Integer Class Reference

Multiple precision integer with arithmetic operations. More...

#include <integer.h>

Inheritance diagram for Integer:

Classes
class	DivideByZero
	Exception thrown when division by 0 is encountered. More...
class	OpenPGPDecodeErr
	Exception thrown when an error is encountered decoding an OpenPGP integer. More...
class	RandomNumberNotFound
	Exception thrown when a random number cannot be found that satisfies the condition. More...

ENUMS, EXCEPTIONS, and TYPEDEFS
enum	Sign { POSITIVE =0 , NEGATIVE =1 }
	Used internally to represent the integer. More...
enum	Signedness { UNSIGNED , SIGNED }
	Used when importing and exporting integers. More...
enum	RandomNumberType { ANY , PRIME }
	Properties of a random integer. More...

INPUT/OUTPUT
CRYPTOPP_DLL std::istream &	operator>> (std::istream &in, Integer &a)
	Extraction operator.
CRYPTOPP_DLL std::ostream &	operator<< (std::ostream &out, const Integer &a)
	Insertion operator.
CRYPTOPP_DLL friend Integer	a_times_b_mod_c (const Integer &x, const Integer &y, const Integer &m)
	Modular multiplication.
CRYPTOPP_DLL friend Integer	a_exp_b_mod_c (const Integer &x, const Integer &e, const Integer &m)
	Modular exponentiation.

CREATORS
	Integer ()
	Creates the zero integer.
	Integer (const Integer &t)
	copy constructor
	Integer (signed long value)
	Convert from signed long.
	Integer (Sign sign, lword value)
	Convert from lword.
	Integer (Sign sign, word highWord, word lowWord)
	Convert from two words.
	Integer (const char *str, ByteOrder order=BIG_ENDIAN_ORDER)
	Convert from a C-string.
	Integer (const wchar_t *str, ByteOrder order=BIG_ENDIAN_ORDER)
	Convert from a wide C-string.
	Integer (const byte *encodedInteger, size_t byteCount, Signedness sign=UNSIGNED, ByteOrder order=BIG_ENDIAN_ORDER)
	Convert from a big-endian byte array.
	Integer (BufferedTransformation &bt, size_t byteCount, Signedness sign=UNSIGNED, ByteOrder order=BIG_ENDIAN_ORDER)
	Convert from a big-endian array.
	Integer (BufferedTransformation &bt)
	Convert from a BER encoded byte array.
	Integer (RandomNumberGenerator &rng, size_t bitCount)
	Create a random integer.
	Integer (RandomNumberGenerator &rng, const Integer &min, const Integer &max, RandomNumberType rnType=ANY, const Integer &equiv=Zero(), const Integer &mod=One())
	Create a random integer of special form.
static const Integer &	Zero ()
	Integer representing 0.
static const Integer &	One ()
	Integer representing 1.
static const Integer &	Two ()
	Integer representing 2.
static Integer	Power2 (size_t e)
	Exponentiates to a power of 2.

ENCODE/DECODE
size_t	MinEncodedSize (Signedness sign=UNSIGNED) const
	Minimum number of bytes to encode this integer.
void	Encode (byte *output, size_t outputLen, Signedness sign=UNSIGNED) const
	Encode in big-endian format.
void	Encode (BufferedTransformation &bt, size_t outputLen, Signedness sign=UNSIGNED) const
	Encode in big-endian format.
void	DEREncode (BufferedTransformation &bt) const
	Encode in DER format.
void	DEREncodeAsOctetString (BufferedTransformation &bt, size_t length) const
	Encode absolute value as big-endian octet string.
size_t	OpenPGPEncode (byte *output, size_t bufferSize) const
	Encode absolute value in OpenPGP format.
size_t	OpenPGPEncode (BufferedTransformation &bt) const
	Encode absolute value in OpenPGP format.
void	Decode (const byte *input, size_t inputLen, Signedness sign=UNSIGNED)
	Decode from big-endian byte array.
void	Decode (BufferedTransformation &bt, size_t inputLen, Signedness sign=UNSIGNED)
	Decode nonnegative value from big-endian byte array.
void	BERDecode (const byte *input, size_t inputLen)
	Decode from BER format.
void	BERDecode (BufferedTransformation &bt)
	Decode from BER format.
void	BERDecodeAsOctetString (BufferedTransformation &bt, size_t length)
	Decode nonnegative value from big-endian octet string.
void	OpenPGPDecode (const byte *input, size_t inputLen)
	Decode from OpenPGP format.
void	OpenPGPDecode (BufferedTransformation &bt)
	Decode from OpenPGP format.

