Botan::BigInt Class Reference

#include <bigint.h>

Classes
class	DivideByZero

Public Types
enum	Base { Decimal = 10, Hexadecimal = 16, Binary = 256 }
enum	Sign { Negative = 0, Positive = 1 }

Public Member Functions
BigInt	abs () const
BigInt &	add (const word y[], size_t y_words, Sign sign)
	BigInt ()=default
	BigInt (uint64_t n)
	BigInt (const BigInt &other)=default
	BigInt (const std::string &str)
	BigInt (const uint8_t buf[], size_t length)
template<typename Alloc >
	BigInt (const std::vector< uint8_t, Alloc > &vec)
	BigInt (const uint8_t buf[], size_t length, Base base)
	BigInt (const uint8_t buf[], size_t length, size_t max_bits)
	BigInt (const word words[], size_t length)
	BigInt (RandomNumberGenerator &rng, size_t bits, bool set_high_bit=true)
	Create a random BigInt of the specified size. More...
	BigInt (Sign sign, size_t n)
	BigInt (BigInt &&other)
void	binary_decode (const uint8_t buf[], size_t length)
template<typename Alloc >
void	binary_decode (const std::vector< uint8_t, Alloc > &buf)
void	binary_encode (uint8_t buf[]) const
void	binary_encode (uint8_t buf[], size_t len) const
size_t	bits () const
uint8_t	byte_at (size_t n) const
size_t	bytes () const
void	clear ()
void	clear_bit (size_t n)
int32_t	cmp (const BigInt &n, bool check_signs=true) const
int32_t	cmp_word (word n) const
void	cond_flip_sign (bool predicate)
void	conditionally_set_bit (size_t n, bool set_it)
void	const_time_poison () const
void	const_time_unpoison () const
void	ct_cond_assign (bool predicate, const BigInt &other)
void	ct_cond_swap (bool predicate, BigInt &other)
void	ct_reduce_below (const BigInt &mod, secure_vector< word > &ws, size_t bound)
const word *	data () const
void	encode_words (word out[], size_t size) const
size_t	encoded_size (Base base=Binary) const
void	flip_sign ()
bool	get_bit (size_t n) const
uint32_t	get_substring (size_t offset, size_t length) const
secure_vector< word > &	get_word_vector ()
const secure_vector< word > &	get_word_vector () const
void	grow_to (size_t n) const
bool	is_equal (const BigInt &n) const
bool	is_even () const
bool	is_less_than (const BigInt &n) const
bool	is_negative () const
bool	is_nonzero () const
bool	is_odd () const
bool	is_positive () const
bool	is_zero () const
void	mask_bits (size_t n)
BigInt &	mod_add (const BigInt &y, const BigInt &mod, secure_vector< word > &ws)
BigInt &	mod_mul (uint8_t y, const BigInt &mod, secure_vector< word > &ws)
BigInt &	mod_sub (const BigInt &y, const BigInt &mod, secure_vector< word > &ws)
BigInt &	mul (const BigInt &y, secure_vector< word > &ws)
word *	mutable_data ()
bool	operator! () const
BigInt &	operator%= (const BigInt &y)
word	operator%= (word y)
BigInt &	operator*= (const BigInt &y)
BigInt &	operator*= (word y)
BigInt &	operator++ ()
BigInt	operator++ (int)
BigInt &	operator+= (const BigInt &y)
BigInt &	operator+= (word y)
BigInt	operator- () const
BigInt &	operator-- ()
BigInt	operator-- (int)
BigInt &	operator-= (const BigInt &y)
BigInt &	operator-= (word y)
BigInt &	operator/= (const BigInt &y)
BigInt &	operator<<= (size_t shift)
BigInt &	operator= (BigInt &&other)
BigInt &	operator= (const BigInt &)=default
BigInt &	operator>>= (size_t shift)
void	randomize (RandomNumberGenerator &rng, size_t bitsize, bool set_high_bit=true)
size_t	reduce_below (const BigInt &mod, secure_vector< word > &ws)
void	resize (size_t s)
BigInt &	rev_sub (const word y[], size_t y_words, secure_vector< word > &ws)
Sign	reverse_sign () const
void	set_bit (size_t n)
void	set_sign (Sign sign)
void	set_word_at (size_t i, word w)
void	set_words (const word w[], size_t len)
void	shrink_to_fit (size_t min_size=0)
size_t	sig_words () const
Sign	sign () const
size_t	size () const
BigInt &	square (secure_vector< word > &ws)
BigInt &	sub (const word y[], size_t y_words, Sign sign)
void	swap (BigInt &other)
void	swap_reg (secure_vector< word > &reg)
std::string	to_dec_string () const
std::string	to_hex_string () const
uint32_t	to_u32bit () const
size_t	top_bits_free () const
word	word_at (size_t n) const

Static Public Member Functions
static BigInt	add2 (const BigInt &x, const word y[], size_t y_words, Sign y_sign)
static void	const_time_lookup (secure_vector< word > &output, const std::vector< BigInt > &vec, size_t idx)
static BigInt	decode (const uint8_t buf[], size_t length)
template<typename Alloc >
static BigInt	decode (const std::vector< uint8_t, Alloc > &buf)
static BigInt	decode (const uint8_t buf[], size_t length, Base base)
template<typename Alloc >
static BigInt	decode (const std::vector< uint8_t, Alloc > &buf, Base base)
static std::vector< uint8_t >	encode (const BigInt &n)
static void	encode (uint8_t buf[], const BigInt &n)
static std::vector< uint8_t >	encode (const BigInt &n, Base base)
static void	encode (uint8_t buf[], const BigInt &n, Base base)
static secure_vector< uint8_t >	encode_1363 (const BigInt &n, size_t bytes)
static void	encode_1363 (uint8_t out[], size_t bytes, const BigInt &n)
static secure_vector< uint8_t >	encode_fixed_length_int_pair (const BigInt &n1, const BigInt &n2, size_t bytes)
static secure_vector< uint8_t >	encode_locked (const BigInt &n)
static secure_vector< uint8_t >	encode_locked (const BigInt &n, Base base)
static BigInt	power_of_2 (size_t n)
static BigInt	random_integer (RandomNumberGenerator &rng, const BigInt &min, const BigInt &max)

Detailed Description

Arbitrary precision integer

Definition at line 24 of file bigint.h.

Member Enumeration Documentation

enum Botan::BigInt::Base

Base enumerator for encoding and decoding

Enumerator
Decimal
Hexadecimal
Binary

Definition at line 30 of file bigint.h.

{ Decimal = 10, Hexadecimal = 16, Binary = 256 };

enum Botan::BigInt::Sign

Sign symbol definitions for positive and negative numbers

Enumerator
Negative
Positive

Definition at line 35 of file bigint.h.

{ Negative = 0, Positive = 1 };

Constructor & Destructor Documentation

Botan::BigInt::BigInt ( )

default

Create empty BigInt

Botan::BigInt::BigInt

(

uint64_t

n

)

Create BigInt from 64 bit integer

Parameters

n	initial value of this BigInt

Definition at line 25 of file bigint.cpp.

   {
   if(n > 0)
      {
#if BOTAN_MP_WORD_BITS == 32
      m_data.set_word_at(0, static_cast<word>(n));
      m_data.set_word_at(1, static_cast<word>(n >> 32));
#else
      m_data.set_word_at(0, n);
#endif
      }

   }

Botan::BigInt::BigInt ( const BigInt &  other )

default

Copy Constructor

Parameters

other

the BigInt to copy

Botan::BigInt::BigInt ( const std::string &  str )

explicit

Create BigInt from a string. If the string starts with 0x the rest of the string will be interpreted as hexadecimal digits. Otherwise, it will be interpreted as a decimal number.

Parameters

str	the string to parse for an integer value

Definition at line 51 of file bigint.cpp.

References Botan::cast_char_ptr_to_uint8(), Decimal, decode(), Hexadecimal, Negative, Positive, and set_sign().

   {
   Base base = Decimal;
   size_t markers = 0;
   bool negative = false;

   if(str.length() > 0 && str[0] == '-')
      {
      markers += 1;
      negative = true;
      }

   if(str.length() > markers + 2 && str[markers    ] == '0' &&
                                    str[markers + 1] == 'x')
      {
      markers += 2;
      base = Hexadecimal;
      }

   *this = decode(cast_char_ptr_to_uint8(str.data()) + markers,
                  str.length() - markers, base);

   if(negative) set_sign(Negative);
   else         set_sign(Positive);
   }

Botan::BigInt::BigInt	(	const uint8_t	buf[],
		size_t	length
	)

Create a BigInt from an integer in a byte array

Parameters

buf	the byte array holding the value
length	size of buf

Definition at line 77 of file bigint.cpp.

References binary_decode().

   {
   binary_decode(input, length);
   }

template<typename Alloc >

Botan::BigInt::BigInt ( const std::vector< uint8_t, Alloc > &  vec )

inlineexplicit

Create a BigInt from an integer in a byte array

Parameters

vec	the byte vector holding the value

Definition at line 87 of file bigint.h.

