/*
* FEE_SIG_USING_PROJ true : this is the "no Weierstrass" case
* feeSigVerifyNoProj false : this is redefined to feeSigVerify
*/
feeReturn feeSigVerifyNoProj(feeSig sig,
const unsigned char *data,
unsigned dataLen,
feePubKey pubKey)
{
giant Q = NULL;
giant messageGiant = NULL;
giant scratch = NULL;
sigInst *sinst = (sigInst*) sig;
feeReturn frtn;
curveParams *cp;
key origKey; // may be plus or minus key
if(sinst->PmX == NULL) {
dbgLog(("sigVerify without parse!\n"));
frtn = FR_IllegalArg;
goto out;
}
cp = feePubKeyCurveParams(pubKey);
Q = newGiant(cp->maxDigits);
/*
* pick a key (+/-)
* Q := P1
*/
if(SIG_CURVE == CURVE_PLUS) {
origKey = feePubKeyPlusCurve(pubKey);
gtog(cp->x1Plus, Q);
}
else {
origKey = feePubKeyMinusCurve(pubKey);
gtog(cp->x1Minus, Q);
}
messageGiant = giant_with_data(data, dataLen); // M(ciphertext)
/* Q := u 'o' P1 */
elliptic_simple(Q, sinst->u, cp);
/* scratch := theirPub */
scratch = newGiant(cp->maxDigits);
gtog(origKey->x, scratch);
#if SIG_DEBUG
if(sigDebug) {
printf("verify origKey:\n");
printKey(origKey);
printf("messageGiant: ");
printGiant(messageGiant);
printf("curveParams:\n");
printCurveParams(cp);
}
#endif // SIG_DEBUG
/* scratch := M 'o' theirPub */
elliptic_simple(scratch, messageGiant, cp);
#if SIG_DEBUG
if(sigDebug) {
printf("signature_compare, with\n");
printf("p0 = Q:\n");
printGiant(Q);
printf("p1 = Pm:\n");
printGiant(sinst->PmX);
printf("p2 = scratch = R:\n");
printGiant(scratch);
}
#endif // SIG_DEBUG
if(signature_compare(Q, sinst->PmX, scratch, cp)) {
frtn = FR_InvalidSignature;
#if LOG_BAD_SIG
printf("***yup, bad sig***\n");
#endif // LOG_BAD_SIG
}
else {
frtn = FR_Success;
}
out:
if(messageGiant != NULL) {
freeGiant(messageGiant);
}
if(Q != NULL) {
freeGiant(Q);
}
if(scratch != NULL) {
freeGiant(scratch);
}
return frtn;
}
/*
* Alloc and init a feeFEEDExp object associated with specified feePubKey.
*/
feeFEEDExp feeFEEDExpNewWithPubKey(
feePubKey pubKey,
feeRandFcn randFcn, // optional
void *randRef)
{
feedInst *finst = (feedInst *) fmalloc(sizeof(feedInst));
giant privGiant;
finst->cp = curveParamsCopy(feePubKeyCurveParams(pubKey));
finst->plus = new_public_with_key(feePubKeyPlusCurve(pubKey),
finst->cp);
finst->minus = new_public_with_key(feePubKeyMinusCurve(pubKey),
finst->cp);
/*
* These might yield NULL data; we can only encrypt in that case.
*/
privGiant = feePubKeyPrivData(pubKey);
if(privGiant) {
finst->gPriv = newGiant(finst->cp->maxDigits);
gtog(privGiant, finst->gPriv);
}
else {
finst->gPriv = NULL;
}
/*
* Conservative, rounding down, on plaintext blocks since we don't
* want to split bytes.
*/
if(finst->cp->primeType == FPT_General) {
unsigned blen = bitlen(finst->cp->basePrime);
finst->plainBlockSize = blen / 8;
if((blen % 8) == 0) {
/*
* round down some more...
*/
finst->plainBlockSize--;
}
}
else {
finst->plainBlockSize = finst->cp->q / 8;
if(((finst->cp->q & 0x7) == 0) && (finst->cp->k > 0)) {
/*
* Special case, with q mod 8 == 0. Here we have to trim back
* the plainBlockSize by one byte.
*/
finst->plainBlockSize--;
}
}
/*
* One block of ciphertext - two giants (with implied sign) and a
* parity byte
*/
finst->cipherBlockSize = (2 * finst->cp->minBytes) + 1;
finst->xp = newGiant(finst->cp->maxDigits);
finst->xc = newGiant(finst->cp->maxDigits);
finst->xq = newGiant(finst->cp->maxDigits);
finst->xm = newGiant(finst->cp->maxDigits);
finst->xaux = newGiant(finst->cp->maxDigits);
finst->rand = NULL;
finst->randData = NULL;
finst->randFcn = randFcn;
finst->randRef = randRef;
return finst;
}
/*
* Alloc and init a feeFEED object associated with specified public and
* private keys.
