Utility functions for the Crypto++ library. More...

#include "config.h"
#include "cryptlib.h"
#include "stdcpp.h"
#include "smartptr.h"

Include dependency graph for misc.h:

Classes
struct	CompileAssert< b >

class	Empty
	An Empty class. More...

class	TwoBases< BASE1, BASE2 >

class	ThreeBases< BASE1, BASE2, BASE3 >

class	ObjectHolder< T >
	Uses encapsulation to hide an object in derived classes. More...

class	NotCopyable
	Ensures an object is not copyable. More...

class	NewObject< T >
	An object factory function. More...

class	Singleton< T, F, instance >
	Restricts the instantiation of a class to one static object without locks. More...

class	GetBlock< T, B, A >
	Access a block of memory. More...

class	PutBlock< T, B, A >
	Access a block of memory. More...

class	BlockGetAndPut< T, B, GA, PA >
	Access a block of memory. More...

class	SafeShifter< overflow >
	Safely shift values when undefined behavior could occur. More...

class	SafeShifter< true >
	Shifts a value in the presence of overflow. More...

class	SafeShifter< false >
	Shifts a value in the absence of overflow. More...

Macros
#define	CRYPTOPP_FAST_ROTATE(x) 0

#define	SIZE_MAX ((std::numeric_limits<size_t>::max)())

#define	CRYPTOPP_COMPILE_ASSERT(assertion) CRYPTOPP_COMPILE_ASSERT_INSTANCE(assertion, __LINE__)

#define	CRYPTOPP_COMPILE_ASSERT_INSTANCE(assertion, instance)

#define	CRYPTOPP_ASSERT_JOIN(X, Y) CRYPTOPP_DO_ASSERT_JOIN(X, Y)

#define	CRYPTOPP_DO_ASSERT_JOIN(X, Y) X##Y

#define	COUNTOF(x) (sizeof(x)/sizeof(x[0]))

#define	MEMORY_BARRIER()

#define	RETURN_IF_NONZERO(x) size_t returnedValue = x; if (returnedValue) return returnedValue

#define	GETBYTE(x, y) (unsigned int)byte((x)>>(8*(y)))

#define	CRYPTOPP_GET_BYTE_AS_BYTE(x, y) byte((x)>>(8*(y)))

#define	CRYPTOPP_BLOCK_1(n, t, s) t* m_##n() {return (t )(void )(m_aggregate+0);} size_t SS1() {return sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

#define	CRYPTOPP_BLOCK_2(n, t, s) t* m_##n() {return (t )(void )(m_aggregate+SS1());} size_t SS2() {return SS1()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

#define	CRYPTOPP_BLOCK_3(n, t, s) t* m_##n() {return (t )(void )(m_aggregate+SS2());} size_t SS3() {return SS2()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

#define	CRYPTOPP_BLOCK_4(n, t, s) t* m_##n() {return (t )(void )(m_aggregate+SS3());} size_t SS4() {return SS3()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

#define	CRYPTOPP_BLOCK_5(n, t, s) t* m_##n() {return (t )(void )(m_aggregate+SS4());} size_t SS5() {return SS4()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

#define	CRYPTOPP_BLOCK_6(n, t, s) t* m_##n() {return (t )(void )(m_aggregate+SS5());} size_t SS6() {return SS5()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

#define	CRYPTOPP_BLOCK_7(n, t, s) t* m_##n() {return (t )(void )(m_aggregate+SS6());} size_t SS7() {return SS6()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

#define	CRYPTOPP_BLOCK_8(n, t, s) t* m_##n() {return (t )(void )(m_aggregate+SS7());} size_t SS8() {return SS7()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

#define	CRYPTOPP_BLOCKS_END(i) size_t SST() {return SS##i();} void AllocateBlocks() {m_aggregate.New(SST());} AlignedSecByteBlock m_aggregate;

Typedefs
typedef LittleEndian	NativeByteOrder

Functions
void	memcpy_s (void dest, size_t sizeInBytes, const void src, size_t count)
	Bounds checking replacement for memcpy() More...

void	memmove_s (void dest, size_t sizeInBytes, const void src, size_t count)
	Bounds checking replacement for memmove() More...

template<class T >
void	vec_swap (T &a, T &b)
	Swaps two variables which are arrays. More...

void *	memset_z (void *ptr, int value, size_t num)
	Memory block initializer and eraser that attempts to survive optimizations. More...

template<class T >
const T &	STDMIN (const T &a, const T &b)
	Replacement function for std::min. More...

template<class T >
const T &	STDMAX (const T &a, const T &b)
	Replacement function for std::max. More...

template<class T1 , class T2 >
const T1	UnsignedMin (const T1 &a, const T2 &b)
	Safe comparison of values that could be neagtive and incorrectly promoted. More...

template<class T1 , class T2 >
bool	SafeConvert (T1 from, T2 &to)
	Tests whether a conversion from -> to is safe to perform. More...

template<class T >
std::string	IntToString (T value, unsigned int base=10)
	Converts a value to a string. More...

template<>
CRYPTOPP_DLL std::string	IntToString< word64 > (word64 value, unsigned int base)
	Converts an unsigned value to a string. More...

template<>
CRYPTOPP_DLL std::string	IntToString< Integer > (Integer value, unsigned int base)
	Converts an Integer to a string. More...

template<class T >
unsigned int	Parity (T value)
	Returns the parity of a value. More...

template<class T >
unsigned int	BytePrecision (const T &value)
	Returns the number of 8-bit bytes or octets required for a value. More...

template<class T >
unsigned int	BitPrecision (const T &value)
	Returns the number of bits required for a value. More...

unsigned int	TrailingZeros (word32 v)
	Determines the number of trailing 0-bits in a value. More...

unsigned int	TrailingZeros (word64 v)
	Determines the number of trailing 0-bits in a value. More...

template<class T >
T	Crop (T value, size_t bits)
	Truncates the value to the specified number of bits. More...

size_t	BitsToBytes (size_t bitCount)
	Returns the number of 8-bit bytes or octets required for the specified number of bits. More...

size_t	BytesToWords (size_t byteCount)
	Returns the number of words required for the specified number of bytes. More...

size_t	BitsToWords (size_t bitCount)
	Returns the number of words required for the specified number of bits. More...

size_t	BitsToDwords (size_t bitCount)
	Returns the number of double words required for the specified number of bits. More...

CRYPTOPP_DLL void CRYPTOPP_API	xorbuf (byte buf, const byte mask, size_t count)
	Performs an XOR of a buffer with a mask. More...

