int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
{
int ret;
bn_check_top(n);
if ((b->A == NULL) || (b->Ai == NULL))
{
BNerr(BN_F_BN_BLINDING_INVERT_EX,BN_R_NOT_INITIALIZED);
return(0);
}
if (r != NULL)
ret = BN_mod_mul(n, n, r, b->mod, ctx);
else
ret = BN_mod_mul(n, n, b->Ai, b->mod, ctx);
if (ret >= 0)
{
if (!BN_BLINDING_update(b,ctx))
return(0);
}
bn_check_top(n);
return(ret);
}
BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
{
int i;
BN_ULONG *A;
const BN_ULONG *B;
bn_check_top(b);
if (a == b) return(a);
if (bn_wexpand(a,b->top) == NULL) return(NULL);
#if 1
A=a->d;
B=b->d;
for (i=b->top>>2; i>0; i--,A+=4,B+=4)
{
BN_ULONG a0,a1,a2,a3;
a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
}
switch (b->top&3)
{
case 3: A[2]=B[2];
case 2: A[1]=B[1];
case 1: A[0]=B[0];
case 0: ; /* ultrix cc workaround, see comments in bn_expand_internal */
}
#else
memcpy(a->d,b->d,sizeof(b->d[0])*b->top);
#endif
a->top=b->top;
a->neg=b->neg;
bn_check_top(a);
return(a);
}
static void
BN_POOL_release(BN_POOL *p, unsigned int num)
{
unsigned int offset = (p->used - 1) % BN_CTX_POOL_SIZE;
p->used -= num;
while (num--) {
bn_check_top(p->current->vals + offset);
if (!offset) {
offset = BN_CTX_POOL_SIZE - 1;
p->current = p->current->prev;
} else
offset--;
}
}
int bn_probable_prime_dh(BIGNUM *rnd, int bits,
const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx)
{
int i, ret = 0;
BIGNUM *t1;
BN_CTX_start(ctx);
if ((t1 = BN_CTX_get(ctx)) == NULL)
goto err;
if (!BN_priv_rand(rnd, bits, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ODD))
goto err;
/* we need ((rnd-rem) % add) == 0 */
if (!BN_mod(t1, rnd, add, ctx))
goto err;
if (!BN_sub(rnd, rnd, t1))
goto err;
if (rem == NULL) {
if (!BN_add_word(rnd, 1))
goto err;
} else {
if (!BN_add(rnd, rnd, rem))
goto err;
}
/* we now have a random number 'rand' to test. */
loop:
for (i = 1; i < NUMPRIMES; i++) {
/* check that rnd is a prime */
BN_ULONG mod = BN_mod_word(rnd, (BN_ULONG)primes[i]);
if (mod == (BN_ULONG)-1)
goto err;
if (mod <= 1) {
if (!BN_add(rnd, rnd, add))
goto err;
goto loop;
}
}
ret = 1;
err:
BN_CTX_end(ctx);
bn_check_top(rnd);
return ret;
}
int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
BN_CTX *ctx)
{
int retn = 0;
#ifdef MONT_WORD
BIGNUM *t;
BN_CTX_start(ctx);
if ((t = BN_CTX_get(ctx)) && BN_copy(t, a))
retn = BN_from_montgomery_word(ret, t, mont);
BN_CTX_end(ctx);
#else /* !MONT_WORD */
BIGNUM *t1, *t2;
BN_CTX_start(ctx);
t1 = BN_CTX_get(ctx);
t2 = BN_CTX_get(ctx);
if (t1 == NULL || t2 == NULL)
goto err;
if (!BN_copy(t1, a))
goto err;
BN_mask_bits(t1, mont->ri);
if (!BN_mul(t2, t1, &mont->Ni, ctx))
goto err;
BN_mask_bits(t2, mont->ri);
if (!BN_mul(t1, t2, &mont->N, ctx))
goto err;
if (!BN_add(t2, a, t1))
goto err;
if (!BN_rshift(ret, t2, mont->ri))
goto err;
#if !defined(BRANCH_FREE) || BRANCH_FREE==0
if (BN_ucmp(ret, &(mont->N)) >= 0) {
if (!BN_usub(ret, ret, &(mont->N)))
goto err;
}
#endif
retn = 1;
bn_check_top(ret);
err:
BN_CTX_end(ctx);
#endif /* MONT_WORD */
return (retn);
}
/**
* public static native long longInt(int)
*/
static long long NativeBN_longInt(JNIEnv* env, jclass cls, BIGNUM* a) {
if (!oneValidHandle(env, a)) return -1;
bn_check_top(a);
int intLen = a->top;
BN_ULONG* d = a->d;
switch (intLen) {
case 0:
return 0;
case 1:
if (!a->neg) return d[0] & 0X00000000FFFFFFFFLL;
else return -(d[0] & 0X00000000FFFFFFFFLL);
default:
if (!a->neg) return ((long long)d[1] << 32) | (d[0] & 0XFFFFFFFFLL);
else return -(((long long)d[1] << 32) | (d[0] & 0XFFFFFFFFLL));
}
}
/**
* public static native int putULongInt(int, long, int)
*/
static jboolean NativeBN_putULongInt(JNIEnv* env, jclass cls, BIGNUM* a, unsigned long long dw, jboolean neg) {
if (!oneValidHandle(env, a)) return FALSE;
unsigned int hi = dw >> 32; // This shifts without sign extension.