ACCESSORS
bool	IsConvertableToLong () const
	Determines if the Integer is convertable to Long.
signed long	ConvertToLong () const
	Convert the Integer to Long.
unsigned int	BitCount () const
	Determines the number of bits required to represent the Integer.
unsigned int	ByteCount () const
	Determines the number of bytes required to represent the Integer.
unsigned int	WordCount () const
	Determines the number of words required to represent the Integer.
bool	GetBit (size_t i) const
	Provides the i-th bit of the Integer.
byte	GetByte (size_t i) const
	Provides the i-th byte of the Integer.
lword	GetBits (size_t i, size_t n) const
	Provides the low order bits of the Integer.
bool	IsZero () const
	Determines if the Integer is 0.
bool	NotZero () const
	Determines if the Integer is non-0.
bool	IsNegative () const
	Determines if the Integer is negative.
bool	NotNegative () const
	Determines if the Integer is non-negative.
bool	IsPositive () const
	Determines if the Integer is positive.
bool	NotPositive () const
	Determines if the Integer is non-positive.
bool	IsEven () const
	Determines if the Integer is even parity.
bool	IsOdd () const
	Determines if the Integer is odd parity.

MANIPULATORS
Integer &	operator= (const Integer &t)
	Assignment.
Integer &	operator+= (const Integer &t)
	Addition Assignment.
Integer &	operator-= (const Integer &t)
	Subtraction Assignment.
Integer &	operator*= (const Integer &t)
	Multiplication Assignment.
Integer &	operator/= (const Integer &t)
	Division Assignment.
Integer &	operator%= (const Integer &t)
	Remainder Assignment.
Integer &	operator/= (word t)
	Division Assignment.
Integer &	operator%= (word t)
	Remainder Assignment.
Integer &	operator<<= (size_t n)
	Left-shift Assignment.
Integer &	operator>>= (size_t n)
	Right-shift Assignment.
Integer &	operator&= (const Integer &t)
	Bitwise AND Assignment.
Integer &	operator|= (const Integer &t)
	Bitwise OR Assignment.
Integer &	operator^= (const Integer &t)
	Bitwise XOR Assignment.
void	Randomize (RandomNumberGenerator &rng, size_t bitCount)
	Set this Integer to random integer.
void	Randomize (RandomNumberGenerator &rng, const Integer &min, const Integer &max)
	Set this Integer to random integer.
bool	Randomize (RandomNumberGenerator &rng, const Integer &min, const Integer &max, RandomNumberType rnType, const Integer &equiv=Zero(), const Integer &mod=One())
	Set this Integer to random integer of special form.
bool	GenerateRandomNoThrow (RandomNumberGenerator &rng, const NameValuePairs &params=g_nullNameValuePairs)
	Generate a random number.
void	GenerateRandom (RandomNumberGenerator &rng, const NameValuePairs &params=g_nullNameValuePairs)
	Generate a random number.
void	SetBit (size_t n, bool value=1)
	Set the n-th bit to value.
void	SetByte (size_t n, byte value)
	Set the n-th byte to value.
void	Negate ()
	Reverse the Sign of the Integer.
void	SetPositive ()
	Sets the Integer to positive.
void	SetNegative ()
	Sets the Integer to negative.
void	swap (Integer &a)
	Swaps this Integer with another Integer.

UNARY OPERATORS
bool	operator! () const
	Negation.
Integer	operator+ () const
	Addition.
Integer	operator- () const
	Subtraction.
Integer &	operator++ ()
	Pre-increment.
Integer &	operator-- ()
	Pre-decrement.
Integer	operator++ (int)
	Post-increment.
Integer	operator-- (int)
	Post-decrement.

BINARY OPERATORS
int	Compare (const Integer &a) const
	Perform signed comparison.
Integer	Plus (const Integer &b) const
	Addition.
Integer	Minus (const Integer &b) const
	Subtraction.
Integer	Times (const Integer &b) const
	Multiplication.
Integer	DividedBy (const Integer &b) const
	Division.
Integer	Modulo (const Integer &b) const
	Remainder.
Integer	DividedBy (word b) const
	Division.
word	Modulo (word b) const
	Remainder.
Integer	And (const Integer &t) const
	Bitwise AND.
Integer	Or (const Integer &t) const
	Bitwise OR.
Integer	Xor (const Integer &t) const
	Bitwise XOR.
Integer	operator>> (size_t n) const
	Right-shift.
Integer	operator<< (size_t n) const
	Left-shift.

OTHER ARITHMETIC FUNCTIONS
Integer	AbsoluteValue () const
	Retrieve the absolute value of this integer.
Integer	Doubled () const
	Add this integer to itself.
Integer	Squared () const
	Multiply this integer by itself.
Integer	SquareRoot () const
	Extract square root.
bool	IsSquare () const
	Determine whether this integer is a perfect square.
bool	IsUnit () const
	Determine if 1 or -1.
Integer	MultiplicativeInverse () const
	Calculate multiplicative inverse.
Integer	InverseMod (const Integer &n) const
	Calculate multiplicative inverse.
word	InverseMod (word n) const
	Calculate multiplicative inverse.
static void	Divide (Integer &r, Integer &q, const Integer &a, const Integer &d)
	Extended Division.
static void	Divide (word &r, Integer &q, const Integer &a, word d)
	Extended Division.
static void	DivideByPowerOf2 (Integer &r, Integer &q, const Integer &a, unsigned int n)
	Extended Division.
static Integer	Gcd (const Integer &a, const Integer &n)
	Calculate greatest common divisor.

