __func__)))
goto End;
if (!EC_POINT_oct2point(ecGrp, ptPk, publicKey.begin(), EC_COMPRESSED_SIZE, bnCtx)
&& (rv = errorN(1, "%s: EC_POINT_oct2point failed.", __func__)))
goto End;
// PublicKey * Hash(PublicKey)
if (!EC_POINT_mul(ecGrp, ptPk, NULL, ptPk, bnTmp, bnCtx)
&& (rv = errorN(1, "%s: EC_POINT_mul failed.", __func__)))
goto End;
try { keyImage.resize(EC_COMPRESSED_SIZE); } catch (std::exception& e)
{
LogPrintf("%s: keyImage.resize threw: %s.\n", __func__, e.what());
rv = 1; goto End;
}
// Point to BIGNUM to bin
if (!(EC_POINT_point2bn(ecGrp, ptPk, POINT_CONVERSION_COMPRESSED, bnTmp, bnCtx))
||BN_num_bytes(bnTmp) != (int) EC_COMPRESSED_SIZE
||BN_bn2bin(bnTmp, &keyImage[0]) != (int) EC_COMPRESSED_SIZE)
rv = errorN(1, "%s: point -> keyImage failed.", __func__);
End:
EC_POINT_free(ptPk);
BN_CTX_end(bnCtx);
return 0;
}
static int hashToEC(const uint8_t *p, uint32_t len, BIGNUM *bnTmp, EC_POINT *ptRet, bool fNew=false)
{
// - bn(hash(data)) * (G + bn1)
int count = 0;
uint256 pkHash = Hash(p, p + len);
BIGNUM *bnOne = BN_CTX_get(bnCtx);
BN_one(bnOne);
if (!bnTmp || !BN_bin2bn(pkHash.begin(), EC_SECRET_SIZE, bnTmp))
return errorN(1, "%s: BN_bin2bn failed.", __func__);
if (fNew || Params().IsProtocolV3(nBestHeight))
while(!EC_POINT_set_compressed_coordinates_GFp(ecGrp, ptRet, bnTmp, 0, bnCtx) && count < 100)
{
count += 1;
if (count == 100)
return errorN(1, "%s: Failed to find a valid point for public key.", __func__);
BN_add(bnTmp, bnTmp, bnOne);
}
else
if (!EC_POINT_mul(ecGrp, ptRet, bnTmp, NULL, NULL, bnCtx))
return errorN(1, "%s: EC_POINT_mul failed.", __func__);
return 0;
}
int generateKeyImage(ec_point &publicKey, ec_secret secret, ec_point &keyImage)
{
// - keyImage = secret * hash(publicKey) * G
if (publicKey.size() != EC_COMPRESSED_SIZE)
return errorN(1, "%s: Invalid publicKey.", __func__);
BN_CTX_start(bnCtx);
int rv = 0;
BIGNUM *bnTmp = BN_CTX_get(bnCtx);
BIGNUM *bnSec = BN_CTX_get(bnCtx);
EC_POINT *hG = NULL;
if (!(hG = EC_POINT_new(ecGrp))
&& (rv = errorN(1, "%s: EC_POINT_new failed.", __func__)))
goto End;
if (hashToEC(&publicKey[0], publicKey.size(), bnTmp, hG, true)
&& (rv = errorN(1, "%s: hashToEC failed.", __func__)))
goto End;
if (!(BN_bin2bn(&secret.e[0], EC_SECRET_SIZE, bnSec))
&& (rv = errorN(1, "%s: BN_bin2bn failed.", __func__)))
goto End;
if (!EC_POINT_mul(ecGrp, hG, NULL, hG, bnSec, bnCtx)
&& (rv = errorN(1, "%s: kimg EC_POINT_mul failed.", __func__)))
goto End;
try { keyImage.resize(EC_COMPRESSED_SIZE); } catch (std::exception& e)
{
LogPrintf("%s: keyImage.resize threw: %s.\n", __func__, e.what());
rv = 1; goto End;
}
if ((!(EC_POINT_point2bn(ecGrp, hG, POINT_CONVERSION_COMPRESSED, bnTmp, bnCtx))
|| BN_num_bytes(bnTmp) != (int) EC_COMPRESSED_SIZE
|| BN_bn2bin(bnTmp, &keyImage[0]) != (int) EC_COMPRESSED_SIZE)
&& (rv = errorN(1, "%s: point -> keyImage failed.", __func__)))
goto End;