CRYPTOPP_DLL void CRYPTOPP_API	xorbuf (byte output, const byte input, const byte *mask, size_t count)
	Performs an XOR of an input buffer with a mask and stores the result in an output buffer. More...

CRYPTOPP_DLL bool CRYPTOPP_API	VerifyBufsEqual (const byte buf1, const byte buf2, size_t count)
	Performs a near constant-time comparison of two equally sized buffers. More...

template<class T >
bool	IsPowerOf2 (const T &value)
	Tests whether a value is a power of 2. More...

template<class T1 , class T2 >
T1	SaturatingSubtract (const T1 &a, const T2 &b)
	Performs a saturating subtract clamped at 0. More...

template<class T1 , class T2 >
T1	SaturatingSubtract1 (const T1 &a, const T2 &b)
	Performs a saturating subtract clamped at 1. More...

template<class T1 , class T2 >
T2	ModPowerOf2 (const T1 &a, const T2 &b)
	Reduces a value to a power of 2. More...

template<class T1 , class T2 >
T1	RoundDownToMultipleOf (const T1 &n, const T2 &m)
	Rounds a value down to a multiple of a second value. More...

template<class T1 , class T2 >
T1	RoundUpToMultipleOf (const T1 &n, const T2 &m)
	Rounds a value up to a multiple of a second value. More...

template<class T >
unsigned int	GetAlignmentOf ()
	Returns the minimum alignment requirements of a type. More...

bool	IsAlignedOn (const void *ptr, unsigned int alignment)
	Determines whether ptr is aligned to a minimum value. More...

template<class T >
bool	IsAligned (const void *ptr)
	Determines whether ptr is minimally aligned. More...

ByteOrder	GetNativeByteOrder ()
	Returns NativeByteOrder as an enumerated ByteOrder value. More...

bool	NativeByteOrderIs (ByteOrder order)
	Determines whether order follows native byte ordering. More...

template<class T >
CipherDir	GetCipherDir (const T &obj)
	Returns the direction the cipher is being operated. More...

CRYPTOPP_DLL void CRYPTOPP_API	CallNewHandler ()
	Attempts to reclaim unused memory. More...

void	IncrementCounterByOne (byte *inout, unsigned int size)
	Performs an addition with carry on a block of bytes. More...

void	IncrementCounterByOne (byte output, const byte input, unsigned int size)
	Performs an addition with carry on a block of bytes. More...

template<class T >
void	ConditionalSwap (bool c, T &a, T &b)
	Performs a branchless swap of values a and b if condition c is true. More...

template<class T >
void	ConditionalSwapPointers (bool c, T &a, T &b)
	Performs a branchless swap of pointers a and b if condition c is true. More...

template<class T >
void	SecureWipeBuffer (T *buf, size_t n)
	Sets each element of an array to 0. More...

template<class T >
void	SecureWipeArray (T *buf, size_t n)
	Sets each element of an array to 0. More...

std::string	StringNarrow (const wchar_t *str, bool throwOnError=true)
	Converts a wide character C-string to a multibyte string. More...

CRYPTOPP_DLL void *CRYPTOPP_API	UnalignedAllocate (size_t size)
	Allocates a buffer. More...

CRYPTOPP_DLL void CRYPTOPP_API	UnalignedDeallocate (void *ptr)
	Frees a buffer allocated with UnalignedAllocate. More...

template<class T >
T	rotlFixed (T x, unsigned int y)
	Performs a left rotate. More...

template<class T >
T	rotrFixed (T x, unsigned int y)
	Performs a right rotate. More...

template<class T >
T	rotlVariable (T x, unsigned int y)
	Performs a left rotate. More...

template<class T >
T	rotrVariable (T x, unsigned int y)
	Performs a right rotate. More...

template<class T >
T	rotlMod (T x, unsigned int y)
	Performs a left rotate. More...

template<class T >
T	rotrMod (T x, unsigned int y)
	Performs a right rotate. More...

template<class T >
unsigned int	GetByte (ByteOrder order, T value, unsigned int index)
	Gets a byte from a value. More...

byte	ByteReverse (byte value)
	Reverses bytes in a 8-bit value. More...

word16	ByteReverse (word16 value)
	Reverses bytes in a 16-bit value. More...

word32	ByteReverse (word32 value)
	Reverses bytes in a 32-bit value. More...

word64	ByteReverse (word64 value)
	Reverses bytes in a 64-bit value. More...

byte	BitReverse (byte value)
	Reverses bits in a 8-bit value. More...

word16	BitReverse (word16 value)
	Reverses bits in a 16-bit value. More...

word32	BitReverse (word32 value)
	Reverses bits in a 32-bit value. More...

word64	BitReverse (word64 value)
	Reverses bits in a 64-bit value. More...

template<class T >
T	BitReverse (T value)
	Reverses bits in a value. More...

template<class T >
T	ConditionalByteReverse (ByteOrder order, T value)
	Reverses bytes in a value depending upon endianness. More...

template<class T >
void	ByteReverse (T out, const T in, size_t byteCount)
	Reverses bytes in an element from an array of elements. More...

template<class T >
void	ConditionalByteReverse (ByteOrder order, T out, const T in, size_t byteCount)
	Conditionally reverses bytes in an element from an array of elements. More...

template<class T >
void	GetUserKey (ByteOrder order, T out, size_t outlen, const byte in, size_t inlen)

byte	UnalignedGetWordNonTemplate (ByteOrder order, const byte block, const byte )

word16	UnalignedGetWordNonTemplate (ByteOrder order, const byte block, const word16 )

word32	UnalignedGetWordNonTemplate (ByteOrder order, const byte block, const word32 )

word64	UnalignedGetWordNonTemplate (ByteOrder order, const byte block, const word64 )

void	UnalignedbyteNonTemplate (ByteOrder order, byte block, byte value, const byte xorBlock)

void	UnalignedbyteNonTemplate (ByteOrder order, byte block, word16 value, const byte xorBlock)

void	UnalignedbyteNonTemplate (ByteOrder order, byte block, word32 value, const byte xorBlock)

void	UnalignedbyteNonTemplate (ByteOrder order, byte block, word64 value, const byte xorBlock)

template<class T >
T	GetWord (bool assumeAligned, ByteOrder order, const byte *block)
	Access a block of memory. More...

template<class T >
void	GetWord (bool assumeAligned, ByteOrder order, T &result, const byte *block)
	Access a block of memory. More...

template<class T >
void	PutWord (bool assumeAligned, ByteOrder order, byte block, T value, const byte xorBlock=NULL)
	Access a block of memory. More...

template<class T >
std::string	WordToString (T value, ByteOrder order=BIG_ENDIAN_ORDER)

template<class T >
T	StringToWord (const std::string &str, ByteOrder order=BIG_ENDIAN_ORDER)

template<unsigned int bits, class T >
T	SafeRightShift (T value)

template<unsigned int bits, class T >
T	SafeLeftShift (T value)

Detailed Description

Utility functions for the Crypto++ library.