Additional Inherited Members
Public Member Functions inherited from ASN1Object
virtual void	BEREncode (BufferedTransformation &bt) const
	Encode this object into a BufferedTransformation.

Detailed Description

Multiple precision integer with arithmetic operations.

The Integer class can represent positive and negative integers with absolute value less than (256**sizeof(word))^{(256**sizeof(int))}.

Internally, the library uses a sign magnitude representation, and the class has two data members. The first is a IntegerSecBlock (a SecBlock<word>) and it is used to hold the representation. The second is a Sign (an enumeration), and it is used to track the sign of the Integer.

For details on how the Integer class initializes its function pointers using InitializeInteger and how it creates Integer::Zero(), Integer::One(), and Integer::Two(), then see the comments at the top of integer.cpp.

Since

Crypto++ 1.0

Definition at line 49 of file integer.h.

Member Enumeration Documentation

Sign

enum Integer::Sign

Used internally to represent the integer.

Sign is used internally to represent the integer. It is also used in a few API functions.

See also

SetPositive(), SetNegative(), Signedness

Enumerator
POSITIVE	the value is positive or 0
NEGATIVE	the value is negative

Definition at line 73 of file integer.h.

Signedness

enum Integer::Signedness

Used when importing and exporting integers.

Signedness is usually used in API functions.

See also

Sign

Enumerator
UNSIGNED	an unsigned value
SIGNED	a signed value

Definition at line 83 of file integer.h.

RandomNumberType

enum Integer::RandomNumberType

Properties of a random integer.

Enumerator
ANY	a number with no special properties
PRIME	a number which is probabilistically prime

Definition at line 91 of file integer.h.

Constructor & Destructor Documentation

Integer() [1/9]

Integer::Integer	(	Sign	sign,
		lword	value )

Convert from lword.

Parameters

sign	enumeration indicating Sign
value	the long word

Integer() [2/9]

Integer::Integer	(	Sign	sign,
		word	highWord,
		word	lowWord )

Convert from two words.

Parameters

sign	enumeration indicating Sign
highWord	the high word
lowWord	the low word

Integer() [3/9]

Integer::Integer ( const char * str, ByteOrder order = BIG_ENDIAN_ORDER )

explicit

Convert from a C-string.

Parameters

str	C-string value
order	the ByteOrder of the string to be processed

str can be in base 8, 10, or 16. Base is determined by a case insensitive suffix of 'o' (8), '.' (10), or 'h' (16). No suffix means base 10.

Byte order was added at Crypto++ 5.7 to allow use of little-endian integers with curve25519, Poly1305 and Microsoft CAPI.

Integer() [4/9]

Integer::Integer ( const wchar_t * str, ByteOrder order = BIG_ENDIAN_ORDER )

explicit

Convert from a wide C-string.

Parameters

str	wide C-string value
order	the ByteOrder of the string to be processed

str can be in base 8, 10, or 16. Base is determined by a case insensitive suffix of 'o' (8), '.' (10), or 'h' (16). No suffix means base 10.

Byte order was added at Crypto++ 5.7 to allow use of little-endian integers with curve25519, Poly1305 and Microsoft CAPI.

Integer() [5/9]

Integer::Integer	(	const byte *	encodedInteger,
		size_t	byteCount,
		Signedness	sign = UNSIGNED,
		ByteOrder	order = BIG_ENDIAN_ORDER )

Convert from a big-endian byte array.

Parameters

encodedInteger	big-endian byte array
byteCount	length of the byte array
sign	enumeration indicating Signedness
order	the ByteOrder of the array to be processed

Byte order was added at Crypto++ 5.7 to allow use of little-endian integers with curve25519, Poly1305 and Microsoft CAPI.

Integer() [6/9]

Integer::Integer	(	BufferedTransformation &	bt,
		size_t	byteCount,
		Signedness	sign = UNSIGNED,
		ByteOrder	order = BIG_ENDIAN_ORDER )

Convert from a big-endian array.

Parameters

bt	BufferedTransformation object with big-endian byte array
byteCount	length of the byte array
sign	enumeration indicating Signedness
order	the ByteOrder of the data to be processed

Byte order was added at Crypto++ 5.7 to allow use of little-endian integers with curve25519, Poly1305 and Microsoft CAPI.

Integer() [7/9]

Integer::Integer ( BufferedTransformation & bt )

explicit

Convert from a BER encoded byte array.

Parameters

bt	BufferedTransformation object with BER encoded byte array

Integer() [8/9]

Integer::Integer	(	RandomNumberGenerator &	rng,
		size_t	bitCount )

Create a random integer.