if (fDebugRingSig)
LogPrintf("keyImage %s\n", HexStr(keyImage).c_str());
End:
EC_POINT_free(hG);
BN_CTX_end(bnCtx);
return rv;
}
int generateRingSignature(data_chunk &keyImage, uint256 &txnHash, int nRingSize, int nSecretOffset, ec_secret secret, const uint8_t *pPubkeys, uint8_t *pSigc, uint8_t *pSigr)
{
if (fDebugRingSig)
LogPrintf("%s: Ring size %d.\n", __func__, nRingSize);
int rv = 0;
int nBytes;
BN_CTX_start(bnCtx);
BIGNUM *bnKS = BN_CTX_get(bnCtx);
BIGNUM *bnK1 = BN_CTX_get(bnCtx);
BIGNUM *bnK2 = BN_CTX_get(bnCtx);
BIGNUM *bnT = BN_CTX_get(bnCtx);
BIGNUM *bnH = BN_CTX_get(bnCtx);
BIGNUM *bnSum = BN_CTX_get(bnCtx);
EC_POINT *ptT1 = NULL;
EC_POINT *ptT2 = NULL;
EC_POINT *ptT3 = NULL;
EC_POINT *ptPk = NULL;
EC_POINT *ptKi = NULL;
EC_POINT *ptL = NULL;
EC_POINT *ptR = NULL;
uint8_t tempData[66]; // hold raw point data to hash
uint256 commitHash;
ec_secret scData1, scData2;
CHashWriter ssCommitHash(SER_GETHASH, PROTOCOL_VERSION);
ssCommitHash << txnHash;
// zero signature
memset(pSigc, 0, EC_SECRET_SIZE * nRingSize);
memset(pSigr, 0, EC_SECRET_SIZE * nRingSize);
// ks = random 256 bit int mod P
if (GenerateRandomSecret(scData1)
&& (rv = errorN(1, "%s: GenerateRandomSecret failed.", __func__)))
goto End;
if (!bnKS || !(BN_bin2bn(&scData1.e[0], EC_SECRET_SIZE, bnKS)))
{
LogPrintf("%s: BN_bin2bn failed.\n", __func__);
rv = 1; goto End;
}
// zero sum
if (!bnSum || !(BN_zero(bnSum)))
{
LogPrintf("%s: BN_zero failed.\n", __func__);
rv = 1; goto End;
}
if ( !(ptT1 = EC_POINT_new(ecGrp))
|| !(ptT2 = EC_POINT_new(ecGrp))
|| !(ptT3 = EC_POINT_new(ecGrp))
|| !(ptPk = EC_POINT_new(ecGrp))
|| !(ptKi = EC_POINT_new(ecGrp))
|| !(ptL = EC_POINT_new(ecGrp))
|| !(ptR = EC_POINT_new(ecGrp)))
{
LogPrintf("%s: EC_POINT_new failed.\n", __func__);
rv = 1; goto End;
}
// get keyimage as point
if (!EC_POINT_oct2point(ecGrp, ptKi, &keyImage[0], EC_COMPRESSED_SIZE, bnCtx)
&&(rv = errorN(1, "%s: extract ptKi failed.", __func__)))
goto End;
for (int i = 0; i < nRingSize; ++i)
{
if (i == nSecretOffset)
{
// k = random 256 bit int mod P
// L = k * G
// R = k * HashToEC(PKi)
if (!EC_POINT_mul(ecGrp, ptL, bnKS, NULL, NULL, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
if (hashToEC(&pPubkeys[i * EC_COMPRESSED_SIZE], EC_COMPRESSED_SIZE, bnT, ptT1) != 0)
{
LogPrintf("%s: hashToEC failed.\n", __func__);
rv = 1; goto End;
}
if (!EC_POINT_mul(ecGrp, ptR, NULL, ptT1, bnKS, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
} else
{
// k1 = random 256 bit int mod P
// k2 = random 256 bit int mod P
// Li = k1 * Pi + k2 * G
// Ri = k1 * I + k2 * Hp(Pi)
// ci = k1
// ri = k2
if (GenerateRandomSecret(scData1) != 0
|| !bnK1 || !(BN_bin2bn(&scData1.e[0], EC_SECRET_SIZE, bnK1))
|| GenerateRandomSecret(scData2) != 0
|| !bnK2 || !(BN_bin2bn(&scData2.e[0], EC_SECRET_SIZE, bnK2)))
{
LogPrintf("%s: k1 and k2 failed.\n", __func__);
rv = 1; goto End;
}
// get Pk i as point
