- const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *in_mont)
- {
- int i,bits,ret=0,idx,window,wvalue;
- int top;
- BIGNUM *r;
- const BIGNUM *aa;
- BN_MONT_CTX *mont=NULL;
-
- int numPowers;
- unsigned char *powerbufFree=NULL;
- int powerbufLen = 0;
- unsigned char *powerbuf=NULL;
- BIGNUM *computeTemp=NULL, *am=NULL;
-
- bn_check_top(a);
- bn_check_top(p);
- bn_check_top(m);
-
- top = m->top;
-
- if (!(m->d[0] & 1))
- {
- BNerr(BN_F_BN_MOD_EXP_MONT_CONSTTIME,BN_R_CALLED_WITH_EVEN_MODULUS);
- return(0);
- }
- bits=BN_num_bits(p);
- if (bits == 0)
- {
- ret = BN_one(rr);
- return ret;
- }
-
- /* Initialize BIGNUM context and allocate intermediate result */
- BN_CTX_start(ctx);
- r = BN_CTX_get(ctx);
- if (r == NULL) goto err;
-
- /* Allocate a montgomery context if it was not supplied by the caller.
- * If this is not done, things will break in the montgomery part.
- */
- if (in_mont != NULL)
- mont=in_mont;
- else
- {
- if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
- if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
- }
-
- /* Get the window size to use with size of p. */
- window = BN_window_bits_for_ctime_exponent_size(bits);
-
- /* Allocate a buffer large enough to hold all of the pre-computed
- * powers of a.
- */
- numPowers = 1 << window;
- powerbufLen = sizeof(m->d[0])*top*numPowers;
- if ((powerbufFree=(unsigned char*)OPENSSL_malloc(powerbufLen+MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH)) == NULL)
- goto err;
-
- powerbuf = MOD_EXP_CTIME_ALIGN(powerbufFree);
- memset(powerbuf, 0, powerbufLen);
-
- /* Initialize the intermediate result. Do this early to save double conversion,
- * once each for a^0 and intermediate result.
- */
- if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
- if (!MOD_EXP_CTIME_COPY_TO_PREBUF(r, top, powerbuf, 0, numPowers)) goto err;
-
- /* Initialize computeTemp as a^1 with montgomery precalcs */
- computeTemp = BN_CTX_get(ctx);
- am = BN_CTX_get(ctx);
- if (computeTemp==NULL || am==NULL) goto err;
-
- if (a->neg || BN_ucmp(a,m) >= 0)
- {
- if (!BN_mod(am,a,m,ctx))
- goto err;
- aa= am;
- }
- else
- aa=a;
- if (!BN_to_montgomery(am,aa,mont,ctx)) goto err;
- if (!BN_copy(computeTemp, am)) goto err;
- if (!MOD_EXP_CTIME_COPY_TO_PREBUF(am, top, powerbuf, 1, numPowers)) goto err;
-
- /* If the window size is greater than 1, then calculate
- * val[i=2..2^winsize-1]. Powers are computed as a*a^(i-1)
- * (even powers could instead be computed as (a^(i/2))^2
- * to use the slight performance advantage of sqr over mul).
- */
- if (window > 1)
- {
- for (i=2; i<numPowers; i++)
- {
- /* Calculate a^i = a^(i-1) * a */
- if (!BN_mod_mul_montgomery(computeTemp,am,computeTemp,mont,ctx))
- goto err;
- if (!MOD_EXP_CTIME_COPY_TO_PREBUF(computeTemp, top, powerbuf, i, numPowers)) goto err;
- }
- }
-
- /* Adjust the number of bits up to a multiple of the window size.
- * If the exponent length is not a multiple of the window size, then
- * this pads the most significant bits with zeros to normalize the
- * scanning loop to there's no special cases.
- *
- * * NOTE: Making the window size a power of two less than the native
- * * word size ensures that the padded bits won't go past the last
- * * word in the internal BIGNUM structure. Going past the end will
- * * still produce the correct result, but causes a different branch
- * * to be taken in the BN_is_bit_set function.
- */
- bits = ((bits+window-1)/window)*window;
- idx=bits-1; /* The top bit of the window */
-
- /* Scan the exponent one window at a time starting from the most
- * significant bits.
