int BN_div(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m, const BIGNUM *d,
BN_CTX *ctx)
{
int i, nm, nd;
int ret = 0;
BIGNUM *D;
bn_check_top(m);
bn_check_top(d);
if (BN_is_zero(d)) {
BNerr(BN_F_BN_DIV, BN_R_DIV_BY_ZERO);
return (0);
}
if (BN_ucmp(m, d) < 0) {
if (rem != NULL) {
if (BN_copy(rem, m) == NULL)
return (0);
}
if (dv != NULL)
BN_zero(dv);
return (1);
}
BN_CTX_start(ctx);
D = BN_CTX_get(ctx);
if (dv == NULL)
dv = BN_CTX_get(ctx);
if (rem == NULL)
rem = BN_CTX_get(ctx);
if (D == NULL || dv == NULL || rem == NULL)
goto end;
nd = BN_num_bits(d);
nm = BN_num_bits(m);
if (BN_copy(D, d) == NULL)
goto end;
if (BN_copy(rem, m) == NULL)
goto end;
/*
* The next 2 are needed so we can do a dv->d[0]|=1 later since
* BN_lshift1 will only work once there is a value :-)
*/
BN_zero(dv);
if (bn_wexpand(dv, 1) == NULL)
goto end;
dv->top = 1;
if (!BN_lshift(D, D, nm - nd))
goto end;
for (i = nm - nd; i >= 0; i--) {
if (!BN_lshift1(dv, dv))
goto end;
if (BN_ucmp(rem, D) >= 0) {
dv->d[0] |= 1;
if (!BN_usub(rem, rem, D))
goto end;
}
/* CAN IMPROVE (and have now :=) */
if (!BN_rshift1(D, D))
goto end;
}
rem->neg = BN_is_zero(rem) ? 0 : m->neg;
dv->neg = m->neg ^ d->neg;
ret = 1;
end:
BN_CTX_end(ctx);
return (ret);
}
BIGNUM *BN_mod_inverse(BIGNUM *in,
const BIGNUM *a, const BIGNUM *n, BN_CTX *ctx)
{
BIGNUM *A,*B,*X,*Y,*M,*D,*T,*R=NULL;
BIGNUM *ret=NULL;
int sign;
if ((BN_get_flags(a, BN_FLG_CONSTTIME) != 0) || (BN_get_flags(n, BN_FLG_CONSTTIME) != 0))
{
return BN_mod_inverse_no_branch(in, a, n, ctx);
}
bn_check_top(a);
bn_check_top(n);
BN_CTX_start(ctx);
A = BN_CTX_get(ctx);
B = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
D = BN_CTX_get(ctx);
M = BN_CTX_get(ctx);
Y = BN_CTX_get(ctx);
T = BN_CTX_get(ctx);
if (T == NULL) goto err;
if (in == NULL)
R=BN_new();
else
R=in;
if (R == NULL) goto err;
BN_one(X);
BN_zero(Y);
if (BN_copy(B,a) == NULL) goto err;
if (BN_copy(A,n) == NULL) goto err;
A->neg = 0;
if (B->neg || (BN_ucmp(B, A) >= 0))
{
if (!BN_nnmod(B, B, A, ctx)) goto err;
}
sign = -1;
/* From B = a mod |n|, A = |n| it follows that
*
* 0 <= B < A,
* -sign*X*a == B (mod |n|),
* sign*Y*a == A (mod |n|).
*/
#if 0
if (BN_is_odd(n) && (BN_num_bits(n) <= (BN_BITS <= 32 ? 450 : 2048)))
{
/* Binary inversion algorithm; requires odd modulus.
* This is faster than the general algorithm if the modulus
* is sufficiently small (about 400 .. 500 bits on 32-bit
* sytems, but much more on 64-bit systems) */
int shift;
while (!BN_is_zero(B))
{
/*
* 0 < B < |n|,
* 0 < A <= |n|,
* (1) -sign*X*a == B (mod |n|),
* (2) sign*Y*a == A (mod |n|)
*/
/* Now divide B by the maximum possible power of two in the integers,
* and divide X by the same value mod |n|.
* When we're done, (1) still holds. */
shift = 0;
while (!BN_is_bit_set(B, shift)) /* note that 0 < B */
{
shift++;
if (BN_is_odd(X))
{
if (!BN_uadd(X, X, n)) goto err;
}
/* now X is even, so we can easily divide it by two */
if (!BN_rshift1(X, X)) goto err;
}
if (shift > 0)
{
if (!BN_rshift(B, B, shift)) goto err;
}
/* Same for A and Y. Afterwards, (2) still holds. */
shift = 0;
while (!BN_is_bit_set(A, shift)) /* note that 0 < A */
{
shift++;
if (BN_is_odd(Y))
{
if (!BN_uadd(Y, Y, n)) goto err;
}
/* now Y is even */
if (!BN_rshift1(Y, Y)) goto err;
}
if (shift > 0)
{
if (!BN_rshift(A, A, shift)) goto err;
}
/* We still have (1) and (2).
* Both A and B are odd.
* The following computations ensure that
*
* 0 <= B < |n|,
* 0 < A < |n|,
* (1) -sign*X*a == B (mod |n|),
* (2) sign*Y*a == A (mod |n|),
*
* and that either A or B is even in the next iteration.
*/
if (BN_ucmp(B, A) >= 0)
{
/* -sign*(X + Y)*a == B - A (mod |n|) */
if (!BN_uadd(X, X, Y)) goto err;
/* NB: we could use BN_mod_add_quick(X, X, Y, n), but that
* actually makes the algorithm slower */
if (!BN_usub(B, B, A)) goto err;
}
else
{
/* sign*(X + Y)*a == A - B (mod |n|) */
if (!BN_uadd(Y, Y, X)) goto err;
/* as above, BN_mod_add_quick(Y, Y, X, n) would slow things down */
if (!BN_usub(A, A, B)) goto err;
}
}
}
else
#endif
{
/* general inversion algorithm */
while (!BN_is_zero(B))
{
BIGNUM *tmp;
/*
* 0 < B < A,
* (*) -sign*X*a == B (mod |n|),
* sign*Y*a == A (mod |n|)
*/
/* (D, M) := (A/B, A%B) ... */
if (BN_num_bits(A) == BN_num_bits(B))
{
if (!BN_one(D)) goto err;
if (!BN_sub(M,A,B)) goto err;
}
else if (BN_num_bits(A) == BN_num_bits(B) + 1)
{
/* A/B is 1, 2, or 3 */
if (!BN_lshift1(T,B)) goto err;
if (BN_ucmp(A,T) < 0)
{
/* A < 2*B, so D=1 */
if (!BN_one(D)) goto err;
if (!BN_sub(M,A,B)) goto err;
}
else
{
/* A >= 2*B, so D=2 or D=3 */
if (!BN_sub(M,A,T)) goto err;
if (!BN_add(D,T,B)) goto err; /* use D (:= 3*B) as temp */
if (BN_ucmp(A,D) < 0)
{
/* A < 3*B, so D=2 */
if (!BN_set_word(D,2)) goto err;
/* M (= A - 2*B) already has the correct value */
}
else
{
/* only D=3 remains */
if (!BN_set_word(D,3)) goto err;
/* currently M = A - 2*B, but we need M = A - 3*B */
if (!BN_sub(M,M,B)) goto err;
}
}
}
else
{
if (!BN_div(D,M,A,B,ctx)) goto err;
}
/* Now
* A = D*B + M;
* thus we have
* (**) sign*Y*a == D*B + M (mod |n|).
*/
tmp=A; /* keep the BIGNUM object, the value does not matter */
/* (A, B) := (B, A mod B) ... */
A=B;
B=M;
/* ... so we have 0 <= B < A again */
/* Since the former M is now B and the former B is now A,
* (**) translates into
* sign*Y*a == D*A + B (mod |n|),
* i.e.
* sign*Y*a - D*A == B (mod |n|).
* Similarly, (*) translates into
* -sign*X*a == A (mod |n|).
*
* Thus,
* sign*Y*a + D*sign*X*a == B (mod |n|),
* i.e.
* sign*(Y + D*X)*a == B (mod |n|).
*
* So if we set (X, Y, sign) := (Y + D*X, X, -sign), we arrive back at
* -sign*X*a == B (mod |n|),
* sign*Y*a == A (mod |n|).
* Note that X and Y stay non-negative all the time.
*/
/* most of the time D is very small, so we can optimize tmp := D*X+Y */
if (BN_is_one(D))
{
if (!BN_add(tmp,X,Y)) goto err;
}
else
{
if (BN_is_word(D,2))
{
if (!BN_lshift1(tmp,X)) goto err;
}
else if (BN_is_word(D,4))
{
if (!BN_lshift(tmp,X,2)) goto err;
}
else if (D->top == 1)
{
if (!BN_copy(tmp,X)) goto err;
if (!BN_mul_word(tmp,D->d[0])) goto err;
}
else
{
if (!BN_mul(tmp,D,X,ctx)) goto err;
}
if (!BN_add(tmp,tmp,Y)) goto err;
}
M=Y; /* keep the BIGNUM object, the value does not matter */
Y=X;
X=tmp;
sign = -sign;
}
}
/*
* The while loop (Euclid's algorithm) ends when
* A == gcd(a,n);
* we have
* sign*Y*a == A (mod |n|),
* where Y is non-negative.
*/
if (sign < 0)
{
if (!BN_sub(Y,n,Y)) goto err;
}
/* Now Y*a == A (mod |n|). */
if (BN_is_one(A))
{
/* Y*a == 1 (mod |n|) */
if (!Y->neg && BN_ucmp(Y,n) < 0)
{
if (!BN_copy(R,Y)) goto err;
}
else
{
if (!BN_nnmod(R,Y,n,ctx)) goto err;
}
}
else
{
BNerr(BN_F_BN_MOD_INVERSE,BN_R_NO_INVERSE);
goto err;
}
ret=R;
err:
if ((ret == NULL) && (in == NULL)) BN_free(R);
BN_CTX_end(ctx);
bn_check_top(ret);
return(ret);
}
int BN_div_recp(BIGNUM *dv, BIGNUM *rem, const BIGNUM *m,
BN_RECP_CTX *recp, BN_CTX *ctx)
{
int i, j, ret = 0;
BIGNUM *a, *b, *d, *r;
BN_CTX_start(ctx);
a = BN_CTX_get(ctx);
b = BN_CTX_get(ctx);
if (dv != NULL)
d = dv;
else
d = BN_CTX_get(ctx);
if (rem != NULL)
r = rem;
else
r = BN_CTX_get(ctx);
if (a == NULL || b == NULL || d == NULL || r == NULL)
goto err;
if (BN_ucmp(m, &(recp->N)) < 0) {
BN_zero(d);
if (!BN_copy(r, m)) {
BN_CTX_end(ctx);
return 0;
}
BN_CTX_end(ctx);
return (1);
}
/*
* We want the remainder Given input of ABCDEF / ab we need multiply
* ABCDEF by 3 digests of the reciprocal of ab
*/
/* i := max(BN_num_bits(m), 2*BN_num_bits(N)) */
i = BN_num_bits(m);
j = recp->num_bits << 1;
if (j > i)
i = j;
/* Nr := round(2^i / N) */
if (i != recp->shift)
recp->shift = BN_reciprocal(&(recp->Nr), &(recp->N), i, ctx);
/* BN_reciprocal could have returned -1 for an error */
if (recp->shift == -1)
goto err;
/*-
* d := |round(round(m / 2^BN_num_bits(N)) * recp->Nr / 2^(i - BN_num_bits(N)))|
* = |round(round(m / 2^BN_num_bits(N)) * round(2^i / N) / 2^(i - BN_num_bits(N)))|
* <= |(m / 2^BN_num_bits(N)) * (2^i / N) * (2^BN_num_bits(N) / 2^i)|
* = |m/N|
*/
if (!BN_rshift(a, m, recp->num_bits))
goto err;
if (!BN_mul(b, a, &(recp->Nr), ctx))
goto err;
if (!BN_rshift(d, b, i - recp->num_bits))
goto err;
d->neg = 0;
if (!BN_mul(b, &(recp->N), d, ctx))
goto err;
if (!BN_usub(r, m, b))
goto err;
r->neg = 0;
#if 1
j = 0;
while (BN_ucmp(r, &(recp->N)) >= 0) {
if (j++ > 2) {
BNerr(BN_F_BN_DIV_RECP, BN_R_BAD_RECIPROCAL);
goto err;
}
if (!BN_usub(r, r, &(recp->N)))
goto err;
if (!BN_add_word(d, 1))
goto err;
}
#endif
r->neg = BN_is_zero(r) ? 0 : m->neg;
d->neg = m->neg ^ recp->N.neg;
ret = 1;
err:
BN_CTX_end(ctx);
bn_check_top(dv);
bn_check_top(rem);
return (ret);
}
int verifyRingSignature(data_chunk &keyImage, uint256 &txnHash, int nRingSize, const uint8_t *pPubkeys, const uint8_t *pSigc, const uint8_t *pSigr)
{
if (fDebugRingSig)
{
// LogPrintf("%s size %d\n", __func__, nRingSize); // happens often
};
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;
EC_POINT *ptSi = 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))
|| !(ptSi = 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 (!(bnT = BN_bin2bn(&keyImage[0], EC_COMPRESSED_SIZE, bnT))
|| !(ptKi) || !(ptKi = EC_POINT_bn2point(ecGrp, bnT, ptKi, bnCtx)))
{
LogPrintf("%s: extract ptKi failed.\n", __func__);
rv = 1; 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;
};
// DEBUGGING: ------- check if we can find the signer...