if (!(bnT = BN_bin2bn(&pPubkeys[i * EC_COMPRESSED_SIZE], EC_COMPRESSED_SIZE, bnT))
|| !(ptPk) || !(ptPk = EC_POINT_bn2point(ecGrp, bnT, ptPk, bnCtx)))
{
LogPrintf("%s: extract ptPk failed.\n", __func__);
rv = 1; goto End;
}
// ptT1 = k1 * Pi
if (!EC_POINT_mul(ecGrp, ptT1, NULL, ptPk, bnK1, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
// ptT2 = k2 * G
if (!EC_POINT_mul(ecGrp, ptT2, bnK2, NULL, NULL, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
// ptL = ptT1 + ptT2
if (!EC_POINT_add(ecGrp, ptL, ptT1, ptT2, bnCtx))
{
LogPrintf("%s: EC_POINT_add failed.\n", __func__);
rv = 1; goto End;
}
// ptT3 = Hp(Pi)
if (hashToEC(&pPubkeys[i * EC_COMPRESSED_SIZE], EC_COMPRESSED_SIZE, bnT, ptT3) != 0)
{
LogPrintf("%s: hashToEC failed.\n", __func__);
rv = 1; goto End;
}
// ptT1 = k1 * I
if (!EC_POINT_mul(ecGrp, ptT1, NULL, ptKi, bnK1, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
// ptT2 = k2 * ptT3
if (!EC_POINT_mul(ecGrp, ptT2, NULL, ptT3, bnK2, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
// ptR = ptT1 + ptT2
if (!EC_POINT_add(ecGrp, ptR, ptT1, ptT2, bnCtx))
{
LogPrintf("%s: EC_POINT_add failed.\n", __func__);
rv = 1; goto End;
}
memcpy(&pSigc[i * EC_SECRET_SIZE], &scData1.e[0], EC_SECRET_SIZE);
memcpy(&pSigr[i * EC_SECRET_SIZE], &scData2.e[0], EC_SECRET_SIZE);
// sum = (sum + sigc) % N , sigc == bnK1
if (!BN_mod_add(bnSum, bnSum, bnK1, bnOrder, bnCtx))
{
LogPrintf("%s: BN_mod_add failed.\n", __func__);
rv = 1; goto End;
}
}
// -- add ptL and ptR to hash
if ( !(EC_POINT_point2oct(ecGrp, ptL, POINT_CONVERSION_COMPRESSED, &tempData[0], 33, bnCtx) == (int) EC_COMPRESSED_SIZE)
|| !(EC_POINT_point2oct(ecGrp, ptR, POINT_CONVERSION_COMPRESSED, &tempData[33], 33, bnCtx) == (int) EC_COMPRESSED_SIZE))
{
LogPrintf("%s: extract ptL and ptR failed.\n", __func__);
rv = 1; goto End;
}
ssCommitHash.write((const char*)&tempData[0], 66);
}
commitHash = ssCommitHash.GetHash();
if (!(bnH) || !(bnH = BN_bin2bn(commitHash.begin(), EC_SECRET_SIZE, bnH)))
{
LogPrintf("%s: commitHash -> bnH failed.\n", __func__);
rv = 1; goto End;
}
if (!BN_mod(bnH, bnH, bnOrder, bnCtx)) // this is necessary
{
LogPrintf("%s: BN_mod failed.\n", __func__);
rv = 1; goto End;
}
// sigc[nSecretOffset] = (bnH - bnSum) % N
if (!BN_mod_sub(bnT, bnH, bnSum, bnOrder, bnCtx))
{
LogPrintf("%s: BN_mod_sub failed.\n", __func__);
rv = 1; goto End;
}
if ((nBytes = BN_num_bytes(bnT)) > (int)EC_SECRET_SIZE
|| BN_bn2bin(bnT, &pSigc[nSecretOffset * EC_SECRET_SIZE + (EC_SECRET_SIZE-nBytes)]) != nBytes)
{
LogPrintf("%s: bnT -> pSigc failed.\n", __func__);
rv = 1; goto End;
}
// sigr[nSecretOffset] = (bnKS - sigc[nSecretOffset] * bnSecret) % N
// reuse bnH for bnSecret
if (!bnH || !(BN_bin2bn(&secret.e[0], EC_SECRET_SIZE, bnH)))
{
LogPrintf("%s: BN_bin2bn failed.\n", __func__);
rv = 1; goto End;
}
// bnT = sigc[nSecretOffset] * bnSecret , TODO: mod N ?
