bn16.c

包含哈希,对称以及非对称的经典算法 包含经典事例

/*
 * bn16.c - the high-level bignum interface
 *
 * Like lbn16.c, this reserves the string "16" for textual replacement.
 * The string must not appear anywhere unless it is intended to be replaced
 * to generate other bignum interface functions.
 *
 * Copyright (c) 1995  Colin Plumb.  All rights reserved.
 * For licensing and other legal details, see the file legal.c.
 */

#if HAVE_CONFIG_H
#include "config.h"
#endif

#if !NO_ASSERT_H
#include <assert.h>
#else
#define assert(x) (void)0
#endif

#if !NO_STRING_H
#include <string.h>	/* for memmove() in bnMakeOdd */
#elif HAVE_STRINGS_H
#include <strings.h>
#endif

/*
 * This was useful during debugging, so it's left in here.
 * You can ignore it.  DBMALLOC is generally undefined.
 */
#if DBMALLOC
#include "../dbmalloc/malloc.h"
#define MALLOCDB malloc_chain_check(1)
#else
#define MALLOCDB (void)0
#endif

#include "lbn.h"
#include "lbn16.h"
#include "lbnmem.h"
#include "bn16.h"
#include "bn.h"

#include "kludge.h"	/* For memmove() */

/* Functions */
void
bnInit_16(void)
{
	bnEnd = bnEnd_16;
	bnPrealloc = bnPrealloc_16;
	bnCopy = bnCopy_16;
	bnNorm = bnNorm_16;
	bnExtractBigBytes = bnExtractBigBytes_16;
	bnInsertBigBytes = bnInsertBigBytes_16;
	bnExtractLittleBytes = bnExtractLittleBytes_16;
	bnInsertLittleBytes = bnInsertLittleBytes_16;
	bnLSWord = bnLSWord_16;
	bnBits = bnBits_16;
	bnAdd = bnAdd_16;
	bnSub = bnSub_16;
	bnSetQ = bnSetQ_16;
	bnAddQ = bnAddQ_16;
	bnSubQ = bnSubQ_16;
	bnCmp = bnCmp_16;
	bnSquare = bnSquare_16;
	bnMul = bnMul_16;
	bnMulQ = bnMulQ_16;
	bnDivMod = bnDivMod_16;
	bnMod = bnMod_16;
	bnModQ = bnModQ_16;
	bnExpMod = bnExpMod_16;
	bnDoubleExpMod = bnDoubleExpMod_16;
	bnTwoExpMod = bnTwoExpMod_16;
	bnGcd = bnGcd_16;
	bnInv = bnInv_16;
	bnLShift = bnLShift_16;
	bnRShift = bnRShift_16;
	bnMakeOdd = bnMakeOdd_16;
}

void
bnEnd_16(struct BigNum *bn)
{
	if (bn->ptr) {
		LBNFREE((BNWORD16 *)bn->ptr, bn->allocated);
		bn->ptr = 0;
	}
	bn->size = 0;
	bn->allocated = 0;

	MALLOCDB;
}

/* Internal function.  It operates in words. */
static int
bnResize_16(struct BigNum *bn, unsigned len)
{
	void *p;

	/* Round size up: most mallocs impose 8-byte granularity anyway */
	len = (len + (8/sizeof(BNWORD16) - 1)) & ~(8/sizeof(BNWORD16) - 1);
	p = LBNREALLOC((BNWORD16 *)bn->ptr, bn->allocated, len);
	if (!p)
		return -1;
	bn->ptr = p;
	bn->allocated = len;

	MALLOCDB;

	return 0;
}

#define bnSizeCheck(bn, size) \
	if (bn->allocated < size && bnResize_16(bn, size) < 0) \
		return -1

int
bnPrealloc_16(struct BigNum *bn, unsigned bits)
{
	bits = (bits + 16-1)/16;
	bnSizeCheck(bn, bits);
	MALLOCDB;
	return 0;
}

int
bnCopy_16(struct BigNum *dest, struct BigNum const *src)
{
	bnSizeCheck(dest, src->size);
	dest->size = src->size;
	lbnCopy_16((BNWORD16 *)dest->ptr, (BNWORD16 *)src->ptr, src->size);
	MALLOCDB;
	return 0;
}

void
bnNorm_16(struct BigNum *bn)
{
	bn->size = lbnNorm_16((BNWORD16 *)bn->ptr, bn->size);
}