// ptSi = Pi * bnT
if ((!EC_POINT_mul(ecGrp, ptSi, NULL, ptPk, bnT, bnCtx)
|| false)
&& (rv = errorN(1, "%s: EC_POINT_mul failed.1", __func__)))
goto End;
if (0 == EC_POINT_cmp(ecGrp, ptSi, ptKi, bnCtx) )
LogPrintf("signer is index %d\n", i);
// DEBUGGING: - End - check if we can find the signer...
// 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);
EC_POINT_free(ptSi);
BN_CTX_end(bnCtx);
return rv;
};
int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
{
int i, ret = 0;
BIGNUM *Ri, *R;
if (BN_is_zero(mod))
return 0;
BN_CTX_start(ctx);
if ((Ri = BN_CTX_get(ctx)) == NULL)
goto err;
R = &(mont->RR); /* grab RR as a temp */
if (!BN_copy(&(mont->N), mod))
goto err; /* Set N */
if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
BN_set_flags(&(mont->N), BN_FLG_CONSTTIME);
mont->N.neg = 0;
#ifdef MONT_WORD
{
BIGNUM tmod;
BN_ULONG buf[2];
bn_init(&tmod);
tmod.d = buf;
tmod.dmax = 2;
tmod.neg = 0;
if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
BN_set_flags(&tmod, BN_FLG_CONSTTIME);
mont->ri = (BN_num_bits(mod) + (BN_BITS2 - 1)) / BN_BITS2 * BN_BITS2;
# if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2<=32)
/*
* Only certain BN_BITS2<=32 platforms actually make use of n0[1],
* and we could use the #else case (with a shorter R value) for the
* others. However, currently only the assembler files do know which
* is which.
*/
BN_zero(R);
if (!(BN_set_bit(R, 2 * BN_BITS2)))
goto err;
tmod.top = 0;
if ((buf[0] = mod->d[0]))
tmod.top = 1;
if ((buf[1] = mod->top > 1 ? mod->d[1] : 0))
tmod.top = 2;
if (BN_is_one(&tmod))
BN_zero(Ri);
else if ((BN_mod_inverse(Ri, R, &tmod, ctx)) == NULL)
goto err;
if (!BN_lshift(Ri, Ri, 2 * BN_BITS2))
goto err; /* R*Ri */
if (!BN_is_zero(Ri)) {
if (!BN_sub_word(Ri, 1))
goto err;
} else { /* if N mod word size == 1 */
if (bn_expand(Ri, (int)sizeof(BN_ULONG) * 2) == NULL)
goto err;
/* Ri-- (mod double word size) */
Ri->neg = 0;
Ri->d[0] = BN_MASK2;
Ri->d[1] = BN_MASK2;
Ri->top = 2;
}
if (!BN_div(Ri, NULL, Ri, &tmod, ctx))
goto err;
/*
* Ni = (R*Ri-1)/N, keep only couple of least significant words:
*/
mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
mont->n0[1] = (Ri->top > 1) ? Ri->d[1] : 0;
# else
BN_zero(R);
if (!(BN_set_bit(R, BN_BITS2)))
goto err; /* R */
buf[0] = mod->d[0]; /* tmod = N mod word size */
buf[1] = 0;
tmod.top = buf[0] != 0 ? 1 : 0;
/* Ri = R^-1 mod N */
if (BN_is_one(&tmod))
BN_zero(Ri);
else if ((BN_mod_inverse(Ri, R, &tmod, ctx)) == NULL)
goto err;
if (!BN_lshift(Ri, Ri, BN_BITS2))
goto err; /* R*Ri */
if (!BN_is_zero(Ri)) {
if (!BN_sub_word(Ri, 1))
goto err;
} else { /* if N mod word size == 1 */
if (!BN_set_word(Ri, BN_MASK2))
goto err; /* Ri-- (mod word size) */
}
if (!BN_div(Ri, NULL, Ri, &tmod, ctx))
goto err;
/*
* Ni = (R*Ri-1)/N, keep only least significant word:
*/
mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
mont->n0[1] = 0;
# endif
}
#else /* !MONT_WORD */
{ /* bignum version */
mont->ri = BN_num_bits(&mont->N);
BN_zero(R);
if (!BN_set_bit(R, mont->ri))
goto err; /* R = 2^ri */
/* Ri = R^-1 mod N */
if ((BN_mod_inverse(Ri, R, &mont->N, ctx)) == NULL)
goto err;
if (!BN_lshift(Ri, Ri, mont->ri))
goto err; /* R*Ri */
if (!BN_sub_word(Ri, 1))
goto err;
/*
* Ni = (R*Ri-1) / N
*/
if (!BN_div(&(mont->Ni), NULL, Ri, &mont->N, ctx))
goto err;
}
#endif
/* setup RR for conversions */
BN_zero(&(mont->RR));
if (!BN_set_bit(&(mont->RR), mont->ri * 2))
goto err;
if (!BN_mod(&(mont->RR), &(mont->RR), &(mont->N), ctx))
goto err;
for (i = mont->RR.top, ret = mont->N.top; i < ret; i++)
mont->RR.d[i] = 0;
mont->RR.top = ret;
mont->RR.flags |= BN_FLG_FIXED_TOP;
ret = 1;
err:
BN_CTX_end(ctx);
return ret;
}
/* random number r: 0 <= r < range */
static int bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range)
{
int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand;
int n;
int count = 100;
if (range->neg || BN_is_zero(range))
{
BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE);
return 0;
}
n = BN_num_bits(range); /* n > 0 */
/* BN_is_bit_set(range, n - 1) always holds */
if (n == 1)
BN_zero(r);
#ifdef OPENSSL_FIPS
/* FIPS 186-3 is picky about how random numbers for keys etc are
* generated. So we just use the second case which is equivalent to
* "Generation by Testing Candidates" mentioned in B.1.2 et al.
*/
else if (!FIPS_mode() && !BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3))
#else
else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3))
#endif
{
/* range = 100..._2,
* so 3*range (= 11..._2) is exactly one bit longer than range */
do
{
if (!bn_rand(r, n + 1, -1, 0)) return 0;
/* If r < 3*range, use r := r MOD range
* (which is either r, r - range, or r - 2*range).
* Otherwise, iterate once more.
* Since 3*range = 11..._2, each iteration succeeds with
* probability >= .75. */
if (BN_cmp(r ,range) >= 0)
{
if (!BN_sub(r, r, range)) return 0;
if (BN_cmp(r, range) >= 0)
if (!BN_sub(r, r, range)) return 0;
}
if (!--count)
{
BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
return 0;
}
}
while (BN_cmp(r, range) >= 0);
}
else
{
do
{
/* range = 11..._2 or range = 101..._2 */
if (!bn_rand(r, n, -1, 0)) return 0;
if (!--count)
{
BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
return 0;
}
}
while (BN_cmp(r, range) >= 0);
}
bn_check_top(r);
return 1;
}
int
MKEMParams_init(MKEMParams *params)
{
const mk_curve_params *p = &mk_curves[MK_CURVE_163_0];
BIGNUM *maxu = 0;
size_t bitsize, bytesize, bitcap, k;
memset(params, 0, sizeof(MKEMParams));
FAILZ(params->ctx = BN_CTX_new());
FAILZ(params->m = BN_bin2bn(p->m, p->L_m, 0));
FAILZ(params->b = BN_bin2bn(p->b, p->L_b, 0));
FAILZ(params->a0 = BN_new()); FAILZ(BN_zero((BIGNUM *)params->a0));
FAILZ(params->a1 = BN_value_one());
FAILZ(params->p0 = BN_bin2bn(p->p0, p->L_p0, 0));
FAILZ(params->p1 = BN_bin2bn(p->p1, p->L_p1, 0));
FAILZ(params->n0 = BN_bin2bn(p->n0, p->L_n0, 0));
FAILZ(params->n1 = BN_bin2bn(p->n1, p->L_n1, 0));
FAILZ(params->c0 = EC_GROUP_new_curve_GF2m(params->m, params->a0, params->b,
params->ctx));
FAILZ(params->c1 = EC_GROUP_new_curve_GF2m(params->m, params->a1, params->b,
params->ctx));
FAILZ(params->g0 = EC_POINT_new(params->c0));
FAILZ(EC_POINT_oct2point(params->c0, (EC_POINT *)params->g0, p->g0, p->L_g0,
params->ctx));
FAILZ(params->g1 = EC_POINT_new(params->c1));
FAILZ(EC_POINT_oct2point(params->c1, (EC_POINT *)params->g1, p->g1, p->L_g1,
params->ctx));
/* Calculate the upper limit for the random integer U input to
MKEM_generate_message_u.
The paper calls for us to choose between curve 0 and curve 1 with
probability proportional to the number of points on that curve, and
then choose a random integer in the range 0 < u < n{curve}. The
easiest way to do this accurately is to choose a random integer in the
range [1, n0 + n1 - 2]. If it is less than n0, MKEM_generate_message_u
will use it unmodified with curve 0. If it is greater than or equal
to n0, MKEM_generate_message_u will subtract n0-1, leaving a number in
the range [1, n1-1], and use that with curve 1. */
FAILZ(maxu = BN_dup(params->n0));
FAILZ(BN_add(maxu, maxu, params->n1));
FAILZ(BN_sub(maxu, maxu, BN_value_one()));
FAILZ(BN_sub(maxu, maxu, BN_value_one()));
params->maxu = maxu; maxu = 0;
/* Calculate the maximum size of a message and the padding mask applied
to the high byte of each message. See MKEM_generate_message_u for
further exposition. */
bitsize = EC_GROUP_get_degree(params->c0);
if ((size_t)EC_GROUP_get_degree(params->c1) != bitsize)
goto fail;
bytesize = (bitsize + 7) / 8;
bitcap = bytesize * 8;
k = bitcap - bitsize;
if (k == 0)
goto fail;
params->msgsize = bytesize;
params->pad_bits = k - 1;
params->pad_mask = ~((1 << (8 - params->pad_bits)) - 1);
params->curve_bit = 1 << (8 - k);
return 0;
fail:
if (maxu) BN_free(maxu);
MKEMParams_teardown(params);
return -1;
}
static int FIPS_dsa_builtin_paramgen(DSA *ret, int bits,
unsigned char *seed_in, int seed_len,
int *counter_ret, unsigned long *h_ret, BN_GENCB *cb)
{
int ok=0;
unsigned char seed[SHA_DIGEST_LENGTH];
unsigned char md[SHA_DIGEST_LENGTH];
unsigned char buf[SHA_DIGEST_LENGTH],buf2[SHA_DIGEST_LENGTH];
BIGNUM *r0,*W,*X,*c,*test;
BIGNUM *g=NULL,*q=NULL,*p=NULL;
BN_MONT_CTX *mont=NULL;
int k,n=0,i,b,m=0;
int counter=0;
int r=0;
BN_CTX *ctx=NULL;
unsigned int h=2;
if(FIPS_selftest_failed())
{
FIPSerr(FIPS_F_DSA_BUILTIN_PARAMGEN,
FIPS_R_FIPS_SELFTEST_FAILED);
goto err;
}
if (FIPS_mode() && (bits < OPENSSL_DSA_FIPS_MIN_MODULUS_BITS))
{
DSAerr(DSA_F_DSA_BUILTIN_PARAMGEN, DSA_R_KEY_SIZE_TOO_SMALL);
goto err;
}
if (bits < 512) bits=512;
bits=(bits+63)/64*64;
/* NB: seed_len == 0 is special case: copy generated seed to
* seed_in if it is not NULL.