Definition in file misc.h.

Macro Definition Documentation

#define COUNTOF ( x ) (sizeof(x)/sizeof(x[0]))

Definition at line 175 of file misc.h.

#define CRYPTOPP_ASSERT_JOIN	(	X,
		Y
	)	CRYPTOPP_DO_ASSERT_JOIN(X, Y)

Definition at line 153 of file misc.h.

#define CRYPTOPP_BLOCK_1	(	n,
		t,
		s
	)	t* m_##n() {return (t )(void )(m_aggregate+0);} size_t SS1() {return sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

Definition at line 2360 of file misc.h.

#define CRYPTOPP_BLOCK_2	(	n,
		t,
		s
	)	t* m_##n() {return (t )(void )(m_aggregate+SS1());} size_t SS2() {return SS1()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

Definition at line 2361 of file misc.h.

#define CRYPTOPP_BLOCK_3	(	n,
		t,
		s
	)	t* m_##n() {return (t )(void )(m_aggregate+SS2());} size_t SS3() {return SS2()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

Definition at line 2362 of file misc.h.

#define CRYPTOPP_BLOCK_4	(	n,
		t,
		s
	)	t* m_##n() {return (t )(void )(m_aggregate+SS3());} size_t SS4() {return SS3()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

Definition at line 2363 of file misc.h.

#define CRYPTOPP_BLOCK_5	(	n,
		t,
		s
	)	t* m_##n() {return (t )(void )(m_aggregate+SS4());} size_t SS5() {return SS4()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

Definition at line 2364 of file misc.h.

#define CRYPTOPP_BLOCK_6	(	n,
		t,
		s
	)	t* m_##n() {return (t )(void )(m_aggregate+SS5());} size_t SS6() {return SS5()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

Definition at line 2365 of file misc.h.

#define CRYPTOPP_BLOCK_7	(	n,
		t,
		s
	)	t* m_##n() {return (t )(void )(m_aggregate+SS6());} size_t SS7() {return SS6()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

Definition at line 2366 of file misc.h.

#define CRYPTOPP_BLOCK_8	(	n,
		t,
		s
	)	t* m_##n() {return (t )(void )(m_aggregate+SS7());} size_t SS8() {return SS7()+sizeof(t)*(s);} size_t m_##n##Size() {return (s);}

Definition at line 2367 of file misc.h.

#define CRYPTOPP_BLOCKS_END ( i ) size_t SST() {return SS##i();} void AllocateBlocks() {m_aggregate.New(SST());} AlignedSecByteBlock m_aggregate;

Definition at line 2368 of file misc.h.

#define CRYPTOPP_COMPILE_ASSERT ( assertion ) CRYPTOPP_COMPILE_ASSERT_INSTANCE(assertion, __LINE__)

Definition at line 139 of file misc.h.

#define CRYPTOPP_COMPILE_ASSERT_INSTANCE	(	assertion,
		instance
	)

Value:

static CompileAssert<(assertion)> \

CRYPTOPP_ASSERT_JOIN(cryptopp_CRYPTOPP_ASSERT_, instance)

CompileAssert

Definition: misc.h:133

CRYPTOPP_ASSERT_JOIN

#define CRYPTOPP_ASSERT_JOIN(X, Y)

Definition: misc.h:153

Definition at line 148 of file misc.h.

#define CRYPTOPP_DO_ASSERT_JOIN	(	X,
		Y
	)	X##Y

Definition at line 154 of file misc.h.

#define CRYPTOPP_FAST_ROTATE ( x ) 0

Definition at line 57 of file misc.h.

#define CRYPTOPP_GET_BYTE_AS_BYTE	(	x,
		y
	)	byte((x)>>(8*(y)))

Definition at line 615 of file misc.h.

#define GETBYTE	(	x,
		y
	)	(unsigned int)byte((x)>>(8*(y)))

Definition at line 610 of file misc.h.

#define MEMORY_BARRIER ( )

Definition at line 256 of file misc.h.

#define RETURN_IF_NONZERO ( x ) size_t returnedValue = x; if (returnedValue) return returnedValue

Definition at line 607 of file misc.h.

#define SIZE_MAX ((std::numeric_limits<size_t>::max)())

Definition at line 113 of file misc.h.

Typedef Documentation

typedef LittleEndian NativeByteOrder

Definition at line 970 of file misc.h.

Function Documentation

template<class T >

unsigned int BitPrecision ( const T & value )

Returns the number of bits required for a value.

Parameters

value the value to test

Returns: the maximum number of bits required to represent a value.

Definition at line 654 of file misc.h.

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byte BitReverse ( byte value )

inline

Reverses bits in a 8-bit value.

Parameters

value the 8-bit value to reverse

BitReverse performs a combination of shifts on the byte

Definition at line 1733 of file misc.h.

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word16 BitReverse ( word16 value )

inline

Reverses bits in a 16-bit value.

Parameters

value the 16-bit value to reverse

BitReverse performs a combination of shifts on the word16

Definition at line 1743 of file misc.h.

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word32 BitReverse ( word32 value )

inline

Reverses bits in a 32-bit value.

Parameters

value the 32-bit value to reverse

BitReverse performs a combination of shifts on the word32

Definition at line 1754 of file misc.h.

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word64 BitReverse ( word64 value )

inline

Reverses bits in a 64-bit value.

Parameters

value the 64-bit value to reverse

BitReverse performs a combination of shifts on the word64

Definition at line 1765 of file misc.h.

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template<class T >

T BitReverse ( T value )

inline

Reverses bits in a value.

Parameters

value the value to reverse

The template overload of BitReverse operates on signed and unsigned values. Internally the size of T is checked, and then value is cast to a byte, word16, word32 or word64. After the cast, the appropriate BitReverse overload is called.

Definition at line 1784 of file misc.h.

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size_t BitsToBytes ( size_t bitCount )

inline

Returns the number of 8-bit bytes or octets required for the specified number of bits.

Parameters

bitCount the number of bits

Returns: the minimum number of 8-bit bytes or octets required by bitCount

BitsToBytes is effectively a ceiling function based on 8-bit bytes.

Definition at line 749 of file misc.h.

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size_t BitsToDwords ( size_t bitCount )

inline

Returns the number of double words required for the specified number of bits.

