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Signature generation and Spend APIs
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SDCDev committed Dec 16, 2014
1 parent 94bfb03 commit 317b9b1
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291 changes: 291 additions & 0 deletions src/ringsig.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -232,6 +232,297 @@ int generateKeyImage(ec_point &publicKey, ec_secret secret, ec_point &keyImage)
};







int generateRingSignature(std::vector<uint8_t>& keyImage, uint256& txnHash, int nRingSize, int nSecretOffset, ec_secret secret, const uint8_t *pPubkeys, uint8_t *pSigc, uint8_t *pSigr)
{
if (fDebugRingSig)
printf("generateRingSignature() size %d\n", 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) != 0)
{
printf("generateRingSignature(): GenerateRandomSecret failed.\n");
rv = 1; goto End;
};

if (!bnKS || !(BN_bin2bn(&scData1.e[0], 32, bnKS)))
{
printf("generateRingSignature(): BN_bin2bn failed.\n");
rv = 1; goto End;
};

// zero sum
if (!bnSum || !(BN_zero(bnSum)))
{
printf("generateRingSignature(): BN_zero failed.\n");
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)))
{
printf("generateRingSignature(): EC_POINT_new failed.\n");
rv = 1; goto End;
};

// get keyimage as point
if (!(bnT = BN_bin2bn(&keyImage[0], ec_compressed_size, bnT))
|| !(ptKi) || !(ptKi = EC_POINT_bn2point(ecGrp, bnT, ptKi, bnCtx)))
{
printf("generateRingSignature(): extract ptKi failed\n");
rv = 1; 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))
{
printf("generateRingSignature(): EC_POINT_mul failed.\n");
rv = 1; goto End;
};

if (hashToEC(&pPubkeys[i * ec_compressed_size], ec_compressed_size, bnT, ptT1) != 0)
{
printf("generateRingSignature(): hashToEC failed.\n");
rv = 1; goto End;
};

if (!EC_POINT_mul(ecGrp, ptR, NULL, ptT1, bnKS, bnCtx))
{
printf("generateRingSignature(): EC_POINT_mul failed.\n");
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], 32, bnK1))
|| GenerateRandomSecret(scData2) != 0
|| !bnK2 || !(BN_bin2bn(&scData2.e[0], 32, bnK2)))
{
printf("generateRingSignature(): k1 and k2 failed.\n");
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)))
{
printf("generateRingSignature(): extract ptPk failed\n");
rv = 1; goto End;
};

// ptT1 = k1 * Pi
if (!EC_POINT_mul(ecGrp, ptT1, NULL, ptPk, bnK1, bnCtx))
{
printf("generateRingSignature(): EC_POINT_mul failed.\n");
rv = 1; goto End;
};

// ptT2 = k2 * G
if (!EC_POINT_mul(ecGrp, ptT2, bnK2, NULL, NULL, bnCtx))
{
printf("generateRingSignature(): EC_POINT_mul failed.\n");
rv = 1; goto End;
};

// ptL = ptT1 + ptT2
if (!EC_POINT_add(ecGrp, ptL, ptT1, ptT2, bnCtx))
{
printf("generateRingSignature(): EC_POINT_add failed.\n");
rv = 1; goto End;
};

// ptT3 = Hp(Pi)
if (hashToEC(&pPubkeys[i * ec_compressed_size], ec_compressed_size, bnT, ptT3) != 0)
{
printf("generateRingSignature(): hashToEC failed.\n");
rv = 1; goto End;
};

// ptT1 = k1 * I
if (!EC_POINT_mul(ecGrp, ptT1, NULL, ptKi, bnK1, bnCtx))
{
printf("generateRingSignature(): EC_POINT_mul failed.\n");
rv = 1; goto End;
};

// ptT2 = k2 * ptT3
if (!EC_POINT_mul(ecGrp, ptT2, NULL, ptT3, bnK2, bnCtx))
{
printf("generateRingSignature(): EC_POINT_mul failed.\n");
rv = 1; goto End;
};

// ptR = ptT1 + ptT2
if (!EC_POINT_add(ecGrp, ptR, ptT1, ptT2, bnCtx))
{
printf("generateRingSignature(): EC_POINT_add failed.\n");
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, bnN, bnCtx))
{
printf("generateRingSignature(): BN_mod_add failed.\n");
rv = 1; goto End;
};
};