- */
- while (idx >= 0)
- {
- wvalue=0; /* The 'value' of the window */
-
- /* Scan the window, squaring the result as we go */
- for (i=0; i<window; i++,idx--)
- {
- if (!BN_mod_mul_montgomery(r,r,r,mont,ctx)) goto err;
- wvalue = (wvalue<<1)+BN_is_bit_set(p,idx);
- }
-
- /* Fetch the appropriate pre-computed value from the pre-buf */
- if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(computeTemp, top, powerbuf, wvalue, numPowers)) goto err;
-
- /* Multiply the result into the intermediate result */
- if (!BN_mod_mul_montgomery(r,r,computeTemp,mont,ctx)) goto err;
- }
-
- /* Convert the final result from montgomery to standard format */
- if (!BN_from_montgomery(rr,r,mont,ctx)) goto err;
- ret=1;
-err:
- if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
- if (powerbuf!=NULL)
- {
- OPENSSL_cleanse(powerbuf,powerbufLen);
- OPENSSL_free(powerbufFree);
- }
- if (am!=NULL) BN_clear(am);
- if (computeTemp!=NULL) BN_clear(computeTemp);
- BN_CTX_end(ctx);
- return(ret);
- }
+ const BIGNUM *m, BN_CTX *ctx,
+ BN_MONT_CTX *in_mont)
+{
+ int i, bits, ret = 0, window, wvalue;
+ int top;
+ BN_MONT_CTX *mont = NULL;
+
+ int numPowers;
+ unsigned char *powerbufFree = NULL;
+ int powerbufLen = 0;
+ unsigned char *powerbuf = NULL;
+ BIGNUM tmp, am;
+#if defined(SPARC_T4_MONT)
+ unsigned int t4 = 0;
+#endif
+
+ bn_check_top(a);
+ bn_check_top(p);
+ bn_check_top(m);
+
+ if (!BN_is_odd(m)) {
+ BNerr(BN_F_BN_MOD_EXP_MONT_CONSTTIME, BN_R_CALLED_WITH_EVEN_MODULUS);
+ return (0);
+ }
+
+ top = m->top;
+
+ bits = BN_num_bits(p);
+ if (bits == 0) {
+ /* x**0 mod 1 is still zero. */
+ if (BN_is_one(m)) {
+ ret = 1;
+ BN_zero(rr);
+ } else {
+ ret = BN_one(rr);
+ }
+ return ret;
+ }
+
+ BN_CTX_start(ctx);
+
+ /*
+ * Allocate a montgomery context if it was not supplied by the caller. If
+ * this is not done, things will break in the montgomery part.
+ */
+ if (in_mont != NULL)
+ mont = in_mont;
+ else {
+ if ((mont = BN_MONT_CTX_new()) == NULL)
+ goto err;
+ if (!BN_MONT_CTX_set(mont, m, ctx))
+ goto err;
+ }
+
+#ifdef RSAZ_ENABLED
+ /*
+ * If the size of the operands allow it, perform the optimized
+ * RSAZ exponentiation. For further information see
+ * crypto/bn/rsaz_exp.c and accompanying assembly modules.
+ */
+ if ((16 == a->top) && (16 == p->top) && (BN_num_bits(m) == 1024)
+ && rsaz_avx2_eligible()) {
+ if (NULL == bn_wexpand(rr, 16))
+ goto err;
+ RSAZ_1024_mod_exp_avx2(rr->d, a->d, p->d, m->d, mont->RR.d,
+ mont->n0[0]);
+ rr->top = 16;
+ rr->neg = 0;
+ bn_correct_top(rr);
+ ret = 1;
+ goto err;
+ } else if ((8 == a->top) && (8 == p->top) && (BN_num_bits(m) == 512)) {
+ if (NULL == bn_wexpand(rr, 8))
+ goto err;
+ RSAZ_512_mod_exp(rr->d, a->d, p->d, m->d, mont->n0[0], mont->RR.d);
+ rr->top = 8;
+ rr->neg = 0;
+ bn_correct_top(rr);
+ ret = 1;
+ goto err;
+ }
+#endif
+
+ /* Get the window size to use with size of p. */
+ window = BN_window_bits_for_ctime_exponent_size(bits);
+#if defined(SPARC_T4_MONT)
+ if (window >= 5 && (top & 15) == 0 && top <= 64 &&
+ (OPENSSL_sparcv9cap_P[1] & (CFR_MONTMUL | CFR_MONTSQR)) ==
+ (CFR_MONTMUL | CFR_MONTSQR) && (t4 = OPENSSL_sparcv9cap_P[0]))
+ window = 5;
+ else
+#endif
+#if defined(OPENSSL_BN_ASM_MONT5)
+ if (window >= 5) {
+ window = 5; /* ~5% improvement for RSA2048 sign, and even
+ * for RSA4096 */
+ /* reserve space for mont->N.d[] copy */
+ powerbufLen += top * sizeof(mont->N.d[0]);
+ }
+#endif
+ (void)0;
+
+ /*
+ * Allocate a buffer large enough to hold all of the pre-computed powers
+ * of am, am itself and tmp.