if (!BN_mul(bnT, bnT, bnH, bnCtx))
{
LogPrintf("%s: BN_mul failed.\n", __func__);
rv = 1; goto End;
}
if (!BN_mod_sub(bnT, bnKS, bnT, bnOrder, bnCtx))
{
LogPrintf("%s: BN_mod_sub failed.\n", __func__);
rv = 1; goto End;
}
if ((nBytes = BN_num_bytes(bnT)) > (int) EC_SECRET_SIZE
|| BN_bn2bin(bnT, &pSigr[nSecretOffset * EC_SECRET_SIZE + (EC_SECRET_SIZE-nBytes)]) != nBytes)
{
LogPrintf("%s: bnT -> pSigr failed.\n", __func__);
rv = 1; goto End;
}
End:
EC_POINT_free(ptT1);
EC_POINT_free(ptT2);
EC_POINT_free(ptT3);
EC_POINT_free(ptPk);
EC_POINT_free(ptKi);
EC_POINT_free(ptL);
EC_POINT_free(ptR);
BN_CTX_end(bnCtx);
return rv;
}
int verifyRingSignature(data_chunk &keyImage, uint256 &txnHash, int nRingSize, const uint8_t *pPubkeys, const uint8_t *pSigc, const uint8_t *pSigr)
{
int rv = 0;
BN_CTX_start(bnCtx);
BIGNUM *bnT = BN_CTX_get(bnCtx);
BIGNUM *bnH = BN_CTX_get(bnCtx);
BIGNUM *bnC = BN_CTX_get(bnCtx);
BIGNUM *bnR = BN_CTX_get(bnCtx);
BIGNUM *bnSum = BN_CTX_get(bnCtx);
EC_POINT *ptT1 = NULL;
EC_POINT *ptT2 = NULL;
EC_POINT *ptT3 = NULL;
EC_POINT *ptPk = NULL;
EC_POINT *ptKi = NULL;
EC_POINT *ptL = NULL;
EC_POINT *ptR = NULL;
uint8_t tempData[66]; // hold raw point data to hash
uint256 commitHash;
CHashWriter ssCommitHash(SER_GETHASH, PROTOCOL_VERSION);
ssCommitHash << txnHash;
// zero sum
if (!bnSum || !(BN_zero(bnSum)))
{
LogPrintf("%s: BN_zero failed.\n", __func__);
rv = 1; goto End;
}
if ( !(ptT1 = EC_POINT_new(ecGrp))
|| !(ptT2 = EC_POINT_new(ecGrp))
|| !(ptT3 = EC_POINT_new(ecGrp))
|| !(ptPk = EC_POINT_new(ecGrp))
|| !(ptKi = EC_POINT_new(ecGrp))
|| !(ptL = EC_POINT_new(ecGrp))
|| !(ptR = EC_POINT_new(ecGrp)))
{
LogPrintf("%s: EC_POINT_new failed.\n", __func__);
rv = 1; goto End;
}
// get keyimage as point
if (!EC_POINT_oct2point(ecGrp, ptKi, &keyImage[0], EC_COMPRESSED_SIZE, bnCtx)
&&(rv = errorN(1, "%s: extract ptKi failed.", __func__)))
goto End;
for (int i = 0; i < nRingSize; ++i)
{
// Li = ci * Pi + ri * G
// Ri = ci * I + ri * Hp(Pi)
if ( !bnC || !(bnC = BN_bin2bn(&pSigc[i * EC_SECRET_SIZE], EC_SECRET_SIZE, bnC))
|| !bnR || !(bnR = BN_bin2bn(&pSigr[i * EC_SECRET_SIZE], EC_SECRET_SIZE, bnR)))
{
LogPrintf("%s: extract bnC and bnR failed.\n", __func__);
rv = 1; goto End;
}
// get Pk i as point
if (!(bnT = BN_bin2bn(&pPubkeys[i * EC_COMPRESSED_SIZE], EC_COMPRESSED_SIZE, bnT))
|| !(ptPk) || !(ptPk = EC_POINT_bn2point(ecGrp, bnT, ptPk, bnCtx)))
{
LogPrintf("%s: extract ptPk failed.\n", __func__);
rv = 1; goto End;
}
// ptT1 = ci * Pi
if (!EC_POINT_mul(ecGrp, ptT1, NULL, ptPk, bnC, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
// ptT2 = ri * G
if (!EC_POINT_mul(ecGrp, ptT2, bnR, NULL, NULL, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
// ptL = ptT1 + ptT2
if (!EC_POINT_add(ecGrp, ptL, ptT1, ptT2, bnCtx))
{
LogPrintf("%s: EC_POINT_add failed.\n", __func__);
