scc::crypto::Bignum Class Reference

Big number. More...

#include <bignum.h>

Public Member Functions
	Bignum ()
	Construct and set to 0.
	Bignum (Bignum &&other)
	Move constructor.
Bignum &	operator= (Bignum &&other)
	Move assignment.
	Bignum (const Bignum &other)
	Copy constructor.
Bignum &	operator= (const Bignum &other)
	Copy assignment.
	Bignum (uint32_t w)
	Word constructor.
Bignum &	operator= (uint32_t w)
	Word assignment.
	Bignum (const void *loc, int len)
	Set to data.
void *	bn ()
	Bignum context for use by external services.
const void *	const_bn () const
	Bignum context for use by external services.
void	set_width (int)
	Set the number to a specified bit width.
void	set (uint32_t)
	Set to a word. More...
void	set (const void *, int)
	Set a positive integer from input bytes.
void	set_2sc (const void *, int)
	Set integer from twos complement input stream.
int	len () const
	Required length of get() output in bytes. More...
void	get (void *, int) const
	Octal (byte) output of a positive number. More...
int	len_2sc () const
	Get the length of octal output in twos complement form.
void	get_2sc (void *, int) const
	Octal (byte) output, in two's complement form. More...
void	copy (const Bignum &)
	Copy into this bignum.
void	move (Bignum &)
	Move into this bignum. More...
void	clear ()
	Clear and set to 0.
int	width () const
	Number of significant bits. More...
void	exp (const Bignum &)
	Exponent a^b.
void	exp (uint32_t b)
	Exponent a^b.
void	gcd (const Bignum &)
	Greatest common divisor for a and b.
void	gen_rand (int, bool=false, bool=false)
	Generate a random number of the specified bit width. More...
bool	is_prime (int=-1)
	Perform a Miller-Rabin prime test to test primality. More...
void	gen_prime (int)
	Generate a random pseudo-prime number of the specified bit width. More...
void	lshift (int)
	Left bit shift.
void	rshift (int)
	Right bit shift.
void	add (const Bignum &)
	Add a+b.
void	add (uint32_t b)
	Word add a+b.
void	sub (const Bignum &)
	Subtract a-b.
void	sub (uint32_t b)
	Subtract an integer.
void	mul (const Bignum &)
	Mulitply a*b.
void	mul (uint32_t b)
	Word multiply.
void	div (const Bignum &, Bignum *)
	Divide a/b. More...
void	div (uint32_t b, Bignum *rem)
	Divide a/b. More...
void	mod (const Bignum &)
	Modulus ab.
void	mod (uint32_t b)
	Word modulus.
void	negate ()
	Negate (change sign).
void	bit_not ()
	Bitwise not ~a.
void	bit_and (const Bignum &b)
	Bitwise not a&b.
void	bit_or (const Bignum &b)
	Bitwise or a|b.
void	bit_xor (const Bignum &b)
	Bitwise xor a^b.
bool	is_bit_set (int) const
	Is the bit set? More...
void	set_bit (int)
	Set a bit. More...
void	clear_bit (int)
	Clear a bit. More...
void	gcd (uint32_t b)
	Greatest common divisor of a and b.
bool	is_negative () const
	Is negative?
int	cmp (uint32_t w) const
	Arithmetic compare for an integer.
int	cmp (const Bignum &) const
	Arithmetic compare.
bool	operator== (const Bignum &o) const
	Equal operator.
bool	operator!= (const Bignum &o) const
	Not equal operator.
bool	operator< (const Bignum &o) const
	Less than operator.
bool	operator> (const Bignum &o) const
	Greater than operator.
bool	operator<= (const Bignum &o) const
	Less than equal operator.
bool	operator>= (const Bignum &o) const
	Greater than equal operator.
bool	operator== (uint32_t o) const
	Equal operator.
bool	operator!= (uint32_t o) const
	Not equal operator.
bool	operator< (uint32_t o) const
	Less than operator.
bool	operator> (uint32_t o) const
	Greater than operator.
bool	operator<= (uint32_t o) const
	Less than equal operator.
bool	operator>= (uint32_t o) const
	Greater than equal operator.
Bignum	operator<< (int shift) const
	Right shift operator.
Bignum &	operator<<= (int shift)
	Right shift assign operator.
Bignum	operator>> (int shift) const
	Right shift operator.
Bignum &	operator>>= (int shift)
	Right shift assign operator.
Bignum	operator+ (const Bignum &a) const
	Add operator.
Bignum	operator+= (const Bignum &a)
	Add assign operator.
Bignum	operator+ (uint32_t a) const
	Add operator.
Bignum	operator+= (uint32_t a)
	Add assign operator.
Bignum &	operator++ ()
	Prefix addition operator.
Bignum	operator++ (int d)
	Postfix addition operator.
Bignum	operator- ()
	Negation operator -a.
Bignum	operator- (const Bignum &a) const
	Subtract operator.
Bignum	operator-= (const Bignum &a)
	Subtract assign operator.
Bignum	operator- (uint32_t a) const
	Subtract operator.
Bignum	operator-= (uint32_t a)
	Subtract assign operator.
Bignum &	operator-- ()
	Prefix decrement.
Bignum	operator-- (int d)
	Postfix decrement.
Bignum	operator* (const Bignum &a) const
	Multiply operator.
Bignum	operator*= (const Bignum &a)
	Multiply assign operator.
Bignum	operator* (uint32_t a) const
	Multiply operator.
Bignum	operator*= (uint32_t a)
	Multiply assign operator.
Bignum	operator/ (const Bignum &a) const
	Divide operator.
Bignum	operator/= (const Bignum &a)
	Divide assign operator.
Bignum	operator/ (uint32_t a) const
	Divide operator.
Bignum	operator/= (uint32_t a)
	Divide assign operator.
Bignum	operator% (const Bignum &a) const
	Modulus operator.
Bignum	operator%= (const Bignum &a)
	Modulus assign operator.
Bignum	operator% (uint32_t a) const
	Modulus operator.
Bignum	operator%= (uint32_t a)
	Modulus assign operator.
Bignum	operator& (const Bignum &a) const
	And operator.
Bignum	operator&= (const Bignum &a)
	And assign operator.
Bignum	operator& (uint32_t a) const
	And operator.
Bignum	operator&= (uint32_t a)
	And assign operator.
Bignum	operator| (const Bignum &a) const
	Or operator.
Bignum	operator|= (const Bignum &a)
	Or assign operator.
Bignum	operator| (uint32_t a) const
	Or operator.
Bignum	operator|= (uint32_t a)
	Or assign operator.
Bignum	operator^ (const Bignum &a) const
	Xor operator.
Bignum	operator^= (const Bignum &a)
	Xor assign operator.
Bignum	operator^ (uint32_t a) const
	Xor operator.
Bignum	operator^= (uint32_t a)
	Xor assign operator.
Bignum	operator~ () const
	Not operator.
std::string	str (bool=false) const
	Return a string representation in decimal or hex. More...