+ */
+ numPowers = 1 << window;
+ powerbufLen += sizeof(m->d[0]) * (top * numPowers +
+ ((2 * top) >
+ numPowers ? (2 * top) : numPowers));
+#ifdef alloca
+ if (powerbufLen < 3072)
+ powerbufFree =
+ alloca(powerbufLen + MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH);
+ else
+#endif
+ if ((powerbufFree =
+ OPENSSL_malloc(powerbufLen + MOD_EXP_CTIME_MIN_CACHE_LINE_WIDTH))
+ == NULL)
+ goto err;
+
+ powerbuf = MOD_EXP_CTIME_ALIGN(powerbufFree);
+ memset(powerbuf, 0, powerbufLen);
+
+#ifdef alloca
+ if (powerbufLen < 3072)
+ powerbufFree = NULL;
+#endif
+
+ /* lay down tmp and am right after powers table */
+ tmp.d = (BN_ULONG *)(powerbuf + sizeof(m->d[0]) * top * numPowers);
+ am.d = tmp.d + top;
+ tmp.top = am.top = 0;
+ tmp.dmax = am.dmax = top;
+ tmp.neg = am.neg = 0;
+ tmp.flags = am.flags = BN_FLG_STATIC_DATA;
+
+ /* prepare a^0 in Montgomery domain */
+#if 1 /* by Shay Gueron's suggestion */
+ if (m->d[top - 1] & (((BN_ULONG)1) << (BN_BITS2 - 1))) {
+ /* 2^(top*BN_BITS2) - m */
+ tmp.d[0] = (0 - m->d[0]) & BN_MASK2;
+ for (i = 1; i < top; i++)
+ tmp.d[i] = (~m->d[i]) & BN_MASK2;
+ tmp.top = top;
+ } else
+#endif
+ if (!BN_to_montgomery(&tmp, BN_value_one(), mont, ctx))
+ goto err;
+
+ /* prepare a^1 in Montgomery domain */
+ if (a->neg || BN_ucmp(a, m) >= 0) {
+ if (!BN_mod(&am, a, m, ctx))
+ goto err;
+ if (!BN_to_montgomery(&am, &am, mont, ctx))
+ goto err;
+ } else if (!BN_to_montgomery(&am, a, mont, ctx))
+ goto err;
+
+#if defined(SPARC_T4_MONT)
+ if (t4) {
+ typedef int (*bn_pwr5_mont_f) (BN_ULONG *tp, const BN_ULONG *np,
+ const BN_ULONG *n0, const void *table,
+ int power, int bits);
+ int bn_pwr5_mont_t4_8(BN_ULONG *tp, const BN_ULONG *np,
+ const BN_ULONG *n0, const void *table,
+ int power, int bits);
+ int bn_pwr5_mont_t4_16(BN_ULONG *tp, const BN_ULONG *np,
+ const BN_ULONG *n0, const void *table,
+ int power, int bits);
+ int bn_pwr5_mont_t4_24(BN_ULONG *tp, const BN_ULONG *np,
+ const BN_ULONG *n0, const void *table,
+ int power, int bits);
+ int bn_pwr5_mont_t4_32(BN_ULONG *tp, const BN_ULONG *np,
+ const BN_ULONG *n0, const void *table,
+ int power, int bits);
+ static const bn_pwr5_mont_f pwr5_funcs[4] = {
+ bn_pwr5_mont_t4_8, bn_pwr5_mont_t4_16,
+ bn_pwr5_mont_t4_24, bn_pwr5_mont_t4_32
+ };
+ bn_pwr5_mont_f pwr5_worker = pwr5_funcs[top / 16 - 1];
+
+ typedef int (*bn_mul_mont_f) (BN_ULONG *rp, const BN_ULONG *ap,
+ const void *bp, const BN_ULONG *np,
+ const BN_ULONG *n0);
+ int bn_mul_mont_t4_8(BN_ULONG *rp, const BN_ULONG *ap, const void *bp,