int lo = (int)dw; // This truncates implicitely.
// cf. litEndInts2bn:
bn_check_top(a);
if (bn_wexpand(a, 2) != NULL) {
a->d[0] = lo;
a->d[1] = hi;
a->top = 2;
a->neg = neg;
bn_correct_top(a);
return TRUE;
}
else return FALSE;
}
int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
{
int ret;
bn_check_top(n);
if ((b->A == NULL) || (b->Ai == NULL))
{
BNerr(BN_F_BN_BLINDING_INVERT,BN_R_NOT_INITIALIZED);
return(0);
}
if ((ret=BN_mod_mul(n,n,b->Ai,b->mod,ctx)) >= 0)
{
if (!BN_BLINDING_update(b,ctx))
return(0);
}
return(ret);
}
int bn_probable_prime_dh_coprime(BIGNUM *rnd, int bits, BN_CTX *ctx)
{
int i;
BIGNUM *offset_index;
BIGNUM *offset_count;
int ret = 0;
OPENSSL_assert(bits > prime_multiplier_bits);
BN_CTX_start(ctx);
if ((offset_index = BN_CTX_get(ctx)) == NULL)
goto err;
if ((offset_count = BN_CTX_get(ctx)) == NULL)
goto err;
if (!BN_add_word(offset_count, prime_offset_count))
goto err;
loop:
if (!BN_rand(rnd, bits - prime_multiplier_bits, 0, 1))
goto err;
if (BN_is_bit_set(rnd, bits))
goto loop;
if (!BN_rand_range(offset_index, offset_count))
goto err;
if (!BN_mul_word(rnd, prime_multiplier)
|| !BN_add_word(rnd, prime_offsets[BN_get_word(offset_index)]))
goto err;
/* we now have a random number 'rand' to test. */
/* skip coprimes */
for (i = first_prime_index; i < NUMPRIMES; i++) {
/* check that rnd is a prime */
if (BN_mod_word(rnd, (BN_ULONG)primes[i]) <= 1) {
goto loop;
}
}
ret = 1;
err:
BN_CTX_end(ctx);
bn_check_top(rnd);
return ret;
}
/* BN_mod_lshift variant that may be used if a is non-negative
* and less than m */
int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m)
{
if (r != a)
{
if (BN_copy(r, a) == NULL) return 0;
}
while (n > 0)
{
int max_shift;
/* 0 < r < m */
max_shift = BN_num_bits(m) - BN_num_bits(r);
/* max_shift >= 0 */
if (max_shift < 0)
{
BNerr(BN_F_BN_MOD_LSHIFT_QUICK, BN_R_INPUT_NOT_REDUCED);
return 0;
}
if (max_shift > n)
max_shift = n;
if (max_shift)
{
if (!BN_lshift(r, r, max_shift)) return 0;
n -= max_shift;
}
else
{
if (!BN_lshift1(r, r)) return 0;
--n;
}
/* BN_num_bits(r) <= BN_num_bits(m) */
if (BN_cmp(r, m) >= 0)
{
if (!BN_sub(r, r, m)) return 0;
}
}
bn_check_top(r);
return 1;
}
extern "C" void Java_java_math_NativeBN_putULongInt(JNIEnv* env, jclass, jlong a0, unsigned long long dw, jboolean neg) {
if (!oneValidHandle(env, a0)) return;
unsigned int hi = dw >> 32; // This shifts without sign extension.
int lo = (int)dw; // This truncates implicitly.
