bignum.h File Reference

Multi-precision integer library. More...

#include "config.h"
#include <stddef.h>
#include <stdint.h>

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Data Structures
struct	mbedtls_mpi
	MPI structure. More...
Defines
#define	MBEDTLS_ERR_MPI_FILE_IO_ERROR -0x0002
#define	MBEDTLS_ERR_MPI_BAD_INPUT_DATA -0x0004
#define	MBEDTLS_ERR_MPI_INVALID_CHARACTER -0x0006
#define	MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL -0x0008
#define	MBEDTLS_ERR_MPI_NEGATIVE_VALUE -0x000A
#define	MBEDTLS_ERR_MPI_DIVISION_BY_ZERO -0x000C
#define	MBEDTLS_ERR_MPI_NOT_ACCEPTABLE -0x000E
#define	MBEDTLS_ERR_MPI_ALLOC_FAILED -0x0010
#define	MBEDTLS_MPI_CHK(f) do { if( ( ret = f ) != 0 ) goto cleanup; } while( 0 )
#define	MBEDTLS_MPI_MAX_LIMBS 10000
#define	MBEDTLS_MPI_WINDOW_SIZE 6
#define	MBEDTLS_MPI_MAX_SIZE 1024
#define	MBEDTLS_MPI_MAX_BITS ( 8 * MBEDTLS_MPI_MAX_SIZE )
#define	MBEDTLS_MPI_MAX_BITS_SCALE100 ( 100 * MBEDTLS_MPI_MAX_BITS )
#define	MBEDTLS_LN_2_DIV_LN_10_SCALE100 332
#define	MBEDTLS_MPI_RW_BUFFER_SIZE ( ((MBEDTLS_MPI_MAX_BITS_SCALE100 + MBEDTLS_LN_2_DIV_LN_10_SCALE100 - 1) / MBEDTLS_LN_2_DIV_LN_10_SCALE100) + 10 + 6 )
#define	MBEDTLS_HAVE_INT32
#define	MBEDTLS_HAVE_UDBL
Typedefs
typedef int32_t	mbedtls_mpi_sint
typedef uint32_t	mbedtls_mpi_uint
typedef uint64_t	mbedtls_t_udbl
Functions
void	mbedtls_mpi_init (mbedtls_mpi *X)
	Initialize one MPI (make internal references valid) This just makes it ready to be set or freed, but does not define a value for the MPI.
void	mbedtls_mpi_free (mbedtls_mpi *X)
	Unallocate one MPI.
int	mbedtls_mpi_grow (mbedtls_mpi *X, size_t nblimbs)
	Enlarge to the specified number of limbs.
int	mbedtls_mpi_shrink (mbedtls_mpi *X, size_t nblimbs)
	Resize down, keeping at least the specified number of limbs.
int	mbedtls_mpi_copy (mbedtls_mpi X, const mbedtls_mpi Y)
	Copy the contents of Y into X.
void	mbedtls_mpi_swap (mbedtls_mpi X, mbedtls_mpi Y)
	Swap the contents of X and Y.
int	mbedtls_mpi_safe_cond_assign (mbedtls_mpi X, const mbedtls_mpi Y, unsigned char assign)
	Safe conditional assignement X = Y if assign is 1.
int	mbedtls_mpi_safe_cond_swap (mbedtls_mpi X, mbedtls_mpi Y, unsigned char assign)
	Safe conditional swap X <-> Y if swap is 1.
int	mbedtls_mpi_lset (mbedtls_mpi *X, mbedtls_mpi_sint z)
	Set value from integer.
int	mbedtls_mpi_get_bit (const mbedtls_mpi *X, size_t pos)
	Get a specific bit from X.
int	mbedtls_mpi_set_bit (mbedtls_mpi *X, size_t pos, unsigned char val)
	Set a bit of X to a specific value of 0 or 1.
size_t	mbedtls_mpi_lsb (const mbedtls_mpi *X)
	Return the number of zero-bits before the least significant '1' bit.
size_t	mbedtls_mpi_bitlen (const mbedtls_mpi *X)
	Return the number of bits up to and including the most significant '1' bit'.
size_t	mbedtls_mpi_size (const mbedtls_mpi *X)
	Return the total size in bytes.
int	mbedtls_mpi_read_string (mbedtls_mpi X, int radix, const char s)
	Import from an ASCII string.
int	mbedtls_mpi_write_string (const mbedtls_mpi X, int radix, char buf, size_t buflen, size_t *olen)
	Export into an ASCII string.