+ const BN_ULONG *np, const BN_ULONG *n0);
+ int bn_mul_mont_t4_16(BN_ULONG *rp, const BN_ULONG *ap,
+ const void *bp, const BN_ULONG *np,
+ const BN_ULONG *n0);
+ int bn_mul_mont_t4_24(BN_ULONG *rp, const BN_ULONG *ap,
+ const void *bp, const BN_ULONG *np,
+ const BN_ULONG *n0);
+ int bn_mul_mont_t4_32(BN_ULONG *rp, const BN_ULONG *ap,
+ const void *bp, const BN_ULONG *np,
+ const BN_ULONG *n0);
+ static const bn_mul_mont_f mul_funcs[4] = {
+ bn_mul_mont_t4_8, bn_mul_mont_t4_16,
+ bn_mul_mont_t4_24, bn_mul_mont_t4_32
+ };
+ bn_mul_mont_f mul_worker = mul_funcs[top / 16 - 1];
+
+ void bn_mul_mont_vis3(BN_ULONG *rp, const BN_ULONG *ap,
+ const void *bp, const BN_ULONG *np,
+ const BN_ULONG *n0, int num);
+ void bn_mul_mont_t4(BN_ULONG *rp, const BN_ULONG *ap,
+ const void *bp, const BN_ULONG *np,
+ const BN_ULONG *n0, int num);
+ void bn_mul_mont_gather5_t4(BN_ULONG *rp, const BN_ULONG *ap,
+ const void *table, const BN_ULONG *np,
+ const BN_ULONG *n0, int num, int power);
+ void bn_flip_n_scatter5_t4(const BN_ULONG *inp, size_t num,
+ void *table, size_t power);
+ void bn_gather5_t4(BN_ULONG *out, size_t num,
+ void *table, size_t power);
+ void bn_flip_t4(BN_ULONG *dst, BN_ULONG *src, size_t num);
+
+ BN_ULONG *np = mont->N.d, *n0 = mont->n0;
+ int stride = 5 * (6 - (top / 16 - 1)); /* multiple of 5, but less
+ * than 32 */
+
+ /*
+ * BN_to_montgomery can contaminate words above .top [in
+ * BN_DEBUG[_DEBUG] build]...
+ */
+ for (i = am.top; i < top; i++)
+ am.d[i] = 0;
+ for (i = tmp.top; i < top; i++)
+ tmp.d[i] = 0;
+
+ bn_flip_n_scatter5_t4(tmp.d, top, powerbuf, 0);
+ bn_flip_n_scatter5_t4(am.d, top, powerbuf, 1);
+ if (!(*mul_worker) (tmp.d, am.d, am.d, np, n0) &&
+ !(*mul_worker) (tmp.d, am.d, am.d, np, n0))
+ bn_mul_mont_vis3(tmp.d, am.d, am.d, np, n0, top);
+ bn_flip_n_scatter5_t4(tmp.d, top, powerbuf, 2);
+
+ for (i = 3; i < 32; i++) {
+ /* Calculate a^i = a^(i-1) * a */
+ if (!(*mul_worker) (tmp.d, tmp.d, am.d, np, n0) &&
+ !(*mul_worker) (tmp.d, tmp.d, am.d, np, n0))
+ bn_mul_mont_vis3(tmp.d, tmp.d, am.d, np, n0, top);
+ bn_flip_n_scatter5_t4(tmp.d, top, powerbuf, i);
+ }
+
+ /* switch to 64-bit domain */
+ np = alloca(top * sizeof(BN_ULONG));
+ top /= 2;
+ bn_flip_t4(np, mont->N.d, top);
+
+ bits--;
+ for (wvalue = 0, i = bits % 5; i >= 0; i--, bits--)
+ wvalue = (wvalue << 1) + BN_is_bit_set(p, bits);
+ bn_gather5_t4(tmp.d, top, powerbuf, wvalue);
+
+ /*
+ * Scan the exponent one window at a time starting from the most
+ * significant bits.