*/
if (seed_len && (seed_len < 20))
seed_in = NULL; /* seed buffer too small -- ignore */
if (seed_len > 20)
seed_len = 20; /* App. 2.2 of FIPS PUB 186 allows larger SEED,
* but our internal buffers are restricted to 160 bits*/
if ((seed_in != NULL) && (seed_len == 20))
{
memcpy(seed,seed_in,seed_len);
/* set seed_in to NULL to avoid it being copied back */
seed_in = NULL;
}
if ((ctx=BN_CTX_new()) == NULL) goto err;
if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
BN_CTX_start(ctx);
r0 = BN_CTX_get(ctx);
g = BN_CTX_get(ctx);
W = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
c = BN_CTX_get(ctx);
p = BN_CTX_get(ctx);
test = BN_CTX_get(ctx);
if (!BN_lshift(test,BN_value_one(),bits-1))
goto err;
for (;;)
{
for (;;) /* find q */
{
int seed_is_random;
/* step 1 */
if(!BN_GENCB_call(cb, 0, m++))
goto err;
if (!seed_len)
{
RAND_pseudo_bytes(seed,SHA_DIGEST_LENGTH);
seed_is_random = 1;
}
else
{
seed_is_random = 0;
seed_len=0; /* use random seed if 'seed_in' turns out to be bad*/
}
memcpy(buf,seed,SHA_DIGEST_LENGTH);
memcpy(buf2,seed,SHA_DIGEST_LENGTH);
/* precompute "SEED + 1" for step 7: */
for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
{
buf[i]++;
if (buf[i] != 0) break;
}
/* step 2 */
EVP_Digest(seed,SHA_DIGEST_LENGTH,md,NULL,HASH, NULL);
EVP_Digest(buf,SHA_DIGEST_LENGTH,buf2,NULL,HASH, NULL);
for (i=0; i<SHA_DIGEST_LENGTH; i++)
md[i]^=buf2[i];
/* step 3 */
md[0]|=0x80;
md[SHA_DIGEST_LENGTH-1]|=0x01;
if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,q)) goto err;
/* step 4 */
r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
seed_is_random, cb);
if (r > 0)
break;
if (r != 0)
goto err;
/* do a callback call */
/* step 5 */
}
if(!BN_GENCB_call(cb, 2, 0)) goto err;
if(!BN_GENCB_call(cb, 3, 0)) goto err;
/* step 6 */
counter=0;
/* "offset = 2" */
n=(bits-1)/160;
b=(bits-1)-n*160;
for (;;)
{
if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
goto err;
/* step 7 */
BN_zero(W);
/* now 'buf' contains "SEED + offset - 1" */
for (k=0; k<=n; k++)
{
/* obtain "SEED + offset + k" by incrementing: */
for (i=SHA_DIGEST_LENGTH-1; i >= 0; i--)
{
buf[i]++;
if (buf[i] != 0) break;
}
EVP_Digest(buf,SHA_DIGEST_LENGTH,md,NULL,HASH, NULL);
/* step 8 */
if (!BN_bin2bn(md,SHA_DIGEST_LENGTH,r0))
goto err;
if (!BN_lshift(r0,r0,160*k)) goto err;
if (!BN_add(W,W,r0)) goto err;
}
/* more of step 8 */
if (!BN_mask_bits(W,bits-1)) goto err;
if (!BN_copy(X,W)) goto err;
if (!BN_add(X,X,test)) goto err;
/* step 9 */
if (!BN_lshift1(r0,q)) goto err;
if (!BN_mod(c,X,r0,ctx)) goto err;
if (!BN_sub(r0,c,BN_value_one())) goto err;
if (!BN_sub(p,X,r0)) goto err;
/* step 10 */
if (BN_cmp(p,test) >= 0)
{
/* step 11 */
r = BN_is_prime_fasttest_ex(p, DSS_prime_checks,
ctx, 1, cb);
if (r > 0)
goto end; /* found it */
if (r != 0)
goto err;
}
/* step 13 */
counter++;
/* "offset = offset + n + 1" */
/* step 14 */
if (counter >= 4096) break;
}
}
end:
if(!BN_GENCB_call(cb, 2, 1))
goto err;
/* We now need to generate g */
/* Set r0=(p-1)/q */
if (!BN_sub(test,p,BN_value_one())) goto err;
if (!BN_div(r0,NULL,test,q,ctx)) goto err;
if (!BN_set_word(test,h)) goto err;
if (!BN_MONT_CTX_set(mont,p,ctx)) goto err;
for (;;)
{
/* g=test^r0%p */
if (!BN_mod_exp_mont(g,test,r0,p,ctx,mont)) goto err;
if (!BN_is_one(g)) break;
if (!BN_add(test,test,BN_value_one())) goto err;
h++;
}
if(!BN_GENCB_call(cb, 3, 1))
goto err;
ok=1;
err:
if (ok)
{
if(ret->p) BN_free(ret->p);
if(ret->q) BN_free(ret->q);
if(ret->g) BN_free(ret->g);
ret->p=BN_dup(p);
ret->q=BN_dup(q);
ret->g=BN_dup(g);
if (ret->p == NULL || ret->q == NULL || ret->g == NULL)
{
ok=0;
goto err;
}
if (seed_in != NULL) memcpy(seed_in,seed,20);
if (counter_ret != NULL) *counter_ret=counter;
if (h_ret != NULL) *h_ret=h;
}
if(ctx)
{
BN_CTX_end(ctx);
BN_CTX_free(ctx);
}
if (mont != NULL) BN_MONT_CTX_free(mont);
return ok;
}
int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
{
int ret = 0;
BIGNUM *Ri,*R;
BN_CTX_start(ctx);
if((Ri = BN_CTX_get(ctx)) == NULL) goto err;
R= &(mont->RR); /* grab RR as a temp */
if (!BN_copy(&(mont->N),mod)) goto err; /* Set N */
mont->N.neg = 0;
#ifdef MONT_WORD
{
BIGNUM tmod;
BN_ULONG buf[2];
mont->ri=(BN_num_bits(mod)+(BN_BITS2-1))/BN_BITS2*BN_BITS2;
BN_zero(R);
if (!(BN_set_bit(R,BN_BITS2))) goto err; /* R */
buf[0]=mod->d[0]; /* tmod = N mod word size */
buf[1]=0;
tmod.d=buf;
tmod.top = buf[0] != 0 ? 1 : 0;
tmod.dmax=2;
tmod.neg=0;
/* Ri = R^-1 mod N*/
if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL)
goto err;
if (!BN_lshift(Ri,Ri,BN_BITS2)) goto err; /* R*Ri */
if (!BN_is_zero(Ri))
{
if (!BN_sub_word(Ri,1)) goto err;
}
else /* if N mod word size == 1 */
{
if (!BN_set_word(Ri,BN_MASK2)) goto err; /* Ri-- (mod word size) */
}
if (!BN_div(Ri,NULL,Ri,&tmod,ctx)) goto err;
/* Ni = (R*Ri-1)/N,
* keep only least significant word: */
mont->n0 = (Ri->top > 0) ? Ri->d[0] : 0;
}
#else /* !MONT_WORD */
{ /* bignum version */
mont->ri=BN_num_bits(&mont->N);
BN_zero(R);
if (!BN_set_bit(R,mont->ri)) goto err; /* R = 2^ri */
/* Ri = R^-1 mod N*/
if ((BN_mod_inverse(Ri,R,&mont->N,ctx)) == NULL)
goto err;
if (!BN_lshift(Ri,Ri,mont->ri)) goto err; /* R*Ri */
if (!BN_sub_word(Ri,1)) goto err;
/* Ni = (R*Ri-1) / N */
if (!BN_div(&(mont->Ni),NULL,Ri,&mont->N,ctx)) goto err;
}
#endif
/* setup RR for conversions */
BN_zero(&(mont->RR));
if (!BN_set_bit(&(mont->RR),mont->ri*2)) goto err;
if (!BN_mod(&(mont->RR),&(mont->RR),&(mont->N),ctx)) goto err;
ret = 1;
err:
BN_CTX_end(ctx);
return ret;
}
/*
* test_exp_mod_zero tests that x**0 mod 1 == 0. It returns zero on success.
*/
static int test_exp_mod_zero()
{
BIGNUM a, p, m;
BIGNUM r;
BN_ULONG one_word = 1;
BN_CTX *ctx = BN_CTX_new();
int ret = 1, failed = 0;
BN_init(&m);
BN_one(&m);
BN_init(&a);
BN_one(&a);
BN_init(&p);
BN_zero(&p);
BN_init(&r);
if (!BN_rand(&a, 1024, 0, 0))
goto err;
if (!BN_mod_exp(&r, &a, &p, &m, ctx))
goto err;
if (!a_is_zero_mod_one("BN_mod_exp", &r, &a))
failed = 1;
if (!BN_mod_exp_recp(&r, &a, &p, &m, ctx))
goto err;
if (!a_is_zero_mod_one("BN_mod_exp_recp", &r, &a))
failed = 1;
if (!BN_mod_exp_simple(&r, &a, &p, &m, ctx))
goto err;
if (!a_is_zero_mod_one("BN_mod_exp_simple", &r, &a))
failed = 1;
if (!BN_mod_exp_mont(&r, &a, &p, &m, ctx, NULL))
goto err;
if (!a_is_zero_mod_one("BN_mod_exp_mont", &r, &a))
failed = 1;
if (!BN_mod_exp_mont_consttime(&r, &a, &p, &m, ctx, NULL)) {
goto err;
}
if (!a_is_zero_mod_one("BN_mod_exp_mont_consttime", &r, &a))
failed = 1;
/*
* A different codepath exists for single word multiplication
* in non-constant-time only.
*/
if (!BN_mod_exp_mont_word(&r, one_word, &p, &m, ctx, NULL))
goto err;
if (!BN_is_zero(&r)) {
fprintf(stderr, "BN_mod_exp_mont_word failed:\n");
fprintf(stderr, "1 ** 0 mod 1 = r (should be 0)\n");
fprintf(stderr, "r = ");
BN_print_fp(stderr, &r);
fprintf(stderr, "\n");
return 0;
}
ret = failed;
err:
BN_free(&r);
BN_free(&a);
BN_free(&p);
BN_free(&m);
BN_CTX_free(ctx);
return ret;
}
BIGNUM *BN_mod_sqrt(BIGNUM *in, const BIGNUM *a, const BIGNUM *p, BN_CTX *ctx)
/* Returns 'ret' such that
* ret^2 == a (mod p),
* using the Tonelli/Shanks algorithm (cf. Henri Cohen, "A Course
* in Algebraic Computational Number Theory", algorithm 1.5.1).
* 'p' must be prime!
*/
{
BIGNUM *ret = in;
int err = 1;
int r;
BIGNUM *A, *b, *q, *t, *x, *y;
int e, i, j;
if (!BN_is_odd(p) || BN_abs_is_word(p, 1))
{
if (BN_abs_is_word(p, 2))
{
if (ret == NULL)
ret = BN_new();
if (ret == NULL)
goto end;
if (!BN_set_word(ret, BN_is_bit_set(a, 0)))
{
if (ret != in)
BN_free(ret);
return NULL;
}
bn_check_top(ret);
return ret;
}
BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);
return(NULL);
}
if (BN_is_zero(a) || BN_is_one(a))
{
if (ret == NULL)
ret = BN_new();
if (ret == NULL)
goto end;
if (!BN_set_word(ret, BN_is_one(a)))
{
if (ret != in)
BN_free(ret);
return NULL;
}
bn_check_top(ret);
return ret;
}
BN_CTX_start(ctx);
A = BN_CTX_get(ctx);
b = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
t = BN_CTX_get(ctx);
x = BN_CTX_get(ctx);
y = BN_CTX_get(ctx);
if (y == NULL) goto end;
if (ret == NULL)
ret = BN_new();
if (ret == NULL) goto end;
/* A = a mod p */
if (!BN_nnmod(A, a, p, ctx)) goto end;
/* now write |p| - 1 as 2^e*q where q is odd */
e = 1;
while (!BN_is_bit_set(p, e))
e++;
/* we'll set q later (if needed) */
if (e == 1)
{
/* The easy case: (|p|-1)/2 is odd, so 2 has an inverse
* modulo (|p|-1)/2, and square roots can be computed
* directly by modular exponentiation.