: BigInt(vec.data(), vec.size()) {}

Botan::BigInt::BigInt	(	const uint8_t	buf[],
		size_t	length,
		Base	base
	)

Create a BigInt from an integer in a byte array

Parameters

buf	the byte array holding the value
length	size of buf
base	is the number base of the integer in buf

Definition at line 85 of file bigint.cpp.

References decode().

   {
   *this = decode(input, length, base);
   }

Botan::BigInt::BigInt	(	const uint8_t	buf[],
		size_t	length,
		size_t	max_bits
	)

Create a BigInt from an integer in a byte array

Parameters

buf	the byte array holding the value
length	size of buf
max_bits	if the resulting integer is more than max_bits, it will be shifted so it is at most max_bits in length.

Definition at line 90 of file bigint.cpp.

References binary_decode(), and bits().

   {
   const size_t max_bytes = std::min(length, (max_bits + 7) / 8);
   binary_decode(buf, max_bytes);

   const size_t b = this->bits();
   if(b > max_bits)
      {
      *this >>= (b - max_bits);
      }
   }

Botan::BigInt::BigInt	(	const word	words[],
		size_t	length
	)

Create a BigInt from an array of words

Parameters

words	the words
length	number of words

Definition at line 17 of file bigint.cpp.

   {
   m_data.set_words(words, length);
   }

Botan::BigInt::BigInt	(	RandomNumberGenerator &	rng,
		size_t	bits,
		bool	set_high_bit = true
	)

Create a random BigInt of the specified size.

Parameters

rng	random number generator
bits	size in bits
set_high_bit	if true, the highest bit is always set

See also

randomize

Definition at line 105 of file bigint.cpp.

References randomize().

   {
   randomize(rng, bits, set_high_bit);
   }

Botan::BigInt::BigInt	(	Sign	sign,
		size_t	n
	)

Create BigInt of specified size, all zeros

Parameters

sign	the sign
n	size of the internal register in words

Definition at line 42 of file bigint.cpp.

   {
   m_data.set_size(size);
   m_signedness = s;
   }

Botan::BigInt::BigInt ( BigInt &&  other )

inline

Move constructor

Definition at line 134 of file bigint.h.

        {
        this->swap(other);
        }

Member Function Documentation

BigInt Botan::BigInt::abs

(

)

const

Returns

absolute (positive) value of this

Definition at line 384 of file bigint.cpp.

References Positive, and set_sign().

Referenced by Botan::abs().

   {
   BigInt x = (*this);
   x.set_sign(Positive);
   return x;
   }

BigInt & Botan::BigInt::add	(	const word	y[],
		size_t	y_words,
		Sign	sign
	)

Definition at line 15 of file big_ops2.cpp.

References Botan::bigint_add2(), Botan::bigint_cmp(), Botan::bigint_sub2(), Botan::bigint_sub2_rev(), data(), grow_to(), mutable_data(), Positive, set_sign(), sig_words(), sign(), and size().

Referenced by Botan::Modular_Reducer::reduce().

   {
   const size_t x_sw = sig_words();

   grow_to(std::max(x_sw, y_words) + 1);

   if(sign() == y_sign)
      {
      bigint_add2(mutable_data(), size() - 1, y, y_words);
      }
   else
      {
      const int32_t relative_size = bigint_cmp(data(), x_sw, y, y_words);

      if(relative_size >= 0)
         {
         // *this >= y
         bigint_sub2(mutable_data(), x_sw, y, y_words);
         }
      else
         {
         // *this < y
         bigint_sub2_rev(mutable_data(), y, y_words);
         }

      //this->sign_fixup(relative_size, y_sign);
      if(relative_size < 0)
         set_sign(y_sign);
      else if(relative_size == 0)
         set_sign(Positive);
      }

   return (*this);
   }

BigInt Botan::BigInt::add2 ( const BigInt &  x, const word  y[], size_t  y_words, BigInt::Sign  y_sign  )

static

Definition at line 18 of file big_ops3.cpp.

References Botan::bigint_add3(), Botan::bigint_sub_abs(), data(), Positive, sig_words(), and sign().

Referenced by Botan::operator+(), and Botan::operator-().

   {
   const size_t x_sw = x.sig_words();

   BigInt z(x.sign(), std::max(x_sw, y_words) + 1);

   if(x.sign() == y_sign)
      {
      bigint_add3(z.mutable_data(), x.data(), x_sw, y, y_words);
      }
   else
      {
      const int32_t relative_size = bigint_sub_abs(z.mutable_data(), x.data(), x_sw, y, y_words);

      //z.sign_fixup(relative_size, y_sign);
      if(relative_size < 0)
         z.set_sign(y_sign);
      else if(relative_size == 0)
         z.set_sign(BigInt::Positive);
      }

   return z;
   }

void Botan::BigInt::binary_decode	(	const uint8_t	buf[],
		size_t	length
	)

Read integer value from a byte array with given size

Parameters

buf	byte array buffer containing the integer
length	size of buf

Definition at line 424 of file bigint.cpp.

References clear(), and Botan::round_up().

Referenced by BigInt(), botan_mp_from_bin(), decode(), Botan::generate_dsa_primes(), Botan::RFC6979_Nonce_Generator::nonce_for(), and randomize().

   {
   clear();

   const size_t full_words = length / sizeof(word);
   const size_t extra_bytes = length % sizeof(word);

   secure_vector<word> reg((round_up(full_words + (extra_bytes > 0 ? 1 : 0), 8)));

   for(size_t i = 0; i != full_words; ++i)
      {
      reg[i] = load_be<word>(buf + length - sizeof(word)*(i+1), 0);
      }

   if(extra_bytes > 0)
      {
      for(size_t i = 0; i != extra_bytes; ++i)
         reg[full_words] = (reg[full_words] << 8) | buf[i];
      }

   m_data.swap(reg);
   }

template<typename Alloc >

void Botan::BigInt::binary_decode ( const std::vector< uint8_t, Alloc > &  buf )

inline

Read integer value from a byte vector

Parameters

buf	the vector to load from

Definition at line 690 of file bigint.h.

        {
        binary_decode(buf.data(), buf.size());
        }

void Botan::BigInt::binary_encode

(

uint8_t

buf[]

)

const

Store BigInt-value in a given byte array

Parameters

buf	destination byte array for the integer value

Definition at line 391 of file bigint.cpp.

References bytes().

Referenced by Botan::base58_decode(), botan_mp_to_bin(), Botan::DER_Encoder::encode(), encode(), encode_1363(), encode_fixed_length_int_pair(), encode_locked(), and Botan::GOST_3410_PublicKey::public_key_bits().

   {
   this->binary_encode(buf, bytes());
   }

void Botan::BigInt::binary_encode	(	uint8_t	buf[],
		size_t	len
	)		const

Store BigInt-value in a given byte array. If len is less than the size of the value, then it will be truncated. If len is greater than the size of the value, it will be zero-padded. If len exactly equals this->bytes(), this function behaves identically to binary_encode.

Parameters

buf	destination byte array for the integer value
len	how many bytes to write

Definition at line 399 of file bigint.cpp.

References Botan::get_byte(), Botan::store_be(), and word_at().

   {
   const size_t full_words = len / sizeof(word);
   const size_t extra_bytes = len % sizeof(word);

   for(size_t i = 0; i != full_words; ++i)
      {
      const word w = word_at(i);
      store_be(w, output + (len - (i+1)*sizeof(word)));
      }

   if(extra_bytes > 0)
      {
      const word w = word_at(full_words);

      for(size_t i = 0; i != extra_bytes; ++i)
         {
         output[extra_bytes - i - 1] = get_byte(sizeof(word) - i - 1, w);
         }
      }
   }

size_t Botan::BigInt::bits

(

)

const

Get the bit length of the integer

Returns

bit length of the represented integer value

Definition at line 288 of file bigint.cpp.

References sig_words(), and top_bits_free().

Referenced by BigInt(), botan_mp_num_bits(), bytes(), Botan::ct_divide(), Botan::ct_divide_u8(), Botan::ct_inverse_mod_odd_modulus(), Botan::ct_modulo(), Botan::BER_Decoder::decode(), Botan::BER_Decoder::decode_constrained_integer(), Botan::DL_Group::DL_Group(), Botan::DER_Encoder::encode(), encoded_size(), Botan::gcd(), Botan::generate_dsa_primes(), Botan::generate_rsa_prime(), Botan::generate_srp6_verifier(), Botan::is_lucas_probable_prime(), Botan::is_perfect_square(), Botan::is_prime(), Botan::TPM_PrivateKey::key_length(), Botan::monty_multi_exp(), Botan::PointGFp_Base_Point_Precompute::mul(), Botan::PointGFp_Var_Point_Precompute::mul(), Botan::PointGFp_Multi_Point_Precompute::multi_exp(), Botan::operator*(), Botan::operator/(), operator/=(), Botan::passes_miller_rabin_test(), Botan::PointGFp_Base_Point_Precompute::PointGFp_Base_Point_Precompute(), Botan::PointGFp_Var_Point_Precompute::PointGFp_Var_Point_Precompute(), Botan::DL_Group::power_g_p(), Botan::power_mod(), random_integer(), Botan::random_prime(), Botan::RSA_PrivateKey::RSA_PrivateKey(), Botan::srp6_group_identifier(), to_hex_string(), and to_u32bit().