Parameters

bitCount the number of bits

Returns: the minimum number of double words required by bitCount

BitsToDwords is effectively a ceiling function based on 2*WORD_BITS. WORD_BITS is defined in config.h

Definition at line 779 of file misc.h.

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size_t BitsToWords ( size_t bitCount )

inline

Returns the number of words required for the specified number of bits.

Parameters

bitCount the number of bits

Returns: the minimum number of words required by bitCount

BitsToWords is effectively a ceiling function based on WORD_BITS. WORD_BITS is defined in config.h

Definition at line 769 of file misc.h.

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template<class T >

unsigned int BytePrecision ( const T & value )

Returns the number of 8-bit bytes or octets required for a value.

Parameters

value the value to test

Returns: the minimum number of 8-bit bytes or octets required to represent a value

Definition at line 632 of file misc.h.

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byte ByteReverse ( byte value )

inline

Reverses bytes in a 8-bit value.

Parameters

value the 8-bit value to reverse

Note: ByteReverse returns the value passed to it since there is nothing to reverse

Definition at line 1663 of file misc.h.

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word16 ByteReverse ( word16 value )

inline

Reverses bytes in a 16-bit value.

Performs an endian reversal

Parameters

value the 16-bit value to reverse

ByteReverse calls bswap if available. Otherwise the function performs a 8-bit rotate on the word16

Definition at line 1672 of file misc.h.

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word32 ByteReverse ( word32 value )

inline

Reverses bytes in a 32-bit value.

Performs an endian reversal

Parameters

value the 32-bit value to reverse

ByteReverse calls bswap if available. Otherwise the function uses a combination of rotates on the word32

Definition at line 1687 of file misc.h.

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word64 ByteReverse ( word64 value )

inline

Reverses bytes in a 64-bit value.

Performs an endian reversal

Parameters

value the 64-bit value to reverse

ByteReverse calls bswap if available. Otherwise the function uses a combination of rotates on the word64

Definition at line 1712 of file misc.h.

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template<class T >

void ByteReverse	(	T *	out,
		const T *	in,
		size_t	byteCount
	)

Reverses bytes in an element from an array of elements.

Template Parameters

T	the class or type

Parameters

out	the output array of elements
in	the input array of elements
byteCount	the total number of bytes in the array

Internally, ByteReverse visits each element in the in array calls ByteReverse on it, and writes the result to out.

ByteReverse does not process tail byes, or bytes that are not part of a full element. If T is int (and int is 4 bytes), then byteCount = 10 means only the first 2 elements or 8 bytes are reversed.

The follwoing program should help illustrate the behavior.

vector<word32> v1, v2;

v1.push_back(1);
v1.push_back(2);
v1.push_back(3);
v1.push_back(4);

v2.resize(v1.size());
ByteReverse<word32>(&v2[0], &v1[0], 16);

cout << "V1: ";
for(unsigned int i = 0; i < v1.size(); i++)
  cout << std::hex << v1[i] << " ";
cout << endl;

cout << "V2: ";
for(unsigned int i = 0; i < v2.size(); i++)
  cout << std::hex << v2[i] << " ";
cout << endl;

The program above results in the follwoing output.

V1: 00000001 00000002 00000003 00000004
V2: 01000000 02000000 03000000 04000000

See also: ConditionalByteReverse

Definition at line 1848 of file misc.h.

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size_t BytesToWords ( size_t byteCount )

inline

Returns the number of words required for the specified number of bytes.

Parameters

byteCount the number of bytes

Returns: the minimum number of words required by byteCount

BytesToWords is effectively a ceiling function based on WORD_SIZE. WORD_SIZE is defined in config.h

Definition at line 759 of file misc.h.

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CRYPTOPP_DLL void CRYPTOPP_API CallNewHandler ( )

Attempts to reclaim unused memory.

Exceptions

bad_alloc

In the normal course of running a program, a request for memory normally succeeds. If a call to AlignedAllocate or UnalignedAllocate fails, then CallNewHandler is called in an effort to recover. Internally, CallNewHandler calls set_new_handler(NULL) in an effort to free memory. There is no guarantee CallNewHandler will be able to procure more memory so an allocation succeeds. If the call to set_new_handler fails, then CallNewHandler throws a bad_alloc exception.

Definition at line 200 of file misc.cpp.

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template<class T >

T ConditionalByteReverse	(	ByteOrder	order,
		T	value
	)

inline

Reverses bytes in a value depending upon endianness.

Template Parameters

T	the class or type

Parameters

order	the ByteOrder of the data
value	the value to conditionally reverse

Internally, the ConditionalByteReverse calls NativeByteOrderIs. If order matches native byte order, then the original value is returned. If not, then ByteReverse is called on the value before returning to the caller.

Definition at line 1807 of file misc.h.

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template<class T >

void ConditionalByteReverse	(	ByteOrder	order,
		T *	out,
		const T *	in,
		size_t	byteCount
	)

inline

Conditionally reverses bytes in an element from an array of elements.

Template Parameters

T	the class or type

Parameters

order	the ByteOrder of the data
out	the output array of elements
in	the input array of elements
byteCount	the byte count of the arrays

Internally, ByteReverse visits each element in the in array calls ByteReverse on it depending on the desired endianness, and writes the result to out.

ByteReverse does not process tail byes, or bytes that are not part of a full element. If T is int (and int is 4 bytes), then byteCount = 10 means only the first 2 elements or 8 bytes are reversed.

See also: ByteReverse

Definition at line 1870 of file misc.h.

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template<class T >

void ConditionalSwap	(	bool	c,
		T &	a,
		T &	b
	)

inline

Performs a branchless swap of values a and b if condition c is true.

Parameters

c	the condition to perform the swap
a	the first value
b	the second value

Definition at line 1058 of file misc.h.

template<class T >

void ConditionalSwapPointers	(	bool	c,
		T &	a,
		T &	b
	)

inline

Performs a branchless swap of pointers a and b if condition c is true.

Parameters

c	the condition to perform the swap
a	the first pointer
b	the second pointer

Definition at line 1070 of file misc.h.

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template<class T >

T Crop	(	T	value,
		size_t	bits
	)

inline

Truncates the value to the specified number of bits.

Parameters

value	the value to truncate or mask
bits	the number of bits to truncate or mask

Returns: the value truncated to the specified number of bits, starting at the least significant bit position

This function masks the low-order bits of value and returns the result. The mask is created with (1 << bits) - 1.

Definition at line 737 of file misc.h.

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template<class T >

unsigned int GetAlignmentOf ( )

inline

Returns the minimum alignment requirements of a type.