int	mbedtls_mpi_read_binary (mbedtls_mpi X, const unsigned char buf, size_t buflen)
	Import X from unsigned binary data, big endian.
int	mbedtls_mpi_write_binary (const mbedtls_mpi X, unsigned char buf, size_t buflen)
	Export X into unsigned binary data, big endian. Always fills the whole buffer, which will start with zeros if the number is smaller.
int	mbedtls_mpi_shift_l (mbedtls_mpi *X, size_t count)
	Left-shift: X <<= count.
int	mbedtls_mpi_shift_r (mbedtls_mpi *X, size_t count)
	Right-shift: X >>= count.
int	mbedtls_mpi_cmp_abs (const mbedtls_mpi X, const mbedtls_mpi Y)
	Compare unsigned values.
int	mbedtls_mpi_cmp_mpi (const mbedtls_mpi X, const mbedtls_mpi Y)
	Compare signed values.
int	mbedtls_mpi_cmp_int (const mbedtls_mpi *X, mbedtls_mpi_sint z)
	Compare signed values.
int	mbedtls_mpi_add_abs (mbedtls_mpi X, const mbedtls_mpi A, const mbedtls_mpi *B)
	Unsigned addition: X = \|A\| + \|B\|.
int	mbedtls_mpi_sub_abs (mbedtls_mpi X, const mbedtls_mpi A, const mbedtls_mpi *B)
	Unsigned subtraction: X = \|A\| - \|B\|.
int	mbedtls_mpi_add_mpi (mbedtls_mpi X, const mbedtls_mpi A, const mbedtls_mpi *B)
	Signed addition: X = A + B.
int	mbedtls_mpi_sub_mpi (mbedtls_mpi X, const mbedtls_mpi A, const mbedtls_mpi *B)
	Signed subtraction: X = A - B.
int	mbedtls_mpi_add_int (mbedtls_mpi X, const mbedtls_mpi A, mbedtls_mpi_sint b)
	Signed addition: X = A + b.
int	mbedtls_mpi_sub_int (mbedtls_mpi X, const mbedtls_mpi A, mbedtls_mpi_sint b)
	Signed subtraction: X = A - b.
int	mbedtls_mpi_mul_mpi (mbedtls_mpi X, const mbedtls_mpi A, const mbedtls_mpi *B)
	Baseline multiplication: X = A * B.
int	mbedtls_mpi_mul_int (mbedtls_mpi X, const mbedtls_mpi A, mbedtls_mpi_uint b)
	Baseline multiplication: X = A * b.
int	mbedtls_mpi_div_mpi (mbedtls_mpi Q, mbedtls_mpi R, const mbedtls_mpi A, const mbedtls_mpi B)
	Division by mbedtls_mpi: A = Q * B + R.
int	mbedtls_mpi_div_int (mbedtls_mpi Q, mbedtls_mpi R, const mbedtls_mpi *A, mbedtls_mpi_sint b)
	Division by int: A = Q * b + R.
int	mbedtls_mpi_mod_mpi (mbedtls_mpi R, const mbedtls_mpi A, const mbedtls_mpi *B)
	Modulo: R = A mod B.
int	mbedtls_mpi_mod_int (mbedtls_mpi_uint r, const mbedtls_mpi A, mbedtls_mpi_sint b)
	Modulo: r = A mod b.
int	mbedtls_mpi_exp_mod (mbedtls_mpi X, const mbedtls_mpi A, const mbedtls_mpi E, const mbedtls_mpi N, mbedtls_mpi *_RR)
	Sliding-window exponentiation: X = A^E mod N.
int	mbedtls_mpi_fill_random (mbedtls_mpi X, size_t size, int(f_rng)(void , unsigned char , size_t), void *p_rng)
	Fill an MPI X with size bytes of random.
int	mbedtls_mpi_gcd (mbedtls_mpi G, const mbedtls_mpi A, const mbedtls_mpi *B)
	Greatest common divisor: G = gcd(A, B).
int	mbedtls_mpi_inv_mod (mbedtls_mpi X, const mbedtls_mpi A, const mbedtls_mpi *N)
	Modular inverse: X = A^-1 mod N.
int	mbedtls_mpi_is_prime (const mbedtls_mpi X, int(f_rng)(void , unsigned char , size_t), void *p_rng)
	Miller-Rabin primality test.
int	mbedtls_mpi_gen_prime (mbedtls_mpi X, size_t nbits, int dh_flag, int(f_rng)(void , unsigned char , size_t), void *p_rng)
	Prime number generation.
int	mbedtls_mpi_self_test (int verbose)
	Checkup routine.