   {
   const size_t words = sig_words();

   if(words == 0)
      return 0;

   const size_t full_words = (words - 1) * BOTAN_MP_WORD_BITS;
   const size_t top_bits = BOTAN_MP_WORD_BITS - top_bits_free();

   return full_words + top_bits;
   }

uint8_t Botan::BigInt::byte_at

(

size_t

n

)

const

Parameters

n	the offset to get a byte from

Returns

byte at offset n

Definition at line 110 of file bigint.cpp.

References Botan::get_byte(), and word_at().

Referenced by Botan::BER_Decoder::decode(), Botan::BER_Decoder::decode_constrained_integer(), get_substring(), and to_u32bit().

   {
   return get_byte(sizeof(word) - (n % sizeof(word)) - 1,
                   word_at(n / sizeof(word)));
   }

size_t Botan::BigInt::bytes

(

)

const

Give byte length of the integer

Returns

byte length of the represented integer value

Definition at line 273 of file bigint.cpp.

References bits(), and Botan::round_up().

Referenced by Botan::base58_decode(), binary_encode(), botan_mp_num_bytes(), Botan::ECIES_KA_Operation::derive_secret(), Botan::DER_Encoder::encode(), Botan::PointGFp::encode(), encode(), encode_1363(), encode_fixed_length_int_pair(), encode_locked(), encoded_size(), Botan::GOST_3410_PublicKey::public_key_bits(), and Botan::SRP6_Server_Session::step1().

   {
   return round_up(bits(), 8) / 8;
   }

void Botan::BigInt::clear ( )

inline

Zeroize the BigInt. The size of the underlying register is not modified.

Definition at line 364 of file bigint.h.

Referenced by Botan::PointGFp::add(), Botan::PointGFp::add_affine(), binary_decode(), botan_mp_clear(), mul(), operator*=(), and randomize().

{ m_data.set_to_zero(); m_signedness = Positive; }

void Botan::BigInt::clear_bit

(

size_t

n

)

Clear bit at specified position

Parameters

n	bit position to clear

Definition at line 262 of file bigint.cpp.

References size(), and word_at().

Referenced by botan_mp_clear_bit().

   {
   const size_t which = n / BOTAN_MP_WORD_BITS;

   if(which < size())
      {
      const word mask = ~(static_cast<word>(1) << (n % BOTAN_MP_WORD_BITS));
      m_data.set_word_at(which, word_at(which) & mask);
      }
   }

int32_t Botan::BigInt::cmp	(	const BigInt &	n,
		bool	check_signs = true
	)		const

Compare this to another BigInt

Parameters

n	the BigInt value to compare with
check_signs	include sign in comparison?

Returns

if (this<n) return -1, if (this>n) return 1, if both values are identical return 0 [like Perl's <=> operator]

Definition at line 131 of file bigint.cpp.

References Botan::bigint_cmp(), data(), is_negative(), is_positive(), and size().

Referenced by botan_mp_cmp(), Botan::operator<=(), and Botan::operator>=().

   {
   if(check_signs)
      {
      if(other.is_positive() && this->is_negative())
         return -1;

      if(other.is_negative() && this->is_positive())
         return 1;

      if(other.is_negative() && this->is_negative())
         return (-bigint_cmp(this->data(), this->size(),
                             other.data(), other.size()));
      }

   return bigint_cmp(this->data(), this->size(),
                     other.data(), other.size());
   }

int32_t Botan::BigInt::cmp_word

(

word

n

)

const

Compare this to an integer

Parameters

n	the value to compare with

Returns

if (this<n) return -1, if (this>n) return 1, if both values are identical return 0 [like Perl's <=> operator]

Definition at line 116 of file bigint.cpp.

References Botan::bigint_cmp(), data(), is_negative(), and sig_words().

Referenced by Botan::operator!=(), Botan::operator<(), Botan::operator<=(), Botan::operator==(), Botan::operator>(), and Botan::operator>=().

   {
   if(is_negative())
      return -1; // other is positive ...

   const size_t sw = this->sig_words();
   if(sw > 1)
      return 1; // must be larger since other is just one word ...

   return bigint_cmp(this->data(), sw, &other, 1);
   }

void Botan::BigInt::cond_flip_sign

(

bool

predicate

)

If predicate is true flip the sign of *this

Definition at line 456 of file bigint.cpp.

References Botan::CT::Mask< T >::expand(), set_sign(), and sign().

Referenced by ct_cond_assign(), Botan::inverse_euclid(), and rev_sub().

   {
   // This code is assuming Negative == 0, Positive == 1

   const auto mask = CT::Mask<uint8_t>::expand(predicate);

   const uint8_t current_sign = static_cast<uint8_t>(sign());

   const uint8_t new_sign = mask.select(current_sign ^ 1, current_sign);

   set_sign(static_cast<Sign>(new_sign));
   }

void Botan::BigInt::conditionally_set_bit	(	size_t	n,
		bool	set_it
	)

Conditionally set bit at specified position. Note if set_it is false, nothing happens, and if the bit is already set, it remains set.

Parameters

n	bit position to set
set_it	if the bit should be set

Definition at line 252 of file bigint.cpp.

References word_at().

Referenced by Botan::ct_divide(), Botan::ct_divide_u8(), and Botan::ct_modulo().

   {
   const size_t which = n / BOTAN_MP_WORD_BITS;
   const word mask = static_cast<word>(set_it) << (n % BOTAN_MP_WORD_BITS);
   m_data.set_word_at(which, word_at(which) | mask);
   }

void Botan::BigInt::const_time_lookup ( secure_vector< word > &  output, const std::vector< BigInt > &  vec, size_t  idx  )

static

Set output = vec[idx].m_reg in constant time

All elements of vec must have the same size, and output must be pre-allocated with the same size.

Definition at line 506 of file bigint.cpp.

References BOTAN_ASSERT, Botan::clear_mem(), Botan::CT::Mask< T >::is_equal(), Botan::CT::poison(), size(), and Botan::CT::unpoison().

   {
   const size_t words = output.size();

   clear_mem(output.data(), output.size());

   CT::poison(&idx, sizeof(idx));

   for(size_t i = 0; i != vec.size(); ++i)
      {
      BOTAN_ASSERT(vec[i].size() >= words,
                   "Word size as expected in const_time_lookup");

      const auto mask = CT::Mask<word>::is_equal(i, idx);

      for(size_t w = 0; w != words; ++w)
         {
         const word viw = vec[i].word_at(w);
         output[w] = mask.if_set_return(viw);
         }
      }

   CT::unpoison(idx);
   CT::unpoison(output.data(), output.size());
   }

void Botan::BigInt::const_time_poison ( ) const

inline

Definition at line 732 of file bigint.h.

{}

void Botan::BigInt::const_time_unpoison ( ) const

inline

Definition at line 733 of file bigint.h.

{}

void Botan::BigInt::ct_cond_assign	(	bool	predicate,
		const BigInt &	other
	)

If predicate is true assign other to *this Uses a masked operation to avoid side channels

Definition at line 469 of file bigint.cpp.

References cond_flip_sign(), Botan::CT::Mask< T >::expand(), grow_to(), set_word_at(), sign(), size(), and word_at().

Referenced by Botan::gcd(), Botan::inverse_euclid(), Botan::is_lucas_probable_prime(), and Botan::power_mod().

   {
   const size_t t_words = size();
   const size_t o_words = other.size();

   if(o_words < t_words)
      grow_to(o_words);

   const size_t r_words = std::max(t_words, o_words);

   const auto mask = CT::Mask<word>::expand(predicate);

   for(size_t i = 0; i != r_words; ++i)
      {
      const word o_word = other.word_at(i);
      const word t_word = this->word_at(i);
      this->set_word_at(i, mask.select(o_word, t_word));
      }

   if(sign() != other.sign())
      {
      cond_flip_sign(predicate);
      }
   }

void Botan::BigInt::ct_cond_swap	(	bool	predicate,
		BigInt &	other
	)

If predicate is true swap *this and other Uses a masked operation to avoid side channels

Definition at line 447 of file bigint.cpp.

References Botan::bigint_cnd_swap(), grow_to(), mutable_data(), and size().

Referenced by Botan::ct_divide(), Botan::ct_modulo(), and Botan::gcd().

   {
   const size_t max_words = std::max(size(), other.size());
   grow_to(max_words);
   other.grow_to(max_words);

   bigint_cnd_swap(predicate, this->mutable_data(), other.mutable_data(), max_words);
   }

void Botan::BigInt::ct_reduce_below	(	const BigInt &	mod,
		secure_vector< word > &	ws,
		size_t	bound
	)

Return *this % mod

Assumes that *this is (if anything) only slightly larger than mod and performs repeated subtractions. It should not be used if *this is much larger than mod, instead use modulo operator.

Performs exactly bound subtractions, so if *this is >= bound*mod then the result will not be fully reduced. If bound is zero, nothing happens.

Definition at line 358 of file bigint.cpp.