Parameters

rng	RandomNumberGenerator used to generate material
bitCount	the number of bits in the resulting integer

The random integer created is uniformly distributed over [0, 2bitCount].

Integer() [9/9]

Integer::Integer	(	RandomNumberGenerator &	rng,
		const Integer &	min,
		const Integer &	max,
		RandomNumberType	rnType = ANY,
		const Integer &	equiv = Zero(),
		const Integer &	mod = One() )

Create a random integer of special form.

Parameters

rng	RandomNumberGenerator used to generate material
min	the minimum value
max	the maximum value
rnType	RandomNumberType to specify the type
equiv	the equivalence class based on the parameter mod
mod	the modulus used to reduce the equivalence class

Exceptions

RandomNumberNotFound

if the set is empty.

Ideally, the random integer created should be uniformly distributed over {x | min <= x <= max and x is of rnType and x % mod == equiv}. However the actual distribution may not be uniform because sequential search is used to find an appropriate number from a random starting point.

May return (with very small probability) a pseudoprime when a prime is requested and max > lastSmallPrime*lastSmallPrime. lastSmallPrime is declared in nbtheory.h.

Member Function Documentation

Zero()

static const Integer & Integer::Zero ( )

static

Integer representing 0.

Returns

an Integer representing 0

Zero() avoids calling constructors for frequently used integers

One()

static const Integer & Integer::One ( )

static

Integer representing 1.

Returns

an Integer representing 1

One() avoids calling constructors for frequently used integers

Two()

static const Integer & Integer::Two ( )

static

Integer representing 2.

Returns

an Integer representing 2

Two() avoids calling constructors for frequently used integers

Power2()

static Integer Integer::Power2 ( size_t e )

static

Exponentiates to a power of 2.

Returns

the Integer 2^e

See also

a_times_b_mod_c() and a_exp_b_mod_c()

MinEncodedSize()

size_t Integer::MinEncodedSize

(

Signedness

sign = UNSIGNED

)

const

Minimum number of bytes to encode this integer.

Parameters

sign	enumeration indicating Signedness

Note

The MinEncodedSize() of 0 is 1.

Encode() [1/2]

void Integer::Encode	(	byte *	output,
		size_t	outputLen,
		Signedness	sign = UNSIGNED ) const

Encode in big-endian format.

Parameters

output	big-endian byte array
outputLen	length of the byte array
sign	enumeration indicating Signedness

Unsigned means encode absolute value, signed means encode two's complement if negative.

outputLen can be used to ensure an Integer is encoded to an exact size (rather than a minimum size). An exact size is useful, for example, when encoding to a field element size.

Encode() [2/2]

void Integer::Encode	(	BufferedTransformation &	bt,
		size_t	outputLen,
		Signedness	sign = UNSIGNED ) const

Encode in big-endian format.

Parameters

bt	BufferedTransformation object
outputLen	length of the encoding
sign	enumeration indicating Signedness

Unsigned means encode absolute value, signed means encode two's complement if negative.

outputLen can be used to ensure an Integer is encoded to an exact size (rather than a minimum size). An exact size is useful, for example, when encoding to a field element size.

DEREncode()

void Integer::DEREncode ( BufferedTransformation & bt ) const

virtual

Encode in DER format.

Parameters

bt	BufferedTransformation object

Encodes the Integer using Distinguished Encoding Rules The result is placed into a BufferedTransformation object

Implements ASN1Object.

DEREncodeAsOctetString()

void Integer::DEREncodeAsOctetString	(	BufferedTransformation &	bt,
		size_t	length ) const

Encode absolute value as big-endian octet string.

Parameters

bt	BufferedTransformation object
length	the number of mytes to decode

OpenPGPEncode() [1/2]

size_t Integer::OpenPGPEncode	(	byte *	output,
		size_t	bufferSize ) const

Encode absolute value in OpenPGP format.

Parameters

output	big-endian byte array
bufferSize	length of the byte array

Returns

length of the output

OpenPGPEncode places result into the buffer and returns the number of bytes used for the encoding

OpenPGPEncode() [2/2]

size_t Integer::OpenPGPEncode

(

BufferedTransformation &

bt

)

const

Encode absolute value in OpenPGP format.

Parameters

bt	BufferedTransformation object

Returns

length of the output

OpenPGPEncode places result into a BufferedTransformation object and returns the number of bytes used for the encoding

Decode() [1/2]

void Integer::Decode	(	const byte *	input,
		size_t	inputLen,
		Signedness	sign = UNSIGNED )

Decode from big-endian byte array.

Parameters

input	big-endian byte array
inputLen	length of the byte array
sign	enumeration indicating Signedness

Decode() [2/2]

void Integer::Decode	(	BufferedTransformation &	bt,
		size_t	inputLen,
		Signedness	sign = UNSIGNED )

Decode nonnegative value from big-endian byte array.

