bn_lib.c

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				}
			}
		/* If a == NULL, there was an error in allocation in
		   bn_expand_internal(), and NULL should be returned */
		}
	else
		{
		r = BN_dup(b);
		}

	bn_check_top(r);
	return r;
	}
#endif

/* This is an internal function that should not be used in applications.
 * It ensures that 'b' has enough room for a 'words' word number
 * and initialises any unused part of b->d with leading zeros.
 * It is mostly used by the various BIGNUM routines. If there is an error,
 * NULL is returned. If not, 'b' is returned. */

BIGNUM *bn_expand2(BIGNUM *b, int words)
	{
	bn_check_top(b);

	if (words > b->dmax)
		{
		BN_ULONG *a = bn_expand_internal(b, words);
		if(!a) return NULL;
		if(b->d) OPENSSL_free(b->d);
		b->d=a;
		b->dmax=words;
		}

/* None of this should be necessary because of what b->top means! */
#if 0
	/* NB: bn_wexpand() calls this only if the BIGNUM really has to grow */
	if (b->top < b->dmax)
		{
		int i;
		BN_ULONG *A = &(b->d[b->top]);
		for (i=(b->dmax - b->top)>>3; i>0; i--,A+=8)
			{
			A[0]=0; A[1]=0; A[2]=0; A[3]=0;
			A[4]=0; A[5]=0; A[6]=0; A[7]=0;
			}
		for (i=(b->dmax - b->top)&7; i>0; i--,A++)
			A[0]=0;
		assert(A == &(b->d[b->dmax]));
		}
#endif
	bn_check_top(b);
	return b;
	}

BIGNUM *BN_dup(const BIGNUM *a)
	{
	BIGNUM *t;

	if (a == NULL) return NULL;
	bn_check_top(a);

	t = BN_new();
	if (t == NULL) return NULL;
	if(!BN_copy(t, a))
		{
		BN_free(t);
		return NULL;
		}
	bn_check_top(t);
	return t;
	}

BIGNUM *BN_copy(BIGNUM *a, const BIGNUM *b)
	{
	int i;
	BN_ULONG *A;
	const BN_ULONG *B;

	bn_check_top(b);

	if (a == b) return(a);
	if (bn_wexpand(a,b->top) == NULL) return(NULL);

#if 1
	A=a->d;
	B=b->d;
	for (i=b->top>>2; i>0; i--,A+=4,B+=4)
		{
		BN_ULONG a0,a1,a2,a3;
		a0=B[0]; a1=B[1]; a2=B[2]; a3=B[3];
		A[0]=a0; A[1]=a1; A[2]=a2; A[3]=a3;
		}
	switch (b->top&3)
		{
		case 3: A[2]=B[2];
		case 2: A[1]=B[1];
		case 1: A[0]=B[0];
		case 0: ; /* ultrix cc workaround, see comments in bn_expand_internal */
		}
#else
	memcpy(a->d,b->d,sizeof(b->d[0])*b->top);
#endif

	a->top=b->top;
	a->neg=b->neg;
	bn_check_top(a);
	return(a);
	}

void BN_swap(BIGNUM *a, BIGNUM *b)
	{
	int flags_old_a, flags_old_b;
	BN_ULONG *tmp_d;
	int tmp_top, tmp_dmax, tmp_neg;
	
	bn_check_top(a);
	bn_check_top(b);

	flags_old_a = a->flags;
	flags_old_b = b->flags;

	tmp_d = a->d;
	tmp_top = a->top;
	tmp_dmax = a->dmax;
	tmp_neg = a->neg;
	
	a->d = b->d;
	a->top = b->top;
	a->dmax = b->dmax;
	a->neg = b->neg;
	
	b->d = tmp_d;
	b->top = tmp_top;
	b->dmax = tmp_dmax;
	b->neg = tmp_neg;
	
	a->flags = (flags_old_a & BN_FLG_MALLOCED) | (flags_old_b & BN_FLG_STATIC_DATA);
	b->flags = (flags_old_b & BN_FLG_MALLOCED) | (flags_old_a & BN_FLG_STATIC_DATA);
	bn_check_top(a);
	bn_check_top(b);
	}

void BN_clear(BIGNUM *a)
	{
	bn_check_top(a);
	if (a->d != NULL)
		memset(a->d,0,a->dmax*sizeof(a->d[0]));
	a->top=0;
	a->neg=0;
	}

BN_ULONG BN_get_word(const BIGNUM *a)
	{
	if (a->top > 1)
		return BN_MASK2;
	else if (a->top == 1)
		return a->d[0];
	/* a->top == 0 */
	return 0;
	}

int BN_set_word(BIGNUM *a, BN_ULONG w)
	{
	bn_check_top(a);
	if (bn_expand(a,(int)sizeof(BN_ULONG)*8) == NULL) return(0);
	a->neg = 0;
	a->d[0] = w;
	a->top = (w ? 1 : 0);
	bn_check_top(a);
	return(1);
	}

BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
	{
	unsigned int i,m;
	unsigned int n;
	BN_ULONG l;
	BIGNUM  *bn = NULL;

	if (ret == NULL)
		ret = bn = BN_new();
	if (ret == NULL) return(NULL);
	bn_check_top(ret);
	l=0;
	n=len;
	if (n == 0)
		{
		ret->top=0;
		return(ret);
		}
	i=((n-1)/BN_BYTES)+1;
	m=((n-1)%(BN_BYTES));
	if (bn_wexpand(ret, (int)i) == NULL)
		{
		if (bn) BN_free(bn);
		return NULL;
		}
	ret->top=i;
	ret->neg=0;
	while (n--)
		{
		l=(l<<8L)| *(s++);
		if (m-- == 0)
			{
			ret->d[--i]=l;
			l=0;
			m=BN_BYTES-1;
			}
		}
	/* need to call this due to clear byte at top if avoiding
	 * having the top bit set (-ve number) */
	bn_correct_top(ret);
	return(ret);
	}