References Botan::bigint_sub3(), Botan::clear_mem(), data(), grow_to(), is_negative(), Botan::CT::Mask< T >::is_zero(), mutable_data(), sig_words(), and size().

Referenced by Botan::Modular_Reducer::reduce().

   {
   if(mod.is_negative() || this->is_negative())
      throw Invalid_Argument("BigInt::ct_reduce_below both values must be positive");

   const size_t mod_words = mod.sig_words();

   grow_to(mod_words);

   const size_t sz = size();

   ws.resize(sz);

   clear_mem(ws.data(), sz);

   for(size_t i = 0; i != bound; ++i)
      {
      word borrow = bigint_sub3(ws.data(), data(), sz, mod.data(), mod_words);

      CT::Mask<word>::is_zero(borrow).select_n(mutable_data(), ws.data(), data(), sz);
      }
   }

const word* Botan::BigInt::data ( ) const

inline

Return a const pointer to the register

Returns

a pointer to the start of the internal register

Definition at line 618 of file bigint.h.

Referenced by Botan::PointGFp::add(), add(), add2(), Botan::PointGFp::add_affine(), cmp(), cmp_word(), Botan::ct_divide(), Botan::ct_inverse_mod_odd_modulus(), Botan::ct_modulo(), ct_reduce_below(), Botan::CurveGFp_Repr::curve_mul(), Botan::CurveGFp_Repr::curve_sqr(), encode_words(), Botan::FPE::fe1_decrypt(), Botan::FPE::fe1_encrypt(), is_equal(), is_less_than(), mod_add(), mod_sub(), Botan::Montgomery_Params::mul(), mul(), Botan::mul_add(), Botan::Montgomery_Params::mul_by(), Botan::operator*(), Botan::operator+(), operator+=(), Botan::operator-(), operator-=(), Botan::operator<<(), Botan::operator>>(), Botan::Montgomery_Params::redc(), Botan::redc_p521(), Botan::Modular_Reducer::reduce(), reduce_below(), rev_sub(), Botan::Montgomery_Params::sqr(), square(), and Botan::Montgomery_Params::square_this().

{ return m_data.const_data(); }

static BigInt Botan::BigInt::decode ( const uint8_t  buf[], size_t  length  )

inlinestatic

Create a BigInt from an integer in a byte array

Parameters

buf	the binary value to load
length	size of buf

Returns

BigInt representing the integer in the byte array

Definition at line 798 of file bigint.h.

Referenced by BigInt(), Botan::TLS::Client_Key_Exchange::Client_Key_Exchange(), decode(), Botan::BER_Decoder::decode_octet_string_bigint(), Botan::CRL_Entry::encode_into(), Botan::TPM_PrivateKey::get_e(), Botan::TPM_PrivateKey::get_n(), Botan::OCSP::CertID::is_id_for(), Botan::OS2ECP(), and Botan::TLS::Callbacks::tls_dh_agree().

        {
        return BigInt(buf, length);
        }

template<typename Alloc >

static BigInt Botan::BigInt::decode ( const std::vector< uint8_t, Alloc > &  buf )

inlinestatic

Create a BigInt from an integer in a byte array

Parameters

buf	the binary value to load

Returns

BigInt representing the integer in the byte array

Definition at line 809 of file bigint.h.

        {
        return BigInt(buf);
        }

BigInt Botan::BigInt::decode ( const uint8_t  buf[], size_t  length, Base  base  )

static

Create a BigInt from an integer in a byte array

Parameters

buf	the binary value to load
length	size of buf
base	number-base of the integer in buf

Returns

BigInt representing the integer in the byte array

Definition at line 146 of file big_code.cpp.

References Binary, binary_decode(), Botan::cast_uint8_ptr_to_char(), Botan::Charset::char2digit(), Decimal, Botan::hex_decode_locked(), Hexadecimal, Botan::Charset::is_digit(), and Botan::Charset::is_space().

   {
   BigInt r;
   if(base == Binary)
      {
      r.binary_decode(buf, length);
      }
   else if(base == Hexadecimal)
      {
      secure_vector<uint8_t> binary;

      if(length % 2)
         {
         // Handle lack of leading 0
         const char buf0_with_leading_0[2] =
            { '0', static_cast<char>(buf[0]) };

         binary = hex_decode_locked(buf0_with_leading_0, 2);

         binary += hex_decode_locked(cast_uint8_ptr_to_char(&buf[1]),
                                     length - 1,
                                     false);
         }
      else
         binary = hex_decode_locked(cast_uint8_ptr_to_char(buf),
                                    length, false);

      r.binary_decode(binary.data(), binary.size());
      }
   else if(base == Decimal)
      {
      for(size_t i = 0; i != length; ++i)
         {
         if(Charset::is_space(buf[i]))
            continue;

         if(!Charset::is_digit(buf[i]))
            throw Invalid_Argument("BigInt::decode: "
                                   "Invalid character in decimal input");

         const uint8_t x = Charset::char2digit(buf[i]);

         if(x >= 10)
            throw Invalid_Argument("BigInt: Invalid decimal string");

         r *= 10;
         r += x;
         }
      }
   else
      throw Invalid_Argument("Unknown BigInt decoding method");
   return r;
   }

template<typename Alloc >

static BigInt Botan::BigInt::decode ( const std::vector< uint8_t, Alloc > &  buf, Base  base  )

inlinestatic

Create a BigInt from an integer in a byte array

Parameters

buf	the binary value to load
base	number-base of the integer in buf

Returns

BigInt representing the integer in the byte array

Definition at line 871 of file bigint.h.

References decode().

        {
        if(base == Binary)
           return BigInt(buf);
        return BigInt::decode(buf.data(), buf.size(), base);
        }

static std::vector<uint8_t> Botan::BigInt::encode ( const BigInt &  n )

inlinestatic

Encode the integer value from a BigInt to a std::vector of bytes

Parameters

n	the BigInt to use as integer source

Returns

secure_vector of bytes containing the bytes of the integer

Definition at line 763 of file bigint.h.

References binary_encode(), and bytes().

Referenced by Botan::TLS::Client_Key_Exchange::Client_Key_Exchange(), Botan::CRL_Entry::decode_from(), Botan::ECIES_KA_Operation::derive_secret(), encode(), Botan::FPE_FE1::FPE_FE1(), Botan::TLS::Server_Key_Exchange::Server_Key_Exchange(), and to_hex_string().

        {
        std::vector<uint8_t> output(n.bytes());
        n.binary_encode(output.data());
        return output;
        }

static void Botan::BigInt::encode ( uint8_t  buf[], const BigInt &  n  )

inlinestatic

Encode the integer value from a BigInt to a byte array

Parameters

buf	destination byte array for the encoded integer
n	the BigInt to use as integer source

Definition at line 787 of file bigint.h.

        {
        n.binary_encode(buf);
        }

std::vector< uint8_t > Botan::BigInt::encode ( const BigInt &  n, Base  base  )

static

Encode the integer value from a BigInt to a std::vector of bytes

Parameters

n	the BigInt to use as integer source
base	number-base of resulting byte array representation

Returns

secure_vector of bytes containing the integer with given base

Deprecated. If you need Binary, call the version of encode that doesn't take a Base. If you need Hex or Decimal output, use to_hex_string or to_dec_string resp.

Definition at line 81 of file big_code.cpp.

References Binary, Decimal, encode(), Hexadecimal, to_dec_string(), and to_hex_string().

   {
   if(base == Binary)
      return BigInt::encode(n);
   else if(base == Hexadecimal)
      return str_to_vector(n.to_hex_string());
   else if(base == Decimal)
      return str_to_vector(n.to_dec_string());
   else
      throw Invalid_Argument("Unknown BigInt encoding base");
   }

void Botan::BigInt::encode ( uint8_t  buf[], const BigInt &  n, Base  base  )

static

Encode the integer value from a BigInt to a byte array

Parameters

buf	destination byte array for the encoded integer value with given base
n	the BigInt to use as integer source
base	number-base of resulting byte array representation

Deprecated. If you need Binary, call binary_encode. If you need Hex or Decimal output, use to_hex_string or to_dec_string resp.

Definition at line 54 of file big_code.cpp.

References Botan::copy_mem(), and encode_locked().

   {
   secure_vector<uint8_t> enc = n.encode_locked(base);
   copy_mem(output, enc.data(), enc.size());
   }

secure_vector< uint8_t > Botan::BigInt::encode_1363 ( const BigInt &  n, size_t  bytes  )

static

Encode a BigInt to a byte array according to IEEE 1363

Parameters

n	the BigInt to encode
bytes	the length of the resulting secure_vector<uint8_t>

Returns

a secure_vector<uint8_t> containing the encoded BigInt

Definition at line 111 of file big_code.cpp.

References binary_encode(), and bytes().

Referenced by Botan::PK_Verifier::check_signature(), Botan::EC_Group::DER_encode(), Botan::PointGFp::encode(), Botan::RFC6979_Nonce_Generator::nonce_for(), Botan::EC_PrivateKey::private_key_bits(), Botan::DH_PublicKey::public_value(), Botan::RFC6979_Nonce_Generator::RFC6979_Nonce_Generator(), Botan::Montgomery_Int::serialize(), Botan::sm2_compute_za(), Botan::srp6_client_agree(), and Botan::SRP6_Server_Session::step2().