Detailed Description

Multi-precision integer library.

Definition in file bignum.h.

Define Documentation

#define MBEDTLS_ERR_MPI_ALLOC_FAILED -0x0010

Memory allocation failed.

Definition at line 47 of file bignum.h.

#define MBEDTLS_ERR_MPI_BAD_INPUT_DATA -0x0004

Bad input parameters to function.

Definition at line 41 of file bignum.h.

#define MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL -0x0008

The buffer is too small to write to.

Definition at line 43 of file bignum.h.

#define MBEDTLS_ERR_MPI_DIVISION_BY_ZERO -0x000C

The input argument for division is zero, which is not allowed.

Definition at line 45 of file bignum.h.

#define MBEDTLS_ERR_MPI_FILE_IO_ERROR -0x0002

An error occurred while reading from or writing to a file.

Definition at line 40 of file bignum.h.

#define MBEDTLS_ERR_MPI_INVALID_CHARACTER -0x0006

There is an invalid character in the digit string.

Definition at line 42 of file bignum.h.

#define MBEDTLS_ERR_MPI_NEGATIVE_VALUE -0x000A

The input arguments are negative or result in illegal output.

Definition at line 44 of file bignum.h.

#define MBEDTLS_ERR_MPI_NOT_ACCEPTABLE -0x000E

The input arguments are not acceptable.

Definition at line 46 of file bignum.h.

#define MBEDTLS_HAVE_INT32

Definition at line 163 of file bignum.h.

#define MBEDTLS_HAVE_UDBL

Definition at line 169 of file bignum.h.

#define MBEDTLS_LN_2_DIV_LN_10_SCALE100 332

Definition at line 101 of file bignum.h.

#define MBEDTLS_MPI_CHK ( f ) do { if( ( ret = f ) != 0 ) goto cleanup; } while( 0 )

Definition at line 49 of file bignum.h.

#define MBEDTLS_MPI_MAX_BITS ( 8 * MBEDTLS_MPI_MAX_SIZE )

Maximum number of bits for usable MPIs.

Definition at line 80 of file bignum.h.

#define MBEDTLS_MPI_MAX_BITS_SCALE100 ( 100 * MBEDTLS_MPI_MAX_BITS )

Definition at line 100 of file bignum.h.

#define MBEDTLS_MPI_MAX_LIMBS 10000

Definition at line 54 of file bignum.h.

#define MBEDTLS_MPI_MAX_SIZE 1024

Maximum number of bytes for usable MPIs.

Definition at line 77 of file bignum.h.

