1 files changed, 174 insertions, 32 deletions

diff --git a/src/lib/libcrypto/bn/bn_add.c b/src/lib/libcrypto/bn/bn_add.c
index efb2e312e8..6cba07e9f6 100644
--- a/src/lib/libcrypto/bn/bn_add.c
+++ b/src/lib/libcrypto/bn/bn_add.c
@@ -61,76 +61,70 @@
 #include "bn_lcl.h"
 
 /* r can == a or b */
-int BN_add(r, a, b)
-BIGNUM *r;
-BIGNUM *a;
-BIGNUM *b;
+int BN_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
         {
-        int i;
-        BIGNUM *tmp;
+        const BIGNUM *tmp;
+        int a_neg = a->neg;
+
+        bn_check_top(a);
+        bn_check_top(b);
 
         /*  a +  b      a+b
          *  a + -b      a-b
          * -a +  b      b-a
          * -a + -b      -(a+b)
          */
-        if (a->neg ^ b->neg)
+        if (a_neg ^ b->neg)
                 {
                 /* only one is negative */
-                if (a->neg)
+                if (a_neg)
                         { tmp=a; a=b; b=tmp; }
 
                 /* we are now a - b */
 
                 if (BN_ucmp(a,b) < 0)
                         {
-                        if (bn_wexpand(r,b->top) == NULL) return(0);
-                        bn_qsub(r,b,a);
+                        if (!BN_usub(r,b,a)) return(0);
                         r->neg=1;
                         }
                 else
                         {
-                        if (bn_wexpand(r,a->top) == NULL) return(0);
-                        bn_qsub(r,a,b);
+                        if (!BN_usub(r,a,b)) return(0);
                         r->neg=0;
                         }
                 return(1);
                 }
 
-        if (a->neg) /* both are neg */
+        if (!BN_uadd(r,a,b)) return(0);
+        if (a_neg) /* both are neg */
                 r->neg=1;
         else
                 r->neg=0;
-
-        i=(a->top > b->top);
-
-        if (i)
-                {
-                if (bn_wexpand(r,a->top+1) == NULL) return(0);
-                bn_qadd(r,a,b);
-                }
-        else
-                {
-                if (bn_wexpand(r,b->top+1) == NULL) return(0);
-                bn_qadd(r,b,a);
-                }
         return(1);
         }
 
 /* unsigned add of b to a, r must be large enough */
-void bn_qadd(r,a,b)
-BIGNUM *r;
-BIGNUM *a;
-BIGNUM *b;
+int BN_uadd(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
         {
         register int i;
         int max,min;
         BN_ULONG *ap,*bp,*rp,carry,t1;
+        const BIGNUM *tmp;
+
+        bn_check_top(a);
+        bn_check_top(b);
 
+        if (a->top < b->top)
+                { tmp=a; a=b; b=tmp; }
         max=a->top;
         min=b->top;
+
+        if (bn_wexpand(r,max+1) == NULL)
+                return(0);
+
         r->top=max;
 
+
         ap=a->d;
         bp=b->d;
         rp=r->d;
@@ -160,8 +154,156 @@ BIGNUM *b;
                         r->top++;
                         }
                 }
-        for (; i<max; i++)
-                *(rp++)= *(ap++);
+        if (rp != ap)
+                {
+                for (; i<max; i++)
+                        *(rp++)= *(ap++);
+                }
         /* memcpy(rp,ap,sizeof(*ap)*(max-i));*/
+        r->neg = 0;
+        return(1);
+        }
+
+/* unsigned subtraction of b from a, a must be larger than b. */
+int BN_usub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
+        {
+        int max,min;
+        register BN_ULONG t1,t2,*ap,*bp,*rp;
+        int i,carry;
+#if defined(IRIX_CC_BUG) && !defined(LINT)
+        int dummy;
+#endif
+
+        bn_check_top(a);
+        bn_check_top(b);
+
+        if (a->top < b->top) /* hmm... should not be happening */
+                {
+                BNerr(BN_F_BN_USUB,BN_R_ARG2_LT_ARG3);
+                return(0);
+                }
+
+        max=a->top;
+        min=b->top;
+        if (bn_wexpand(r,max) == NULL) return(0);
+
+        ap=a->d;
+        bp=b->d;
+        rp=r->d;
+
+#if 1
+        carry=0;
+        for (i=0; i<min; i++)
+                {
+                t1= *(ap++);
+                t2= *(bp++);
+                if (carry)
+                        {
+                        carry=(t1 <= t2);
+                        t1=(t1-t2-1)&BN_MASK2;
+                        }
+                else
+                        {
+                        carry=(t1 < t2);
+                        t1=(t1-t2)&BN_MASK2;
+                        }
+#if defined(IRIX_CC_BUG) && !defined(LINT)
+                dummy=t1;
+#endif
+                *(rp++)=t1&BN_MASK2;
+                }
+#else
+        carry=bn_sub_words(rp,ap,bp,min);
+        ap+=min;
+        bp+=min;
+        rp+=min;
+        i=min;
+#endif
+        if (carry) /* subtracted */
+                {
+                while (i < max)
+                        {
+                        i++;
+                        t1= *(ap++);
+                        t2=(t1-1)&BN_MASK2;
+                        *(rp++)=t2;
+                        if (t1 > t2) break;
+                        }
+                }
+#if 0
+        memcpy(rp,ap,sizeof(*rp)*(max-i));
+#else
+        if (rp != ap)
+                {
+                for (;;)
+                        {
+                        if (i++ >= max) break;
+                        rp[0]=ap[0];
+                        if (i++ >= max) break;
+                        rp[1]=ap[1];
+                        if (i++ >= max) break;
+                        rp[2]=ap[2];
+                        if (i++ >= max) break;
+                        rp[3]=ap[3];
+                        rp+=4;
+                        ap+=4;
+                        }
+                }
+#endif
+
+        r->top=max;
+        r->neg=0;
+        bn_fix_top(r);
+        return(1);
+        }
+
+int BN_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b)
+        {
+        int max;
+        int add=0,neg=0;
+        const BIGNUM *tmp;
+
+        bn_check_top(a);
+        bn_check_top(b);
+
+        /*  a -  b      a-b
+         *  a - -b      a+b
+         * -a -  b      -(a+b)
+         * -a - -b      b-a
+         */
+        if (a->neg)
+                {
+                if (b->neg)
+                        { tmp=a; a=b; b=tmp; }
+                else
+                        { add=1; neg=1; }
+                }
+        else
+                {
+                if (b->neg) { add=1; neg=0; }
+                }
+
+        if (add)
+                {
+                if (!BN_uadd(r,a,b)) return(0);
+                r->neg=neg;
+                return(1);
+                }
+
+        /* We are actually doing a - b :-) */
+
+        max=(a->top > b->top)?a->top:b->top;
+        if (bn_wexpand(r,max) == NULL) return(0);
+        if (BN_ucmp(a,b) < 0)
+                {
+                if (!BN_usub(r,b,a)) return(0);
+                r->neg=1;
+                }
+        else
+                {
+                if (!BN_usub(r,a,b)) return(0);
+                r->neg=0;
+                }
+        return(1);
         }