bn_lib.c

一个用于点对点传输加密的工具包源码

			case 5:
				A[4]=B[4];
			case 4:
				A[3]=B[3];
			case 3:
				A[2]=B[2];
			case 2:
				A[1]=B[1];
			case 1:
				A[0]=B[0];
			case 0:
				/* I need the 'case 0' entry for utrix cc.
				 * If the optimizer is turned on, it does the
				 * switch table by doing
				 * a=top&7
				 * a--;
				 * goto jump_table[a];
				 * If top is 0, this makes us jump to 0xffffffc 
				 * which is rather bad :-(.
				 * eric 23-Apr-1998
				 */
				;
				}
#else
			for (i=b->top>>2; i>0; i--,A+=4,B+=4)
				{
				/*
				 * The fact that the loop is unrolled
				 * 4-wise is a tribute to Intel. It's
				 * the one that doesn't have enough
				 * registers to accomodate more data.
				 * I'd unroll it 8-wise otherwise:-)
				 *
				 *		<[e-mail]>
				 */
				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 above */
				}
#endif
			OPENSSL_free(b->d);
			}

		b->d=a;
		b->dmax=words;

		/* Now need to zero any data between b->top and b->max */

		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;
#else
			memset(A,0,sizeof(BN_ULONG)*(words+1));
			memcpy(A,b->d,sizeof(b->d[0])*b->top);
			b->d=a;
			b->max=words;
#endif
		
/*		memset(&(p[b->max]),0,((words+1)-b->max)*sizeof(BN_ULONG)); */
/*	{ int i; for (i=b->max; i<words+1; i++) p[i]=i;} */

		}
	return(b);
	}

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

	if (a == NULL) return NULL;

	bn_check_top(a);

	r=BN_new();
	if (r == NULL) return(NULL);
	return((BIGNUM *)BN_copy(r,a));
	}

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_expand2 */
		}
#else
	memcpy(a->d,b->d,sizeof(b->d[0])*b->top);
#endif

/*	memset(&(a->d[b->top]),0,sizeof(a->d[0])*(a->max-b->top));*/
	a->top=b->top;
	if ((a->top == 0) && (a->d != NULL))
		a->d[0]=0;
	a->neg=b->neg;
	return(a);
	}

void BN_clear(BIGNUM *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(BIGNUM *a)
	{
	int i,n;
	BN_ULONG ret=0;

	n=BN_num_bytes(a);
	if (n > sizeof(BN_ULONG))
		return(BN_MASK2);
	for (i=a->top-1; i>=0; i--)
		{
#ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */
		ret<<=BN_BITS4; /* stops the compiler complaining */
		ret<<=BN_BITS4;
#else
		ret=0;
#endif
		ret|=a->d[i];
		}
	return(ret);
	}

int BN_set_word(BIGNUM *a, BN_ULONG w)
	{
	int i,n;
	if (bn_expand(a,sizeof(BN_ULONG)*8) == NULL) return(0);

	n=sizeof(BN_ULONG)/BN_BYTES;
	a->neg=0;
	a->top=0;
	a->d[0]=(BN_ULONG)w&BN_MASK2;
	if (a->d[0] != 0) a->top=1;
	for (i=1; i<n; i++)
		{
		/* the following is done instead of
		 * w>>=BN_BITS2 so compilers don't complain
		 * on builds where sizeof(long) == BN_TYPES */
#ifndef SIXTY_FOUR_BIT /* the data item > unsigned long */
		w>>=BN_BITS4;
		w>>=BN_BITS4;
#else
		w=0;
#endif
		a->d[i]=(BN_ULONG)w&BN_MASK2;
		if (a->d[i] != 0) a->top=i+1;
		}
	return(1);
	}

/* ignore negative */
BIGNUM *BN_bin2bn(const unsigned char *s, int len, BIGNUM *ret)
	{
	unsigned int i,m;
	unsigned int n;
	BN_ULONG l;

	if (ret == NULL) ret=BN_new();
	if (ret == NULL) return(NULL);
	l=0;
	n=len;
	if (n == 0)
		{
		ret->top=0;
		return(ret);
		}
	if (bn_expand(ret,(int)(n+2)*8) == NULL)
		return(NULL);
	i=((n-1)/BN_BYTES)+1;
	m=((n-1)%(BN_BYTES));
	ret->top=i;
	while (n-- > 0)
		{
		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_fix_top(ret);
	return(ret);
	}

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

	n=i=BN_num_bytes(a);
	while (i-- > 0)
		{
		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;

	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);
	return(1);
	}

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

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

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

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

	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;

	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_fix_top(a);
	return(1);
	}

int bn_cmp_words(BN_ULONG *a, 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);
	}