Returns: the minimum alignment requirements of a type, in bytes

Internally the function calls C++11's alignof if available. If not available, then the function uses compiler specific extensions such as __alignof and _alignof_. If an extension is not available, then the function uses __BIGGEST_ALIGNMENT__ if __BIGGEST_ALIGNMENT__ is smaller than sizeof(T). sizeof(T) is used if all others are not available. In all cases, if CRYPTOPP_ALLOW_UNALIGNED_DATA_ACCESS is defined, then the function returns 1.

Definition at line 922 of file misc.h.

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template<class T >

unsigned int GetByte	(	ByteOrder	order,
		T	value,
		unsigned int	index
	)

inline

Gets a byte from a value.

Parameters

order	the ByteOrder of the value
value	the value to retrieve the byte
index	the location of the byte to retrieve

Definition at line 1652 of file misc.h.

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template<class T >

CipherDir GetCipherDir ( const T & obj )

inline

Returns the direction the cipher is being operated.

Parameters

obj	the cipher object being queried

Returns: ENCRYPTION if the cipher obj is being operated in its forward direction, DECRYPTION otherwise

A cipher can be operated in a "forward" direction (encryption) or a "reverse" direction (decryption). The operations do not have to be symmetric, meaning a second application of the transformation does not necessariy return the original message. That is, E(D(m)) may not equal E(E(m)); and D(E(m)) may not equal D(D(m)).

Definition at line 1008 of file misc.h.

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ByteOrder GetNativeByteOrder ( )

inline

Returns NativeByteOrder as an enumerated ByteOrder value.

Returns: LittleEndian if the native byte order is little-endian, and BigEndian if the native byte order is big-endian

NativeByteOrder is a typedef depending on the platform. If IS_LITTLE_ENDIAN is set in config.h, then GetNativeByteOrder returns LittleEndian. If IS_BIG_ENDIAN is set, then GetNativeByteOrder returns BigEndian.

Note: There are other byte orders besides little- and big-endian, and they include bi-endian and PDP-endian. If a system is neither little-endian nor big-endian, then a compile time error occurs.

Definition at line 985 of file misc.h.

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template<class T >

void GetUserKey	(	ByteOrder	order,
		T *	out,
		size_t	outlen,
		const byte *	in,
		size_t	inlen
	)

inline

Definition at line 1879 of file misc.h.

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template<class T >

T GetWord	(	bool	assumeAligned,
		ByteOrder	order,
		const byte *	block
	)

inline

Access a block of memory.

Template Parameters

T	class or type

Parameters

assumeAligned	flag indicating alignment
order	the ByteOrder of the data
block	the byte buffer to be processed

Returns: the word in the specified byte order

GetWord() provides alternate read access to a block of memory. The flag assumeAligned indicates if the memory block is aligned for class or type T. The enumeration ByteOrder is BIG_ENDIAN_ORDER or LITTLE_ENDIAN_ORDER.

An example of reading two word32 values from a block of memory is shown below. w will be 0x03020100.

   word32 w;
   byte buffer[4] = {0,1,2,3};
   w = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, buffer);

Definition at line 2078 of file misc.h.

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template<class T >

void GetWord	(	bool	assumeAligned,
		ByteOrder	order,
		T &	result,
		const byte *	block
	)

inline

Access a block of memory.

Template Parameters

T	class or type

Parameters

assumeAligned	flag indicating alignment
order	the ByteOrder of the data
result	the word in the specified byte order
block	the byte buffer to be processed

GetWord() provides alternate read access to a block of memory. The flag assumeAligned indicates if the memory block is aligned for class or type T. The enumeration ByteOrder is BIG_ENDIAN_ORDER or LITTLE_ENDIAN_ORDER.

An example of reading two word32 values from a block of memory is shown below. w will be 0x03020100.

   word32 w;
   byte buffer[4] = {0,1,2,3};
   w = GetWord<word32>(false, LITTLE_ENDIAN_ORDER, buffer);

Definition at line 2107 of file misc.h.

void IncrementCounterByOne	(	byte *	inout,
		unsigned int	size
	)

inline

Performs an addition with carry on a block of bytes.

Parameters

inout	the byte block
size	the size of the block, in bytes

Performs an addition with carry by adding 1 on a block of bytes starting at the least significant byte. Once carry is 0, the function terminates and returns to the caller.

Note: The function is not constant time because it stops processing when the carry is 0.

Definition at line 1029 of file misc.h.

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void IncrementCounterByOne	(	byte *	output,
		const byte *	input,
		unsigned int	size
	)

inline

Performs an addition with carry on a block of bytes.

Parameters

output	the destination block of bytes
input	the source block of bytes
size	the size of the block

Performs an addition with carry on a block of bytes starting at the least significant byte. Once carry is 0, the remaining bytes from input are copied to output using memcpy.

The function is close to near-constant time because it operates on all the bytes in the blocks.

Definition at line 1043 of file misc.h.

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template<class T >

std::string IntToString	(	T	value,
		unsigned int	base = `10`
	)

Converts a value to a string.

Parameters

value	the value to convert
base	the base to use during the conversion

Returns: the string representation of value in base.

Definition at line 539 of file misc.h.

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template<>

CRYPTOPP_DLL std::string IntToString< Integer >	(	Integer	value,
		unsigned int	base
	)

Converts an Integer to a string.

Parameters

value	the Integer to convert
base	the base to use during the conversion

Returns: the string representation of value in base.

This is a template specialization of IntToString(). Use it like IntToString():

  // Print integer in base 10
  Integer n...
  std::string s = IntToString(n, 10);

The string is presented with lowercase letters by default. A hack is available to switch to uppercase letters without modifying the function signature.

  // Print integer in base 16, uppercase letters
  Integer n...
  const unsigned int UPPER = (1 << 31);
  std::string s = IntToString(n, (UPPER | 16));

Definition at line 4648 of file integer.cpp.

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template<>

CRYPTOPP_DLL std::string IntToString< word64 >	(	word64	value,
		unsigned int	base
	)

Converts an unsigned value to a string.

Parameters

value	the value to convert
base	the base to use during the conversion

Returns: the string representation of value in base.

this template function specialization was added to suppress Coverity findings on IntToString() with unsigned types.

Definition at line 4714 of file integer.cpp.

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template<class T >

bool IsAligned ( const void * ptr )

inline

Determines whether ptr is minimally aligned.

Parameters

ptr	the pointer to check for alignment

Returns: true if ptr follows native byte ordering, false otherwise

Internally the function calls IsAlignedOn with a second parameter of GetAlignmentOf<T>

Definition at line 964 of file misc.h.