/*
 * Convert a bignum to big-endian bytes.  Returns, in big-endian form, a
 * substring of the bignum starting from lsbyte and "len" bytes long.
 * Unused high-order (leading) bytes are filled with 0.
 */
void
bnExtractBigBytes_16(struct BigNum const *bn, unsigned char *dest,
                  unsigned lsbyte, unsigned len)
{
	unsigned s = bn->size * (16 / 8);

	/* Fill unused leading bytes with 0 */
	while (s < lsbyte+len) {
		*dest++ = 0;
		len--;
	}

	if (len)
		lbnExtractBigBytes_16((BNWORD16 *)bn->ptr, dest, lsbyte, len);
	MALLOCDB;
}

int
bnInsertBigBytes_16(struct BigNum *bn, unsigned char const *src,
                 unsigned lsbyte, unsigned len)
{
	unsigned s = bn->size;
	unsigned words = (len+lsbyte+sizeof(BNWORD16)-1) / sizeof(BNWORD16);

	/* Pad with zeros as required */
	bnSizeCheck(bn, words);

	if (s < words) {
		lbnZero_16((BNWORD16 *)bn->ptr BIGLITTLE(-s,+s), words-s);
		s = words;
	}

	lbnInsertBigBytes_16((BNWORD16 *)bn->ptr, src, lsbyte, len);

	bn->size = lbnNorm_16((BNWORD16 *)bn->ptr, s);

	MALLOCDB;
	return 0;
}


/*
 * Convert a bignum to little-endian bytes.  Returns, in little-endian form, a
 * substring of the bignum starting from lsbyte and "len" bytes long.
 * Unused high-order (trailing) bytes are filled with 0.
 */
void
bnExtractLittleBytes_16(struct BigNum const *bn, unsigned char *dest,
                  unsigned lsbyte, unsigned len)
{
	unsigned s = bn->size * (16 / 8);

	/* Fill unused leading bytes with 0 */
	while (s < lsbyte+len)
		dest[--len] = 0;

	if (len)
		lbnExtractLittleBytes_16((BNWORD16 *)bn->ptr, dest,
		                         lsbyte, len);
	MALLOCDB;
}

int
bnInsertLittleBytes_16(struct BigNum *bn, unsigned char const *src,
                       unsigned lsbyte, unsigned len)
{
	unsigned s = bn->size;
	unsigned words = (len+lsbyte+sizeof(BNWORD16)-1) / sizeof(BNWORD16);

	/* Pad with zeros as required */
	bnSizeCheck(bn, words);

	if (s < words) {
		lbnZero_16((BNWORD16 *)bn->ptr BIGLITTLE(-s,+s), words-s);
		s = words;
	}

	lbnInsertLittleBytes_16((BNWORD16 *)bn->ptr, src, lsbyte, len);

	bn->size = lbnNorm_16((BNWORD16 *)bn->ptr, s);

	MALLOCDB;
	return 0;
}

/* Return the least-significant word of the input. */
unsigned
bnLSWord_16(struct BigNum const *src)
{
	return src->size ? (unsigned)((BNWORD16 *)src->ptr)[BIGLITTLE(-1,0)]: 0;
}

unsigned
bnBits_16(struct BigNum const *src)
{
	return lbnBits_16((BNWORD16 *)src->ptr, src->size);
}

int
bnAdd_16(struct BigNum *dest, struct BigNum const *src)
{
	unsigned s = src->size, d = dest->size;
	BNWORD16 t;

	if (!s)
		return 0;

	bnSizeCheck(dest, s);

	if (d < s) {
		lbnZero_16((BNWORD16 *)dest->ptr BIGLITTLE(-d,+d), s-d);
		dest->size = d = s;
		MALLOCDB;
	}
	t = lbnAddN_16((BNWORD16 *)dest->ptr, (BNWORD16 *)src->ptr, s);
	MALLOCDB;
	if (t) {
		if (d > s) {
			t = lbnAdd1_16((BNWORD16 *)dest->ptr BIGLITTLE(-s,+s),
			               d-s, t);
			MALLOCDB;
		}
		if (t) {
			bnSizeCheck(dest, d+1);
			((BNWORD16 *)dest->ptr)[BIGLITTLE(-1-d,d)] = t;
			dest->size = d+1;
		}
	}
	return 0;
}