// cf. litEndInts2bn:
BIGNUM* a = toBigNum(a0);
bn_check_top(a);
if (bn_wexpand(a, 2) != NULL) {
a->d[0] = lo;
a->d[1] = hi;
a->top = 2;
a->neg = neg;
bn_correct_top(a);
} else {
throwExceptionIfNecessary(env);
}
}
/* r := 2^len / m */
int BN_reciprocal(BIGNUM *r, const BIGNUM *m, int len, BN_CTX *ctx)
{
int ret= -1;
BIGNUM *t;
BN_CTX_start(ctx);
if((t = BN_CTX_get(ctx)) == NULL) goto err;
if (!BN_set_bit(t,len)) goto err;
if (!BN_div(r,NULL,t,m,ctx)) goto err;
ret=len;
err:
bn_check_top(r);
BN_CTX_end(ctx);
return(ret);
}
/**
* public static native int bitLength(int)
*/
static int NativeBN_bitLength(JNIEnv* env, jclass cls, BIGNUM* a) {
// We rely on: (BN_BITS2 == 32), i.e. BN_ULONG is unsigned int and has 4 bytes:
//
if (!oneValidHandle(env, a)) return FALSE;
bn_check_top(a);
int intLen = a->top;
if (intLen == 0) return 0;
BN_ULONG* d = a->d;
int i = intLen - 1;
BN_ULONG msd = d[i]; // most significant digit
if (a->neg) {
// Handle negative values correctly:
// i.e. decrement the msd if all other digits are 0:
// while ((i > 0) && (d[i] != 0)) { i--; }
do { i--; } while (!((i < 0) || (d[i] != 0)));
if (i < 0) msd--; // Only if all lower significant digits are 0 we decrement the most significant one.
}
return (intLen - 1) * 32 + BN_num_bits_word(msd);
}
int BN_ucmp_word( const BN_ULONG *ap, const int aTop, const BIGNUM *b) /* pcg */
{
int i;
const BN_ULONG *bp;
BN_ULONG t1,t2;
bn_check_top(b);
i=aTop-b->top;
if (i != 0) return(i);
bp=b->d;
for (i=aTop-1; i>=0; i--)
{
t1= ap[i];
t2= bp[i];
if (t1 != t2)
return((t1 > t2) ? 1 : -1);
}
return(0);
}
BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
{
unsigned int i,m;
unsigned int n;
BN_ULONG l;
BIGNUM *bn = NULL;
if (ret == NULL)
ret = bn = BN_new();
if (ret == NULL) return(NULL);
bn_check_top(ret);
l=0;
n=len;
if (n == 0)
{
ret->top=0;
return(ret);
}
i=((n-1)/BN_BYTES)+1;
m=((n-1)%(BN_BYTES));
if (bn_wexpand(ret, (int)i) == NULL)
{
//if (bn) BN_free(bn);
return NULL;
}
ret->top=i;
ret->neg=0;
while (n--)
{
l=(l<<8L)| *(s++);
if (m-- == 0)
{
ret->d[--i]=l;
l=0;
m=BN_BYTES-1;
}
}
bn_correct_top(ret);
return(ret);
}
int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
{
int ret = 1;
bn_check_top(n);
if ((b->A == NULL) || (b->Ai == NULL))
{
BNerr(BN_F_BN_BLINDING_CONVERT_EX,BN_R_NOT_INITIALIZED);
return(0);
}
if (r != NULL)
{
if (!BN_copy(r, b->Ai)) ret=0;
}
if (!BN_mod_mul(n,n,b->A,b->mod,ctx)) ret=0;
return ret;
}
int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m, BN_CTX *ctx)
{
BIGNUM *abs_m = NULL;
int ret;
if (!BN_nnmod(r, a, m, ctx)) return 0;
if (m->neg)
{
abs_m = BN_dup(m);
if (abs_m == NULL) return 0;
abs_m->neg = 0;
}
ret = BN_mod_lshift_quick(r, r, n, (abs_m ? abs_m : m));
bn_check_top(r);
if (abs_m)
BN_free(abs_m);
return ret;
}
/**
* public static native int[] bn2litEndInts(int, int[])
* cf. litEndInts2bn
*/
static jintArray NativeBN_bn2litEndInts(JNIEnv* env, jclass cls, BIGNUM* a, jintArray to) {
if (!oneValidHandle(env, a)) return NULL;
jintArray returnJInts = to;
bn_check_top(a);
int len = a->top;
if (len > 0) {
// FIXME: Currently ignoring array passed in to:
returnJInts = (*env)->NewIntArray(env, len);
// FIXME: is it neccessary to check for returnJBytes != NULL?