#define MBEDTLS_MPI_RW_BUFFER_SIZE ( ((MBEDTLS_MPI_MAX_BITS_SCALE100 + MBEDTLS_LN_2_DIV_LN_10_SCALE100 - 1) / MBEDTLS_LN_2_DIV_LN_10_SCALE100) + 10 + 6 )

Definition at line 102 of file bignum.h.

#define MBEDTLS_MPI_WINDOW_SIZE 6

Maximum windows size used.

Definition at line 66 of file bignum.h.

Typedef Documentation

typedef int32_t mbedtls_mpi_sint

Definition at line 165 of file bignum.h.

typedef uint32_t mbedtls_mpi_uint

Definition at line 166 of file bignum.h.

typedef uint64_t mbedtls_t_udbl

Definition at line 168 of file bignum.h.

Function Documentation

int mbedtls_mpi_add_abs	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	A,
		const mbedtls_mpi *	B
	)

Unsigned addition: X = |A| + |B|.

Parameters:

	X	Destination MPI
	A	Left-hand MPI
	B	Right-hand MPI

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

int mbedtls_mpi_add_int	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	A,
		mbedtls_mpi_sint	b
	)

Signed addition: X = A + b.

Parameters:

	X	Destination MPI
	A	Left-hand MPI
	b	The integer value to add

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

int mbedtls_mpi_add_mpi	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	A,
		const mbedtls_mpi *	B
	)

Signed addition: X = A + B.

Parameters:

	X	Destination MPI
	A	Left-hand MPI
	B	Right-hand MPI

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

size_t mbedtls_mpi_bitlen ( const mbedtls_mpi * X )

Return the number of bits up to and including the most significant '1' bit'.

Note: Thus also the one-based index of the most significant '1' bit

Parameters:

X

MPI to use

int mbedtls_mpi_cmp_abs	(	const mbedtls_mpi *	X,
		const mbedtls_mpi *	Y
	)

Compare unsigned values.

Parameters:

	X	Left-hand MPI
	Y	Right-hand MPI

Returns:: 1 if |X| is greater than |Y|, -1 if |X| is lesser than |Y| or 0 if |X| is equal to |Y|

int mbedtls_mpi_cmp_int	(	const mbedtls_mpi *	X,
		mbedtls_mpi_sint	z
	)

Compare signed values.

Parameters:

	X	Left-hand MPI
	z	The integer value to compare to

Returns:: 1 if X is greater than z, -1 if X is lesser than z or 0 if X is equal to z

int mbedtls_mpi_cmp_mpi	(	const mbedtls_mpi *	X,
		const mbedtls_mpi *	Y
	)

Compare signed values.

Parameters:

	X	Left-hand MPI
	Y	Right-hand MPI

Returns:: 1 if X is greater than Y, -1 if X is lesser than Y or 0 if X is equal to Y

int mbedtls_mpi_copy	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	Y
	)

Copy the contents of Y into X.

Parameters:

	X	Destination MPI
	Y	Source MPI

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

int mbedtls_mpi_div_int	(	mbedtls_mpi *	Q,
		mbedtls_mpi *	R,
		const mbedtls_mpi *	A,
		mbedtls_mpi_sint	b
	)

Division by int: A = Q * b + R.

Parameters:

	Q	Destination MPI for the quotient
	R	Destination MPI for the rest value
	A	Left-hand MPI
	b	Integer to divide by

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed, MBEDTLS_ERR_MPI_DIVISION_BY_ZERO if b == 0

Note:: Either Q or R can be NULL.

int mbedtls_mpi_div_mpi	(	mbedtls_mpi *	Q,
		mbedtls_mpi *	R,
		const mbedtls_mpi *	A,
		const mbedtls_mpi *	B
	)

Division by mbedtls_mpi: A = Q * B + R.