Static Public Member Functions
static bool	is_prime (uint32_t w)
	Is prime for an integer.

Detailed Description

Big number.

Examples

crypto/unittest/bignum.cc, and scclib/crypto/unittest/der.cc.

Definition at line 58 of file bignum.h.

Member Function Documentation

clear_bit()

void scc::crypto::Bignum::clear_bit

(

int

)

Clear a bit.

Bits are 0 indexed.

Parameters

bit_number

bit to set, must be >= 0.

div() [1/2]

void scc::crypto::Bignum::div	(	const Bignum &	,
		Bignum *
	)

Divide a/b.

Optional remainder.

div() [2/2]

void scc::crypto::Bignum::div ( uint32_t  b, Bignum *  rem  )

inline

Divide a/b.

Optional remainder.

Definition at line 257 of file bignum.h.

gen_prime()

void scc::crypto::Bignum::gen_prime

(

int

)

Generate a random pseudo-prime number of the specified bit width.

Parameters

bit_width

The size of the prime in bits.

gen_rand()

void scc::crypto::Bignum::gen_rand	(	int	,
		bool	= false,
		bool	= false
	)

Generate a random number of the specified bit width.

A cryptographically strong number has the upper two bits set, so that the product of two such numbers will always have 2*bit_width size.

Parameters

bit_width	The size of the prime in bits, must be > 0. If strong, must be > 1.
strong	If this is true, generate a cryptographically strong number (top two bits are on).
odd	If this is true, generates an odd number.

get()

void scc::crypto::Bignum::get	(	void *	,
		int
	)		const

Octal (byte) output of a positive number.

Parameters

loc	data location
len	length of data

Throws an exception if the number is negative.

get_2sc()

void scc::crypto::Bignum::get_2sc	(	void *	,
		int
	)		const

Octal (byte) output, in two's complement form.

Returns the minimum number of bytes required.

Example:

128 bin 0000 0000 1000 0000 hex 00 80 127 bin 0111 1111 hex 7f -1 bin 1111 1111 hex ff -127 bin 1000 0001 hex 81 -128 bin 1000 0000 hex 80 -129 bin 1111 1111 0111 1111 hex ff 7f

Parameters

loc	data location
len	length of data

is_bit_set()

bool scc::crypto::Bignum::is_bit_set

(

int

)

const

Is the bit set?

Bits are 0 indexed.

Parameters

bit_number

bit to set, must be >= 0.

is_prime()

bool scc::crypto::Bignum::is_prime

(

int

= -1

)

Perform a Miller-Rabin prime test to test primality.

The default calculates primes with expected 1/10^80 probability of false positive.

Parameters

trials

Number of trials, <= 0 means calculate trials automatically.

len()

int scc::crypto::Bignum::len

(

)

const

Required length of get() output in bytes.

The number zero has length 1.

move()

void scc::crypto::Bignum::move

(

Bignum &

)

Move into this bignum.

The other bignum will be initialized and set to zero.

set()

void scc::crypto::Bignum::set

(

uint32_t

)

Set to a word.

This setter will not necessarily zero out all data.

set_bit()

void scc::crypto::Bignum::set_bit

(

int

)

Set a bit.

Bits are 0 indexed. Expands the number if necessary.

Parameters

bit_number

bit to set, must be >= 0.

str()

std::string scc::crypto::Bignum::str

(

bool

= false

)

const

Return a string representation in decimal or hex.

Parameters

hex	emit hexadecimal

width()

int scc::crypto::Bignum::width

(

)

const

Number of significant bits.

The number 0 has width 1.

---

The documentation for this class was generated from the following file:

• crypto/pub/crypto/bignum.h