* We have
* 2 * (|p|+1)/4 == 1 (mod (|p|-1)/2),
* so we can use exponent (|p|+1)/4, i.e. (|p|-3)/4 + 1.
*/
if (!BN_rshift(q, p, 2)) goto end;
q->neg = 0;
if (!BN_add_word(q, 1)) goto end;
if (!BN_mod_exp(ret, A, q, p, ctx)) goto end;
err = 0;
goto vrfy;
}
if (e == 2)
{
/* |p| == 5 (mod 8)
*
* In this case 2 is always a non-square since
* Legendre(2,p) = (-1)^((p^2-1)/8) for any odd prime.
* So if a really is a square, then 2*a is a non-square.
* Thus for
* b := (2*a)^((|p|-5)/8),
* i := (2*a)*b^2
* we have
* i^2 = (2*a)^((1 + (|p|-5)/4)*2)
* = (2*a)^((p-1)/2)
* = -1;
* so if we set
* x := a*b*(i-1),
* then
* x^2 = a^2 * b^2 * (i^2 - 2*i + 1)
* = a^2 * b^2 * (-2*i)
* = a*(-i)*(2*a*b^2)
* = a*(-i)*i
* = a.
*
* (This is due to A.O.L. Atkin,
* <URL: http://listserv.nodak.edu/scripts/wa.exe?A2=ind9211&L=nmbrthry&O=T&P=562>,
* November 1992.)
*/
/* t := 2*a */
if (!BN_mod_lshift1_quick(t, A, p)) goto end;
/* b := (2*a)^((|p|-5)/8) */
if (!BN_rshift(q, p, 3)) goto end;
q->neg = 0;
if (!BN_mod_exp(b, t, q, p, ctx)) goto end;
/* y := b^2 */
if (!BN_mod_sqr(y, b, p, ctx)) goto end;
/* t := (2*a)*b^2 - 1*/
if (!BN_mod_mul(t, t, y, p, ctx)) goto end;
if (!BN_sub_word(t, 1)) goto end;
/* x = a*b*t */
if (!BN_mod_mul(x, A, b, p, ctx)) goto end;
if (!BN_mod_mul(x, x, t, p, ctx)) goto end;
if (!BN_copy(ret, x)) goto end;
err = 0;
goto vrfy;
}
/* e > 2, so we really have to use the Tonelli/Shanks algorithm.
* First, find some y that is not a square. */
if (!BN_copy(q, p)) goto end; /* use 'q' as temp */
q->neg = 0;
i = 2;
do
{
/* For efficiency, try small numbers first;
* if this fails, try random numbers.
*/
if (i < 22)
{
if (!BN_set_word(y, i)) goto end;
}
else
{
if (!BN_pseudo_rand(y, BN_num_bits(p), 0, 0)) goto end;
if (BN_ucmp(y, p) >= 0)
{
if (!(p->neg ? BN_add : BN_sub)(y, y, p)) goto end;
}
/* now 0 <= y < |p| */
if (BN_is_zero(y))
if (!BN_set_word(y, i)) goto end;
}
r = BN_kronecker(y, q, ctx); /* here 'q' is |p| */
if (r < -1) goto end;
if (r == 0)
{
/* m divides p */
BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);
goto end;
}
}
while (r == 1 && ++i < 82);
if (r != -1)
{
/* Many rounds and still no non-square -- this is more likely
* a bug than just bad luck.
* Even if p is not prime, we should have found some y
* such that r == -1.
*/
BNerr(BN_F_BN_MOD_SQRT, BN_R_TOO_MANY_ITERATIONS);
goto end;
}
/* Here's our actual 'q': */
if (!BN_rshift(q, q, e)) goto end;
/* Now that we have some non-square, we can find an element
* of order 2^e by computing its q'th power. */
if (!BN_mod_exp(y, y, q, p, ctx)) goto end;
if (BN_is_one(y))
{
BNerr(BN_F_BN_MOD_SQRT, BN_R_P_IS_NOT_PRIME);
goto end;
}
/* Now we know that (if p is indeed prime) there is an integer
* k, 0 <= k < 2^e, such that
*
* a^q * y^k == 1 (mod p).
*
* As a^q is a square and y is not, k must be even.
* q+1 is even, too, so there is an element
*
* X := a^((q+1)/2) * y^(k/2),
*
* and it satisfies
*
* X^2 = a^q * a * y^k
* = a,
*
* so it is the square root that we are looking for.
*/
/* t := (q-1)/2 (note that q is odd) */
if (!BN_rshift1(t, q)) goto end;
/* x := a^((q-1)/2) */
if (BN_is_zero(t)) /* special case: p = 2^e + 1 */
{
if (!BN_nnmod(t, A, p, ctx)) goto end;
if (BN_is_zero(t))
{
/* special case: a == 0 (mod p) */
BN_zero(ret);
err = 0;
goto end;
}
else
if (!BN_one(x)) goto end;
}
else
{
if (!BN_mod_exp(x, A, t, p, ctx)) goto end;
if (BN_is_zero(x))
{
/* special case: a == 0 (mod p) */
BN_zero(ret);
err = 0;
goto end;
}
}
/* b := a*x^2 (= a^q) */
if (!BN_mod_sqr(b, x, p, ctx)) goto end;
if (!BN_mod_mul(b, b, A, p, ctx)) goto end;
/* x := a*x (= a^((q+1)/2)) */
if (!BN_mod_mul(x, x, A, p, ctx)) goto end;
while (1)
{
/* Now b is a^q * y^k for some even k (0 <= k < 2^E
* where E refers to the original value of e, which we
* don't keep in a variable), and x is a^((q+1)/2) * y^(k/2).
*
* We have a*b = x^2,
* y^2^(e-1) = -1,
* b^2^(e-1) = 1.
*/
if (BN_is_one(b))
{
if (!BN_copy(ret, x)) goto end;
err = 0;
goto vrfy;
}
/* find smallest i such that b^(2^i) = 1 */
i = 1;
if (!BN_mod_sqr(t, b, p, ctx)) goto end;
while (!BN_is_one(t))
{
i++;
if (i == e)
{
BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);
goto end;
}
if (!BN_mod_mul(t, t, t, p, ctx)) goto end;
}
/* t := y^2^(e - i - 1) */
if (!BN_copy(t, y)) goto end;
for (j = e - i - 1; j > 0; j--)
{
if (!BN_mod_sqr(t, t, p, ctx)) goto end;
}
if (!BN_mod_mul(y, t, t, p, ctx)) goto end;
if (!BN_mod_mul(x, x, t, p, ctx)) goto end;
if (!BN_mod_mul(b, b, y, p, ctx)) goto end;
e = i;
}
vrfy:
if (!err)
{
/* verify the result -- the input might have been not a square
* (test added in 0.9.8) */
if (!BN_mod_sqr(x, ret, p, ctx))
err = 1;
if (!err && 0 != BN_cmp(x, A))
{
BNerr(BN_F_BN_MOD_SQRT, BN_R_NOT_A_SQUARE);
err = 1;
}
}
end:
if (err)
{
if (ret != NULL && ret != in)
{
BN_clear_free(ret);
}
ret = NULL;
}
BN_CTX_end(ctx);
bn_check_top(ret);
return ret;
}
int BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx)
{
int ret = 0;
int top, al, bl;
BIGNUM *rr;
#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)
int i;
#endif
#ifdef BN_RECURSION
BIGNUM *t = NULL;
int j = 0, k;
#endif
bn_check_top(a);
bn_check_top(b);
bn_check_top(r);
al = a->top;
bl = b->top;
if ((al == 0) || (bl == 0)) {
BN_zero(r);
return (1);
}
top = al + bl;
BN_CTX_start(ctx);
if ((r == a) || (r == b)) {
if ((rr = BN_CTX_get(ctx)) == NULL)
goto err;
} else
rr = r;
rr->neg = a->neg ^ b->neg;
#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)
i = al - bl;
#endif
#ifdef BN_MUL_COMBA
if (i == 0) {
# if 0
if (al == 4) {
if (bn_wexpand(rr, 8) == NULL)
goto err;
rr->top = 8;
bn_mul_comba4(rr->d, a->d, b->d);
goto end;
}
# endif
if (al == 8) {
if (bn_wexpand(rr, 16) == NULL)
goto err;
rr->top = 16;
bn_mul_comba8(rr->d, a->d, b->d);
goto end;
}
}
#endif /* BN_MUL_COMBA */
#ifdef BN_RECURSION
if ((al >= BN_MULL_SIZE_NORMAL) && (bl >= BN_MULL_SIZE_NORMAL)) {
if (i >= -1 && i <= 1) {
/*
* Find out the power of two lower or equal to the longest of the
* two numbers
*/
if (i >= 0) {
j = BN_num_bits_word((BN_ULONG)al);
}
if (i == -1) {
j = BN_num_bits_word((BN_ULONG)bl);
}
j = 1 << (j - 1);
assert(j <= al || j <= bl);
k = j + j;
t = BN_CTX_get(ctx);
if (t == NULL)
goto err;
if (al > j || bl > j) {
if (bn_wexpand(t, k * 4) == NULL)
goto err;
if (bn_wexpand(rr, k * 4) == NULL)
goto err;
bn_mul_part_recursive(rr->d, a->d, b->d,
j, al - j, bl - j, t->d);
} else { /* al <= j || bl <= j */
if (bn_wexpand(t, k * 2) == NULL)
goto err;
if (bn_wexpand(rr, k * 2) == NULL)
goto err;
bn_mul_recursive(rr->d, a->d, b->d, j, al - j, bl - j, t->d);
}
rr->top = top;
goto end;
}
# if 0
if (i == 1 && !BN_get_flags(b, BN_FLG_STATIC_DATA)) {
BIGNUM *tmp_bn = (BIGNUM *)b;
if (bn_wexpand(tmp_bn, al) == NULL)
goto err;
tmp_bn->d[bl] = 0;
bl++;
i--;
} else if (i == -1 && !BN_get_flags(a, BN_FLG_STATIC_DATA)) {
BIGNUM *tmp_bn = (BIGNUM *)a;
if (bn_wexpand(tmp_bn, bl) == NULL)
goto err;
tmp_bn->d[al] = 0;
al++;
i++;
}
if (i == 0) {
/* symmetric and > 4 */
/* 16 or larger */
j = BN_num_bits_word((BN_ULONG)al);
j = 1 << (j - 1);
k = j + j;
t = BN_CTX_get(ctx);
if (al == j) { /* exact multiple */
if (bn_wexpand(t, k * 2) == NULL)
goto err;
if (bn_wexpand(rr, k * 2) == NULL)
goto err;
bn_mul_recursive(rr->d, a->d, b->d, al, t->d);
} else {
if (bn_wexpand(t, k * 4) == NULL)
goto err;
if (bn_wexpand(rr, k * 4) == NULL)
goto err;
bn_mul_part_recursive(rr->d, a->d, b->d, al - j, j, t->d);
}
rr->top = top;
goto end;
}
# endif
}
#endif /* BN_RECURSION */
if (bn_wexpand(rr, top) == NULL)
goto err;
rr->top = top;
bn_mul_normal(rr->d, a->d, al, b->d, bl);
#if defined(BN_MUL_COMBA) || defined(BN_RECURSION)
end:
#endif
bn_correct_top(rr);
if (r != rr)
BN_copy(r, rr);
ret = 1;
err:
bn_check_top(r);
BN_CTX_end(ctx);
return (ret);
}
int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx) {
int ret = 0;
BIGNUM *Ri, *R;
BIGNUM tmod;
BN_ULONG buf[2];
if (BN_is_zero(mod)) {
OPENSSL_PUT_ERROR(BN, BN_R_DIV_BY_ZERO);
return 0;
}
BN_CTX_start(ctx);
Ri = BN_CTX_get(ctx);
if (Ri == NULL) {
goto err;
}
R = &mont->RR; /* grab RR as a temp */
if (!BN_copy(&mont->N, mod)) {
goto err; /* Set N */
}
mont->N.neg = 0;
BN_init(&tmod);
tmod.d = buf;
tmod.dmax = 2;
tmod.neg = 0;
mont->ri = (BN_num_bits(mod) + (BN_BITS2 - 1)) / BN_BITS2 * BN_BITS2;
#if defined(OPENSSL_BN_ASM_MONT) && (BN_BITS2 <= 32)
/* Only certain BN_BITS2<=32 platforms actually make use of
* n0[1], and we could use the #else case (with a shorter R
* value) for the others. However, currently only the assembler
* files do know which is which. */
BN_zero(R);
if (!BN_set_bit(R, 2 * BN_BITS2)) {
goto err;
}
tmod.top = 0;
if ((buf[0] = mod->d[0])) {
tmod.top = 1;
}
if ((buf[1] = mod->top > 1 ? mod->d[1] : 0)) {
tmod.top = 2;
}
if (BN_mod_inverse(Ri, R, &tmod, ctx) == NULL) {
goto err;
}
if (!BN_lshift(Ri, Ri, 2 * BN_BITS2)) {
goto err; /* R*Ri */
}
if (!BN_is_zero(Ri)) {
if (!BN_sub_word(Ri, 1)) {
goto err;
}
} else {
/* if N mod word size == 1 */
if (bn_expand(Ri, (int)sizeof(BN_ULONG) * 2) == NULL) {
goto err;
}
/* Ri-- (mod double word size) */
Ri->neg = 0;
Ri->d[0] = BN_MASK2;
Ri->d[1] = BN_MASK2;
Ri->top = 2;
}
if (!BN_div(Ri, NULL, Ri, &tmod, ctx)) {
goto err;
}
/* Ni = (R*Ri-1)/N,
* keep only couple of least significant words: */
mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
mont->n0[1] = (Ri->top > 1) ? Ri->d[1] : 0;
#else
BN_zero(R);
if (!BN_set_bit(R, BN_BITS2)) {
goto err; /* R */
}
buf[0] = mod->d[0]; /* tmod = N mod word size */
buf[1] = 0;
tmod.top = buf[0] != 0 ? 1 : 0;
/* Ri = R^-1 mod N*/
if (BN_mod_inverse(Ri, R, &tmod, ctx) == NULL) {
goto err;
}
if (!BN_lshift(Ri, Ri, BN_BITS2)) {
goto err; /* R*Ri */
}
if (!BN_is_zero(Ri)) {
if (!BN_sub_word(Ri, 1)) {
goto err;
}
} else {
/* if N mod word size == 1 */
if (!BN_set_word(Ri, BN_MASK2)) {
goto err; /* Ri-- (mod word size) */
}
}
if (!BN_div(Ri, NULL, Ri, &tmod, ctx)) {
goto err;
}
/* Ni = (R*Ri-1)/N,
* keep only least significant word: */
mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
mont->n0[1] = 0;
#endif
/* setup RR for conversions */
BN_zero(&(mont->RR));
if (!BN_set_bit(&(mont->RR), mont->ri * 2)) {
goto err;
}
if (!BN_mod(&(mont->RR), &(mont->RR), &(mont->N), ctx)) {
goto err;
}
ret = 1;
err:
BN_CTX_end(ctx);
return ret;
}
// bn_mul_impl implements |BN_mul| and |bn_mul_consttime|. Note this function
// breaks |BIGNUM| invariants and may return a negative zero. This is handled by
// the callers.