+ */
+ while (bits >= 0) {
+ if (bits < stride)
+ stride = bits + 1;
+ bits -= stride;
+ wvalue = bn_get_bits(p, bits + 1);
+
+ if ((*pwr5_worker) (tmp.d, np, n0, powerbuf, wvalue, stride))
+ continue;
+ /* retry once and fall back */
+ if ((*pwr5_worker) (tmp.d, np, n0, powerbuf, wvalue, stride))
+ continue;
+
+ bits += stride - 5;
+ wvalue >>= stride - 5;
+ wvalue &= 31;
+ bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_mul_mont_t4(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_mul_mont_gather5_t4(tmp.d, tmp.d, powerbuf, np, n0, top,
+ wvalue);
+ }
+
+ bn_flip_t4(tmp.d, tmp.d, top);
+ top *= 2;
+ /* back to 32-bit domain */
+ tmp.top = top;
+ bn_correct_top(&tmp);
+ OPENSSL_cleanse(np, top * sizeof(BN_ULONG));
+ } else
+#endif
+#if defined(OPENSSL_BN_ASM_MONT5)
+ if (window == 5 && top > 1) {
+ /*
+ * This optimization uses ideas from http://eprint.iacr.org/2011/239,
+ * specifically optimization of cache-timing attack countermeasures
+ * and pre-computation optimization.
+ */
+
+ /*
+ * Dedicated window==4 case improves 512-bit RSA sign by ~15%, but as
+ * 512-bit RSA is hardly relevant, we omit it to spare size...
+ */
+ void bn_mul_mont_gather5(BN_ULONG *rp, const BN_ULONG *ap,
+ const void *table, const BN_ULONG *np,
+ const BN_ULONG *n0, int num, int power);
+ void bn_scatter5(const BN_ULONG *inp, size_t num,
+ void *table, size_t power);
+ void bn_gather5(BN_ULONG *out, size_t num, void *table, size_t power);
+ void bn_power5(BN_ULONG *rp, const BN_ULONG *ap,
+ const void *table, const BN_ULONG *np,
+ const BN_ULONG *n0, int num, int power);
+ int bn_get_bits5(const BN_ULONG *ap, int off);
+ int bn_from_montgomery(BN_ULONG *rp, const BN_ULONG *ap,
+ const BN_ULONG *not_used, const BN_ULONG *np,
+ const BN_ULONG *n0, int num);
+
+ BN_ULONG *n0 = mont->n0, *np;
+
+ /*
+ * BN_to_montgomery can contaminate words above .top [in
+ * BN_DEBUG[_DEBUG] build]...
+ */
+ for (i = am.top; i < top; i++)
+ am.d[i] = 0;
+ for (i = tmp.top; i < top; i++)
+ tmp.d[i] = 0;
+
+ /*
+ * copy mont->N.d[] to improve cache locality
+ */
+ for (np = am.d + top, i = 0; i < top; i++)
+ np[i] = mont->N.d[i];
+
+ bn_scatter5(tmp.d, top, powerbuf, 0);
+ bn_scatter5(am.d, am.top, powerbuf, 1);
+ bn_mul_mont(tmp.d, am.d, am.d, np, n0, top);
+ bn_scatter5(tmp.d, top, powerbuf, 2);
+
+# if 0
+ for (i = 3; i < 32; i++) {
+ /* Calculate a^i = a^(i-1) * a */
+ bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
+ bn_scatter5(tmp.d, top, powerbuf, i);
+ }
+# else
+ /* same as above, but uses squaring for 1/2 of operations */
+ for (i = 4; i < 32; i *= 2) {
+ bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_scatter5(tmp.d, top, powerbuf, i);
+ }
+ for (i = 3; i < 8; i += 2) {
+ int j;
+ bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
+ bn_scatter5(tmp.d, top, powerbuf, i);
+ for (j = 2 * i; j < 32; j *= 2) {
+ bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_scatter5(tmp.d, top, powerbuf, j);
+ }
+ }
+ for (; i < 16; i += 2) {
+ bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
+ bn_scatter5(tmp.d, top, powerbuf, i);
+ bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_scatter5(tmp.d, top, powerbuf, 2 * i);
+ }
+ for (; i < 32; i += 2) {
+ bn_mul_mont_gather5(tmp.d, am.d, powerbuf, np, n0, top, i - 1);
+ bn_scatter5(tmp.d, top, powerbuf, i);
+ }
+# endif
+ bits--;
+ for (wvalue = 0, i = bits % 5; i >= 0; i--, bits--)
+ wvalue = (wvalue << 1) + BN_is_bit_set(p, bits);
+ bn_gather5(tmp.d, top, powerbuf, wvalue);
+
+ /*
+ * Scan the exponent one window at a time starting from the most
+ * significant bits.
