another thread-safety fix
[openssl.git] / crypto / bn / bn_mont.c
index 3a087fdce9ee8a5ffd16758146adf9ebedbc54b9..a4612d6639e1a1d2e51a3f368548c2e2370b4aec 100644 (file)
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  * [including the GNU Public Licence.]
  */
+/* ====================================================================
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+ *
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+ *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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+ * ====================================================================
+ *
+ * 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
@@ -152,7 +205,7 @@ static int BN_from_montgomery_word(BIGNUM *ret, BIGNUM *r, BN_MONT_CTX *mont)
 #endif
 
        r->top=max;
-       n0=mont->n0;
+       n0=mont->n0[0];
 
 #ifdef BN_COUNT
        fprintf(stderr,"word BN_from_montgomery_word %d * %d\n",nl,nl);
@@ -323,16 +376,49 @@ int BN_MONT_CTX_set(BN_MONT_CTX *mont, const BIGNUM *mod, BN_CTX *ctx)
                BIGNUM tmod;
                BN_ULONG buf[2];
 
+               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)
+               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 = 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;
@@ -348,7 +434,9 @@ 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 */
@@ -384,25 +472,40 @@ 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)
        {
-       if (*pmont)
-               return *pmont;
-       CRYPTO_w_lock(lock);
+       int got_write_lock = 0;
+       BN_MONT_CTX *ret;
+
+       CRYPTO_r_lock(lock);
        if (!*pmont)
                {
-               *pmont = BN_MONT_CTX_new();
-               if (*pmont && !BN_MONT_CTX_set(*pmont, mod, ctx))
+               CRYPTO_r_unlock(lock);
+               CRYPTO_w_lock(lock);
+               got_write_lock = 1;
+
+               if (!*pmont)
                        {
-                       BN_MONT_CTX_free(*pmont);
-                       *pmont = NULL;
+                       ret = BN_MONT_CTX_new();
+                       if (ret && !BN_MONT_CTX_set(ret, mod, ctx))
+                               BN_MONT_CTX_free(ret);
+                       else
+                               *pmont = ret;
                        }
                }
-       CRYPTO_w_unlock(lock);
-       return *pmont;
+       
+       ret = *pmont;
+       
+       if (got_write_lock)
+               CRYPTO_w_unlock(lock);
+       else
+               CRYPTO_r_unlock(lock);
+               
+       return ret;
        }