static int bn_mul_impl(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
BN_CTX *ctx) {
int al = a->width;
int bl = b->width;
if (al == 0 || bl == 0) {
BN_zero(r);
return 1;
}
int ret = 0;
BIGNUM *rr;
BN_CTX_start(ctx);
if (r == a || r == b) {
rr = BN_CTX_get(ctx);
if (rr == NULL) {
goto err;
}
} else {
rr = r;
}
rr->neg = a->neg ^ b->neg;
int i = al - bl;
if (i == 0) {
if (al == 8) {
if (!bn_wexpand(rr, 16)) {
goto err;
}
rr->width = 16;
bn_mul_comba8(rr->d, a->d, b->d);
goto end;
}
}
int top = al + bl;
static const int kMulNormalSize = 16;
if (al >= kMulNormalSize && bl >= kMulNormalSize) {
if (-1 <= i && i <= 1) {
// Find the larger power of two less than or equal to the larger length.
int j;
if (i >= 0) {
j = BN_num_bits_word((BN_ULONG)al);
} else {
j = BN_num_bits_word((BN_ULONG)bl);
}
j = 1 << (j - 1);
assert(j <= al || j <= bl);
BIGNUM *t = BN_CTX_get(ctx);
if (t == NULL) {
goto err;
}
if (al > j || bl > j) {
// We know |al| and |bl| are at most one from each other, so if al > j,
// bl >= j, and vice versa. Thus we can use |bn_mul_part_recursive|.
assert(al >= j && bl >= j);
if (!bn_wexpand(t, j * 8) ||
!bn_wexpand(rr, j * 4)) {
goto err;
}
bn_mul_part_recursive(rr->d, a->d, b->d, j, al - j, bl - j, t->d);
} else {
// al <= j && bl <= j. Additionally, we know j <= al or j <= bl, so one
// of al - j or bl - j is zero. The other, by the bound on |i| above, is
// zero or -1. Thus, we can use |bn_mul_recursive|.
if (!bn_wexpand(t, j * 4) ||
!bn_wexpand(rr, j * 2)) {
goto err;
}
bn_mul_recursive(rr->d, a->d, b->d, j, al - j, bl - j, t->d);
}
rr->width = top;
goto end;
}
}
if (!bn_wexpand(rr, top)) {
goto err;
}
rr->width = top;
bn_mul_normal(rr->d, a->d, al, b->d, bl);
end:
if (r != rr && !BN_copy(r, rr)) {
goto err;
}
ret = 1;
err:
BN_CTX_end(ctx);
return ret;
}
/**
* Reconstruct secret using the provided shares
*
* @param shares Shares used to reconstruct secret (should contain t entries)
* @param t Threshold used to reconstruct the secret
* @param prime Prime for finite field arithmetic
* @param s Pointer for storage of calculated secred
*/
static int reconstructSecret(secret_share_t *shares, unsigned char t, const BIGNUM prime, BIGNUM *s)
{
unsigned char i;
unsigned char j;
// Array representing the polynomial a(x) = s + a_1 * x + ... + a_n-1 * x^n-1 mod p
BIGNUM **bValue = malloc(t * sizeof(BIGNUM *));
BIGNUM **pbValue;
BIGNUM numerator;
BIGNUM denominator;
BIGNUM temp;
secret_share_t *sp_i;
secret_share_t *sp_j;
BN_CTX *ctx;
// Initialize
pbValue = bValue;
for (i = 0; i < t; i++) {
*pbValue = BN_new();
BN_init(*pbValue);
pbValue++;
}
BN_init(&numerator);
BN_init(&denominator);
BN_init(&temp);
// Create context for temporary variables of engine
ctx = BN_CTX_new();
BN_CTX_init(ctx);
pbValue = bValue;
sp_i = shares;
for (i = 0; i < t; i++) {
BN_one(&numerator);
BN_one(&denominator);
sp_j = shares;
for (j = 0; j < t; j++) {
if (i == j) {
sp_j++;
continue;
}
BN_mul(&numerator, &numerator, &(sp_j->x), ctx);
BN_sub(&temp, &(sp_j->x), &(sp_i->x));
BN_mul(&denominator, &denominator, &temp, ctx);
sp_j++;
}
/*
* Use the modular inverse value of the denominator for the
* multiplication
*/
if (BN_mod_inverse(&denominator, &denominator, &prime, ctx) == NULL ) {
free(bValue);
return -1;
}
BN_mod_mul(*pbValue, &numerator, &denominator, &prime, ctx);
pbValue++;
sp_i++;
}
/*
* Calculate the secret by multiplying all y-values with their
* corresponding intermediate values
*/
pbValue = bValue;
sp_i = shares;
BN_zero(s);
for (i = 0; i < t; i++) {
BN_mul(&temp, &(sp_i->y), *pbValue, ctx);
BN_add(s, s, &temp);
pbValue++;
sp_i++;
}
// Perform modulo operation and copy result
BN_nnmod(&temp, s, &prime, ctx);
BN_copy(s, &temp);
BN_clear_free(&numerator);
BN_clear_free(&denominator);
BN_clear_free(&temp);
BN_CTX_free(ctx);
// Deallocate the resource of the polynomial
pbValue = bValue;
for (i = 0; i < t; i++) {
BN_clear_free(*pbValue);
pbValue++;
}
free(bValue);
return 0;
}
int ec_GFp_simple_add(const EC_GROUP *group, EC_POINT *r, const EC_POINT *a, const EC_POINT *b, BN_CTX *ctx)
{
int (*field_mul)(const EC_GROUP *, BIGNUM *, const BIGNUM *, const BIGNUM *, BN_CTX *);
int (*field_sqr)(const EC_GROUP *, BIGNUM *, const BIGNUM *, BN_CTX *);
const BIGNUM *p;
BN_CTX *new_ctx = NULL;
BIGNUM *n0, *n1, *n2, *n3, *n4, *n5, *n6;
int ret = 0;
if (a == b)
return EC_POINT_dbl(group, r, a, ctx);
if (EC_POINT_is_at_infinity(group, a))
return EC_POINT_copy(r, b);
if (EC_POINT_is_at_infinity(group, b))
return EC_POINT_copy(r, a);
field_mul = group->meth->field_mul;
field_sqr = group->meth->field_sqr;
p = &group->field;
if (ctx == NULL)
{
ctx = new_ctx = BN_CTX_new();
if (ctx == NULL)
return 0;
}
BN_CTX_start(ctx);
n0 = BN_CTX_get(ctx);
n1 = BN_CTX_get(ctx);
n2 = BN_CTX_get(ctx);
n3 = BN_CTX_get(ctx);
n4 = BN_CTX_get(ctx);
n5 = BN_CTX_get(ctx);
n6 = BN_CTX_get(ctx);
if (n6 == NULL) goto end;
/* Note that in this function we must not read components of 'a' or 'b'
* once we have written the corresponding components of 'r'.
* ('r' might be one of 'a' or 'b'.)