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bool IsAlignedOn	(	const void *	ptr,
		unsigned int	alignment
	)

inline

Determines whether ptr is aligned to a minimum value.

Parameters

ptr	the pointer being checked for alignment
alignment	the alignment value to test the pointer against

Returns: true if ptr is aligned on at least align boundary

Internally the function tests whether alignment is 1. If so, the function returns true. If not, then the function effectively performs a modular reduction and returns true if the residue is 0

Definition at line 954 of file misc.h.

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template<class T >

bool IsPowerOf2 ( const T & value )

inline

Tests whether a value is a power of 2.

Parameters

value the value to test

Returns: true if value is a power of 2, false otherwise

The function creates a mask of value - 1 and returns the result of an AND operation compared to 0. If value is 0 or less than 0, then the function returns false.

Definition at line 818 of file misc.h.

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void memcpy_s	(	void *	dest,
		size_t	sizeInBytes,
		const void *	src,
		size_t	count
	)

inline

Bounds checking replacement for memcpy()

Parameters

dest	pointer to the desination memory block
sizeInBytes	the size of the desination memory block, in bytes
src	pointer to the source memory block
count	the size of the source memory block, in bytes

Exceptions

InvalidArgument

ISO/IEC TR-24772 provides bounds checking interfaces for potentially unsafe functions like memcpy(), strcpy() and memmove(). However, not all standard libraries provides them, like Glibc. The library's memcpy_s() is a near-drop in replacement. Its only a near-replacement because the library's version throws an InvalidArgument on a bounds violation.

memcpy_s() and memmove_s() are guarded by STDC_WANT_SECURE_LIB. If STDC_WANT_SECURE_LIB is not defined or defined to 0, then the library makes memcpy_s() and memmove_s() available. The library will also optionally make the symbols available if CRYPTOPP_WANT_SECURE_LIB is defined. CRYPTOPP_WANT_SECURE_LIB is in config.h, but it is disabled by default.

memcpy_s() will assert the pointers src and dest are not NULL in debug builds. Passing NULL for either pointer is undefined behavior.

Definition at line 366 of file misc.h.

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void memmove_s	(	void *	dest,
		size_t	sizeInBytes,
		const void *	src,
		size_t	count
	)

inline

Bounds checking replacement for memmove()

Parameters

dest	pointer to the desination memory block
sizeInBytes	the size of the desination memory block, in bytes
src	pointer to the source memory block
count	the size of the source memory block, in bytes

Exceptions

InvalidArgument

ISO/IEC TR-24772 provides bounds checking interfaces for potentially unsafe functions like memcpy(), strcpy() and memmove(). However, not all standard libraries provides them, like Glibc. The library's memmove_s() is a near-drop in replacement. Its only a near-replacement because the library's version throws an InvalidArgument on a bounds violation.

memcpy_s() and memmove_s() are guarded by STDC_WANT_SECURE_LIB. If STDC_WANT_SECURE_LIB is not defined or defined to 0, then the library makes memcpy_s() and memmove_s() available. The library will also optionally make the symbols available if CRYPTOPP_WANT_SECURE_LIB is defined. CRYPTOPP_WANT_SECURE_LIB is in config.h, but it is disabled by default.

memmove_s() will assert the pointers src and dest are not NULL in debug builds. Passing NULL for either pointer is undefined behavior.

Definition at line 408 of file misc.h.

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void* memset_z	(	void *	ptr,
		int	value,
		size_t	num
	)

inline

Memory block initializer and eraser that attempts to survive optimizations.

Parameters

ptr	pointer to the memory block being written
value	the integer value to write for each byte
num	the size of the source memory block, in bytes

Internally the function calls memset with the value value, and receives the return value from memset as a volatile pointer.

Definition at line 461 of file misc.h.

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template<class T1 , class T2 >

T2 ModPowerOf2	(	const T1 &	a,
		const T2 &	b
	)

inline

Reduces a value to a power of 2.

Parameters

a	the first value
b	the second value

Returns: ModPowerOf2() returns a & (b-1). b must be a power of 2. Use IsPowerOf2() to determine if b is a suitable candidate.

See also: IsPowerOf2

Definition at line 875 of file misc.h.

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bool NativeByteOrderIs ( ByteOrder order )

inline

Determines whether order follows native byte ordering.

Parameters

order the ordering being tested against native byte ordering

Returns: true if order follows native byte ordering, false otherwise

Definition at line 993 of file misc.h.

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template<class T >

unsigned int Parity ( T value )

Returns the parity of a value.

Parameters

value the value to provide the parity

Returns: 1 if the number 1-bits in the value is odd, 0 otherwise

Definition at line 621 of file misc.h.

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template<class T >

void PutWord	(	bool	assumeAligned,
		ByteOrder	order,
		byte *	block,
		T	value,
		const byte *	xorBlock = `NULL`
	)

inline

Access a block of memory.

Template Parameters

T	class or type

Parameters

assumeAligned	flag indicating alignment
order	the ByteOrder of the data
block	the destination byte buffer
value	the word in the specified byte order
xorBlock	an optional byte buffer to xor

PutWord() provides alternate write access to a block of memory. The flag assumeAligned indicates if the memory block is aligned for class or type T. The enumeration ByteOrder is BIG_ENDIAN_ORDER or LITTLE_ENDIAN_ORDER.

Definition at line 2123 of file misc.h.

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template<class T >

T rotlFixed	(	T	x,
		unsigned int	y
	)

inline

Performs a left rotate.

Template Parameters

T	the word type

Parameters

x	the value to rotate
y	the number of bit positions to rotate the value

This is a portable C/C++ implementation. The value x to be rotated can be 8 to 64-bits wide.

y must be in the range [0, sizeof(T)*8 - 1] to avoid undefined behavior. Use rotlMod if the rotate amount y is outside the range.

Note: rotlFixed attempts to enlist a rotate IMM instruction because its often faster than a rotate REG. Immediate rotates can be up to three times faster than their register counterparts.

Definition at line 1263 of file misc.h.

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template<class T >

T rotlMod	(	T	x,
		unsigned int	y
	)

inline

Performs a left rotate.

Template Parameters

T	the word type

Parameters

x	the value to rotate
y	the number of bit positions to rotate the value

This is a portable C/C++ implementation. The value x to be rotated can be 8 to 64-bits wide.

y is reduced to the range [0, sizeof(T)*8 - 1] to avoid undefined behavior.

Note: rotrVariable will use either rotate IMM or rotate REG.

Definition at line 1340 of file misc.h.

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template<class T >

T rotlVariable	(	T	x,
		unsigned int	y
	)

inline

Performs a left rotate.