Parameters

bt	BufferedTransformation object
inputLen	length of the byte array
sign	enumeration indicating Signedness

Note

bt.MaxRetrievable() >= inputLen.

BERDecode() [1/2]

void Integer::BERDecode	(	const byte *	input,
		size_t	inputLen )

Decode from BER format.

Parameters

input	big-endian byte array
inputLen	length of the byte array

BERDecode() [2/2]

void Integer::BERDecode ( BufferedTransformation & bt )

virtual

Decode from BER format.

Parameters

bt	BufferedTransformation object

Implements ASN1Object.

BERDecodeAsOctetString()

void Integer::BERDecodeAsOctetString	(	BufferedTransformation &	bt,
		size_t	length )

Decode nonnegative value from big-endian octet string.

Parameters

bt	BufferedTransformation object
length	length of the byte array

OpenPGPDecode() [1/2]

void Integer::OpenPGPDecode	(	const byte *	input,
		size_t	inputLen )

Decode from OpenPGP format.

Parameters

input	big-endian byte array
inputLen	length of the byte array

OpenPGPDecode() [2/2]

void Integer::OpenPGPDecode

(

BufferedTransformation &

bt

)

Decode from OpenPGP format.

Parameters

bt	BufferedTransformation object

IsConvertableToLong()

bool Integer::IsConvertableToLong

(

)

const

Determines if the Integer is convertable to Long.

Returns

true if *this can be represented as a signed long

See also

ConvertToLong()

ConvertToLong()

signed long Integer::ConvertToLong

(

)

const

Convert the Integer to Long.

Returns

equivalent signed long if possible, otherwise undefined

See also

IsConvertableToLong()

BitCount()

unsigned int Integer::BitCount

(

)

const

Determines the number of bits required to represent the Integer.

Returns

number of significant bits

BitCount is calculated as floor(log2(abs(*this))) + 1.

ByteCount()

unsigned int Integer::ByteCount

(

)

const

Determines the number of bytes required to represent the Integer.

Returns

number of significant bytes

ByteCount is calculated as ceiling(BitCount()/8).

WordCount()

unsigned int Integer::WordCount

(

)

const

Determines the number of words required to represent the Integer.

Returns

number of significant words

WordCount is calculated as ceiling(ByteCount()/sizeof(word)).

GetBit()

bool Integer::GetBit

(

size_t

i

)

const

Provides the i-th bit of the Integer.

Returns

the i-th bit, i=0 being the least significant bit

GetByte()

byte Integer::GetByte

(

size_t

i

)

const

Provides the i-th byte of the Integer.

Returns

the i-th byte

GetBits()

lword Integer::GetBits	(	size_t	i,
		size_t	n ) const

Provides the low order bits of the Integer.

Returns

n lowest bits of *this >> i

IsZero()

bool Integer::IsZero ( ) const

inline

Determines if the Integer is 0.

Returns

true if the Integer is 0, false otherwise

Definition at line 335 of file integer.h.

NotZero()

bool Integer::NotZero ( ) const

inline

Determines if the Integer is non-0.

Returns

true if the Integer is non-0, false otherwise

Definition at line 338 of file integer.h.

IsNegative()

bool Integer::IsNegative ( ) const

inline

Determines if the Integer is negative.

Returns

true if the Integer is negative, false otherwise

Definition at line 341 of file integer.h.

NotNegative()

bool Integer::NotNegative ( ) const

inline

Determines if the Integer is non-negative.

Returns

true if the Integer is non-negative, false otherwise

Definition at line 344 of file integer.h.

IsPositive()

bool Integer::IsPositive ( ) const

inline

Determines if the Integer is positive.

Returns

true if the Integer is positive, false otherwise

Definition at line 347 of file integer.h.

NotPositive()

bool Integer::NotPositive ( ) const

inline

Determines if the Integer is non-positive.

Returns

true if the Integer is non-positive, false otherwise

Definition at line 350 of file integer.h.

IsEven()

bool Integer::IsEven ( ) const

inline

Determines if the Integer is even parity.

Returns

true if the Integer is even, false otherwise

Definition at line 353 of file integer.h.

IsOdd()

bool Integer::IsOdd ( ) const

inline

Determines if the Integer is odd parity.

Returns

true if the Integer is odd, false otherwise

Definition at line 356 of file integer.h.

operator=()

Integer & Integer::operator=

(

const Integer &

t

)

Assignment.

Parameters

t	the other Integer

Returns

the result of assignment

operator+=()

Integer & Integer::operator+=

(

const Integer &

t

)

Addition Assignment.

Parameters

t	the other Integer

Returns

the result of *this + t

operator-=()

Integer & Integer::operator-=

(

const Integer &

t

)

Subtraction Assignment.

Parameters

t	the other Integer

Returns

the result of *this - t

operator*=()

Integer & Integer::operator*= ( const Integer & t )

inline

Multiplication Assignment.