*/
/* n1, n2 */
if (b->Z_is_one)
{
if (!BN_copy(n1, &a->X)) goto end;
if (!BN_copy(n2, &a->Y)) goto end;
/* n1 = X_a */
/* n2 = Y_a */
}
else
{
if (!field_sqr(group, n0, &b->Z, ctx)) goto end;
if (!field_mul(group, n1, &a->X, n0, ctx)) goto end;
/* n1 = X_a * Z_b^2 */
if (!field_mul(group, n0, n0, &b->Z, ctx)) goto end;
if (!field_mul(group, n2, &a->Y, n0, ctx)) goto end;
/* n2 = Y_a * Z_b^3 */
}
/* n3, n4 */
if (a->Z_is_one)
{
if (!BN_copy(n3, &b->X)) goto end;
if (!BN_copy(n4, &b->Y)) goto end;
/* n3 = X_b */
/* n4 = Y_b */
}
else
{
if (!field_sqr(group, n0, &a->Z, ctx)) goto end;
if (!field_mul(group, n3, &b->X, n0, ctx)) goto end;
/* n3 = X_b * Z_a^2 */
if (!field_mul(group, n0, n0, &a->Z, ctx)) goto end;
if (!field_mul(group, n4, &b->Y, n0, ctx)) goto end;
/* n4 = Y_b * Z_a^3 */
}
/* n5, n6 */
if (!BN_mod_sub_quick(n5, n1, n3, p)) goto end;
if (!BN_mod_sub_quick(n6, n2, n4, p)) goto end;
/* n5 = n1 - n3 */
/* n6 = n2 - n4 */
if (BN_is_zero(n5))
{
if (BN_is_zero(n6))
{
/* a is the same point as b */
BN_CTX_end(ctx);
ret = EC_POINT_dbl(group, r, a, ctx);
ctx = NULL;
goto end;
}
else
{
/* a is the inverse of b */
BN_zero(&r->Z);
r->Z_is_one = 0;
ret = 1;
goto end;
}
}
/* 'n7', 'n8' */
if (!BN_mod_add_quick(n1, n1, n3, p)) goto end;
if (!BN_mod_add_quick(n2, n2, n4, p)) goto end;
/* 'n7' = n1 + n3 */
/* 'n8' = n2 + n4 */
/* Z_r */
if (a->Z_is_one && b->Z_is_one)
{
if (!BN_copy(&r->Z, n5)) goto end;
}
else
{
if (a->Z_is_one)
{ if (!BN_copy(n0, &b->Z)) goto end; }
else if (b->Z_is_one)
{ if (!BN_copy(n0, &a->Z)) goto end; }
else
{ if (!field_mul(group, n0, &a->Z, &b->Z, ctx)) goto end; }
if (!field_mul(group, &r->Z, n0, n5, ctx)) goto end;
}
r->Z_is_one = 0;
/* Z_r = Z_a * Z_b * n5 */
/* X_r */
if (!field_sqr(group, n0, n6, ctx)) goto end;
if (!field_sqr(group, n4, n5, ctx)) goto end;
if (!field_mul(group, n3, n1, n4, ctx)) goto end;
if (!BN_mod_sub_quick(&r->X, n0, n3, p)) goto end;
/* X_r = n6^2 - n5^2 * 'n7' */
/* 'n9' */
if (!BN_mod_lshift1_quick(n0, &r->X, p)) goto end;
if (!BN_mod_sub_quick(n0, n3, n0, p)) goto end;
/* n9 = n5^2 * 'n7' - 2 * X_r */
/* Y_r */
if (!field_mul(group, n0, n0, n6, ctx)) goto end;
if (!field_mul(group, n5, n4, n5, ctx)) goto end; /* now n5 is n5^3 */
if (!field_mul(group, n1, n2, n5, ctx)) goto end;
if (!BN_mod_sub_quick(n0, n0, n1, p)) goto end;
if (BN_is_odd(n0))
if (!BN_add(n0, n0, p)) goto end;
/* now 0 <= n0 < 2*p, and n0 is even */
if (!BN_rshift1(&r->Y, n0)) goto end;
/* Y_r = (n6 * 'n9' - 'n8' * 'n5^3') / 2 */
ret = 1;
end:
if (ctx) /* otherwise we already called BN_CTX_end */
BN_CTX_end(ctx);
if (new_ctx != NULL)
BN_CTX_free(new_ctx);
return ret;
}
static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
{
unsigned char *buf=NULL;
int ret=0,bit,bytes,mask;
time_t tim;
if (bits == 0)
{
BN_zero(rnd);
return 1;
}
bytes=(bits+7)/8;
bit=(bits-1)%8;
mask=0xff<<(bit+1);
buf=(unsigned char *)OPENSSL_malloc(bytes);
if (buf == NULL)
{
BNerr(BN_F_BNRAND,ERR_R_MALLOC_FAILURE);
goto err;
}
/* make a random number and set the top and bottom bits */
time(&tim);
RAND_add(&tim,sizeof(tim),0.0);
if (pseudorand)
{
if (RAND_pseudo_bytes(buf, bytes) == -1)
goto err;
}
else
{
if (RAND_bytes(buf, bytes) <= 0)
goto err;
}
#if 1
if (pseudorand == 2)
{
/* generate patterns that are more likely to trigger BN
library bugs */
int i;
unsigned char c;
for (i = 0; i < bytes; i++)
{
RAND_pseudo_bytes(&c, 1);
if (c >= 128 && i > 0)
buf[i] = buf[i-1];
else if (c < 42)
buf[i] = 0;
else if (c < 84)
buf[i] = 255;
}
}
#endif
if (top != -1)
{
if (top)
{
if (bit == 0)
{
buf[0]=1;
buf[1]|=0x80;
}
else
{
buf[0]|=(3<<(bit-1));
}
}
else
{
buf[0]|=(1<<bit);
}
}
buf[0] &= ~mask;
if (bottom) /* set bottom bit if requested */
buf[bytes-1]|=1;
if (!BN_bin2bn(buf,bytes,rnd)) goto err;
ret=1;
err:
if (buf != NULL)
{
OPENSSL_cleanse(buf,bytes);
OPENSSL_free(buf);
}
bn_check_top(rnd);
return(ret);
}
int ec_GFp_simple_dbl(const EC_GROUP *group, EC_POINT *r, const EC_POINT *a, BN_CTX *ctx)
{
int (*field_mul)(const EC_GROUP *, BIGNUM *, const BIGNUM *, const BIGNUM *, BN_CTX *);
int (*field_sqr)(const EC_GROUP *, BIGNUM *, const BIGNUM *, BN_CTX *);
const BIGNUM *p;
BN_CTX *new_ctx = NULL;
BIGNUM *n0, *n1, *n2, *n3;
int ret = 0;
if (EC_POINT_is_at_infinity(group, a))
{
BN_zero(&r->Z);
r->Z_is_one = 0;
return 1;
}
field_mul = group->meth->field_mul;
field_sqr = group->meth->field_sqr;
p = &group->field;
if (ctx == NULL)
{
ctx = new_ctx = BN_CTX_new();
if (ctx == NULL)
return 0;
}
BN_CTX_start(ctx);
n0 = BN_CTX_get(ctx);
n1 = BN_CTX_get(ctx);
n2 = BN_CTX_get(ctx);
n3 = BN_CTX_get(ctx);
if (n3 == NULL) goto err;
/* Note that in this function we must not read components of 'a'
* once we have written the corresponding components of 'r'.
* ('r' might the same as 'a'.)
*/
/* n1 */
if (a->Z_is_one)
{
if (!field_sqr(group, n0, &a->X, ctx)) goto err;
if (!BN_mod_lshift1_quick(n1, n0, p)) goto err;
if (!BN_mod_add_quick(n0, n0, n1, p)) goto err;
if (!BN_mod_add_quick(n1, n0, &group->a, p)) goto err;
/* n1 = 3 * X_a^2 + a_curve */
}
else if (group->a_is_minus3)
{
if (!field_sqr(group, n1, &a->Z, ctx)) goto err;
if (!BN_mod_add_quick(n0, &a->X, n1, p)) goto err;
if (!BN_mod_sub_quick(n2, &a->X, n1, p)) goto err;
if (!field_mul(group, n1, n0, n2, ctx)) goto err;
if (!BN_mod_lshift1_quick(n0, n1, p)) goto err;
if (!BN_mod_add_quick(n1, n0, n1, p)) goto err;
/* n1 = 3 * (X_a + Z_a^2) * (X_a - Z_a^2)
* = 3 * X_a^2 - 3 * Z_a^4 */
}
else
{
if (!field_sqr(group, n0, &a->X, ctx)) goto err;
if (!BN_mod_lshift1_quick(n1, n0, p)) goto err;
if (!BN_mod_add_quick(n0, n0, n1, p)) goto err;
if (!field_sqr(group, n1, &a->Z, ctx)) goto err;
if (!field_sqr(group, n1, n1, ctx)) goto err;
if (!field_mul(group, n1, n1, &group->a, ctx)) goto err;
if (!BN_mod_add_quick(n1, n1, n0, p)) goto err;
/* n1 = 3 * X_a^2 + a_curve * Z_a^4 */
}
/* Z_r */
if (a->Z_is_one)
{
if (!BN_copy(n0, &a->Y)) goto err;
}
else
{
if (!field_mul(group, n0, &a->Y, &a->Z, ctx)) goto err;
}
if (!BN_mod_lshift1_quick(&r->Z, n0, p)) goto err;
r->Z_is_one = 0;
/* Z_r = 2 * Y_a * Z_a */
/* n2 */
if (!field_sqr(group, n3, &a->Y, ctx)) goto err;
if (!field_mul(group, n2, &a->X, n3, ctx)) goto err;
if (!BN_mod_lshift_quick(n2, n2, 2, p)) goto err;
/* n2 = 4 * X_a * Y_a^2 */
/* X_r */
if (!BN_mod_lshift1_quick(n0, n2, p)) goto err;
if (!field_sqr(group, &r->X, n1, ctx)) goto err;
if (!BN_mod_sub_quick(&r->X, &r->X, n0, p)) goto err;
/* X_r = n1^2 - 2 * n2 */
/* n3 */
if (!field_sqr(group, n0, n3, ctx)) goto err;
if (!BN_mod_lshift_quick(n3, n0, 3, p)) goto err;
/* n3 = 8 * Y_a^4 */
/* Y_r */
if (!BN_mod_sub_quick(n0, n2, &r->X, p)) goto err;
if (!field_mul(group, n0, n1, n0, ctx)) goto err;
if (!BN_mod_sub_quick(&r->Y, n0, n3, p)) goto err;
/* Y_r = n1 * (n2 - X_r) - n3 */
ret = 1;
err:
BN_CTX_end(ctx);
if (new_ctx != NULL)
BN_CTX_free(new_ctx);
return ret;
}
/*-
* Compute the x, y affine coordinates from the point (x1, z1) (x2, z2)
* using Montgomery point multiplication algorithm Mxy() in appendix of
* Lopez, J. and Dahab, R. "Fast multiplication on elliptic curves over
* GF(2^m) without precomputation" (CHES '99, LNCS 1717).
* Returns:
* 0 on error
* 1 if return value should be the point at infinity
* 2 otherwise
*/
static int gf2m_Mxy(const EC_GROUP *group, const BIGNUM *x, const BIGNUM *y,
BIGNUM *x1, BIGNUM *z1, BIGNUM *x2, BIGNUM *z2,
BN_CTX *ctx)
{
BIGNUM *t3, *t4, *t5;
int ret = 0;
if (BN_is_zero(z1)) {
BN_zero(x2);
BN_zero(z2);
return 1;
}
if (BN_is_zero(z2)) {
if (!BN_copy(x2, x))
return 0;
if (!BN_GF2m_add(z2, x, y))
return 0;
return 2;
}
/* Since Mxy is static we can guarantee that ctx != NULL. */
BN_CTX_start(ctx);
t3 = BN_CTX_get(ctx);
t4 = BN_CTX_get(ctx);
t5 = BN_CTX_get(ctx);
if (t5 == NULL)
goto err;
if (!BN_one(t5))
goto err;
if (!group->meth->field_mul(group, t3, z1, z2, ctx))
goto err;
if (!group->meth->field_mul(group, z1, z1, x, ctx))
goto err;
if (!BN_GF2m_add(z1, z1, x1))
goto err;
if (!group->meth->field_mul(group, z2, z2, x, ctx))
goto err;
if (!group->meth->field_mul(group, x1, z2, x1, ctx))
goto err;
if (!BN_GF2m_add(z2, z2, x2))
goto err;
if (!group->meth->field_mul(group, z2, z2, z1, ctx))
goto err;
if (!group->meth->field_sqr(group, t4, x, ctx))
goto err;
if (!BN_GF2m_add(t4, t4, y))
goto err;
if (!group->meth->field_mul(group, t4, t4, t3, ctx))
goto err;
if (!BN_GF2m_add(t4, t4, z2))
goto err;
if (!group->meth->field_mul(group, t3, t3, x, ctx))
goto err;
if (!group->meth->field_div(group, t3, t5, t3, ctx))
goto err;
if (!group->meth->field_mul(group, t4, t3, t4, ctx))
goto err;
if (!group->meth->field_mul(group, x2, x1, t3, ctx))
goto err;
if (!BN_GF2m_add(z2, x2, x))
goto err;
if (!group->meth->field_mul(group, z2, z2, t4, ctx))
goto err;
if (!BN_GF2m_add(z2, z2, y))
goto err;
ret = 2;
err:
BN_CTX_end(ctx);
return ret;
}
int ec_GFp_simple_point_set_to_infinity(const EC_GROUP *group, EC_POINT *point)
{
point->Z_is_one = 0;
BN_zero(&point->Z);
return 1;
}
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 (!(bnT = BN_bin2bn(&keyImage[0], EC_COMPRESSED_SIZE, bnT))
|| !(ptKi) || !(ptKi = EC_POINT_bn2point(ecGrp, bnT, ptKi, bnCtx)))
{
LogPrintf("%s: extract ptKi failed.\n", __func__);
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))
{
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 BN_div_recp(BIGNUM *dv, BIGNUM *rem, BIGNUM *m, BN_RECP_CTX *recp,
BN_CTX *ctx)
{
int i,j,ret=0;
BIGNUM *a,*b,*d,*r;
BN_CTX_start(ctx);
a=BN_CTX_get(ctx);
b=BN_CTX_get(ctx);
if (dv != NULL)
d=dv;
else
d=BN_CTX_get(ctx);
if (rem != NULL)
r=rem;
else
r=BN_CTX_get(ctx);
if (a == NULL || b == NULL || d == NULL || r == NULL) goto err;
if (BN_ucmp(m,&(recp->N)) < 0)
{
BN_zero(d);
BN_copy(r,m);
BN_CTX_end(ctx);
return(1);
}
/* We want the remainder
* Given input of ABCDEF / ab
* we need multiply ABCDEF by 3 digests of the reciprocal of ab
*
*/
i=BN_num_bits(m);
j=recp->num_bits<<1;
if (j>i) i=j;
j>>=1;
if (i != recp->shift)
recp->shift=BN_reciprocal(&(recp->Nr),&(recp->N),
i,ctx);
if (!BN_rshift(a,m,j)) goto err;
if (!BN_mul(b,a,&(recp->Nr),ctx)) goto err;
if (!BN_rshift(d,b,i-j)) goto err;
d->neg=0;
if (!BN_mul(b,&(recp->N),d,ctx)) goto err;
if (!BN_usub(r,m,b)) goto err;
r->neg=0;
#if 1
j=0;
while (BN_ucmp(r,&(recp->N)) >= 0)
{
if (j++ > 2)
{
BNerr(BN_F_BN_MOD_MUL_RECIPROCAL,BN_R_BAD_RECIPROCAL);
goto err;
}
if (!BN_usub(r,r,&(recp->N))) goto err;
if (!BN_add_word(d,1)) goto err;
}
#endif
r->neg=BN_is_zero(r)?0:m->neg;
d->neg=m->neg^recp->N.neg;
ret=1;
err:
BN_CTX_end(ctx);
return(ret);
}
// Perform ECDSA key recovery (see SEC1 4.1.6) for curves over (mod p)-fields
// recid selects which key is recovered
// if check is nonzero, 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;
}
/* random number r: 0 <= r < range */
static int
bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range)
{
int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand;
int n;
int count = 100;
if (range->neg || BN_is_zero(range)) {
BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE);
return 0;
}
n = BN_num_bits(range); /* n > 0 */
/* BN_is_bit_set(range, n - 1) always holds */
if (n == 1)
BN_zero(r);
else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3)) {
/* range = 100..._2,
* so 3*range (= 11..._2) is exactly one bit longer than range */
do {
if (!bn_rand(r, n + 1, -1, 0))
return 0;
/* If r < 3*range, use r := r MOD range
* (which is either r, r - range, or r - 2*range).
