BN_div_word() was breaking when called from BN_bn2dec() (actually, this is

the only function that uses it) because it would trip up an assertion in
bn_div_words() when first invoked. This also adds BN_div_word() testing to
bntest.

Submitted by: Nils Larsch
Reviewed by: Geoff Thorpe

diff --git a/crypto/bn/bn_word.c b/crypto/bn/bn_word.c
index 7aa2a33d2d092e803024f00467558be7ff5b3257..1bcb37e29222f76dce1baefd9d1bf949389e725e 100644 (file)
--- a/crypto/bn/bn_word.c
+++ b/crypto/bn/bn_word.c
@@ -87,7 +87,7 @@ BN_ULONG BN_mod_word(const BIGNUM *a, BN_ULONG w)
 BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w)
        {
        BN_ULONG ret = 0;
-       int i;
+       int i, j;
 
        bn_check_top(a);
        w &= BN_MASK2;
@@ -98,6 +98,12 @@ BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w)
        if (a->top == 0)
                return 0;
 
+       /* normalize input (so bn_div_words doesn't complain) */
+       j = BN_BITS2 - BN_num_bits_word(w);
+       w <<= j;
+       if (!BN_lshift(a, a, j))
+               return 0;
+
        for (i=a->top-1; i>=0; i--)
                {
                BN_ULONG l,d;
@@ -109,6 +115,7 @@ BN_ULONG BN_div_word(BIGNUM *a, BN_ULONG w)
                }
        if ((a->top > 0) && (a->d[a->top-1] == 0))
                a->top--;
+       ret >>= j;
        bn_check_top(a);
        return(ret);
        }

diff --git a/crypto/bn/bntest.c b/crypto/bn/bntest.c
index 0d37dcff4d89b79ae9e00fa11f008faac7d442e0..d4cb92f84725ea22fbb7c04f1411ea8015792c74 100644 (file)
--- a/crypto/bn/bntest.c
+++ b/crypto/bn/bntest.c
@@ -98,6 +98,7 @@ int test_lshift(BIO *bp,BN_CTX *ctx,BIGNUM *a_);
 int test_rshift1(BIO *bp);
 int test_rshift(BIO *bp,BN_CTX *ctx);
 int test_div(BIO *bp,BN_CTX *ctx);
+int test_div_word(BIO *bp);
 int test_div_recp(BIO *bp,BN_CTX *ctx);
 int test_mul(BIO *bp);
 int test_sqr(BIO *bp,BN_CTX *ctx);
@@ -221,6 +222,10 @@ int main(int argc, char *argv[])
        if (!test_div(out,ctx)) goto err;
        BIO_flush(out);
 
+       message(out,"BN_div_word");
+       if (!test_div_word(out)) goto err;
+       BIO_flush(out);
+
        message(out,"BN_div_recp");
        if (!test_div_recp(out,ctx)) goto err;
        BIO_flush(out);
@@ -463,6 +468,62 @@ int test_div(BIO *bp, BN_CTX *ctx)
        return(1);
        }
 
+int test_div_word(BIO *bp)
+       {
+       BIGNUM   a,b;
+       BN_ULONG r,s;
+       int i;
+
+       BN_init(&a);
+       BN_init(&b);
+
+       for (i=0; i<num0; i++)
+               {
+               do {
+                       BN_bntest_rand(&a,512,-1,0);
+                       BN_bntest_rand(&b,BN_BITS2,-1,0);
+                       s = b.d[0];
+               } while (!s);
+
+               BN_copy(&b, &a);
+               r = BN_div_word(&b, s);
+
+               if (bp != NULL)
+                       {
+                       if (!results)
+                               {
+                               BN_print(bp,&a);
+                               BIO_puts(bp," / ");
+                               BIO_printf(bp,"%lX",s);
+                               BIO_puts(bp," - ");
+                               }
+                       BN_print(bp,&b);
+                       BIO_puts(bp,"\n");
+
+                       if (!results)
+                               {
+                               BN_print(bp,&a);
+                               BIO_puts(bp," % ");
+                               BIO_printf(bp,"%lX",s);
+                               BIO_puts(bp," - ");
+                               }
+                       BIO_printf(bp,"%lX",r);
+                       BIO_puts(bp,"\n");
+                       }
+               BN_mul_word(&b,s);
+               BN_add_word(&b,r);
+               BN_sub(&b,&a,&b);
+               if(!BN_is_zero(&b))
+                   {
+                   fprintf(stderr,"Division (word) test failed!\n");
+                   return 0;
+                   }
+               }
+       BN_free(&a);
+       BN_free(&b);
+       return(1);
+       }
+
 int test_div_recp(BIO *bp, BN_CTX *ctx)
        {
        BIGNUM a,b,c,d,e;