Template Parameters

T	the word type

Parameters

x	the value to rotate
y	the number of bit positions to rotate the value

This is a portable C/C++ implementation. The value x to be rotated can be 8 to 64-bits wide.

y must be in the range [0, sizeof(T)*8 - 1] to avoid undefined behavior. Use rotlMod if the rotate amount y is outside the range.

Note: rotlVariable attempts to enlist a rotate IMM instruction because its often faster than a rotate REG. Immediate rotates can be up to three times faster than their register counterparts.

Definition at line 1307 of file misc.h.

template<class T >

T rotrFixed	(	T	x,
		unsigned int	y
	)

inline

Performs a right rotate.

Template Parameters

T	the word type

Parameters

x	the value to rotate
y	the number of bit positions to rotate the value

This is a portable C/C++ implementation. The value x to be rotated can be 8 to 64-bits wide.

y must be in the range [0, sizeof(T)*8 - 1] to avoid undefined behavior. Use rotrMod if the rotate amount y is outside the range.

Note: rotrFixed attempts to enlist a rotate IMM instruction because its often faster than a rotate REG. Immediate rotates can be up to three times faster than their register counterparts.

Definition at line 1285 of file misc.h.

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template<class T >

T rotrMod	(	T	x,
		unsigned int	y
	)

inline

Performs a right rotate.

Template Parameters

T	the word type

Parameters

x	the value to rotate
y	the number of bit positions to rotate the value

This is a portable C/C++ implementation. The value x to be rotated can be 8 to 64-bits wide.

y is reduced to the range [0, sizeof(T)*8 - 1] to avoid undefined behavior.

Note: rotrVariable will use either rotate IMM or rotate REG.

Definition at line 1354 of file misc.h.

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template<class T >

T rotrVariable	(	T	x,
		unsigned int	y
	)

inline

Performs a right rotate.

Template Parameters

T	the word type

Parameters

x	the value to rotate
y	the number of bit positions to rotate the value

This is a portable C/C++ implementation. The value x to be rotated can be 8 to 64-bits wide.

y must be in the range [0, sizeof(T)*8 - 1] to avoid undefined behavior. Use rotrMod if the rotate amount y is outside the range.

Note: rotrVariable attempts to enlist a rotate IMM instruction because its often faster than a rotate REG. Immediate rotates can be up to three times faster than their register counterparts.

Definition at line 1325 of file misc.h.

template<class T1 , class T2 >

T1 RoundDownToMultipleOf	(	const T1 &	n,
		const T2 &	m
	)

inline

Rounds a value down to a multiple of a second value.

Parameters

n	the value to reduce
m	the value to reduce to to a multiple

Returns: the possibly unmodified value

RoundDownToMultipleOf is effectively a floor function based on m. The function returns the value n - n%m. If n is a multiple of m, then the original value is returned.

Definition at line 889 of file misc.h.

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template<class T1 , class T2 >

T1 RoundUpToMultipleOf	(	const T1 &	n,
		const T2 &	m
	)

inline

Rounds a value up to a multiple of a second value.

Parameters

n	the value to reduce
m	the value to reduce to to a multiple

Returns: the possibly unmodified value

RoundUpToMultipleOf is effectively a ceiling function based on m. The function returns the value n + n%m. If n is a multiple of m, then the original value is returned. If the value n would overflow, then an InvalidArgument exception is thrown.

Definition at line 905 of file misc.h.

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template<class T1 , class T2 >

bool SafeConvert	(	T1	from,
		T2 &	to
	)

inline

Tests whether a conversion from -> to is safe to perform.

Parameters

from	the first value
to	the second value

Returns: true if its safe to convert from into to, false otherwise.

Definition at line 526 of file misc.h.

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template<unsigned int bits, class T >

T SafeLeftShift ( T value )

inline

Definition at line 2353 of file misc.h.

template<unsigned int bits, class T >

T SafeRightShift ( T value )

inline

Definition at line 2338 of file misc.h.

template<class T1 , class T2 >

T1 SaturatingSubtract	(	const T1 &	a,
		const T2 &	b
	)

inline

Performs a saturating subtract clamped at 0.

Parameters

a	the minuend
b	the subtrahend

Returns: the difference produced by the saturating subtract

Saturating arithmetic restricts results to a fixed range. Results that are less than 0 are clamped at 0.

Use of saturating arithmetic in places can be advantageous because it can avoid a branch by using an instruction like a conditional move (CMOVE).

Definition at line 847 of file misc.h.

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template<class T1 , class T2 >

T1 SaturatingSubtract1	(	const T1 &	a,
		const T2 &	b
	)

inline

Performs a saturating subtract clamped at 1.

Parameters

a	the minuend
b	the subtrahend

Returns: the difference produced by the saturating subtract

Saturating arithmetic restricts results to a fixed range. Results that are less than 1 are clamped at 1.

Use of saturating arithmetic in places can be advantageous because it can avoid a branch by using an instruction like a conditional move (CMOVE).

Definition at line 862 of file misc.h.

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template<class T >

void SecureWipeArray	(	T *	buf,
		size_t	n
	)

inline

Sets each element of an array to 0.

Parameters

buf	an array of elements
n	the number of elements in the array

The operation performs a wipe or zeroization. The function attempts to survive optimizations and dead code removal.

Definition at line 1192 of file misc.h.

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template<class T >

void SecureWipeBuffer	(	T *	buf,
		size_t	n
	)

Sets each element of an array to 0.

Parameters

buf	an array of elements
n	the number of elements in the array

The operation performs a wipe or zeroization. The function attempts to survive optimizations and dead code removal

Definition at line 1085 of file misc.h.

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template<class T >

const T& STDMAX	(	const T &	a,
		const T &	b
	)

inline

Replacement function for std::max.

Parameters

a	the first value
b	the second value

Returns: the minimum value based on a comparison of a < b using operator<

STDMAX was provided because the library could not easily use std::min or std::max in Windows or Cygwin 1.1.0

Definition at line 487 of file misc.h.

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template<class T >

const T& STDMIN	(	const T &	a,
		const T &	b
	)

inline

Replacement function for std::min.

Parameters

a	the first value
b	the second value

Returns: the minimum value based on a comparison of b < a using operator<

STDMIN was provided because the library could not easily use std::min or std::max in Windows or Cygwin 1.1.0

Definition at line 477 of file misc.h.

std::string StringNarrow	(	const wchar_t *	str,
		bool	throwOnError = `true`
	)

Converts a wide character C-string to a multibyte string.

Parameters

str	C-string consisting of wide characters
throwOnError	flag indication the function should throw on error

Returns: str converted to a multibyte string or an empty string.