Parameters

t	the other Integer

Returns

the result of *this * t

See also

a_times_b_mod_c() and a_exp_b_mod_c()

Definition at line 377 of file integer.h.

operator/=() [1/2]

Integer & Integer::operator/= ( const Integer & t )

inline

Division Assignment.

Parameters

t	the other Integer

Returns

the result of *this / t

Definition at line 381 of file integer.h.

operator%=() [1/2]

Integer & Integer::operator%= ( const Integer & t )

inline

Remainder Assignment.

Parameters

t	the other Integer

Returns

the result of *this % t

See also

a_times_b_mod_c() and a_exp_b_mod_c()

Definition at line 386 of file integer.h.

operator/=() [2/2]

Integer & Integer::operator/= ( word t )

inline

Division Assignment.

Parameters

t	the other word

Returns

the result of *this / t

Definition at line 390 of file integer.h.

operator%=() [2/2]

Integer & Integer::operator%= ( word t )

inline

Remainder Assignment.

Parameters

t	the other word

Returns

the result of *this % t

See also

a_times_b_mod_c() and a_exp_b_mod_c()

Definition at line 395 of file integer.h.

operator<<=()

Integer & Integer::operator<<=

(

size_t

n

)

Left-shift Assignment.

Parameters

n	number of bits to shift

Returns

reference to this Integer

operator>>=()

Integer & Integer::operator>>=

(

size_t

n

)

Right-shift Assignment.

Parameters

n	number of bits to shift

Returns

reference to this Integer

operator&=()

Integer & Integer::operator&=

(

const Integer &

t

)

Bitwise AND Assignment.

Parameters

t	the other Integer

Returns

the result of *this & t

operator&=() performs a bitwise AND on *this. Missing bits are truncated at the most significant bit positions, so the result is as small as the smaller of the operands.

Internally, Crypto++ uses a sign-magnitude representation. The library does not attempt to interpret bits, and the result is always POSITIVE. If needed, the integer should be converted to a 2's compliment representation before performing the operation.

Since

Crypto++ 6.0

operator|=()

Integer & Integer::operator|=

(

const Integer &

t

)

Bitwise OR Assignment.

Parameters

t	the second Integer

Returns

the result of *this | t

operator|=() performs a bitwise OR on *this. Missing bits are shifted in at the most significant bit positions, so the result is as large as the larger of the operands.

Internally, Crypto++ uses a sign-magnitude representation. The library does not attempt to interpret bits, and the result is always POSITIVE. If needed, the integer should be converted to a 2's compliment representation before performing the operation.

Since

Crypto++ 6.0

operator^=()

Integer & Integer::operator^=

(

const Integer &

t

)

Bitwise XOR Assignment.

Parameters

t	the other Integer

Returns

the result of *this ^ t

operator^=() performs a bitwise XOR on *this. Missing bits are shifted in at the most significant bit positions, so the result is as large as the larger of the operands.

Internally, Crypto++ uses a sign-magnitude representation. The library does not attempt to interpret bits, and the result is always POSITIVE. If needed, the integer should be converted to a 2's compliment representation before performing the operation.

Since

Crypto++ 6.0

Randomize() [1/3]

void Integer::Randomize	(	RandomNumberGenerator &	rng,
		size_t	bitCount )

Set this Integer to random integer.

Parameters

rng	RandomNumberGenerator used to generate material
bitCount	the number of bits in the resulting integer

The random integer created is uniformly distributed over [0, 2bitCount].

Note

If bitCount is 0, then this Integer is set to 0 (and not 0 or 1).

Randomize() [2/3]

void Integer::Randomize	(	RandomNumberGenerator &	rng,
		const Integer &	min,
		const Integer &	max )

Set this Integer to random integer.

Parameters

rng	RandomNumberGenerator used to generate material
min	the minimum value
max	the maximum value

The random integer created is uniformly distributed over [min, max].

Randomize() [3/3]

bool Integer::Randomize	(	RandomNumberGenerator &	rng,
		const Integer &	min,
		const Integer &	max,
		RandomNumberType	rnType,
		const Integer &	equiv = Zero(),
		const Integer &	mod = One() )

Set this Integer to random integer of special form.

Parameters

rng	RandomNumberGenerator used to generate material
min	the minimum value
max	the maximum value
rnType	RandomNumberType to specify the type
equiv	the equivalence class based on the parameter mod
mod	the modulus used to reduce the equivalence class

Exceptions

RandomNumberNotFound

if the set is empty.

Ideally, the random integer created should be uniformly distributed over {x | min <= x <= max and x is of rnType and x % mod == equiv}. However the actual distribution may not be uniform because sequential search is used to find an appropriate number from a random starting point.

May return (with very small probability) a pseudoprime when a prime is requested and max > lastSmallPrime*lastSmallPrime. lastSmallPrime is declared in nbtheory.h.