   {
   if(n.bytes() > bytes)
      throw Encoding_Error("encode_1363: n is too large to encode properly");

   secure_vector<uint8_t> output(bytes);
   n.binary_encode(output.data(), output.size());
   return output;
   }

void Botan::BigInt::encode_1363 ( uint8_t  out[], size_t  bytes, const BigInt &  n  )

static

Definition at line 122 of file big_code.cpp.

References binary_encode(), and bytes().

   {
   if(n.bytes() > bytes)
      throw Encoding_Error("encode_1363: n is too large to encode properly");

   n.binary_encode(output, bytes);
   }

secure_vector< uint8_t > Botan::BigInt::encode_fixed_length_int_pair ( const BigInt &  n1, const BigInt &  n2, size_t  bytes  )

static

Encode two BigInt to a byte array according to IEEE 1363

Parameters

n1	the first BigInt to encode
n2	the second BigInt to encode
bytes	the length of the encoding of each single BigInt

Returns

a secure_vector<uint8_t> containing the concatenation of the two encoded BigInt

Definition at line 133 of file big_code.cpp.

References binary_encode(), and bytes().

   {
   if(n1.bytes() > bytes || n2.bytes() > bytes)
      throw Encoding_Error("encode_fixed_length_int_pair: values too large to encode properly");
   secure_vector<uint8_t> output(2 * bytes);
   n1.binary_encode(output.data()        , bytes);
   n2.binary_encode(output.data() + bytes, bytes);
   return output;
   }

static secure_vector<uint8_t> Botan::BigInt::encode_locked ( const BigInt &  n )

inlinestatic

Encode the integer value from a BigInt to a secure_vector of bytes

Parameters

n	the BigInt to use as integer source

Returns

secure_vector of bytes containing the bytes of the integer

Definition at line 775 of file bigint.h.

References binary_encode(), and bytes().

Referenced by encode(), and encode_locked().

        {
        secure_vector<uint8_t> output(n.bytes());
        n.binary_encode(output.data());
        return output;
        }

secure_vector< uint8_t > Botan::BigInt::encode_locked ( const BigInt &  n, Base  base  )

static

Encode the integer value from a BigInt to a secure_vector of bytes

Parameters

n	the BigInt to use as integer source
base	number-base of resulting byte array representation

Returns

secure_vector of bytes containing the integer with given base

Deprecated. If you need Binary, call the version of encode_locked that doesn't take a Base. If you need Hex or Decimal output, use to_hex_string or to_dec_string resp.

Definition at line 96 of file big_code.cpp.

References Binary, Decimal, encode_locked(), Hexadecimal, to_dec_string(), and to_hex_string().

   {
   if(base == Binary)
      return BigInt::encode_locked(n);
   else if(base == Hexadecimal)
      return str_to_lvector(n.to_hex_string());
   else if(base == Decimal)
      return str_to_lvector(n.to_dec_string());
   else
      throw Invalid_Argument("Unknown BigInt encoding base");
   }

void Botan::BigInt::encode_words	(	word	out[],
		size_t	size
	)		const

Place the value into out, zero-padding up to size words Throw if *this cannot be represented in size words

Definition at line 177 of file bigint.cpp.

References Botan::clear_mem(), Botan::copy_mem(), data(), and sig_words().

   {
   const size_t words = sig_words();

   if(words > size)
      throw Encoding_Error("BigInt::encode_words value too large to encode");

   clear_mem(out, size);
   copy_mem(out, data(), words);
   }

size_t Botan::BigInt::encoded_size

(

Base

base = Binary

)

const

Parameters

base	the base to measure the size for

Returns

size of this integer in base base

Deprecated. This is only needed when using the encode and encode_locked functions, which are also deprecated.

Definition at line 304 of file bigint.cpp.

References Binary, bits(), bytes(), Decimal, and Hexadecimal.

   {
   static const double LOG_2_BASE_10 = 0.30102999566;

   if(base == Binary)
      return bytes();
   else if(base == Hexadecimal)
      return 2*bytes();
   else if(base == Decimal)
      return static_cast<size_t>((bits() * LOG_2_BASE_10) + 1);
   else
      throw Invalid_Argument("Unknown base for BigInt encoding");
   }

void Botan::BigInt::flip_sign ( )

inline

Flip the sign of this BigInt

Definition at line 552 of file bigint.h.

Referenced by botan_mp_flip_sign(), Botan::ct_divide_u8(), Botan::BER_Decoder::decode(), Botan::is_lucas_probable_prime(), and operator-().

        {
        set_sign(reverse_sign());
        }

bool Botan::BigInt::get_bit ( size_t  n ) const

inline

Return bit value at specified position

Parameters

n	the bit offset to test

Returns

true, if the bit at position n is set, false otherwise

Definition at line 463 of file bigint.h.

Referenced by Botan::ct_divide(), Botan::ct_divide_u8(), Botan::ct_modulo(), Botan::PointGFp::encode(), Botan::is_lucas_probable_prime(), Botan::operator*(), and Botan::power_mod().

        {
        return ((word_at(n / BOTAN_MP_WORD_BITS) >> (n % BOTAN_MP_WORD_BITS)) & 1);
        }

uint32_t Botan::BigInt::get_substring	(	size_t	offset,
		size_t	length
	)		const

Return (a maximum of) 32 bits of the complete value

Parameters

offset	the offset to start extracting
length	amount of bits to extract (starting at offset)

Returns

the integer extracted from the register starting at offset with specified length

Definition at line 214 of file bigint.cpp.

References byte_at(), and Botan::make_uint64().

Referenced by Botan::monty_multi_exp(), Botan::PointGFp_Base_Point_Precompute::mul(), Botan::PointGFp_Var_Point_Precompute::mul(), and Botan::PointGFp_Multi_Point_Precompute::multi_exp().

   {
   if(length == 0 || length > 32)
      throw Invalid_Argument("BigInt::get_substring invalid substring length");

   const size_t byte_offset = offset / 8;
   const size_t shift = (offset % 8);
   const uint32_t mask = 0xFFFFFFFF >> (32 - length);

   const uint8_t b0 = byte_at(byte_offset);
   const uint8_t b1 = byte_at(byte_offset + 1);
   const uint8_t b2 = byte_at(byte_offset + 2);
   const uint8_t b3 = byte_at(byte_offset + 3);
   const uint8_t b4 = byte_at(byte_offset + 4);
   const uint64_t piece = make_uint64(0, 0, 0, b4, b3, b2, b1, b0);

   return static_cast<uint32_t>((piece >> shift) & mask);
   }

secure_vector<word>& Botan::BigInt::get_word_vector ( )

inline

Don't use this function in application code

Definition at line 623 of file bigint.h.

Referenced by Botan::PointGFp::add_affine(), Botan::ct_inverse_mod_odd_modulus(), Botan::Montgomery_Int::fix_size(), and Botan::PointGFp_Var_Point_Precompute::PointGFp_Var_Point_Precompute().

{ return m_data.mutable_vector(); }

const secure_vector<word>& Botan::BigInt::get_word_vector ( ) const

inline

Don't use this function in application code

Definition at line 628 of file bigint.h.

{ return m_data.const_vector(); }

void Botan::BigInt::grow_to ( size_t  n ) const

inline

Increase internal register buffer to at least n words

Parameters

n	new size of register

Definition at line 634 of file bigint.h.

Referenced by add(), ct_cond_assign(), ct_cond_swap(), Botan::ct_inverse_mod_odd_modulus(), ct_reduce_below(), Botan::divide(), mod_add(), mod_sub(), mul(), Botan::Montgomery_Params::mul_by(), Botan::Montgomery_Params::redc(), Botan::redc_p521(), reduce_below(), and Botan::Montgomery_Params::square_this().

{ m_data.grow_to(n); }

bool Botan::BigInt::is_equal

(

const BigInt &

n

)

const

Compare this to another BigInt

Parameters

n	the BigInt value to compare with

Returns

true if this == n or false otherwise

Definition at line 150 of file bigint.cpp.

References Botan::bigint_ct_is_eq(), data(), sig_words(), and sign().

Referenced by Botan::operator!=().

   {
   if(this->sign() != other.sign())
      return false;

   return bigint_ct_is_eq(this->data(), this->sig_words(),
                          other.data(), other.sig_words()).is_set();
   }

bool Botan::BigInt::is_even ( ) const

inline

Test if the integer has an even value

Returns

true if the integer is even, false otherwise

Definition at line 401 of file bigint.h.

Referenced by Botan::almost_montgomery_inverse(), botan_mp_is_even(), Botan::ct_inverse_mod_odd_modulus(), Botan::gcd(), Botan::generate_rsa_prime(), Botan::inverse_euclid(), Botan::is_lucas_probable_prime(), Botan::is_prime(), Botan::jacobi(), Botan::Montgomery_Params::Montgomery_Params(), Botan::random_prime(), and Botan::ressol().