// -- add ptL and ptR to hash
if (!(EC_POINT_point2bn(ecGrp, ptL, POINT_CONVERSION_COMPRESSED, bnT, bnCtx))
|| BN_num_bytes(bnT) != (int) ec_compressed_size
|| BN_bn2bin(bnT, &tempData[0]) != (int) ec_compressed_size
|| !(EC_POINT_point2bn(ecGrp, ptR, POINT_CONVERSION_COMPRESSED, bnT, bnCtx))
|| BN_num_bytes(bnT) != (int) ec_compressed_size
|| BN_bn2bin(bnT, &tempData[33]) != (int) ec_compressed_size)
{
printf("extract ptL and ptR failed.\n");
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)))
{
printf("generateRingSignature(): commitHash -> bnH failed\n");
rv = 1; goto End;
};


if (!BN_mod(bnH, bnH, bnN, bnCtx)) // this is necessary
{
printf("generateRingSignature(): BN_mod failed.\n");
rv = 1; goto End;
};

//printBN(bnSum, "[rem]2 bnSum");
//printBN(bnH, "[rem]2 bnH");

// sigc[nSecretOffset] = (bnH - bnSum) % N
if (!BN_mod_sub(bnT, bnH, bnSum, bnN, bnCtx))
{
printf("generateRingSignature(): BN_mod_sub failed.\n");
rv = 1; goto End;
};

if ((nBytes = BN_num_bytes(bnT)) > (int)ec_secret_size
|| BN_bn2bin(bnT, &pSigc[nSecretOffset * ec_secret_size + (32-nBytes)]) != nBytes)
{
printf("bnT -> pSigc failed.\n");
rv = 1; goto End;
};

// sigr[nSecretOffset] = (bnKS - sigc[nSecretOffset] * bnSecret) % N
// reuse bnH for bnSecret
if (!bnH || !(BN_bin2bn(&secret.e[0], 32, bnH)))
{
printf("generateRingSignature(): BN_bin2bn failed.\n");
rv = 1; goto End;
};

// bnT = sigc[nSecretOffset] * bnSecret , TODO: mod N ?
if (!BN_mul(bnT, bnT, bnH, bnCtx))
{
printf("generateRingSignature(): BN_mul failed.\n");
rv = 1; goto End;
};

if (!BN_mod_sub(bnT, bnKS, bnT, bnN, bnCtx))
{
printf("generateRingSignature(): BN_mod_sub failed.\n");
rv = 1; goto End;
};

if ((nBytes = BN_num_bytes(bnT)) > (int)ec_secret_size
|| BN_bn2bin(bnT, &pSigr[nSecretOffset * ec_secret_size + (32-nBytes)]) != nBytes)
{
printf("bnT -> pSigr failed.\n");
rv = 1; goto End;
};

End:
if (ptT1)
EC_POINT_free(ptT1);
if (ptT2)
EC_POINT_free(ptT2);
if (ptT3)
EC_POINT_free(ptT3);
if (ptPk)
EC_POINT_free(ptPk);
if (ptKi)
EC_POINT_free(ptKi);
if (ptL)
EC_POINT_free(ptL);
if (ptR)
EC_POINT_free(ptR);

BN_CTX_end(bnCtx);

return rv;
};

int verifyRingSignature(std::vector<uint8_t>& keyImage, uint256& txnHash, int nRingSize, const uint8_t *pPubkeys, const uint8_t *pSigc, const uint8_t *pSigr)
{
if (fDebugRingSig)
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3 changes: 3 additions & 0 deletions src/ringsig.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,9 @@ int splitAmount(int64_t nValue, std::vector<int64_t>& vOut);

int generateKeyImage(ec_point &publicKey, ec_secret secret, ec_point &keyImage);


int generateRingSignature(std::vector<uint8_t>& keyImage, uint256& txnHash, int nRingSize, int nSecretOffset, ec_secret secret, const uint8_t *pPubkeys, uint8_t *pSigc, uint8_t *pSigr);

int verifyRingSignature(std::vector<uint8_t>& keyImage, uint256& txnHash, int nRingSize, const uint8_t *pPubkeys, const uint8_t *pSigc, const uint8_t *pSigr);


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