BN_ULONG* tmpInts = (BN_ULONG*)((*env)->GetPrimitiveArrayCritical(env, returnJInts, NULL));
if (tmpInts != NULL) {
int i = len; do { i--; tmpInts[i] = a->d[i]; } while (i > 0);
(*env)->ReleasePrimitiveArrayCritical(env, returnJInts, tmpInts, 0);
return returnJInts;
}
else return NULL;
}
else { // value = 0
return NULL; // Client should not call when sign = 0!
}
}
static void NativeBN_putULongInt(JNIEnv* env, jclass, jlong a0, jlong java_dw, jboolean neg) {
if (!oneValidHandle(env, a0)) return;
uint64_t dw = java_dw;
// cf. litEndInts2bn:
BIGNUM* a = toBigNum(a0);
bn_check_top(a);
if (bn_wexpand(a, 8/BN_BYTES) != NULL) {
#ifdef __LP64__
a->d[0] = dw;
#else
unsigned int hi = dw >> 32; // This shifts without sign extension.
int lo = (int)dw; // This truncates implicitly.
a->d[0] = lo;
a->d[1] = hi;
#endif
a->top = 8 / BN_BYTES;
a->neg = neg;
bn_correct_top(a);
} else {
BN_BLINDING *BN_BLINDING_new (const BIGNUM * A, const BIGNUM * Ai, BIGNUM * mod)
{
BN_BLINDING *ret = NULL;
bn_check_top (mod);
if ((ret = (BN_BLINDING *) OPENSSL_malloc (sizeof (BN_BLINDING))) == NULL)
{
BNerr (BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE);
return (NULL);
}
memset (ret, 0, sizeof (BN_BLINDING));
if (A != NULL)
{
if ((ret->A = BN_dup (A)) == NULL)
goto err;
}
if (Ai != NULL)
{
if ((ret->Ai = BN_dup (Ai)) == NULL)
goto err;
}
/* save a copy of mod in the BN_BLINDING structure */
if ((ret->mod = BN_dup (mod)) == NULL)
goto err;
if (BN_get_flags (mod, BN_FLG_CONSTTIME) != 0)
BN_set_flags (ret->mod, BN_FLG_CONSTTIME);
/* Set the counter to the special value -1
* to indicate that this is never-used fresh blinding
* that does not need updating before first use. */
ret->counter = -1;
CRYPTO_THREADID_current (&ret->tid);
return (ret);
err:
if (ret != NULL)
BN_BLINDING_free (ret);
return (NULL);
}
BIGNUM *BN_mpi2bn(const unsigned char *d, int n, BIGNUM *a)
{
long len;
int neg=0;
if (n < 4)
{
BNerr(BN_F_BN_MPI2BN,BN_R_INVALID_LENGTH);
return(NULL);
}
len=((long)d[0]<<24)|((long)d[1]<<16)|((int)d[2]<<8)|(int)d[3];
if ((len+4) != n)
{
BNerr(BN_F_BN_MPI2BN,BN_R_ENCODING_ERROR);
return(NULL);
}
if (a == NULL) a=BN_new();
if (a == NULL) return(NULL);
if (len == 0)
{
a->neg=0;
a->top=0;
return(a);
}
d+=4;
if ((*d) & 0x80)
neg=1;
if (BN_bin2bn(d,(int)len,a) == NULL)
return(NULL);
a->neg=neg;
if (neg)
{
BN_clear_bit(a,BN_num_bits(a)-1);
}
bn_check_top(a);
return(a);
}
static jintArray NativeBN_bn2litEndInts(JNIEnv* env, jclass, BIGNUM* a) {
if (!oneValidHandle(env, a)) return NULL;
bn_check_top(a);
int len = a->top;
if (len == 0) {
return NULL;
}
jintArray result = env->NewIntArray(len);
if (result == NULL) {
return NULL;
}
ScopedIntArrayRW ints(env, result);
if (ints.get() == NULL) {
return NULL;
}
BN_ULONG* ulongs = reinterpret_cast<BN_ULONG*>(ints.get());
if (ulongs == NULL) {
return NULL;
}
int i = len; do { i--; ulongs[i] = a->d[i]; } while (i > 0);
return result;
}
extern "C" long long Java_java_math_NativeBN_longInt(JNIEnv* env, jclass, jlong a0) {
if (!oneValidHandle(env, a0)) return -1;
BIGNUM* a = toBigNum(a0);