*/
feeFEED feeFEEDNewWithPubKey(feePubKey myPrivKey,
feePubKey theirPubKey,
int forEncrypt, // 0 ==> decrypt 1 ==> encrypt
feeRandFcn randFcn, // optional
void *randRef)
{
feedInst *finst;
giant privGiant;
key k;
unsigned expPlainSize;
unsigned expCipherSize;
unsigned expBlocks;
if(!curveParamsEquivalent(feePubKeyCurveParams(theirPubKey),
feePubKeyCurveParams(myPrivKey))) {
dbgLog(("feeFEEDNewWithPubKey: Incompatible Keys\n"));
return NULL;
}
finst = (feedInst*) fmalloc(sizeof(feedInst));
bzero(finst, sizeof(feedInst));
finst->forEncrypt = forEncrypt;
finst->cp = curveParamsCopy(feePubKeyCurveParams(theirPubKey));
finst->rsBlockCount = 0;
finst->xp = newGiant(finst->cp->maxDigits);
finst->xm = newGiant(finst->cp->maxDigits);
finst->tmp1 = newGiant(finst->cp->maxDigits);
if(forEncrypt) {
finst->tmp2 = newGiant(finst->cp->maxDigits);
}
/*
* cluePlus = ourPriv * theirPub+
* clueMinus = ourPriv * theirPub-
*/
finst->cluePlus = newGiant(finst->cp->maxDigits);
finst->clueMinus = newGiant(finst->cp->maxDigits);
privGiant = feePubKeyPrivData(myPrivKey);
if(privGiant == NULL) {
dbgLog(("feeFEEDNewWithPubKey: no private key\n"));
goto abort;
}
k = feePubKeyPlusCurve(theirPubKey);
gtog(k->x, finst->cluePlus); // cluePlus = theirPub+
elliptic_simple(finst->cluePlus, privGiant, finst->cp);
k = feePubKeyMinusCurve(theirPubKey);
gtog(k->x, finst->clueMinus); // theirPub-
elliptic_simple(finst->clueMinus, privGiant, finst->cp);
/*
* Set up block sizes.
*/
if(finst->cp->primeType == FPT_General) {
unsigned blen = bitlen(finst->cp->basePrime);
finst->plainBlockSize = blen / 8;
if((blen & 0x7) == 0) {
/*
* round down some more...
*/
finst->plainBlockSize--;
}
}
else {
finst->plainBlockSize = finst->cp->q / 8;
if(((finst->cp->q & 0x7) == 0) && (finst->cp->k > 0)) {
/*
* Special case, with q mod 8 == 0. Here we have to
* trim back the plainBlockSize by one byte.
*/
finst->plainBlockSize--;
}
}
finst->cipherBlockSize = finst->cp->minBytes + 1;
/*
* the size of initialRS is subject to tweaking - if we make it
* not a multiple of plainBlockSize, we save one FEEDExp cipherBlock
* in our ciphertext.
*/
finst->initialRSSize = finst->plainBlockSize * 2;
if(finst->initialRSSize > RS_MIN_SIZE) {
unsigned minPlainBlocks;
unsigned maxSize;
/*
* How many plainblocks to hold RS_MIN_SIZE?
*/
minPlainBlocks = (RS_MIN_SIZE + finst->plainBlockSize - 1) /
finst->plainBlockSize;
/*
* Max size = that many plainblocks, less 2 bytes (to avoid
* extra residue block).
*/
maxSize = minPlainBlocks * finst->plainBlockSize - 2;
/*
* But don't bother with more than 2 plainblocks worth
*/
if(finst->initialRSSize > maxSize) {
finst->initialRSSize = maxSize;
}
}
/* else leave it alone, that's small enough */
if(forEncrypt) {
feeRand frand = NULL;
/*
* Encrypt-capable FEEDExp object
*/
finst->feedExp = feeFEEDExpNewWithPubKey(theirPubKey,
randFcn,
randRef);
if(finst->feedExp == NULL) {
goto abort;
}
/*
* Generate initial r and s data.
*/
finst->initialRS = (unsigned char*) fmalloc(finst->initialRSSize);
if(randFcn != NULL) {
randFcn(randRef, finst->initialRS, finst->initialRSSize);
}
else {
frand = feeRandAlloc();
feeRandBytes(frand, finst->initialRS, finst->initialRSSize);
feeRandFree(frand);
}
if(initFromRS(finst)) {
goto abort;
}
}
else {
/*
* Decrypt-capable FEEDExp object
*/
finst->feedExp = feeFEEDExpNewWithPubKey(myPrivKey,
randFcn,
randRef);
if(finst->feedExp == NULL) {
goto abort;
}
}
/*
* Figure out how many of our cipherblocks it takes to hold
* a FEEDExp-encrypted initialRS. If initialRSSize is an exact
* multiple of expPlainSize, we get an additional feedExp
* residue block.
*/
expPlainSize = feeFEEDExpPlainBlockSize(finst->feedExp);
expCipherSize = feeFEEDExpCipherBlockSize(finst->feedExp);
expBlocks = (finst->initialRSSize + expPlainSize - 1) /
expPlainSize;
if((finst->initialRSSize % expPlainSize) == 0) {
expBlocks++;
}
/*
* Total meaningful bytes of encrypted initialRS
*/
finst->rsCtextSize = expBlocks * expCipherSize;
/*
* Number of our cipherblocks it takes to hold rsCtextSize
*/
finst->rsSizeCipherBlocks = (finst->rsCtextSize +
finst->cipherBlockSize - 1) / finst->cipherBlockSize;
if(!forEncrypt) {
finst->rsCtext = (unsigned char*) fmalloc(finst->rsSizeCipherBlocks *
finst->cipherBlockSize);
}
/*
* Sanity check...
*/
#if FEED_DEBUG
{
unsigned fexpBlockSize = feeFEEDExpCipherBlockSize(finst->feedExp);
/*
* FEEDExp has one more giant in ciphertext, plaintext is
* same size
*/
if((finst->cipherBlockSize + finst->cp->minBytes) !=
fexpBlockSize) {
dbgLog(("feeFEEDNewWithPubKey: FEEDExp CBlock Size "
"screwup\n"));
goto abort;
}
fexpBlockSize = feeFEEDExpPlainBlockSize(finst->feedExp);
if(fexpBlockSize != finst->plainBlockSize) {
dbgLog(("feeFEEDNewWithPubKey: FEEDExp PBlock Size "
"screwup\n"));
goto abort;
}
}
#endif // FEED_DEBUG
return finst;
abort:
feeFEEDFree(finst);
return NULL;
}