/*
 * dest -= src.
 * If dest goes negative, this produces the absolute value of
 * the difference (the negative of the true value) and returns 1.
 * Otherwise, it returls 0.
 */
int
bnSub_16(struct BigNum *dest, struct BigNum const *src)
{
	unsigned s = src->size, d = dest->size;
	BNWORD16 t;

	if (d < s  &&  d < (s = lbnNorm_16((BNWORD16 *)src->ptr, s))) {
		bnSizeCheck(dest, s);
		lbnZero_16((BNWORD16 *)dest->ptr BIGLITTLE(-d,+d), s-d);
		dest->size = d = s;
		MALLOCDB;
	}
	if (!s)
		return 0;
	t = lbnSubN_16((BNWORD16 *)dest->ptr, (BNWORD16 *)src->ptr, s);
	MALLOCDB;
	if (t) {
		if (d > s) {
			t = lbnSub1_16((BNWORD16 *)dest->ptr BIGLITTLE(-s,+s),
			               d-s, t);
			MALLOCDB;
		}
		if (t) {
			lbnNeg_16((BNWORD16 *)dest->ptr, d);
			dest->size = lbnNorm_16((BNWORD16 *)dest->ptr,
			                        dest->size);
			MALLOCDB;
			return 1;
		}
	}
	dest->size = lbnNorm_16((BNWORD16 *)dest->ptr, dest->size);
	return 0;
}

int
bnSetQ_16(struct BigNum *dest, unsigned src)
{
	if (src) {
		bnSizeCheck(dest, 1);

		((BNWORD16 *)dest->ptr)[BIGLITTLE(-1,0)] = (BNWORD16)src;
		dest->size = 1;
	} else {
		dest->size = 0;
	}
	return 0;
}

int
bnAddQ_16(struct BigNum *dest, unsigned src)
{
	BNWORD16 t;

	if (!dest->size)
		return bnSetQ(dest, src);
	
	t = lbnAdd1_16((BNWORD16 *)dest->ptr, dest->size, (BNWORD16)src);
	MALLOCDB;
	if (t) {
		src = dest->size;
		bnSizeCheck(dest, src+1);
		((BNWORD16 *)dest->ptr)[BIGLITTLE(-1-src,src)] = t;
		dest->size = src+1;
	}
	return 0;
}

/*
 * Return value as for bnSub: 1 if subtract underflowed, in which
 * case the return is the negative of the computed value.
 */
int
bnSubQ_16(struct BigNum *dest, unsigned src)
{
	BNWORD16 t;

	if (!dest->size)
		return bnSetQ(dest, src) < 0 ? -1 : (src != 0);

	t = lbnSub1_16((BNWORD16 *)dest->ptr, dest->size, src);
	MALLOCDB;
	if (t) {
		/* Underflow. <= 1 word, so do it simply. */
		lbnNeg_16((BNWORD16 *)dest->ptr, 1);
		dest->size = 1;
		return 1;
	}
/* Try to normalize?  Needing this is going to be pretty damn rare. */
/*		dest->size = lbnNorm_16((BNWORD16 *)dest->ptr, dest->size); */
	return 0;
}

/*
 * Compare two BigNums.  Returns -1. 0 or 1 if a<b, a == b or a>b.
 * a <=> b --> bnCmp(a,b) <=> 0
 */
int
bnCmp_16(struct BigNum const *a, struct BigNum const *b)
{
	unsigned s, t;

	s = lbnNorm_16((BNWORD16 *)a->ptr, a->size);
	t = lbnNorm_16((BNWORD16 *)b->ptr, b->size);
	
	if (s != t)
		return s > t ? 1 : -1;
	return lbnCmp_16((BNWORD16 *)a->ptr, (BNWORD16 *)b->ptr, s);
}

int
bnSquare_16(struct BigNum *dest, struct BigNum const *src)
{
	unsigned s;
	BNWORD16 *srcbuf;

	s = lbnNorm_16((BNWORD16 *)src->ptr, src->size);
	if (!s) {
		dest->size = 0;
		return 0;
	}
	bnSizeCheck(dest, 2*s);

	if (src == dest) {
		LBNALLOC(srcbuf, s);
		if (!srcbuf)
			return -1;
		lbnCopy_16(srcbuf, (BNWORD16 *)src->ptr, s);
		lbnSquare_16((BNWORD16 *)dest->ptr, (BNWORD16 *)srcbuf, s);
		LBNFREE(srcbuf, s);
	} else {
		lbnSquare_16((BNWORD16 *)dest->ptr, (BNWORD16 *)src->ptr, s);
	}

	dest->size = lbnNorm_16((BNWORD16 *)dest->ptr, 2*s);
	MALLOCDB;
	return 0;
}

int
bnMul_16(struct BigNum *dest, struct BigNum const *a, struct BigNum const *b)
{
	unsigned s, t;
	BNWORD16 *srcbuf;

	s = lbnNorm_16((BNWORD16 *)a->ptr, a->size);
	t = lbnNorm_16((BNWORD16 *)b->ptr, b->size);