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-rw-r--r--crypto/bn/bn_mont.c293
1 files changed, 254 insertions, 39 deletions
diff --git a/crypto/bn/bn_mont.c b/crypto/bn/bn_mont.c
index 61416483cb..7224637ab3 100644
--- a/crypto/bn/bn_mont.c
+++ b/crypto/bn/bn_mont.c
@@ -55,6 +55,59 @@
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
+/* ====================================================================
+ * Copyright (c) 1998-2006 The OpenSSL Project. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in
+ * the documentation and/or other materials provided with the
+ * distribution.
+ *
+ * 3. All advertising materials mentioning features or use of this
+ * software must display the following acknowledgment:
+ * "This product includes software developed by the OpenSSL Project
+ * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ * endorse or promote products derived from this software without
+ * prior written permission. For written permission, please contact
+ * openssl-core@openssl.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ * nor may "OpenSSL" appear in their names without prior written
+ * permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ * acknowledgment:
+ * "This product includes software developed by the OpenSSL Project
+ * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ====================================================================
+ *
+ * This product includes cryptographic software written by Eric Young
+ * (eay@cryptsoft.com). This product includes software written by Tim
+ * Hudson (tjh@cryptsoft.com).
+ *
+ */
/*
* Details about Montgomery multiplication algorithms can be found at
@@ -69,11 +122,30 @@
#define MONT_WORD /* use the faster word-based algorithm */
+#ifdef MONT_WORD
+static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont);
+#endif
+
int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
BN_MONT_CTX *mont, BN_CTX *ctx)
{
BIGNUM *tmp;
int ret=0;
+#if defined(OPENSSL_BN_ASM_MONT) && defined(MONT_WORD)
+ int num = mont->N.top;
+
+ if (num>1 && a->top==num && b->top==num)
+ {
+ if (bn_wexpand(r,num) == NULL) return(0);
+ if (bn_mul_mont(r->d,a->d,b->d,mont->N.d,mont->n0,num))
+ {
+ r->neg = a->neg^b->neg;
+ r->top = num;
+ bn_correct_top(r);
+ return(1);
+ }
+ }
+#endif
BN_CTX_start(ctx);
tmp = BN_CTX_get(ctx);
@@ -89,7 +161,11 @@ int BN_mod_mul_montgomery(BIGNUM *r, const BIGNUM *a, const BIGNUM *b,
if (!BN_mul(tmp,a,b,ctx)) goto err;
}
/* reduce from aRR to aR */
+#ifdef MONT_WORD
+ if (!BN_from_montgomery_word(r,tmp,mont)) goto err;
+#else
if (!BN_from_montgomery(r,tmp,mont,ctx)) goto err;
+#endif
bn_check_top(r);
ret=1;
err:
@@ -97,35 +173,25 @@ err:
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 *n,*r;
+static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont)
+ {
+ BIGNUM *n;
BN_ULONG *ap,*np,*rp,n0,v,*nrp;
int al,nl,max,i,x,ri;
- BN_CTX_start(ctx);
- if ((r = BN_CTX_get(ctx)) == NULL) goto err;
-
- if (!BN_copy(r,a)) goto err;
n= &(mont->N);
-
- ap=a->d;
/* mont->ri is the size of mont->N in bits (rounded up
to the word size) */
al=ri=mont->ri/BN_BITS2;
-
+
nl=n->top;
- if ((al == 0) || (nl == 0)) { r->top=0; return(1); }
+ if ((al == 0) || (nl == 0)) { ret->top=0; return(1); }
max=(nl+al+1); /* allow for overflow (no?) XXX */
- if (bn_wexpand(r,max) == NULL) goto err;
- if (bn_wexpand(ret,max) == NULL) goto err;
+ if (bn_wexpand(r,max) == NULL) return(0);
- r->neg=a->neg^n->neg;
+ r->neg^=n->neg;
np=n->d;
rp=r->d;
nrp= &(r->d[nl]);
@@ -139,10 +205,10 @@ int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
#endif
r->top=max;
- n0=mont->n0;
+ n0=mont->n0[0];
#ifdef BN_COUNT
- fprintf(stderr,"word BN_from_montgomery %d * %d\n",nl,nl);
+ fprintf(stderr,"word BN_from_montgomery_word %d * %d\n",nl,nl);
#endif
for (i=0; i<nl; i++)
{
@@ -174,20 +240,72 @@ int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
}
}
bn_correct_top(r);
-
- /* mont->ri will be a multiple of the word size */
-#if 0
- BN_rshift(ret,r,mont->ri);
-#else
- ret->neg = r->neg;
- x=ri;
+
+ /* mont->ri will be a multiple of the word size and below code