Parameters:

	Q	Destination MPI for the quotient
	R	Destination MPI for the rest value
	A	Left-hand MPI
	B	Right-hand MPI

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed, MBEDTLS_ERR_MPI_DIVISION_BY_ZERO if B == 0

Note:: Either Q or R can be NULL.

int mbedtls_mpi_exp_mod	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	A,
		const mbedtls_mpi *	E,
		const mbedtls_mpi *	N,
		mbedtls_mpi *	_RR
	)

Sliding-window exponentiation: X = A^E mod N.

Parameters:

	X	Destination MPI
	A	Left-hand MPI
	E	Exponent MPI
	N	Modular MPI
	_RR	Speed-up MPI used for recalculations

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed, MBEDTLS_ERR_MPI_BAD_INPUT_DATA if N is negative or even or if E is negative

Note:: _RR is used to avoid re-computing R*R mod N across multiple calls, which speeds up things a bit. It can be set to NULL if the extra performance is unneeded.

int mbedtls_mpi_fill_random	(	mbedtls_mpi *	X,
		size_t	size,
		int()(void , unsigned char *, size_t)	f_rng,
		void *	p_rng
	)

Fill an MPI X with size bytes of random.

Parameters:

	X	Destination MPI
	size	Size in bytes
	f_rng	RNG function
	p_rng	RNG parameter

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

Note:: The bytes obtained from the PRNG are interpreted as a big-endian representation of an MPI; this can be relevant in applications like deterministic ECDSA.

void mbedtls_mpi_free ( mbedtls_mpi * X )

Unallocate one MPI.

Parameters:

X

One MPI to unallocate.

int mbedtls_mpi_gcd	(	mbedtls_mpi *	G,
		const mbedtls_mpi *	A,
		const mbedtls_mpi *	B
	)

Greatest common divisor: G = gcd(A, B).

Parameters:

	G	Destination MPI
	A	Left-hand MPI
	B	Right-hand MPI

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

int mbedtls_mpi_gen_prime	(	mbedtls_mpi *	X,
		size_t	nbits,
		int	dh_flag,
		int()(void , unsigned char *, size_t)	f_rng,
		void *	p_rng
	)

Prime number generation.

Parameters:

	X	Destination MPI
	nbits	Required size of X in bits ( 3 <= nbits <= MBEDTLS_MPI_MAX_BITS )
	dh_flag	If 1, then (X-1)/2 will be prime too
	f_rng	RNG function
	p_rng	RNG parameter

Returns:: 0 if successful (probably prime), MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed, MBEDTLS_ERR_MPI_BAD_INPUT_DATA if nbits is < 3

int mbedtls_mpi_get_bit	(	const mbedtls_mpi *	X,
		size_t	pos
	)

Get a specific bit from X.

Parameters:

	X	MPI to use
	pos	Zero-based index of the bit in X

Returns:: Either a 0 or a 1

int mbedtls_mpi_grow	(	mbedtls_mpi *	X,
		size_t	nblimbs
	)

Enlarge to the specified number of limbs.

Parameters:

	X	MPI to grow
	nblimbs	The target number of limbs

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

void mbedtls_mpi_init ( mbedtls_mpi * X )

Initialize one MPI (make internal references valid) This just makes it ready to be set or freed, but does not define a value for the MPI.

Parameters:

X

One MPI to initialize.

int mbedtls_mpi_inv_mod	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	A,
		const mbedtls_mpi *	N
	)

Modular inverse: X = A^-1 mod N.

Parameters:

	X	Destination MPI
	A	Left-hand MPI
	N	Right-hand MPI

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed, MBEDTLS_ERR_MPI_BAD_INPUT_DATA if N is <= 1, MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if A has no inverse mod N.

int mbedtls_mpi_is_prime	(	const mbedtls_mpi *	X,
		int()(void , unsigned char *, size_t)	f_rng,
		void *	p_rng
	)

Miller-Rabin primality test.