GenerateRandomNoThrow()

bool Integer::GenerateRandomNoThrow	(	RandomNumberGenerator &	rng,
		const NameValuePairs &	params = g_nullNameValuePairs )

Generate a random number.

Parameters

rng	RandomNumberGenerator used to generate material
params	additional parameters that cannot be passed directly to the function

Returns

true if a random number was generated, false otherwise

GenerateRandomNoThrow attempts to generate a random number according to the parameters specified in params. The function does not throw RandomNumberNotFound.

The example below generates a prime number using NameValuePairs that Integer class recognizes. The names are not provided in argnames.h.

   AutoSeededRandomPool prng;
   AlgorithmParameters params = MakeParameters("BitLength", 2048)
                                              ("RandomNumberType", Integer::PRIME);
   Integer x;
   if (x.GenerateRandomNoThrow(prng, params) == false)
       throw std::runtime_error("Failed to generate prime number");

GenerateRandom()

void Integer::GenerateRandom ( RandomNumberGenerator & rng, const NameValuePairs & params = g_nullNameValuePairs )

inline

Generate a random number.

Parameters

rng	RandomNumberGenerator used to generate material
params	additional parameters that cannot be passed directly to the function

Exceptions

RandomNumberNotFound

if a random number is not found

GenerateRandom attempts to generate a random number according to the parameters specified in params.

The example below generates a prime number using NameValuePairs that Integer class recognizes. The names are not provided in argnames.h.

   AutoSeededRandomPool prng;
   AlgorithmParameters params = MakeParameters("BitLength", 2048)
                                              ("RandomNumberType", Integer::PRIME);
   Integer x;
   try { x.GenerateRandom(prng, params); }
   catch (RandomNumberNotFound&) { x = -1; }

Definition at line 509 of file integer.h.

SetBit()

void Integer::SetBit	(	size_t	n,
		bool	value = 1 )

Set the n-th bit to value.

0-based numbering.

SetByte()

void Integer::SetByte	(	size_t	n,
		byte	value )

Set the n-th byte to value.

0-based numbering.

SetPositive()

void Integer::SetPositive ( )

inline

Sets the Integer to positive.

Definition at line 527 of file integer.h.

SetNegative()

void Integer::SetNegative ( )

inline

Sets the Integer to negative.

Definition at line 530 of file integer.h.

operator+()

Integer Integer::operator+ ( ) const

inline

Addition.

Definition at line 541 of file integer.h.

operator++()

Integer Integer::operator++ ( int )

inline

Post-increment.

Definition at line 549 of file integer.h.

operator--()

Integer Integer::operator-- ( int )

inline

Post-decrement.

Definition at line 551 of file integer.h.

Compare()

int Integer::Compare

(

const Integer &

a

)

const

Perform signed comparison.

Parameters

a	the Integer to compare

Return values

-1	if *this < a
0	if *this = a
1	if *this > a

Times()

Integer Integer::Times

(

const Integer &

b

)

const

Multiplication.

See also

a_times_b_mod_c() and a_exp_b_mod_c()

Modulo() [1/2]

Integer Integer::Modulo

(

const Integer &

b

)

const

Remainder.

See also

a_times_b_mod_c() and a_exp_b_mod_c()

Modulo() [2/2]

word Integer::Modulo

(

word

b

)

const

Remainder.

See also

a_times_b_mod_c() and a_exp_b_mod_c()

And()

Integer Integer::And

(

const Integer &

t

)

const

Bitwise AND.

Parameters

t	the other Integer

Returns

the result of *this & t

And() performs a bitwise AND on the operands. Missing bits are truncated at the most significant bit positions, so the result is as small as the smaller of the operands.

Internally, Crypto++ uses a sign-magnitude representation. The library does not attempt to interpret bits, and the result is always POSITIVE. If needed, the integer should be converted to a 2's compliment representation before performing the operation.

Since

Crypto++ 6.0

Or()

Integer Integer::Or

(

const Integer &

t

)

const

Bitwise OR.

Parameters

t	the other Integer

Returns

the result of *this | t

Or() performs a bitwise OR on the operands. Missing bits are shifted in at the most significant bit positions, so the result is as large as the larger of the operands.

Internally, Crypto++ uses a sign-magnitude representation. The library does not attempt to interpret bits, and the result is always POSITIVE. If needed, the integer should be converted to a 2's compliment representation before performing the operation.

Since

Crypto++ 6.0

Xor()

Integer Integer::Xor

(

const Integer &

t

)

const

Bitwise XOR.

Parameters

t	the other Integer

Returns

the result of *this ^ t

Xor() performs a bitwise XOR on the operands. Missing bits are shifted in at the most significant bit positions, so the result is as large as the larger of the operands.

Internally, Crypto++ uses a sign-magnitude representation. The library does not attempt to interpret bits, and the result is always POSITIVE. If needed, the integer should be converted to a 2's compliment representation before performing the operation.