* Otherwise, iterate once more.
* Since 3*range = 11..._2, each iteration succeeds with
* probability >= .75. */
if (BN_cmp(r, range) >= 0) {
if (!BN_sub(r, r, range))
return 0;
if (BN_cmp(r, range) >= 0)
if (!BN_sub(r, r, range))
return 0;
}
if (!--count) {
BNerr(BN_F_BN_RAND_RANGE,
BN_R_TOO_MANY_ITERATIONS);
return 0;
}
} while (BN_cmp(r, range) >= 0);
} else {
do {
/* range = 11..._2 or range = 101..._2 */
if (!bn_rand(r, n, -1, 0))
return 0;
if (!--count) {
BNerr(BN_F_BN_RAND_RANGE,
BN_R_TOO_MANY_ITERATIONS);
return 0;
}
} while (BN_cmp(r, range) >= 0);
}
bn_check_top(r);
return 1;
}
int dsa_builtin_paramgen(DSA *ret, size_t bits, size_t qbits,
const EVP_MD *evpmd, const unsigned char *seed_in,
size_t seed_len, int *counter_ret,
unsigned long *h_ret, BN_GENCB *cb)
{
int ok = 0;
unsigned char seed[SHA256_DIGEST_LENGTH];
unsigned char md[SHA256_DIGEST_LENGTH];
unsigned char buf[SHA256_DIGEST_LENGTH], buf2[SHA256_DIGEST_LENGTH];
BIGNUM *r0, *W, *X, *c, *test;
BIGNUM *g = NULL, *q = NULL, *p = NULL;
BN_MONT_CTX *mont = NULL;
int i, k, n = 0, m = 0, qsize = qbits >> 3;
int counter = 0;
int r = 0;
BN_CTX *ctx = NULL;
unsigned int h = 2;
if (qsize != SHA_DIGEST_LENGTH && qsize != SHA224_DIGEST_LENGTH &&
qsize != SHA256_DIGEST_LENGTH)
/* invalid q size */
return 0;
if (evpmd == NULL)
/* use SHA1 as default */
evpmd = EVP_sha1();
if (bits < 512)
bits = 512;
bits = (bits + 63) / 64 * 64;
/*
* NB: seed_len == 0 is special case: copy generated seed to seed_in if
* it is not NULL.
*/
if (seed_len && (seed_len < (size_t)qsize))
seed_in = NULL; /* seed buffer too small -- ignore */
if (seed_len > (size_t)qsize)
seed_len = qsize; /* App. 2.2 of FIPS PUB 186 allows larger
* SEED, but our internal buffers are
* restricted to 160 bits */
if (seed_in != NULL)
memcpy(seed, seed_in, seed_len);
if ((ctx = BN_CTX_new()) == NULL)
goto err;
if ((mont = BN_MONT_CTX_new()) == NULL)
goto err;
BN_CTX_start(ctx);
r0 = BN_CTX_get(ctx);
g = BN_CTX_get(ctx);
W = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
c = BN_CTX_get(ctx);
p = BN_CTX_get(ctx);
test = BN_CTX_get(ctx);
if (!BN_lshift(test, BN_value_one(), bits - 1))
goto err;
for (;;) {
for (;;) { /* find q */
int seed_is_random;
/* step 1 */
if (!BN_GENCB_call(cb, 0, m++))
goto err;
if (!seed_len) {
RAND_pseudo_bytes(seed, qsize);
seed_is_random = 1;
} else {
seed_is_random = 0;
seed_len = 0; /* use random seed if 'seed_in' turns out to
* be bad */
}
memcpy(buf, seed, qsize);
memcpy(buf2, seed, qsize);
/* precompute "SEED + 1" for step 7: */
for (i = qsize - 1; i >= 0; i--) {
buf[i]++;
if (buf[i] != 0)
break;
}
/* step 2 */
EVP_Digest(seed, qsize, md, NULL, evpmd, NULL);
EVP_Digest(buf, qsize, buf2, NULL, evpmd, NULL);
for (i = 0; i < qsize; i++)
md[i] ^= buf2[i];
/* step 3 */
md[0] |= 0x80;
md[qsize - 1] |= 0x01;
if (!BN_bin2bn(md, qsize, q))
goto err;
/* step 4 */
r = BN_is_prime_fasttest_ex(q, DSS_prime_checks, ctx,
seed_is_random, cb);
if (r > 0)
break;
if (r != 0)
goto err;
/* do a callback call */
/* step 5 */
}
if (!BN_GENCB_call(cb, 2, 0))
goto err;
if (!BN_GENCB_call(cb, 3, 0))
goto err;
/* step 6 */
counter = 0;
/* "offset = 2" */
n = (bits - 1) / 160;
for (;;) {
if ((counter != 0) && !BN_GENCB_call(cb, 0, counter))
goto err;
/* step 7 */
BN_zero(W);
/* now 'buf' contains "SEED + offset - 1" */
for (k = 0; k <= n; k++) {
/*
* obtain "SEED + offset + k" by incrementing:
*/
for (i = qsize - 1; i >= 0; i--) {
buf[i]++;
if (buf[i] != 0)
break;
}
EVP_Digest(buf, qsize, md, NULL, evpmd, NULL);
/* step 8 */
if (!BN_bin2bn(md, qsize, r0))
goto err;
if (!BN_lshift(r0, r0, (qsize << 3) * k))
goto err;
if (!BN_add(W, W, r0))
goto err;
}
/* more of step 8 */
if (!BN_mask_bits(W, bits - 1))
goto err;
if (!BN_copy(X, W))
goto err;
if (!BN_add(X, X, test))
goto err;
/* step 9 */
if (!BN_lshift1(r0, q))
goto err;
if (!BN_mod(c, X, r0, ctx))
goto err;
if (!BN_sub(r0, c, BN_value_one()))
goto err;
if (!BN_sub(p, X, r0))
goto err;
/* step 10 */
if (BN_cmp(p, test) >= 0) {
/* step 11 */
r = BN_is_prime_fasttest_ex(p, DSS_prime_checks, ctx, 1, cb);
if (r > 0)
goto end; /* found it */
if (r != 0)
goto err;
}
/* step 13 */
counter++;
/* "offset = offset + n + 1" */
/* step 14 */
if (counter >= 4096)
break;
}
}
end:
if (!BN_GENCB_call(cb, 2, 1))
goto err;
/* We now need to generate g */
/* Set r0=(p-1)/q */
if (!BN_sub(test, p, BN_value_one()))
goto err;
if (!BN_div(r0, NULL, test, q, ctx))
goto err;
if (!BN_set_word(test, h))
goto err;
if (!BN_MONT_CTX_set(mont, p, ctx))
goto err;
for (;;) {
/* g=test^r0%p */
if (!BN_mod_exp_mont(g, test, r0, p, ctx, mont))
goto err;
if (!BN_is_one(g))
break;
if (!BN_add(test, test, BN_value_one()))
goto err;
h++;
}
if (!BN_GENCB_call(cb, 3, 1))
goto err;
ok = 1;
err:
if (ok) {
if (ret->p)
BN_free(ret->p);
if (ret->q)
BN_free(ret->q);
if (ret->g)
BN_free(ret->g);
ret->p = BN_dup(p);
ret->q = BN_dup(q);
ret->g = BN_dup(g);
if (ret->p == NULL || ret->q == NULL || ret->g == NULL) {
ok = 0;
goto err;
}
if (counter_ret != NULL)
*counter_ret = counter;
if (h_ret != NULL)
*h_ret = h;
}
if (ctx) {
BN_CTX_end(ctx);
BN_CTX_free(ctx);
}
if (mont != NULL)
BN_MONT_CTX_free(mont);
return ok;
}
/*-
* BN_div computes dv := num / divisor, rounding towards
* zero, and sets up rm such that dv*divisor + rm = num holds.
* Thus:
* dv->neg == num->neg ^ divisor->neg (unless the result is zero)
* rm->neg == num->neg (unless the remainder is zero)
* If 'dv' or 'rm' is NULL, the respective value is not returned.
*/
int BN_div(BIGNUM *dv, BIGNUM *rm, const BIGNUM *num, const BIGNUM *divisor,
BN_CTX *ctx)
{
int norm_shift, i, loop;
BIGNUM *tmp, wnum, *snum, *sdiv, *res;
BN_ULONG *resp, *wnump;
BN_ULONG d0, d1;
int num_n, div_n;
int no_branch = 0;
/*
* Invalid zero-padding would have particularly bad consequences so don't
* just rely on bn_check_top() here (bn_check_top() works only for
* BN_DEBUG builds)
*/
if ((num->top > 0 && num->d[num->top - 1] == 0) ||
(divisor->top > 0 && divisor->d[divisor->top - 1] == 0)) {
BNerr(BN_F_BN_DIV, BN_R_NOT_INITIALIZED);
return 0;
}
bn_check_top(num);
bn_check_top(divisor);
if ((BN_get_flags(num, BN_FLG_CONSTTIME) != 0)
|| (BN_get_flags(divisor, BN_FLG_CONSTTIME) != 0)) {
no_branch = 1;
}
bn_check_top(dv);
bn_check_top(rm);
/*- bn_check_top(num); *//*
* 'num' has been checked already
*/
/*- bn_check_top(divisor); *//*
* 'divisor' has been checked already
*/
if (BN_is_zero(divisor)) {
BNerr(BN_F_BN_DIV, BN_R_DIV_BY_ZERO);
return (0);
}
if (!no_branch && BN_ucmp(num, divisor) < 0) {
if (rm != NULL) {
if (BN_copy(rm, num) == NULL)
return (0);
}
if (dv != NULL)
BN_zero(dv);
return (1);
}
BN_CTX_start(ctx);
tmp = BN_CTX_get(ctx);
snum = BN_CTX_get(ctx);
sdiv = BN_CTX_get(ctx);
if (dv == NULL)
res = BN_CTX_get(ctx);
else
res = dv;
if (sdiv == NULL || res == NULL || tmp == NULL || snum == NULL)
goto err;
/* First we normalise the numbers */
norm_shift = BN_BITS2 - ((BN_num_bits(divisor)) % BN_BITS2);
if (!(BN_lshift(sdiv, divisor, norm_shift)))
goto err;
sdiv->neg = 0;
norm_shift += BN_BITS2;
if (!(BN_lshift(snum, num, norm_shift)))
goto err;
snum->neg = 0;
if (no_branch) {
/*
* Since we don't know whether snum is larger than sdiv, we pad snum
* with enough zeroes without changing its value.