/* ignore negative */
int BN_bn2bin(const BIGNUM *a, unsigned char *to)
	{
	int n,i;
	BN_ULONG l;

	bn_check_top(a);
	n=i=BN_num_bytes(a);
	while (i--)
		{
		l=a->d[i/BN_BYTES];
		*(to++)=(unsigned char)(l>>(8*(i%BN_BYTES)))&0xff;
		}
	return(n);
	}

int BN_ucmp(const BIGNUM *a, const BIGNUM *b)
	{
	int i;
	BN_ULONG t1,t2,*ap,*bp;

	bn_check_top(a);
	bn_check_top(b);

	i=a->top-b->top;
	if (i != 0) return(i);
	ap=a->d;
	bp=b->d;
	for (i=a->top-1; i>=0; i--)
		{
		t1= ap[i];
		t2= bp[i];
		if (t1 != t2)
			return((t1 > t2) ? 1 : -1);
		}
	return(0);
	}

int BN_cmp(const BIGNUM *a, const BIGNUM *b)
	{
	int i;
	int gt,lt;
	BN_ULONG t1,t2;

	if ((a == NULL) || (b == NULL))
		{
		if (a != NULL)
			return(-1);
		else if (b != NULL)
			return(1);
		else
			return(0);
		}

	bn_check_top(a);
	bn_check_top(b);

	if (a->neg != b->neg)
		{
		if (a->neg)
			return(-1);
		else	return(1);
		}
	if (a->neg == 0)
		{ gt=1; lt= -1; }
	else	{ gt= -1; lt=1; }

	if (a->top > b->top) return(gt);
	if (a->top < b->top) return(lt);
	for (i=a->top-1; i>=0; i--)
		{
		t1=a->d[i];
		t2=b->d[i];
		if (t1 > t2) return(gt);
		if (t1 < t2) return(lt);
		}
	return(0);
	}

int BN_set_bit(BIGNUM *a, int n)
	{
	int i,j,k;

	if (n < 0)
		return 0;

	i=n/BN_BITS2;
	j=n%BN_BITS2;
	if (a->top <= i)
		{
		if (bn_wexpand(a,i+1) == NULL) return(0);
		for(k=a->top; k<i+1; k++)
			a->d[k]=0;
		a->top=i+1;
		}

	a->d[i]|=(((BN_ULONG)1)<<j);
	bn_check_top(a);
	return(1);
	}

int BN_clear_bit(BIGNUM *a, int n)
	{
	int i,j;

	bn_check_top(a);
	if (n < 0) return 0;

	i=n/BN_BITS2;
	j=n%BN_BITS2;
	if (a->top <= i) return(0);

	a->d[i]&=(~(((BN_ULONG)1)<<j));
	bn_correct_top(a);
	return(1);
	}

int BN_is_bit_set(const BIGNUM *a, int n)
	{
	int i,j;

	bn_check_top(a);
	if (n < 0) return 0;
	i=n/BN_BITS2;
	j=n%BN_BITS2;
	if (a->top <= i) return 0;
	return((a->d[i]&(((BN_ULONG)1)<<j))?1:0);
	}

int BN_mask_bits(BIGNUM *a, int n)
	{
	int b,w;

	bn_check_top(a);
	if (n < 0) return 0;

	w=n/BN_BITS2;
	b=n%BN_BITS2;
	if (w >= a->top) return 0;
	if (b == 0)
		a->top=w;
	else
		{
		a->top=w+1;
		a->d[w]&= ~(BN_MASK2<<b);
		}
	bn_correct_top(a);
	return(1);
	}

void BN_set_negative(BIGNUM *a, int b)
	{
	if (b && !BN_is_zero(a))
		a->neg = 1;
	else
		a->neg = 0;
	}

int bn_cmp_words(const BN_ULONG *a, const BN_ULONG *b, int n)
	{
	int i;
	BN_ULONG aa,bb;

	aa=a[n-1];
	bb=b[n-1];
	if (aa != bb) return((aa > bb)?1:-1);
	for (i=n-2; i>=0; i--)
		{
		aa=a[i];
		bb=b[i];
		if (aa != bb) return((aa > bb)?1:-1);
		}
	return(0);
	}

/* Here follows a specialised variants of bn_cmp_words().  It has the
   property of performing the operation on arrays of different sizes.
   The sizes of those arrays is expressed through cl, which is the
   common length ( basicall, min(len(a),len(b)) ), and dl, which is the
   delta between the two lengths, calculated as len(a)-len(b).
   All lengths are the number of BN_ULONGs...  */

int bn_cmp_part_words(const BN_ULONG *a, const BN_ULONG *b,
	int cl, int dl)
	{
	int n,i;
	n = cl-1;

	if (dl < 0)
		{
		for (i=dl; i<0; i++)
			{
			if (b[n-i] != 0)
				return -1; /* a < b */
			}
		}
	if (dl > 0)
		{
		for (i=dl; i>0; i--)
			{
			if (a[n+i] != 0)
				return 1; /* a > b */
			}
		}
	return bn_cmp_words(a,b,cl);
	}