rv = 1; goto End;
}
// ptT3 = Hp(Pi)
if (hashToEC(&pPubkeys[i * EC_COMPRESSED_SIZE], EC_COMPRESSED_SIZE, bnT, ptT3) != 0)
{
LogPrintf("%s: hashToEC failed.\n", __func__);
rv = 1; goto End;
}
// ptT1 = k1 * I
if (!EC_POINT_mul(ecGrp, ptT1, NULL, ptKi, bnC, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
// ptT2 = k2 * ptT3
if (!EC_POINT_mul(ecGrp, ptT2, NULL, ptT3, bnR, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
// ptR = ptT1 + ptT2
if (!EC_POINT_add(ecGrp, ptR, ptT1, ptT2, bnCtx))
{
LogPrintf("%s: EC_POINT_add failed.\n", __func__);
rv = 1; goto End;
}
// sum = (sum + ci) % N
if (!BN_mod_add(bnSum, bnSum, bnC, bnOrder, bnCtx))
{
LogPrintf("%s: BN_mod_add failed.\n", __func__);
rv = 1; goto End;
}
// -- add ptL and ptR to hash
if (!(EC_POINT_point2oct(ecGrp, ptL, POINT_CONVERSION_COMPRESSED, &tempData[0], 33, bnCtx) == (int) EC_COMPRESSED_SIZE)
||!(EC_POINT_point2oct(ecGrp, ptR, POINT_CONVERSION_COMPRESSED, &tempData[33], 33, bnCtx) == (int) EC_COMPRESSED_SIZE))
{
LogPrintf("%s: extract ptL and ptR failed.\n", __func__);
rv = 1; goto End;
}
ssCommitHash.write((const char*)&tempData[0], 66);
}
commitHash = ssCommitHash.GetHash();
if (!(bnH) || !(bnH = BN_bin2bn(commitHash.begin(), EC_SECRET_SIZE, bnH)))
{
LogPrintf("%s: commitHash -> bnH failed.\n", __func__);
rv = 1; goto End;
}
if (!BN_mod(bnH, bnH, bnOrder, bnCtx))
{
LogPrintf("%s: BN_mod failed.\n", __func__);
rv = 1; goto End;
}
// bnT = (bnH - bnSum) % N
if (!BN_mod_sub(bnT, bnH, bnSum, bnOrder, bnCtx))
{
LogPrintf("%s: BN_mod_sub failed.\n", __func__);
rv = 1; goto End;
}
// test bnT == 0 (bnSum == bnH)
if (!BN_is_zero(bnT))
{
LogPrintf("%s: signature does not verify.\n", __func__);
rv = 2;
}
End:
EC_POINT_free(ptT1);
EC_POINT_free(ptT2);
EC_POINT_free(ptT3);
EC_POINT_free(ptPk);
EC_POINT_free(ptKi);
EC_POINT_free(ptL);
EC_POINT_free(ptR);
BN_CTX_end(bnCtx);
return rv;
}
int generateRingSignatureAB(data_chunk &keyImage, uint256 &txnHash, int nRingSize, int nSecretOffset, ec_secret secret, const uint8_t *pPubkeys, data_chunk &sigC, uint8_t *pSigS)
{
// https://bitcointalk.org/index.php?topic=972541.msg10619684
if (fDebugRingSig)
LogPrintf("%s: Ring size %d.\n", __func__, nRingSize);
assert(nRingSize < 200);
RandAddSeedPerfmon();
memset(pSigS, 0, EC_SECRET_SIZE * nRingSize);
int rv = 0;
int nBytes;
uint256 tmpPkHash;
uint256 tmpHash;
uint8_t tempData[66]; // hold raw point data to hash
ec_secret sAlpha;
if (0 != GenerateRandomSecret(sAlpha))
return errorN(1, "%s: GenerateRandomSecret failed.", __func__);
CHashWriter ssPkHash(SER_GETHASH, PROTOCOL_VERSION);
CHashWriter ssCjHash(SER_GETHASH, PROTOCOL_VERSION);
uint256 test;
for (int i = 0; i < nRingSize; ++i)
{
ssPkHash.write((const char*)&pPubkeys[i * EC_COMPRESSED_SIZE], EC_COMPRESSED_SIZE);
if (i == nSecretOffset)
continue;
int k;
// NOTE: necessary to clamp?