bn_check_top(a);
int intLen = a->top;
BN_ULONG* d = a->d;
switch (intLen) {
case 0:
return 0;
case 1:
if (!a->neg) {
return d[0] & 0X00000000FFFFFFFFLL;
} else {
return -(d[0] & 0X00000000FFFFFFFFLL);
}
default:
if (!a->neg) {
return ((long long)d[1] << 32) | (d[0] & 0XFFFFFFFFLL);
} else {
return -(((long long)d[1] << 32) | (d[0] & 0XFFFFFFFFLL));
}
}
}
BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w)
{
#ifndef BN_LLONG
BN_ULONG ret=0;
#else
BN_ULLONG ret=0;
#endif
int i;
bn_check_top(a);
w&=BN_MASK2;
for (i=a->top-1; i>=0; i--)
{
#ifndef BN_LLONG
ret=((ret<<BN_BITS4)|((a->d[i]>>BN_BITS4)&BN_MASK2l))%w;
ret=((ret<<BN_BITS4)|(a->d[i]&BN_MASK2l))%w;
#else
ret=(BN_ULLONG)(((ret<<(BN_ULLONG)BN_BITS2)|a->d[i])%
(BN_ULLONG)w);
#endif
}
return((BN_ULONG)ret);
}
int bn_probable_prime_dh_retry(BIGNUM *rnd, int bits, BN_CTX *ctx)
{
int i;
int ret = 0;
loop:
if (!BN_rand(rnd, bits, 0, 1))
goto err;
/* we now have a random number 'rand' to test. */
for (i = 1; i < NUMPRIMES; i++) {
/* check that rnd is a prime */
if (BN_mod_word(rnd, (BN_ULONG)primes[i]) <= 1) {
goto loop;
}
}
ret = 1;
err:
bn_check_top(rnd);
return (ret);
}
/*
* Most often limb sizes will be the same. If not, we use hex conversion
* which is neat, but extremely inefficient.
*/
static int bn2gmp(const BIGNUM *bn, mpz_t g)
{
bn_check_top(bn);
if (((sizeof(bn->d[0]) * 8) == GMP_NUMB_BITS) &&
(BN_BITS2 == GMP_NUMB_BITS)) {
/* The common case */
if (!_mpz_realloc(g, bn->top))
return 0;
memcpy(&g->_mp_d[0], &bn->d[0], bn->top * sizeof(bn->d[0]));
g->_mp_size = bn->top;
if (bn->neg)
g->_mp_size = -g->_mp_size;
return 1;
} else {
int toret;
char *tmpchar = BN_bn2hex(bn);
if (!tmpchar)
return 0;
toret = (mpz_set_str(g, tmpchar, 16) == 0 ? 1 : 0);
OPENSSL_free(tmpchar);
return toret;
}
}
static int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1,
const BIGNUM *a1_odd, int k, BN_CTX *ctx, BN_MONT_CTX *mont)
{
if (!BN_mod_exp_mont(w, w, a1_odd, a, ctx, mont)) /* w := w^a1_odd mod a */
return -1;
if (BN_is_one(w))
return 0; /* probably prime */
if (BN_cmp(w, a1) == 0)
return 0; /* w == -1 (mod a), 'a' is probably prime */
while (--k)
{
if (!BN_mod_mul(w, w, w, a, ctx)) /* w := w^2 mod a */
return -1;
if (BN_is_one(w))
return 1; /* 'a' is composite, otherwise a previous 'w' would
* have been == -1 (mod 'a') */
if (BN_cmp(w, a1) == 0)
return 0; /* w == -1 (mod a), 'a' is probably prime */
}
/* If we get here, 'w' is the (a-1)/2-th power of the original 'w',
* and it is neither -1 nor +1 -- so 'a' cannot be prime */
bn_check_top(w);
return 1;
}
/* 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);
}
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 (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
{
/* 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_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;
#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
rr->neg = a->neg ^ b->neg;
bn_correct_top(rr);
if (r != rr && BN_copy(r, rr) == NULL)
goto err;
ret = 1;
err:
bn_check_top(r);
BN_CTX_end(ctx);
return (ret);
}