*/
if (snum->top <= sdiv->top + 1) {
if (bn_wexpand(snum, sdiv->top + 2) == NULL)
goto err;
for (i = snum->top; i < sdiv->top + 2; i++)
snum->d[i] = 0;
snum->top = sdiv->top + 2;
} else {
if (bn_wexpand(snum, snum->top + 1) == NULL)
goto err;
snum->d[snum->top] = 0;
snum->top++;
}
}
div_n = sdiv->top;
num_n = snum->top;
loop = num_n - div_n;
/*
* Lets setup a 'window' into snum This is the part that corresponds to
* the current 'area' being divided
*/
wnum.neg = 0;
wnum.d = &(snum->d[loop]);
wnum.top = div_n;
/*
* only needed when BN_ucmp messes up the values between top and max
*/
wnum.dmax = snum->dmax - loop; /* so we don't step out of bounds */
/* Get the top 2 words of sdiv */
/* div_n=sdiv->top; */
d0 = sdiv->d[div_n - 1];
d1 = (div_n == 1) ? 0 : sdiv->d[div_n - 2];
/* pointer to the 'top' of snum */
wnump = &(snum->d[num_n - 1]);
/* Setup to 'res' */
res->neg = (num->neg ^ divisor->neg);
if (!bn_wexpand(res, (loop + 1)))
goto err;
res->top = loop - no_branch;
resp = &(res->d[loop - 1]);
/* space for temp */
if (!bn_wexpand(tmp, (div_n + 1)))
goto err;
if (!no_branch) {
if (BN_ucmp(&wnum, sdiv) >= 0) {
/*
* If BN_DEBUG_RAND is defined BN_ucmp changes (via bn_pollute)
* the const bignum arguments => clean the values between top and
* max again
*/
bn_clear_top2max(&wnum);
bn_sub_words(wnum.d, wnum.d, sdiv->d, div_n);
*resp = 1;
} else
res->top--;
}
/*
* if res->top == 0 then clear the neg value otherwise decrease the resp
* pointer
*/
if (res->top == 0)
res->neg = 0;
else
resp--;
for (i = 0; i < loop - 1; i++, wnump--, resp--) {
BN_ULONG q, l0;
/*
* the first part of the loop uses the top two words of snum and sdiv
* to calculate a BN_ULONG q such that | wnum - sdiv * q | < sdiv
*/
# if defined(BN_DIV3W) && !defined(OPENSSL_NO_ASM)
BN_ULONG bn_div_3_words(BN_ULONG *, BN_ULONG, BN_ULONG);
q = bn_div_3_words(wnump, d1, d0);
# else
BN_ULONG n0, n1, rem = 0;
n0 = wnump[0];
n1 = wnump[-1];
if (n0 == d0)
q = BN_MASK2;
else { /* n0 < d0 */
# ifdef BN_LLONG
BN_ULLONG t2;
# if defined(BN_LLONG) && defined(BN_DIV2W) && !defined(bn_div_words)
q = (BN_ULONG)(((((BN_ULLONG) n0) << BN_BITS2) | n1) / d0);
# else
q = bn_div_words(n0, n1, d0);
# endif
# ifndef REMAINDER_IS_ALREADY_CALCULATED
/*
* rem doesn't have to be BN_ULLONG. The least we
* know it's less that d0, isn't it?
*/
rem = (n1 - q * d0) & BN_MASK2;
# endif
t2 = (BN_ULLONG) d1 *q;
for (;;) {
if (t2 <= ((((BN_ULLONG) rem) << BN_BITS2) | wnump[-2]))
break;
q--;
rem += d0;
if (rem < d0)
break; /* don't let rem overflow */
t2 -= d1;
}
# else /* !BN_LLONG */
BN_ULONG t2l, t2h;
q = bn_div_words(n0, n1, d0);
# ifndef REMAINDER_IS_ALREADY_CALCULATED
rem = (n1 - q * d0) & BN_MASK2;
# endif
# if defined(BN_UMULT_LOHI)
BN_UMULT_LOHI(t2l, t2h, d1, q);
# elif defined(BN_UMULT_HIGH)
t2l = d1 * q;
t2h = BN_UMULT_HIGH(d1, q);
# else
{
BN_ULONG ql, qh;
t2l = LBITS(d1);
t2h = HBITS(d1);
ql = LBITS(q);
qh = HBITS(q);
mul64(t2l, t2h, ql, qh); /* t2=(BN_ULLONG)d1*q; */
}
# endif
for (;;) {
if ((t2h < rem) || ((t2h == rem) && (t2l <= wnump[-2])))
break;
q--;
rem += d0;
if (rem < d0)
break; /* don't let rem overflow */
if (t2l < d1)
t2h--;
t2l -= d1;
}
# endif /* !BN_LLONG */
}
# endif /* !BN_DIV3W */
l0 = bn_mul_words(tmp->d, sdiv->d, div_n, q);
tmp->d[div_n] = l0;
wnum.d--;
/*
* ingore top values of the bignums just sub the two BN_ULONG arrays
* with bn_sub_words
*/
if (bn_sub_words(wnum.d, wnum.d, tmp->d, div_n + 1)) {
/*
* Note: As we have considered only the leading two BN_ULONGs in
* the calculation of q, sdiv * q might be greater than wnum (but
* then (q-1) * sdiv is less or equal than wnum)
*/
q--;
if (bn_add_words(wnum.d, wnum.d, sdiv->d, div_n))
/*
* we can't have an overflow here (assuming that q != 0, but
* if q == 0 then tmp is zero anyway)
*/
(*wnump)++;
}
/* store part of the result */
*resp = q;
}
bn_correct_top(snum);
if (rm != NULL) {
/*
* Keep a copy of the neg flag in num because if rm==num BN_rshift()
* will overwrite it.
*/
int neg = num->neg;
BN_rshift(rm, snum, norm_shift);
if (!BN_is_zero(rm))
rm->neg = neg;
bn_check_top(rm);
}
if (no_branch)
bn_correct_top(res);
BN_CTX_end(ctx);
return (1);
err:
bn_check_top(rm);
BN_CTX_end(ctx);
return (0);
}
/* BN_mod_inverse_no_branch is a special version of BN_mod_inverse.
* It does not contain branches that may leak sensitive information.
*/
static BIGNUM *BN_mod_inverse_no_branch(BIGNUM *in,
const BIGNUM *a, const BIGNUM *n, BN_CTX *ctx)
{
BIGNUM *A,*B,*X,*Y,*M,*D,*T,*R=NULL;
BIGNUM local_A, local_B;
BIGNUM *pA, *pB;
BIGNUM *ret=NULL;
int sign;
bn_check_top(a);
bn_check_top(n);
BN_CTX_start(ctx);
A = BN_CTX_get(ctx);
B = BN_CTX_get(ctx);
X = BN_CTX_get(ctx);
D = BN_CTX_get(ctx);
M = BN_CTX_get(ctx);
Y = BN_CTX_get(ctx);
T = BN_CTX_get(ctx);
if (T == NULL) goto err;
if (in == NULL)
R=BN_new();
else
R=in;
if (R == NULL) goto err;
BN_one(X);
BN_zero(Y);
if (BN_copy(B,a) == NULL) goto err;
if (BN_copy(A,n) == NULL) goto err;
A->neg = 0;
if (B->neg || (BN_ucmp(B, A) >= 0))
{
/* Turn BN_FLG_CONSTTIME flag on, so that when BN_div is invoked,
* BN_div_no_branch will be called eventually.
*/
pB = &local_B;
BN_with_flags(pB, B, BN_FLG_CONSTTIME);
if (!BN_nnmod(B, pB, A, ctx)) goto err;
}
sign = -1;
/* From B = a mod |n|, A = |n| it follows that
*
* 0 <= B < A,
* -sign*X*a == B (mod |n|),
* sign*Y*a == A (mod |n|).
*/
while (!BN_is_zero(B))
{
BIGNUM *tmp;
/*
* 0 < B < A,
* (*) -sign*X*a == B (mod |n|),
* sign*Y*a == A (mod |n|)
*/
/* Turn BN_FLG_CONSTTIME flag on, so that when BN_div is invoked,
* BN_div_no_branch will be called eventually.
*/
pA = &local_A;
BN_with_flags(pA, A, BN_FLG_CONSTTIME);
/* (D, M) := (A/B, A%B) ... */
if (!BN_div(D,M,pA,B,ctx)) goto err;
/* Now
* A = D*B + M;
* thus we have
* (**) sign*Y*a == D*B + M (mod |n|).
*/
tmp=A; /* keep the BIGNUM object, the value does not matter */
/* (A, B) := (B, A mod B) ... */
A=B;
B=M;
/* ... so we have 0 <= B < A again */
/* Since the former M is now B and the former B is now A,
* (**) translates into
* sign*Y*a == D*A + B (mod |n|),
* i.e.
* sign*Y*a - D*A == B (mod |n|).
* Similarly, (*) translates into
* -sign*X*a == A (mod |n|).
*
* Thus,
* sign*Y*a + D*sign*X*a == B (mod |n|),
* i.e.
* sign*(Y + D*X)*a == B (mod |n|).
*
* So if we set (X, Y, sign) := (Y + D*X, X, -sign), we arrive back at
* -sign*X*a == B (mod |n|),
* sign*Y*a == A (mod |n|).
* Note that X and Y stay non-negative all the time.
*/
if (!BN_mul(tmp,D,X,ctx)) goto err;
if (!BN_add(tmp,tmp,Y)) goto err;
M=Y; /* keep the BIGNUM object, the value does not matter */
Y=X;
X=tmp;
sign = -sign;
}
/*
* The while loop (Euclid's algorithm) ends when
* A == gcd(a,n);
* we have
* sign*Y*a == A (mod |n|),
* where Y is non-negative.
*/
if (sign < 0)
{
if (!BN_sub(Y,n,Y)) goto err;
}
/* Now Y*a == A (mod |n|). */
if (BN_is_one(A))
{
/* Y*a == 1 (mod |n|) */
if (!Y->neg && BN_ucmp(Y,n) < 0)
{
if (!BN_copy(R,Y)) goto err;
}
else
{
if (!BN_nnmod(R,Y,n,ctx)) goto err;
}
}
else
{
BNerr(BN_F_BN_MOD_INVERSE_NO_BRANCH,BN_R_NO_INVERSE);
goto err;
}
ret=R;
err:
if ((ret == NULL) && (in == NULL)) BN_free(R);
BN_CTX_end(ctx);
bn_check_top(ret);
return(ret);
}
int BN_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, BN_CTX *ctx) {
int ret = 0;
int top, al, bl;
BIGNUM *rr;
int i;
BIGNUM *t = NULL;
int j = 0, k;
al = a->top;
bl = b->top;
if ((al == 0) || (bl == 0)) {
BN_zero(r);
return 1;
}
top = al + bl;
BN_CTX_start(ctx);
if ((r == a) || (r == b)) {
if ((rr = BN_CTX_get(ctx)) == NULL) {
goto err;
}
} else {
rr = r;
}
rr->neg = a->neg ^ b->neg;
i = al - bl;
if (i == 0) {
if (al == 8) {
if (!bn_wexpand(rr, 16)) {
goto err;
}
rr->top = 16;
bn_mul_comba8(rr->d, a->d, b->d);
goto end;
}
}
static const int kMulNormalSize = 16;
if (al >= kMulNormalSize && bl >= kMulNormalSize) {
if (i >= -1 && i <= 1) {
/* Find out the power of two lower or equal
to the longest of the two numbers */
if (i >= 0) {
j = BN_num_bits_word((BN_ULONG)al);
}
if (i == -1) {
j = BN_num_bits_word((BN_ULONG)bl);
}
j = 1 << (j - 1);
assert(j <= al || j <= bl);
k = j + j;
t = BN_CTX_get(ctx);
if (t == NULL) {
goto err;
}
if (al > j || bl > j) {
if (!bn_wexpand(t, k * 4)) {
goto err;
}
if (!bn_wexpand(rr, k * 4)) {
goto err;
}
bn_mul_part_recursive(rr->d, a->d, b->d, j, al - j, bl - j, t->d);
} else {
/* al <= j || bl <= j */
if (!bn_wexpand(t, k * 2)) {
goto err;
}
if (!bn_wexpand(rr, k * 2)) {
goto err;
}
bn_mul_recursive(rr->d, a->d, b->d, j, al - j, bl - j, t->d);
}
rr->top = top;
goto end;
}
}
if (!bn_wexpand(rr, top)) {
goto err;
}
rr->top = top;
bn_mul_normal(rr->d, a->d, al, b->d, bl);
end:
bn_correct_top(rr);
if (r != rr && !BN_copy(r, rr)) {
goto err;
}
ret = 1;
err:
BN_CTX_end(ctx);
return ret;
}