for (k = 0; k < 32; ++k)
{
if (1 != RAND_bytes(&pSigS[i * EC_SECRET_SIZE], 32))
return errorN(1, "%s: RAND_bytes ERR_get_error %u.", __func__, ERR_get_error());
memcpy(test.begin(), &pSigS[i * EC_SECRET_SIZE], 32);
if (test > MIN_SECRET && test < MAX_SECRET)
break;
}
if (k > 31)
return errorN(1, "%s: Failed to generate a valid key.", __func__);
}
tmpPkHash = ssPkHash.GetHash();
BN_CTX_start(bnCtx);
BIGNUM *bnT = BN_CTX_get(bnCtx);
BIGNUM *bnT2 = BN_CTX_get(bnCtx);
BIGNUM *bnS = BN_CTX_get(bnCtx);
BIGNUM *bnC = BN_CTX_get(bnCtx);
BIGNUM *bnCj = BN_CTX_get(bnCtx);
BIGNUM *bnA = BN_CTX_get(bnCtx);
EC_POINT *ptKi = NULL;
EC_POINT *ptPk = NULL;
EC_POINT *ptT1 = NULL;
EC_POINT *ptT2 = NULL;
EC_POINT *ptT3 = NULL;
EC_POINT *ptT4 = NULL;
if (!(ptKi = EC_POINT_new(ecGrp))
||!(ptPk = EC_POINT_new(ecGrp))
||!(ptT1 = EC_POINT_new(ecGrp))
||!(ptT2 = EC_POINT_new(ecGrp))
||!(ptT3 = EC_POINT_new(ecGrp))
||!(ptT4 = EC_POINT_new(ecGrp)))
{
LogPrintf("%s: EC_POINT_new failed.\n", __func__);
rv = 1; goto End;
}
// get keyimage as point
if (!EC_POINT_oct2point(ecGrp, ptKi, &keyImage[0], EC_COMPRESSED_SIZE, bnCtx)
&&(rv = errorN(1, "%s: extract ptKi failed.", __func__)))
goto End;
// c_{j+1} = h(P_1,...,P_n,alpha*G,alpha*H(P_j))
if (!bnA || !(BN_bin2bn(&sAlpha.e[0], EC_SECRET_SIZE, bnA)))
{
LogPrintf("%s: BN_bin2bn failed.\n", __func__);
rv = 1; goto End;
}
// ptT1 = alpha * G
if (!EC_POINT_mul(ecGrp, ptT1, bnA, NULL, NULL, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
// ptT3 = H(Pj)
if (hashToEC(&pPubkeys[nSecretOffset * EC_COMPRESSED_SIZE], EC_COMPRESSED_SIZE, bnT2, ptT3) != 0)
{
LogPrintf("%s: hashToEC failed.\n", __func__);
rv = 1; goto End;
}
ssCjHash.write((const char*)tmpPkHash.begin(), 32);
// ptT2 = alpha * H(P_j)
// ptT2 = alpha * ptT3
if (!EC_POINT_mul(ecGrp, ptT2, NULL, ptT3, bnA, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
if ( !(EC_POINT_point2oct(ecGrp, ptT1, POINT_CONVERSION_COMPRESSED, &tempData[0], 33, bnCtx) == (int) EC_COMPRESSED_SIZE)
|| !(EC_POINT_point2oct(ecGrp, ptT2, POINT_CONVERSION_COMPRESSED, &tempData[33], 33, bnCtx) == (int) EC_COMPRESSED_SIZE))
{
LogPrintf("%s: extract ptL and ptR failed.\n", __func__);
rv = 1; goto End;
}
ssCjHash.write((const char*)&tempData[0], 66);
tmpHash = ssCjHash.GetHash();
if (!bnC || !(BN_bin2bn(tmpHash.begin(), EC_SECRET_SIZE, bnC)) // bnC lags i by 1