+ * is kind of BN_rshift(ret,r,mont->ri) equivalent */
+ if (r->top <= ri)
+ {
+ ret->top=0;
+ return(1);
+ }
+ al=r->top-ri;
+
+#define BRANCH_FREE 1
+#if BRANCH_FREE
+ if (bn_wexpand(ret,ri) == NULL) return(0);
+ x=0-(((al-ri)>>(sizeof(al)*8-1))&1);
+ ret->top=x=(ri&~x)|(al&x); /* min(ri,al) */
+ ret->neg=r->neg;
+
rp=ret->d;
- ap= &(r->d[x]);
- if (r->top < x)
- al=0;
- else
- al=r->top-x;
+ ap=&(r->d[ri]);
+
+ {
+ size_t m1,m2;
+
+ v=bn_sub_words(rp,ap,np,ri);
+ /* this ----------------^^ works even in al<ri case
+ * thanks to zealous zeroing of top of the vector in the
+ * beginning. */
+
+ /* if (al==ri && !v) || al>ri) nrp=rp; else nrp=ap; */
+ /* in other words if subtraction result is real, then
+ * trick unconditional memcpy below to perform in-place
+ * "refresh" instead of actual copy. */
+ m1=0-(size_t)(((al-ri)>>(sizeof(al)*8-1))&1); /* al<ri */
+ m2=0-(size_t)(((ri-al)>>(sizeof(al)*8-1))&1); /* al>ri */
+ m1|=m2; /* (al!=ri) */
+ m1|=(0-(size_t)v); /* (al!=ri || v) */
+ m1&=~m2; /* (al!=ri || v) && !al>ri */
+ nrp=(BN_ULONG *)(((size_t)rp&~m1)|((size_t)ap&m1));
+ }
+
+ /* 'i<ri' is chosen to eliminate dependency on input data, even
+ * though it results in redundant copy in al<ri case. */
+ for (i=0,ri-=4; i<ri; i+=4)
+ {
+ BN_ULONG t1,t2,t3,t4;
+
+ t1=nrp[i+0];
+ t2=nrp[i+1];
+ t3=nrp[i+2]; ap[i+0]=0;
+ t4=nrp[i+3]; ap[i+1]=0;
+ rp[i+0]=t1; ap[i+2]=0;
+ rp[i+1]=t2; ap[i+3]=0;
+ rp[i+2]=t3;
+ rp[i+3]=t4;
+ }
+ for (ri+=4; i<ri; i++)
+ rp[i]=nrp[i], ap[i]=0;
+ bn_correct_top(r);
+ bn_correct_top(ret);
+#else
+ if (bn_wexpand(ret,al) == NULL) return(0);
ret->top=al;
+ ret->neg=r->neg;
+
+ rp=ret->d;
+ ap=&(r->d[ri]);
al-=4;
for (i=0; i<al; i+=4)
{
@@ -205,8 +323,30 @@ int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
al+=4;
for (; i<al; i++)
rp[i]=ap[i];
+
+ if (BN_ucmp(ret, &(mont->N)) >= 0)
+ {
+ if (!BN_usub(ret,ret,&(mont->N))) return(0);
+ }
#endif
-#else /* !MONT_WORD */
+ bn_check_top(ret);
+
+ return(1);
+ }
+#endif /* MONT_WORD */
+
+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);
@@ -223,7 +363,6 @@ int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
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;
-#endif /* MONT_WORD */
if (BN_ucmp(ret, &(mont->N)) >= 0)
{
@@ -233,6 +372,7 @@ int BN_from_montgomery(BIGNUM *ret, const BIGNUM *a, BN_MONT_CTX *mont,
bn_check_top(ret);
err:
BN_CTX_end(ctx);
+#endif /* MONT_WORD */
return(retn);
}
@@ -254,6 +394,7 @@ void BN_MONT_CTX_init(BN_MONT_CTX *ctx)
BN_init(&(ctx->RR));
BN_init(&(ctx->N));
BN_init(&(ctx->Ni));
+ ctx->n0[0] = ctx->n0[1] = 0;
ctx->flags=0;
}
@@ -285,16 +426,55 @@ int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
BIGNUM tmod;
BN_ULONG buf[2];
+ 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.d=buf;
- tmod.top=1;
- tmod.dmax=2;
- tmod.neg=0;
+ tmod.top = buf[0] != 0 ? 1 : 0;
/* Ri = R^-1 mod N*/
if ((BN_mod_inverse(Ri,R,&tmod,ctx)) == NULL)
goto err;
@@ -310,7 +490,9 @@ int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
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;
+ mont->n0[0] = (Ri->top > 0) ? Ri->d[0] : 0;
+ mont->n0[1] = 0;
+#endif
}
#else /* !MONT_WORD */
{ /* bignum version */
@@ -346,7 +528,40 @@ BN_MONT_CTX *BN_MONT_CTX_copy(BN_MONT_CTX *to, BN_MONT_CTX *from)
if (!BN_copy(&(to->N),&(from->N))) return NULL;
if (!BN_copy(&(to->Ni),&(from->Ni))) return NULL;
to->ri=from->ri;
- to->n0=from->n0;
+ to->n0[0]=from->n0[0];
+ to->n0[1]=from->n0[1];
return(to);
}
+BN_MONT_CTX *BN_MONT_CTX_set_locked(BN_MONT_CTX **pmont, int lock,
+ const BIGNUM *mod, BN_CTX *ctx)
+ {
+ int got_write_lock = 0;
+ BN_MONT_CTX *ret;
+
+ CRYPTO_r_lock(lock);
+ if (!*pmont)
+ {
+ CRYPTO_r_unlock(lock);
+ CRYPTO_w_lock(lock);
+ got_write_lock = 1;
+
+ if (!*pmont)
+ {
+ ret = BN_MONT_CTX_new();
+ if (ret && !BN_MONT_CTX_set(ret, mod, ctx))
+ BN_MONT_CTX_free(ret);
+ else
+ *pmont = ret;
+ }
+ }
+
+ ret = *pmont;
+
+ if (got_write_lock)
+ CRYPTO_w_unlock(lock);
+ else
+ CRYPTO_r_unlock(lock);
+
+ return ret;
+ }
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