Parameters:

	X	MPI to check
	f_rng	RNG function
	p_rng	RNG parameter

Returns:: 0 if successful (probably prime), MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed, MBEDTLS_ERR_MPI_NOT_ACCEPTABLE if X is not prime

size_t mbedtls_mpi_lsb ( const mbedtls_mpi * X )

Return the number of zero-bits before the least significant '1' bit.

Note: Thus also the zero-based index of the least significant '1' bit

Parameters:

X

MPI to use

int mbedtls_mpi_lset	(	mbedtls_mpi *	X,
		mbedtls_mpi_sint	z
	)

Set value from integer.

Parameters:

	X	MPI to set
	z	Value to use

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

int mbedtls_mpi_mod_int	(	mbedtls_mpi_uint *	r,
		const mbedtls_mpi *	A,
		mbedtls_mpi_sint	b
	)

Modulo: r = A mod b.

Parameters:

	r	Destination mbedtls_mpi_uint
	A	Left-hand MPI
	b	Integer to divide by

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed, MBEDTLS_ERR_MPI_DIVISION_BY_ZERO if b == 0, MBEDTLS_ERR_MPI_NEGATIVE_VALUE if b < 0

int mbedtls_mpi_mod_mpi	(	mbedtls_mpi *	R,
		const mbedtls_mpi *	A,
		const mbedtls_mpi *	B
	)

Modulo: R = A mod B.

Parameters:

	R	Destination MPI for the rest value
	A	Left-hand MPI
	B	Right-hand MPI

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed, MBEDTLS_ERR_MPI_DIVISION_BY_ZERO if B == 0, MBEDTLS_ERR_MPI_NEGATIVE_VALUE if B < 0

int mbedtls_mpi_mul_int	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	A,
		mbedtls_mpi_uint	b
	)

Baseline multiplication: X = A * b.

Parameters:

	X	Destination MPI
	A	Left-hand MPI
	b	The unsigned integer value to multiply with

Note:: b is unsigned

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

int mbedtls_mpi_mul_mpi	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	A,
		const mbedtls_mpi *	B
	)

Baseline multiplication: X = A * B.

Parameters:

	X	Destination MPI
	A	Left-hand MPI
	B	Right-hand MPI

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

int mbedtls_mpi_read_binary	(	mbedtls_mpi *	X,
		const unsigned char *	buf,
		size_t	buflen
	)

Import X from unsigned binary data, big endian.

Parameters:

	X	Destination MPI
	buf	Input buffer
	buflen	Input buffer size

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

int mbedtls_mpi_read_string	(	mbedtls_mpi *	X,
		int	radix,
		const char *	s
	)

Import from an ASCII string.

Parameters:

	X	Destination MPI
	radix	Input numeric base
	s	Null-terminated string buffer

Returns:: 0 if successful, or a MBEDTLS_ERR_MPI_XXX error code

int mbedtls_mpi_safe_cond_assign	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	Y,
		unsigned char	assign
	)

Safe conditional assignement X = Y if assign is 1.

Parameters:

	X	MPI to conditionally assign to
	Y	Value to be assigned
	assign	1: perform the assignment, 0: keep X's original value

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed,

Note:: This function is equivalent to if( assign ) mbedtls_mpi_copy( X, Y ); except that it avoids leaking any information about whether the assignment was done or not (the above code may leak information through branch prediction and/or memory access patterns analysis).

int mbedtls_mpi_safe_cond_swap	(	mbedtls_mpi *	X,
		mbedtls_mpi *	Y,
		unsigned char	assign
	)

Safe conditional swap X <-> Y if swap is 1.

Parameters:

	X	First mbedtls_mpi value
	Y	Second mbedtls_mpi value
	assign	1: perform the swap, 0: keep X and Y's original values

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed,

Note:: This function is equivalent to if( assign ) mbedtls_mpi_swap( X, Y ); except that it avoids leaking any information about whether the assignment was done or not (the above code may leak information through branch prediction and/or memory access patterns analysis).

int mbedtls_mpi_self_test ( int verbose )

Checkup routine.