{ return (get_bit(0) == 0); }

bool Botan::BigInt::is_less_than

(

const BigInt &

n

)

const

Compare this to another BigInt

Parameters

n	the BigInt value to compare with

Returns

true if this < n or false otherwise

Definition at line 159 of file bigint.cpp.

References Botan::bigint_ct_is_lt(), data(), is_negative(), is_positive(), and sig_words().

Referenced by Botan::operator<(), and Botan::operator>().

   {
   if(this->is_negative() && other.is_positive())
      return true;

   if(this->is_positive() && other.is_negative())
      return false;

   if(other.is_negative() && this->is_negative())
      {
      return !bigint_ct_is_lt(other.data(), other.sig_words(),
                              this->data(), this->sig_words(), true).is_set();
      }

   return bigint_ct_is_lt(this->data(), this->sig_words(),
                          other.data(), other.sig_words()).is_set();
   }

bool Botan::BigInt::is_negative ( ) const

inline

Tests if the sign of the integer is negative

Returns

true, iff the integer has a negative sign

Definition at line 525 of file bigint.h.

Referenced by botan_mp_is_negative(), cmp(), cmp_word(), Botan::ct_divide_u8(), Botan::ct_inverse_mod_odd_modulus(), Botan::ct_modulo(), ct_reduce_below(), Botan::BER_Decoder::decode(), Botan::divide(), Botan::inverse_euclid(), Botan::inverse_mod(), is_less_than(), Botan::is_lucas_probable_prime(), mod_add(), mod_mul(), mod_sub(), Botan::Montgomery_Params::Montgomery_Params(), Botan::monty_multi_exp(), Botan::PointGFp_Base_Point_Precompute::mul(), Botan::PointGFp_Var_Point_Precompute::mul(), Botan::mul_add(), Botan::mul_sub(), Botan::PointGFp_Multi_Point_Precompute::multi_exp(), Botan::operator%(), Botan::operator*(), Botan::operator>>(), operator>>=(), Botan::power_mod(), random_integer(), Botan::random_prime(), Botan::Modular_Reducer::reduce(), reduce_below(), Botan::Power_Mod::set_base(), Botan::Power_Mod::set_exponent(), Botan::sub_mul(), and to_u32bit().

{ return (sign() == Negative); }

bool Botan::BigInt::is_nonzero ( ) const

inline

Test if the integer is not zero

Returns

true if the integer is non-zero, false otherwise

Definition at line 413 of file bigint.h.

Referenced by Botan::ct_modulo(), Botan::inverse_euclid(), Botan::low_zero_bits(), and Botan::Modular_Reducer::reduce().

{ return (!is_zero()); }

bool Botan::BigInt::is_odd ( ) const

inline

Test if the integer has an odd value

Returns

true if the integer is odd, false otherwise

Definition at line 407 of file bigint.h.

Referenced by botan_mp_is_odd(), Botan::gcd(), Botan::inverse_euclid(), Botan::inverse_mod(), Botan::is_lucas_probable_prime(), Botan::normalized_montgomery_inverse(), Botan::power_mod(), and Botan::Power_Mod::set_modulus().

{ return (get_bit(0) == 1); }

bool Botan::BigInt::is_positive ( ) const

inline

Tests if the sign of the integer is positive

Returns

true, iff the integer has a positive sign

Definition at line 531 of file bigint.h.

Referenced by botan_mp_is_positive(), cmp(), is_less_than(), Botan::low_zero_bits(), and Botan::operator%().

{ return (sign() == Positive); }

bool Botan::BigInt::is_zero ( ) const

inline

Test if the integer is zero

Returns

true if the integer is zero, false otherwise

Definition at line 419 of file bigint.h.

Referenced by Botan::PointGFp::add(), Botan::PointGFp::add_affine(), botan_mp_is_zero(), Botan::ct_inverse_mod_odd_modulus(), Botan::ct_modulo(), Botan::DH_PrivateKey::DH_PrivateKey(), Botan::divide(), Botan::ElGamal_PrivateKey::ElGamal_PrivateKey(), Botan::gcd(), Botan::inverse_euclid(), Botan::inverse_mod(), Botan::Montgomery_Int::is_zero(), Botan::jacobi(), Botan::mul_sub(), Botan::PointGFp::mult2(), Botan::PointGFp::mult2i(), Botan::operator%(), operator>>=(), Botan::DL_Group::PEM_for_named_group(), Botan::power_mod(), Botan::random_prime(), Botan::RSA_PrivateKey::RSA_PrivateKey(), and Botan::DL_Group::verify_public_element().

        {
        return (sig_words() == 0);
        }

void Botan::BigInt::mask_bits ( size_t  n )

inline

Clear all but the lowest n bits

Parameters

n	amount of bits to keep

Definition at line 453 of file bigint.h.

Referenced by Botan::redc_p192(), Botan::redc_p224(), Botan::redc_p256(), Botan::redc_p384(), Botan::redc_p521(), and Botan::Modular_Reducer::reduce().

        {
        m_data.mask_bits(n);
        }

BigInt & Botan::BigInt::mod_add	(	const BigInt &	y,
		const BigInt &	mod,
		secure_vector< word > &	ws
	)

Set *this to (*this + y) % mod This function assumes *this is >= 0 && < mod

Parameters

y	the BigInt to add - assumed y >= 0 and y < mod
mod	the positive modulus
ws	a temp workspace

Definition at line 50 of file big_ops2.cpp.

References Botan::bigint_add3_nc(), Botan::bigint_sub3(), BOTAN_ARG_CHECK, BOTAN_DEBUG_ASSERT, Botan::CT::conditional_copy_mem(), data(), grow_to(), is_negative(), set_words(), and sig_words().

Referenced by Botan::Montgomery_Int::add(), Botan::PointGFp::mult2(), and Botan::Montgomery_Int::operator+().

   {
   if(this->is_negative() || s.is_negative() || mod.is_negative())
      throw Invalid_Argument("BigInt::mod_add expects all arguments are positive");

   BOTAN_DEBUG_ASSERT(*this < mod);
   BOTAN_DEBUG_ASSERT(s < mod);

   /*
   t + s or t + s - p == t - (p - s)

   So first compute ws = p - s

   Then compute t + s and t - ws

   If t - ws does not borrow, then that is the correct valued
   */

   const size_t mod_sw = mod.sig_words();
   BOTAN_ARG_CHECK(mod_sw > 0, "BigInt::mod_add modulus must be positive");

   this->grow_to(mod_sw);
   s.grow_to(mod_sw);

   // First mod_sw for p - s, 2*mod_sw for bigint_addsub workspace
   if(ws.size() < 3*mod_sw)
      ws.resize(3*mod_sw);

   word borrow = bigint_sub3(&ws[0], mod.data(), mod_sw, s.data(), mod_sw);
   BOTAN_DEBUG_ASSERT(borrow == 0);

   // Compute t - ws
   borrow = bigint_sub3(&ws[mod_sw], this->data(), mod_sw, &ws[0], mod_sw);

   // Compute t + s
   bigint_add3_nc(&ws[mod_sw*2], this->data(), mod_sw, s.data(), mod_sw);

   CT::conditional_copy_mem(borrow, &ws[0], &ws[mod_sw*2], &ws[mod_sw], mod_sw);
   set_words(&ws[0], mod_sw);

   return (*this);
   }

BigInt & Botan::BigInt::mod_mul	(	uint8_t	y,
		const BigInt &	mod,
		secure_vector< word > &	ws
	)

Set *this to (*this * y) % mod This function assumes *this is >= 0 && < mod y should be small, less than 16

Parameters

y	the small integer to multiply by
mod	the positive modulus
ws	a temp workspace

Definition at line 139 of file big_ops2.cpp.

References BOTAN_ARG_CHECK, BOTAN_DEBUG_ASSERT, is_negative(), and reduce_below().

Referenced by Botan::Montgomery_Int::mul_by_2(), Botan::Montgomery_Int::mul_by_3(), Botan::Montgomery_Int::mul_by_4(), Botan::Montgomery_Int::mul_by_8(), and Botan::PointGFp::mult2().

   {
   BOTAN_ARG_CHECK(this->is_negative() == false, "*this must be positive");
   BOTAN_ARG_CHECK(y < 16, "y too large");

   BOTAN_DEBUG_ASSERT(*this < mod);

   *this *= static_cast<word>(y);
   this->reduce_below(mod, ws);
   return (*this);
   }

BigInt & Botan::BigInt::mod_sub	(	const BigInt &	y,
		const BigInt &	mod,
		secure_vector< word > &	ws
	)

Set *this to (*this - y) % mod This function assumes *this is >= 0 && < mod

Parameters

y	the BigInt to subtract - assumed y >= 0 and y < mod
mod	the positive modulus
ws	a temp workspace

Definition at line 93 of file big_ops2.cpp.

References Botan::bigint_mod_sub(), Botan::bigint_sub2_rev(), Botan::bigint_sub3(), BOTAN_DEBUG_ASSERT, data(), grow_to(), is_negative(), mutable_data(), sig_words(), and swap_reg().

Referenced by Botan::PointGFp::add(), Botan::PointGFp::add_affine(), Botan::PointGFp::mult2(), Botan::Montgomery_Int::operator-(), and Botan::Montgomery_Int::sub().