StringNarrow converts a wide string to a narrow string using C++ std::wcstombs() under the executing thread's locale. A locale must be set before using this function, and it can be set with std::setlocale() if needed. Upon success, the converted string is returned.

Upon failure with throwOnError as false, the function returns an empty string. If throwOnError as true, the function throws an InvalidArgument() exception.

Note: If you try to convert, say, the Chinese character for "bone" from UTF-16 (0x9AA8) to UTF-8 (0xE9 0xAA 0xA8), then you must ensure the locale is available. If the locale is not available, then a 0x21 error is returned on Windows which eventually results in an InvalidArgument() exception.

Definition at line 136 of file misc.cpp.

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template<class T >

T StringToWord	(	const std::string &	str,
		ByteOrder	order = `BIG_ENDIAN_ORDER`
	)

Definition at line 2250 of file misc.h.

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unsigned int TrailingZeros ( word32 v )

inline

Determines the number of trailing 0-bits in a value.

Parameters

v	the 32-bit value to test

Returns: the number of trailing 0-bits in v, starting at the least significant bit position

TrailingZeros returns the number of trailing 0-bits in v, starting at the least significant bit position. The return value is undefined if there are no 1-bits set in the value v.

Note: The function does not return 0 if no 1-bits are set because 0 collides with a 1-bit at the 0-th position.

Definition at line 679 of file misc.h.

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unsigned int TrailingZeros ( word64 v )

inline

Determines the number of trailing 0-bits in a value.

Parameters

v	the 64-bit value to test

Returns: the number of trailing 0-bits in v, starting at the least significant bit position

TrailingZeros returns the number of trailing 0-bits in v, starting at the least significant bit position. The return value is undefined if there are no 1-bits set in the value v.

Note: The function does not return 0 if no 1-bits are set because 0 collides with a 1-bit at the 0-th position.

Definition at line 710 of file misc.h.

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CRYPTOPP_DLL void* CRYPTOPP_API UnalignedAllocate ( size_t size )

Allocates a buffer.

Parameters

size	the size of the buffer

Definition at line 257 of file misc.cpp.

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void UnalignedbyteNonTemplate	(	ByteOrder	order,
		byte *	block,
		byte	value,
		const byte *	xorBlock
	)

inline

Definition at line 1932 of file misc.h.

void UnalignedbyteNonTemplate	(	ByteOrder	order,
		byte *	block,
		word16	value,
		const byte *	xorBlock
	)

inline

Definition at line 1938 of file misc.h.

void UnalignedbyteNonTemplate	(	ByteOrder	order,
		byte *	block,
		word32	value,
		const byte *	xorBlock
	)

inline

Definition at line 1968 of file misc.h.

void UnalignedbyteNonTemplate	(	ByteOrder	order,
		byte *	block,
		word64	value,
		const byte *	xorBlock
	)

inline

Definition at line 2006 of file misc.h.

CRYPTOPP_DLL void CRYPTOPP_API UnalignedDeallocate ( void * ptr )

Frees a buffer allocated with UnalignedAllocate.

Parameters

ptr	the buffer to free

Definition at line 265 of file misc.cpp.

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byte UnalignedGetWordNonTemplate	(	ByteOrder	order,
		const byte *	block,
		const byte *
	)

inline

Definition at line 1889 of file misc.h.

word16 UnalignedGetWordNonTemplate	(	ByteOrder	order,
		const byte *	block,
		const word16 *
	)

inline

Definition at line 1895 of file misc.h.

word32 UnalignedGetWordNonTemplate	(	ByteOrder	order,
		const byte *	block,
		const word32 *
	)

inline

Definition at line 1902 of file misc.h.

word64 UnalignedGetWordNonTemplate	(	ByteOrder	order,
		const byte *	block,
		const word64 *
	)

inline

Definition at line 1909 of file misc.h.

template<class T1 , class T2 >

const T1 UnsignedMin	(	const T1 &	a,
		const T2 &	b
	)

inline

Safe comparison of values that could be neagtive and incorrectly promoted.

Parameters

a	the first value
b	the second value

Returns: the minimum value based on a comparison a and b using operator<.

The comparison b < a is performed and the value returned is a's type T1.

Definition at line 512 of file misc.h.

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template<class T >

void vec_swap	(	T &	a,
		T &	b
	)

inline

Swaps two variables which are arrays.

Parameters

a	the first value
b	the second value

C++03 does not provide support for std::swap(__m128i a, __m128i b) because __m128i is an unsigned long long[2]. Most compilers support it out of the box, but Sun Studio C++ compilers 12.2 and 12.3 do not.

See also: How to swap two __m128i variables in C++03 given its an opaque type and an array? on Stack Overflow.

Definition at line 449 of file misc.h.

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CRYPTOPP_DLL bool CRYPTOPP_API VerifyBufsEqual	(	const byte *	buf1,
		const byte *	buf2,
		size_t	count
	)

Performs a near constant-time comparison of two equally sized buffers.

Parameters

buf1	the first buffer
buf2	the second buffer
count	the size of the buffers, in bytes

The function effectively performs an XOR of the elements in two equally sized buffers and retruns a result based on the XOR operation. The function is near constant-time because CPU micro-code timings could affect the "constant-ness". Calling code is responsible for mitigating timing attacks if the buffers are not equally sized.

See also: ModPowerOf2

Definition at line 96 of file misc.cpp.

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template<class T >

std::string WordToString	(	T	value,
		ByteOrder	order = `BIG_ENDIAN_ORDER`
	)

Definition at line 2241 of file misc.h.

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CRYPTOPP_DLL void CRYPTOPP_API xorbuf	(	byte *	buf,
		const byte *	mask,
		size_t	count
	)

Performs an XOR of a buffer with a mask.

Parameters

buf	the buffer to XOR with the mask
mask	the mask to XOR with the buffer
count	the size of the buffers, in bytes

The function effectively visits each element in the buffers and performs buf[i] ^= mask[i]. buf and mask must be of equal size.

Definition at line 28 of file misc.cpp.

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CRYPTOPP_DLL void CRYPTOPP_API xorbuf	(	byte *	output,
		const byte *	input,
		const byte *	mask,
		size_t	count
	)

Performs an XOR of an input buffer with a mask and stores the result in an output buffer.

Parameters

output	the destination buffer
input	the source buffer to XOR with the mask
mask	the mask buffer to XOR with the input buffer
count	the size of the buffers, in bytes

The function effectively visits each element in the buffers and performs output[i] = input[i] ^ mask[i]. output, input and mask must be of equal size.

Definition at line 61 of file misc.cpp.

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