+ */
+ if (top & 7)
+ while (bits >= 0) {
+ for (wvalue = 0, i = 0; i < 5; i++, bits--)
+ wvalue = (wvalue << 1) + BN_is_bit_set(p, bits);
+
+ bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_mul_mont(tmp.d, tmp.d, tmp.d, np, n0, top);
+ bn_mul_mont_gather5(tmp.d, tmp.d, powerbuf, np, n0, top,
+ wvalue);
+ } else {
+ while (bits >= 0) {
+ wvalue = bn_get_bits5(p->d, bits - 4);
+ bits -= 5;
+ bn_power5(tmp.d, tmp.d, powerbuf, np, n0, top, wvalue);
+ }
+ }
+
+ ret = bn_from_montgomery(tmp.d, tmp.d, NULL, np, n0, top);
+ tmp.top = top;
+ bn_correct_top(&tmp);
+ if (ret) {
+ if (!BN_copy(rr, &tmp))
+ ret = 0;
+ goto err; /* non-zero ret means it's not error */
+ }
+ } else
+#endif
+ {
+ if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 0, window))
+ goto err;
+ if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&am, top, powerbuf, 1, window))
+ goto err;
+
+ /*
+ * If the window size is greater than 1, then calculate
+ * val[i=2..2^winsize-1]. Powers are computed as a*a^(i-1) (even
+ * powers could instead be computed as (a^(i/2))^2 to use the slight
+ * performance advantage of sqr over mul).
+ */
+ if (window > 1) {
+ if (!BN_mod_mul_montgomery(&tmp, &am, &am, mont, ctx))
+ goto err;
+ if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, 2,
+ window))
+ goto err;
+ for (i = 3; i < numPowers; i++) {
+ /* Calculate a^i = a^(i-1) * a */
+ if (!BN_mod_mul_montgomery(&tmp, &am, &tmp, mont, ctx))
+ goto err;
+ if (!MOD_EXP_CTIME_COPY_TO_PREBUF(&tmp, top, powerbuf, i,
+ window))
+ goto err;
+ }
+ }
+
+ bits--;
+ for (wvalue = 0, i = bits % window; i >= 0; i--, bits--)
+ wvalue = (wvalue << 1) + BN_is_bit_set(p, bits);
+ if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&tmp, top, powerbuf, wvalue,
+ window))
+ goto err;
+
+ /*
+ * Scan the exponent one window at a time starting from the most
+ * significant bits.
+ */
+ while (bits >= 0) {
+ wvalue = 0; /* The 'value' of the window */
+
+ /* Scan the window, squaring the result as we go */
+ for (i = 0; i < window; i++, bits--) {
+ if (!BN_mod_mul_montgomery(&tmp, &tmp, &tmp, mont, ctx))
+ goto err;
+ wvalue = (wvalue << 1) + BN_is_bit_set(p, bits);
+ }
+
+ /*
+ * Fetch the appropriate pre-computed value from the pre-buf
+ */
+ if (!MOD_EXP_CTIME_COPY_FROM_PREBUF(&am, top, powerbuf, wvalue,
+ window))
+ goto err;
+
+ /* Multiply the result into the intermediate result */
+ if (!BN_mod_mul_montgomery(&tmp, &tmp, &am, mont, ctx))
+ goto err;
+ }
+ }
+
+ /* Convert the final result from montgomery to standard format */
+#if defined(SPARC_T4_MONT)
+ if (OPENSSL_sparcv9cap_P[0] & (SPARCV9_VIS3 | SPARCV9_PREFER_FPU)) {
+ am.d[0] = 1; /* borrow am */
+ for (i = 1; i < top; i++)
+ am.d[i] = 0;
+ if (!BN_mod_mul_montgomery(rr, &tmp, &am, mont, ctx))
+ goto err;
+ } else
+#endif
+ if (!BN_from_montgomery(rr, &tmp, mont, ctx))
+ goto err;
+ ret = 1;
+ err:
+ if (in_mont == NULL)
+ BN_MONT_CTX_free(mont);
+ if (powerbuf != NULL) {
+ OPENSSL_cleanse(powerbuf, powerbufLen);
+ OPENSSL_free(powerbufFree);
+ }
+ BN_CTX_end(ctx);
+ return (ret);
+}