Returns:: 0 if successful, or 1 if the test failed

int mbedtls_mpi_set_bit	(	mbedtls_mpi *	X,
		size_t	pos,
		unsigned char	val
	)

Set a bit of X to a specific value of 0 or 1.

Note:: Will grow X if necessary to set a bit to 1 in a not yet existing limb. Will not grow if bit should be set to 0

Parameters:

	X	MPI to use
	pos	Zero-based index of the bit in X
	val	The value to set the bit to (0 or 1)

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed, MBEDTLS_ERR_MPI_BAD_INPUT_DATA if val is not 0 or 1

int mbedtls_mpi_shift_l	(	mbedtls_mpi *	X,
		size_t	count
	)

Left-shift: X <<= count.

Parameters:

	X	MPI to shift
	count	Amount to shift

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

int mbedtls_mpi_shift_r	(	mbedtls_mpi *	X,
		size_t	count
	)

Right-shift: X >>= count.

Parameters:

	X	MPI to shift
	count	Amount to shift

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

int mbedtls_mpi_shrink	(	mbedtls_mpi *	X,
		size_t	nblimbs
	)

Resize down, keeping at least the specified number of limbs.

Parameters:

	X	MPI to shrink
	nblimbs	The minimum number of limbs to keep

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

size_t mbedtls_mpi_size ( const mbedtls_mpi * X )

Return the total size in bytes.

Parameters:

X

MPI to use

int mbedtls_mpi_sub_abs	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	A,
		const mbedtls_mpi *	B
	)

Unsigned subtraction: X = |A| - |B|.

Parameters:

	X	Destination MPI
	A	Left-hand MPI
	B	Right-hand MPI

Returns:: 0 if successful, MBEDTLS_ERR_MPI_NEGATIVE_VALUE if B is greater than A

int mbedtls_mpi_sub_int	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	A,
		mbedtls_mpi_sint	b
	)

Signed subtraction: X = A - b.

Parameters:

	X	Destination MPI
	A	Left-hand MPI
	b	The integer value to subtract

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

int mbedtls_mpi_sub_mpi	(	mbedtls_mpi *	X,
		const mbedtls_mpi *	A,
		const mbedtls_mpi *	B
	)

Signed subtraction: X = A - B.

Parameters:

	X	Destination MPI
	A	Left-hand MPI
	B	Right-hand MPI

Returns:: 0 if successful, MBEDTLS_ERR_MPI_ALLOC_FAILED if memory allocation failed

void mbedtls_mpi_swap	(	mbedtls_mpi *	X,
		mbedtls_mpi *	Y
	)

Swap the contents of X and Y.

Parameters:

	X	First MPI value
	Y	Second MPI value

int mbedtls_mpi_write_binary	(	const mbedtls_mpi *	X,
		unsigned char *	buf,
		size_t	buflen
	)

Export X into unsigned binary data, big endian. Always fills the whole buffer, which will start with zeros if the number is smaller.

Parameters:

	X	Source MPI
	buf	Output buffer
	buflen	Output buffer size

Returns:: 0 if successful, MBEDTLS_ERR_MPI_BUFFER_TOO_SMALL if buf isn't large enough

int mbedtls_mpi_write_string	(	const mbedtls_mpi *	X,
		int	radix,
		char *	buf,
		size_t	buflen,
		size_t *	olen
	)

Export into an ASCII string.

Parameters:

	X	Source MPI
	radix	Output numeric base
	buf	Buffer to write the string to
	buflen	Length of buf
	olen	Length of the string written, including final NUL byte

Returns:: 0 if successful, or a MBEDTLS_ERR_MPI_XXX error code. *olen is always updated to reflect the amount of data that has (or would have) been written.

Note:: Call this function with buflen = 0 to obtain the minimum required buffer size in *olen.

bignum.h File Reference

Data Structures

Defines

Typedefs

Functions

Detailed Description

Define Documentation

Typedef Documentation

Function Documentation