Since

Crypto++ 6.0

operator>>()

Integer Integer::operator>> ( size_t n ) const

inline

Right-shift.

Definition at line 621 of file integer.h.

operator<<()

Integer Integer::operator<< ( size_t n ) const

inline

Left-shift.

Definition at line 623 of file integer.h.

Doubled()

Integer Integer::Doubled ( ) const

inline

Add this integer to itself.

Definition at line 631 of file integer.h.

Squared()

Integer Integer::Squared ( ) const

inline

Multiply this integer by itself.

See also

a_times_b_mod_c() and a_exp_b_mod_c()

Definition at line 634 of file integer.h.

SquareRoot()

Integer Integer::SquareRoot

(

)

const

Extract square root.

if negative return 0, else return floor of square root

IsUnit()

bool Integer::IsUnit

(

)

const

Determine if 1 or -1.

Returns

true if this integer is 1 or -1, false otherwise

MultiplicativeInverse()

Integer Integer::MultiplicativeInverse

(

)

const

Calculate multiplicative inverse.

Returns

MultiplicativeInverse inverse if 1 or -1, otherwise return 0.

Divide() [1/2]

static void Integer::Divide ( Integer & r, Integer & q, const Integer & a, const Integer & d )

static

Extended Division.

Parameters

r	a reference for the remainder
q	a reference for the quotient
a	reference to the dividend
d	reference to the divisor

Divide calculates r and q such that (a == d*q + r) && (0 <= r < abs(d)).

Divide() [2/2]

static void Integer::Divide ( word & r, Integer & q, const Integer & a, word d )

static

Extended Division.

Parameters

r	a reference for the remainder
q	a reference for the quotient
a	reference to the dividend
d	reference to the divisor

Divide calculates r and q such that (a == d*q + r) && (0 <= r < abs(d)). This overload uses a faster division algorithm because the divisor is short.

DivideByPowerOf2()

static void Integer::DivideByPowerOf2 ( Integer & r, Integer & q, const Integer & a, unsigned int n )

static

Extended Division.

Parameters

r	a reference for the remainder
q	a reference for the quotient
a	reference to the dividend
n	reference to the divisor

DivideByPowerOf2 calculates r and q such that (a == d*q + r) && (0 <= r < abs(d)). It returns same result as Divide(r, q, a, Power2(n)), but faster. This overload uses a faster division algorithm because the divisor is a power of 2.

Gcd()

static Integer Integer::Gcd ( const Integer & a, const Integer & n )

static

Calculate greatest common divisor.

Parameters

a	reference to the first number
n	reference to the secind number

Returns

the greatest common divisor a and n.

InverseMod() [1/2]

Integer Integer::InverseMod

(

const Integer &

n

)

const

Calculate multiplicative inverse.

Parameters

n	reference to the modulus

Returns

an Integer *this % n.

InverseMod returns the multiplicative inverse of the Integer *this modulo the Integer n. If no Integer exists then Integer 0 is returned.

See also

a_times_b_mod_c() and a_exp_b_mod_c()

InverseMod() [2/2]

word Integer::InverseMod

(

word

n

)

const

Calculate multiplicative inverse.

Parameters

n	the modulus

Returns

a word *this % n.

InverseMod returns the multiplicative inverse of the Integer *this modulo the word n. If no Integer exists then word 0 is returned.

See also

a_times_b_mod_c() and a_exp_b_mod_c()

Friends And Related Symbol Documentation

operator>>

CRYPTOPP_DLL std::istream & operator>> ( std::istream & in, Integer & a )

friend

Extraction operator.

Parameters

in	reference to a std::istream
a	reference to an Integer

Returns

reference to a std::istream reference

operator<<

CRYPTOPP_DLL std::ostream & operator<< ( std::ostream & out, const Integer & a )

friend

Insertion operator.

Parameters

out	reference to a std::ostream
a	a constant reference to an Integer

Returns

reference to a std::ostream reference

The output integer responds to hex, std::oct, std::hex, std::upper and std::lower. The output includes the suffix h (for hex), . (dot, for dec) and o (for octal). There is currently no way to suppress the suffix.

If you want to print an Integer without the suffix or using an arbitrary base, then use IntToString<Integer>().

See also

IntToString<Integer>

a_times_b_mod_c

CRYPTOPP_DLL friend Integer a_times_b_mod_c ( const Integer & x, const Integer & y, const Integer & m )

friend

Modular multiplication.

Parameters

x	reference to the first term
y	reference to the second term
m	reference to the modulus

Returns

an Integer (a * b) % m.

a_exp_b_mod_c

CRYPTOPP_DLL friend Integer a_exp_b_mod_c ( const Integer & x, const Integer & e, const Integer & m )

friend

Modular exponentiation.

Parameters

x	reference to the base
e	reference to the exponent
m	reference to the modulus

Returns

an Integer (a ^ b) % m.

---

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

• integer.h