|| !BN_mod(bnC, bnC, bnOrder, bnCtx))
{
LogPrintf("%s: hash -> bnC failed.\n", __func__);
rv = 1; goto End;
}
// c_{j+2} = h(P_1,...,P_n,s_{j+1}*G+c_{j+1}*P_{j+1},s_{j+1}*H(P_{j+1})+c_{j+1}*I_j)
for (int k = 0, ib = (nSecretOffset + 1) % nRingSize, i = (nSecretOffset + 2) % nRingSize;
k < nRingSize;
++k, ib=i, i=(i+1) % nRingSize)
{
if (k == nRingSize - 1)
{
// s_j = alpha - c_j*x_j mod n.
if (!bnT || !BN_bin2bn(&secret.e[0], EC_SECRET_SIZE, bnT))
{
LogPrintf("%s: BN_bin2bn failed.\n", __func__);
rv = 1; goto End;
}
if (!BN_mul(bnT2, bnCj, bnT, bnCtx))
{
LogPrintf("%s: BN_mul failed.\n", __func__);
rv = 1; goto End;
}
if (!BN_mod_sub(bnS, bnA, bnT2, bnOrder, bnCtx))
{
LogPrintf("%s: BN_mod_sub failed.\n", __func__);
rv = 1; goto End;
}
if (!bnS || (nBytes = BN_num_bytes(bnS)) > (int) EC_SECRET_SIZE
|| BN_bn2bin(bnS, &pSigS[nSecretOffset * EC_SECRET_SIZE + (EC_SECRET_SIZE-nBytes)]) != nBytes)
{
LogPrintf("%s: bnS -> pSigS failed.\n", __func__);
rv = 1; goto End;
}
if (nSecretOffset != nRingSize - 1)
break;
}
if (!bnS || !(BN_bin2bn(&pSigS[ib * EC_SECRET_SIZE], EC_SECRET_SIZE, bnS)))
{
LogPrintf("%s: BN_bin2bn failed.\n", __func__);
rv = 1; goto End;
}
// bnC is from last round (ib)
if (!EC_POINT_oct2point(ecGrp, ptPk, &pPubkeys[ib * EC_COMPRESSED_SIZE], EC_COMPRESSED_SIZE, bnCtx))
{
LogPrintf("%s: EC_POINT_oct2point failed.\n", __func__);
rv = 1; goto End;
}
// ptT1 = s_{j+1}*G+c_{j+1}*P_{j+1}
if (!EC_POINT_mul(ecGrp, ptT1, bnS, ptPk, bnC, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
//s_{j+1}*H(P_{j+1})+c_{j+1}*I_j
if (hashToEC(&pPubkeys[ib * EC_COMPRESSED_SIZE], EC_COMPRESSED_SIZE, bnT2, ptT2) != 0)
{
LogPrintf("%s: hashToEC failed.\n", __func__);
rv = 1; goto End;
}
// ptT3 = s_{j+1}*H(P_{j+1})
if (!EC_POINT_mul(ecGrp, ptT3, NULL, ptT2, bnS, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
// ptT4 = c_{j+1}*I_j
if (!EC_POINT_mul(ecGrp, ptT4, NULL, ptKi, bnC, bnCtx))
{
LogPrintf("%s: EC_POINT_mul failed.\n", __func__);
rv = 1; goto End;
}
// ptT2 = ptT3 + ptT4
if (!EC_POINT_add(ecGrp, ptT2, ptT3, ptT4, bnCtx))
{
LogPrintf("%s: EC_POINT_add failed.\n", __func__);
rv = 1; goto End;
}
if (!(EC_POINT_point2oct(ecGrp, ptT1, POINT_CONVERSION_COMPRESSED, &tempData[0], 33, bnCtx) == (int) EC_COMPRESSED_SIZE)
||!(EC_POINT_point2oct(ecGrp, ptT2, POINT_CONVERSION_COMPRESSED, &tempData[33], 33, bnCtx) == (int) EC_COMPRESSED_SIZE))