   {
   if(this->is_negative() || s.is_negative() || mod.is_negative())
      throw Invalid_Argument("BigInt::mod_sub expects all arguments are positive");

   // We are assuming in this function that *this and s are no more than mod_sw words long
   BOTAN_DEBUG_ASSERT(*this < mod);
   BOTAN_DEBUG_ASSERT(s < mod);

   const size_t mod_sw = mod.sig_words();

   this->grow_to(mod_sw);
   s.grow_to(mod_sw);

   if(ws.size() < mod_sw)
      ws.resize(mod_sw);

#if 0
   //Faster but not const time:

   // Compute t - s
   word borrow = bigint_sub3(ws.data(), data(), mod_sw, s.data(), mod_sw);

   if(borrow)
      {
      // If t < s, instead compute p - (s - t)
      bigint_sub2_rev(mutable_data(), s.data(), mod_sw);
      bigint_sub2_rev(mutable_data(), mod.data(), mod_sw);
      }
   else
      {
      // No borrow so we already have the result we need
      swap_reg(ws);
      }
#else
   if(mod_sw == 4)
      bigint_mod_sub_n<4>(mutable_data(), s.data(), mod.data(), ws.data());
   else if(mod_sw == 6)
      bigint_mod_sub_n<6>(mutable_data(), s.data(), mod.data(), ws.data());
   else
      bigint_mod_sub(mutable_data(), s.data(), mod.data(), mod_sw, ws.data());
#endif

   return (*this);
   }

BigInt & Botan::BigInt::mul	(	const BigInt &	y,
		secure_vector< word > &	ws
	)

Multiply this with y

Parameters

y	the BigInt to multiply with this
ws	a temp workspace

Definition at line 178 of file big_ops2.cpp.

References Botan::bigint_linmul2(), Botan::bigint_linmul3(), Botan::bigint_mul(), Botan::carry(), clear(), data(), grow_to(), mutable_data(), Negative, Positive, set_sign(), set_word_at(), sig_words(), sign(), size(), swap_reg(), and word_at().

Referenced by operator*=(), and Botan::Modular_Reducer::reduce().

   {
   const size_t x_sw = sig_words();
   const size_t y_sw = y.sig_words();
   set_sign((sign() == y.sign()) ? Positive : Negative);

   if(x_sw == 0 || y_sw == 0)
      {
      clear();
      set_sign(Positive);
      }
   else if(x_sw == 1 && y_sw)
      {
      grow_to(y_sw + 1);
      bigint_linmul3(mutable_data(), y.data(), y_sw, word_at(0));
      }
   else if(y_sw == 1 && x_sw)
      {
      word carry = bigint_linmul2(mutable_data(), x_sw, y.word_at(0));
      set_word_at(x_sw, carry);
      }
   else
      {
      const size_t new_size = x_sw + y_sw + 1;
      ws.resize(new_size);
      secure_vector<word> z_reg(new_size);

      bigint_mul(z_reg.data(), z_reg.size(),
                 data(), size(), x_sw,
                 y.data(), y.size(), y_sw,
                 ws.data(), ws.size());

      this->swap_reg(z_reg);
      }

   return (*this);
   }

word* Botan::BigInt::mutable_data ( )

inline

Return a mutable pointer to the register

Returns

a pointer to the start of the internal register

Definition at line 612 of file bigint.h.

Referenced by add(), ct_cond_swap(), Botan::ct_divide(), Botan::ct_modulo(), ct_reduce_below(), Botan::divide(), mod_sub(), Botan::Montgomery_Params::mul(), mul(), Botan::mul_add(), Botan::Montgomery_Params::mul_by(), Botan::operator*(), operator*=(), Botan::operator<<(), Botan::Montgomery_Params::redc(), Botan::redc_p192(), Botan::redc_p224(), Botan::redc_p256(), Botan::redc_p384(), Botan::redc_p521(), Botan::Montgomery_Params::sqr(), and Botan::Montgomery_Params::square_this().

{ return m_data.mutable_data(); }

bool Botan::BigInt::operator! ( ) const

inline

! operator

Returns

true iff this is zero, otherwise false

Definition at line 279 of file bigint.h.

{ return (!is_nonzero()); }

BigInt & Botan::BigInt::operator%=

(

const BigInt &

y

)

Modulo operator

Parameters

y	the modulus to reduce this by

Definition at line 262 of file big_ops2.cpp.

   {
   return (*this = (*this) % mod);
   }

word Botan::BigInt::operator%=

(

word

y

)

Modulo operator

Parameters

y	the modulus (word) to reduce this by

Definition at line 270 of file big_ops2.cpp.

References Botan::bigint_modop(), Botan::is_power_of_2(), Negative, Positive, set_sign(), sig_words(), sign(), and word_at().

   {
   if(mod == 0)
      throw BigInt::DivideByZero();

   word remainder = 0;

   if(is_power_of_2(mod))
       {
       remainder = (word_at(0) & (mod - 1));
       }
   else
      {
      const size_t sw = sig_words();
      for(size_t i = sw; i > 0; --i)
         remainder = bigint_modop(remainder, word_at(i-1), mod);
      }

   if(remainder && sign() == BigInt::Negative)
      remainder = mod - remainder;

   m_data.set_to_zero();
   m_data.set_word_at(0, remainder);
   set_sign(BigInt::Positive);
   return remainder;
   }

BigInt & Botan::BigInt::operator*=

(

const BigInt &

y

)

*= operator

Parameters

y	the BigInt to multiply with this

Definition at line 172 of file big_ops2.cpp.

References mul().

   {
   secure_vector<word> ws;
   return this->mul(y, ws);
   }

BigInt & Botan::BigInt::operator*=

(

word

y

)

*= operator

Parameters

y	the word to multiply with this

Definition at line 233 of file big_ops2.cpp.

References Botan::bigint_linmul2(), Botan::carry(), clear(), mutable_data(), Positive, set_sign(), set_word_at(), and size().

   {
   if(y == 0)
      {
      clear();
      set_sign(Positive);
      }

   const word carry = bigint_linmul2(mutable_data(), size(), y);
   set_word_at(size(), carry);

   return (*this);
   }

BigInt& Botan::BigInt::operator++ ( )

inline

Increment operator

Definition at line 252 of file bigint.h.

{ return (*this += 1); }

BigInt Botan::BigInt::operator++ ( int  )

inline

Postfix increment operator

Definition at line 262 of file bigint.h.

{ BigInt x = (*this); ++(*this); return x; }

BigInt& Botan::BigInt::operator+= ( const BigInt &  y )

inline

+= operator

Parameters

y	the BigInt to add to this

Definition at line 175 of file bigint.h.

References data(), sig_words(), and sign().

        {
        return add(y.data(), y.sig_words(), y.sign());
        }

BigInt& Botan::BigInt::operator+= ( word  y )

inline

+= operator

Parameters

y	the word to add to this

Definition at line 184 of file bigint.h.

        {
        return add(&y, 1, Positive);
        }

BigInt Botan::BigInt::operator-

(

)

const

Unary negation operator

Returns

negative this

Definition at line 321 of file bigint.cpp.

References flip_sign().

   {
   BigInt x = (*this);
   x.flip_sign();
   return x;
   }

BigInt& Botan::BigInt::operator-- ( )

inline

Decrement operator

Definition at line 257 of file bigint.h.

{ return (*this -= 1); }

BigInt Botan::BigInt::operator-- ( int  )

inline

Postfix decrement operator

Definition at line 267 of file bigint.h.

{ BigInt x = (*this); --(*this); return x; }

BigInt& Botan::BigInt::operator-= ( const BigInt &  y )

inline

-= operator

Parameters

y	the BigInt to subtract from this

Definition at line 193 of file bigint.h.

References data(), sig_words(), and sign().

        {
        return sub(y.data(), y.sig_words(), y.sign());
        }

BigInt& Botan::BigInt::operator-= ( word  y )

inline

-= operator

Parameters

y	the word to subtract from this

Definition at line 202 of file bigint.h.

        {
        return sub(&y, 1, Positive);
        }

BigInt & Botan::BigInt::operator/=

(

const BigInt &

y

)

/= operator

Parameters

y	the BigInt to divide this by

Definition at line 250 of file big_ops2.cpp.

References bits(), Botan::is_power_of_2(), sig_words(), and word_at().

   {
   if(y.sig_words() == 1 && is_power_of_2(y.word_at(0)))
      (*this) >>= (y.bits() - 1);
   else
      (*this) = (*this) / y;
   return (*this);
   }

BigInt & Botan::BigInt::operator<<=

(

size_t

shift

)

Left shift operator

Parameters

shift

the number of bits to shift this left by

Definition at line 300 of file big_ops2.cpp.

References Botan::bigint_shl1(), sig_words(), size(), and top_bits_free().

