bignum.c File Reference

Big number math. More...

#include "includes.h"
#include "common.h"
#include "bignum.h"
#include <tommath.h>

Functions
struct bignum *	bignum_init (void)
	Allocate memory for bignum. More...
void	bignum_deinit (struct bignum *n)
	Free bignum. More...
size_t	bignum_get_unsigned_bin_len (struct bignum *n)
	Get length of bignum as an unsigned binary buffer. More...
int	bignum_get_unsigned_bin (const struct bignum *n, u8 *buf, size_t *len)
	Set binary buffer to unsigned bignum. More...
int	bignum_set_unsigned_bin (struct bignum *n, const u8 *buf, size_t len)
	Set bignum based on unsigned binary buffer. More...
int	bignum_cmp (const struct bignum *a, const struct bignum *b)
	Signed comparison. More...
int	bignum_cmp_d (const struct bignum *a, unsigned long b)
	Compare bignum to standard integer. More...
int	bignum_add (const struct bignum *a, const struct bignum *b, struct bignum *c)
	c = a + b More...
int	bignum_sub (const struct bignum *a, const struct bignum *b, struct bignum *c)
	c = a - b More...
int	bignum_mul (const struct bignum *a, const struct bignum *b, struct bignum *c)
	c = a * b More...
int	bignum_mulmod (const struct bignum *a, const struct bignum *b, const struct bignum *c, struct bignum *d)
	d = a * b (mod c) More...
int	bignum_exptmod (const struct bignum *a, const struct bignum *b, const struct bignum *c, struct bignum *d)
	Modular exponentiation: d = a^b (mod c) More...

Detailed Description

Big number math.

Function Documentation

int bignum_add	(	const struct bignum *	a,
		const struct bignum *	b,
		struct bignum *	c
	)

c = a + b

Parameters

a	Bignum from bignum_init()
b	Bignum from bignum_init()
c	Bignum from bignum_init(); used to store the result of a + b

Returns

0 on success, -1 on failure

int bignum_cmp	(	const struct bignum *	a,
		const struct bignum *	b
	)

Signed comparison.

Parameters

a	Bignum from bignum_init()
b	Bignum from bignum_init()

Returns

0 on success, -1 on failure

int bignum_cmp_d	(	const struct bignum *	a,
		unsigned long	b
	)

Compare bignum to standard integer.

Parameters

a	Bignum from bignum_init()
b	Small integer

Returns

0 on success, -1 on failure

void bignum_deinit

(

struct bignum *

n

)

Free bignum.

Parameters

n	Bignum from bignum_init()

int bignum_exptmod	(	const struct bignum *	a,
		const struct bignum *	b,
		const struct bignum *	c,
		struct bignum *	d
	)

Modular exponentiation: d = a^b (mod c)

Parameters

a	Bignum from bignum_init(); base
b	Bignum from bignum_init(); exponent
c	Bignum from bignum_init(); modulus
d	Bignum from bignum_init(); used to store the result of a^b (mod c)

Returns

0 on success, -1 on failure

int bignum_get_unsigned_bin	(	const struct bignum *	n,
		u8 *	buf,
		size_t *	len
	)

Set binary buffer to unsigned bignum.

Parameters

n	Bignum from bignum_init()
buf	Buffer for the binary number
len	Length of the buffer, can be NULL if buffer is known to be long enough. Set to used buffer length on success if not NULL.

Returns

0 on success, -1 on failure

size_t bignum_get_unsigned_bin_len

(

struct bignum *

n

)

Get length of bignum as an unsigned binary buffer.

Parameters

n	Bignum from bignum_init()

Returns

Length of n if written to a binary buffer

struct bignum* bignum_init

(

void

)

Allocate memory for bignum.

Returns

Pointer to allocated bignum or NULL on failure

int bignum_mul	(	const struct bignum *	a,
		const struct bignum *	b,
		struct bignum *	c
	)

c = a * b

Parameters

a	Bignum from bignum_init()
b	Bignum from bignum_init()
c	Bignum from bignum_init(); used to store the result of a * b

Returns

0 on success, -1 on failure

int bignum_mulmod	(	const struct bignum *	a,
		const struct bignum *	b,
		const struct bignum *	c,
		struct bignum *	d
	)

d = a * b (mod c)

Parameters

a	Bignum from bignum_init()
b	Bignum from bignum_init()
c	Bignum from bignum_init(); modulus
d	Bignum from bignum_init(); used to store the result of a * b (mod c)

Returns

0 on success, -1 on failure

int bignum_set_unsigned_bin	(	struct bignum *	n,
		const u8 *	buf,
		size_t	len
	)

Set bignum based on unsigned binary buffer.

Parameters

n	Bignum from bignum_init(); to be set to the given value
buf	Buffer with unsigned binary value
len	Length of buf in octets

Returns

0 on success, -1 on failure

int bignum_sub	(	const struct bignum *	a,
		const struct bignum *	b,
		struct bignum *	c
	)

c = a - b

Parameters

a	Bignum from bignum_init()
b	Bignum from bignum_init()
c	Bignum from bignum_init(); used to store the result of a - b

Returns

0 on success, -1 on failure