{
LogPrintf("%s: extract ptL and ptR failed.\n", __func__);
rv = 1; goto End;
}
CHashWriter ssCHash(SER_GETHASH, PROTOCOL_VERSION);
ssCHash.write((const char*)tmpPkHash.begin(), 32);
ssCHash.write((const char*)&tempData[0], 66);
tmpHash = ssCHash.GetHash();
if ((!bnC
||!BN_bin2bn(tmpHash.begin(), EC_SECRET_SIZE, bnC) // bnC lags i by 1
||!BN_mod(bnC, bnC, bnOrder, bnCtx))
&& (rv = errorN(1, "%s: hash -> bnC failed.", __func__)))
goto End;
if (i == nSecretOffset
&&!BN_copy(bnCj, bnC)
&& (rv = errorN(1, "%s: BN_copy failed.\n", __func__)))
goto End;
if (i == 0)
{
memset(tempData, 0, EC_SECRET_SIZE);
if ((nBytes = BN_num_bytes(bnC)) > (int) EC_SECRET_SIZE
|| BN_bn2bin(bnC, &tempData[0 + (EC_SECRET_SIZE-nBytes)]) != nBytes)
{
LogPrintf("%s: bnC -> sigC failed.\n", __func__);
rv = 1; goto End;
}
try { sigC.resize(32); } catch (std::exception& e)
{
LogPrintf("%s: sigC.resize failed.\n", __func__);
rv = 1; goto End;
}
memcpy(&sigC[0], tempData, EC_SECRET_SIZE);
}
}
End:
EC_POINT_free(ptKi);
EC_POINT_free(ptPk);
EC_POINT_free(ptT1);
EC_POINT_free(ptT2);
EC_POINT_free(ptT3);
EC_POINT_free(ptT4);
BN_CTX_end(bnCtx);
return rv;
}
int verifyRingSignatureAB(data_chunk &keyImage, uint256 &txnHash, int nRingSize, const uint8_t *pPubkeys, const data_chunk &sigC, const uint8_t *pSigS)
{
// https://bitcointalk.org/index.php?topic=972541.msg10619684
// forall_{i=1..n} compute e_i=s_i*G+c_i*P_i and E_i=s_i*H(P_i)+c_i*I_j and c_{i+1}=h(P_1,...,P_n,e_i,E_i)
// check c_{n+1}=c_1
if (sigC.size() != EC_SECRET_SIZE)
return errorN(1, "%s: sigC size != EC_SECRET_SIZE.", __func__);
if (keyImage.size() != EC_COMPRESSED_SIZE)
return errorN(1, "%s: keyImage size != EC_COMPRESSED_SIZE.", __func__);
int rv = 0;
uint256 tmpPkHash;
uint256 tmpHash;
uint8_t tempData[66]; // hold raw point data to hash
CHashWriter ssPkHash(SER_GETHASH, PROTOCOL_VERSION);
CHashWriter ssCjHash(SER_GETHASH, PROTOCOL_VERSION);
for (int i = 0; i < nRingSize; ++i)
{
ssPkHash.write((const char*)&pPubkeys[i * EC_COMPRESSED_SIZE], EC_COMPRESSED_SIZE);
}
tmpPkHash = ssPkHash.GetHash();
BN_CTX_start(bnCtx);
BIGNUM *bnC = BN_CTX_get(bnCtx);
BIGNUM *bnC1 = BN_CTX_get(bnCtx);
BIGNUM *bnT = BN_CTX_get(bnCtx);
BIGNUM *bnS = BN_CTX_get(bnCtx);
EC_POINT *ptKi = NULL;
EC_POINT *ptT1 = NULL;
EC_POINT *ptT2 = NULL;