   {
   const size_t shift_words = shift / BOTAN_MP_WORD_BITS;
   const size_t shift_bits  = shift % BOTAN_MP_WORD_BITS;
   const size_t size = sig_words();

   const size_t bits_free = top_bits_free();

   const size_t new_size = size + shift_words + (bits_free < shift_bits);

   m_data.grow_to(new_size);

   bigint_shl1(m_data.mutable_data(), new_size, size, shift_words, shift_bits);

   return (*this);
   }

BigInt& Botan::BigInt::operator= ( BigInt &&  other )

inline

Move assignment

Definition at line 142 of file bigint.h.

        {
        if(this != &other)
           this->swap(other);

        return (*this);
        }

BigInt& Botan::BigInt::operator= ( const BigInt &  )

default

Copy assignment

BigInt & Botan::BigInt::operator>>=

(

size_t

shift

)

Right shift operator

Parameters

shift

the number of bits to shift this right by

Definition at line 320 of file big_ops2.cpp.

References Botan::bigint_shr1(), is_negative(), is_zero(), Positive, and set_sign().

   {
   const size_t shift_words = shift / BOTAN_MP_WORD_BITS;
   const size_t shift_bits  = shift % BOTAN_MP_WORD_BITS;

   bigint_shr1(m_data.mutable_data(), m_data.size(), shift_words, shift_bits);

   if(is_negative() && is_zero())
      set_sign(Positive);

   return (*this);
   }

static BigInt Botan::BigInt::power_of_2 ( size_t  n )

inlinestatic

Create a power of two

Parameters

n	the power of two to create

Returns

bigint representing 2^n

Definition at line 751 of file bigint.h.

References set_bit().

Referenced by Botan::is_perfect_square(), Botan::Montgomery_Params::Montgomery_Params(), and Botan::ressol().

        {
        BigInt b;
        b.set_bit(n);
        return b;
        }

BigInt Botan::BigInt::random_integer ( RandomNumberGenerator &  rng, const BigInt &  min, const BigInt &  max  )

static

Parameters

rng	a random number generator
min	the minimum value (must be non-negative)
max	the maximum value (must be non-negative and > min)

Returns

random integer in [min,max)

Definition at line 45 of file big_rand.cpp.

References bits(), is_negative(), and randomize().

Referenced by botan_mp_rand_range(), Botan::DSA_PrivateKey::DSA_PrivateKey(), Botan::is_miller_rabin_probable_prime(), Botan::EC_Group::random_scalar(), and Botan::PointGFp::randomize_repr().

   {
   if(min.is_negative() || max.is_negative() || max <= min)
      throw Invalid_Argument("BigInt::random_integer invalid range");

   BigInt r;

   const size_t bits = max.bits();

   do
      {
      r.randomize(rng, bits, false);
      }
   while(r < min || r >= max);

   return r;
   }

void Botan::BigInt::randomize	(	RandomNumberGenerator &	rng,
		size_t	bitsize,
		bool	set_high_bit = true
	)

Fill BigInt with a random number with size of bitsize

If set_high_bit is true, the highest bit will be set, which causes the entropy to be bits-1. Otherwise the highest bit is randomly chosen by the rng, causing the entropy to be bits.

Parameters

rng	the random number generator to use
bitsize	number of bits the created random value should have
set_high_bit	if true, the highest bit is always set

Definition at line 17 of file big_rand.cpp.

References binary_decode(), clear(), Positive, Botan::RandomNumberGenerator::random_vec(), Botan::round_up(), and set_sign().

Referenced by BigInt(), Botan::DH_PrivateKey::DH_PrivateKey(), Botan::DL_Group::DL_Group(), Botan::ElGamal_PrivateKey::ElGamal_PrivateKey(), Botan::PointGFp_Var_Point_Precompute::PointGFp_Var_Point_Precompute(), and random_integer().

   {
   set_sign(Positive);

   if(bitsize == 0)
      {
      clear();
      }
   else
      {
      secure_vector<uint8_t> array = rng.random_vec(round_up(bitsize, 8) / 8);

      // Always cut unwanted bits
      if(bitsize % 8)
         array[0] &= 0xFF >> (8 - (bitsize % 8));

      // Set the highest bit if wanted
      if (set_high_bit)
         array[0] |= 0x80 >> ((bitsize % 8) ? (8 - bitsize % 8) : 0);

      binary_decode(array);
      }
   }

size_t Botan::BigInt::reduce_below	(	const BigInt &	mod,
		secure_vector< word > &	ws
	)

Return *this % mod

Assumes that *this is (if anything) only slightly larger than mod and performs repeated subtractions. It should not be used if *this is much larger than mod, instead use modulo operator.

Definition at line 328 of file bigint.cpp.

References Botan::bigint_sub3(), Botan::clear_mem(), data(), grow_to(), is_negative(), sig_words(), size(), and swap_reg().

Referenced by Botan::divide(), and mod_mul().

   {
   if(p.is_negative() || this->is_negative())
      throw Invalid_Argument("BigInt::reduce_below both values must be positive");

   const size_t p_words = p.sig_words();

   if(size() < p_words + 1)
      grow_to(p_words + 1);

   if(ws.size() < p_words + 1)
      ws.resize(p_words + 1);

   clear_mem(ws.data(), ws.size());

   size_t reductions = 0;

   for(;;)
      {
      word borrow = bigint_sub3(ws.data(), data(), p_words + 1, p.data(), p_words);
      if(borrow)
         break;

      ++reductions;
      swap_reg(ws);
      }

   return reductions;
   }

void Botan::BigInt::resize ( size_t  s )

inline

Definition at line 645 of file bigint.h.

Referenced by Botan::PointGFp::force_all_affine(), Botan::redc_p192(), Botan::redc_p224(), Botan::redc_p256(), and Botan::redc_p384().

{ m_data.resize(s); }

BigInt & Botan::BigInt::rev_sub	(	const word	y[],
		size_t	y_words,
		secure_vector< word > &	ws
	)

Set *this to y - *this

Parameters

y	the BigInt to subtract from as a sequence of words
y_words	length of y in words
ws	a temp workspace

Definition at line 151 of file big_ops2.cpp.

References Botan::bigint_sub_abs(), Botan::clear_mem(), cond_flip_sign(), data(), Positive, sig_words(), sign(), and swap_reg().

Referenced by Botan::Modular_Reducer::reduce().

   {
   if(this->sign() != BigInt::Positive)
      throw Invalid_State("BigInt::sub_rev requires this is positive");

   const size_t x_sw = this->sig_words();

   ws.resize(std::max(x_sw, y_sw));
   clear_mem(ws.data(), ws.size());

   const int32_t relative_size = bigint_sub_abs(ws.data(), data(), x_sw, y, y_sw);

   this->cond_flip_sign(relative_size > 0);
   this->swap_reg(ws);

   return (*this);
   }

Sign Botan::BigInt::reverse_sign ( ) const

inline

Returns

the opposite sign of the represented integer value

Definition at line 542 of file bigint.h.

Referenced by Botan::operator-().

        {
        if(sign() == Positive)
           return Negative;
        return Positive;
        }

void Botan::BigInt::set_bit ( size_t  n )

inline

Set bit at specified position

Parameters

n	bit position to set

Definition at line 428 of file bigint.h.

Referenced by botan_mp_set_bit(), Botan::generate_dsa_primes(), Botan::generate_rsa_prime(), Botan::Modular_Reducer::Modular_Reducer(), Botan::PointGFp_Var_Point_Precompute::PointGFp_Var_Point_Precompute(), power_of_2(), and Botan::random_prime().

        {
        conditionally_set_bit(n, true);
        }

void Botan::BigInt::set_sign ( Sign  sign )

inline

Set sign of the integer

Parameters

sign	new Sign to set

Definition at line 561 of file bigint.h.

Referenced by abs(), add(), BigInt(), cond_flip_sign(), Botan::divide(), Botan::gcd(), mul(), operator%=(), Botan::operator*(), operator*=(), operator>>=(), randomize(), Botan::Modular_Reducer::reduce(), square(), and to_dec_string().

        {
        if(sign == Negative && is_zero())
           sign = Positive;

        m_signedness = sign;
        }

void Botan::BigInt::set_word_at ( size_t  i, word  w  )

inline

Definition at line 511 of file bigint.h.

Referenced by ct_cond_assign(), mul(), and operator*=().

        {
        m_data.set_word_at(i, w);
        }

void Botan::BigInt::set_words ( const word  w[], size_t  len  )

inline

Definition at line 516 of file bigint.h.

Referenced by Botan::PointGFp::add(), Botan::PointGFp::add_affine(), and mod_add().

        {
        m_data.set_words(w, len);
        }

void Botan::BigInt::shrink_to_fit ( size_t  min_size = 0 )

inline

Resize the vector to the minimum word size to hold the integer, or min_size words, whichever is larger

Definition at line 640 of file bigint.h.

Referenced by Botan::gcd().

        {
        m_data.shrink_to_fit(min_size);
        }

size_t Botan::BigInt::sig_words ( ) const

inline

Return how many words we need to hold this value

Returns

significant words of the represented integer value

Definition at line 584 of file bigint.h.

Referenced by add(), add2(), bits(), cmp_word(), Botan::ct_divide(), Botan::ct_divide_u8(), Botan::ct_inverse_mod_odd_modulus(), Botan::ct_modulo(), ct_reduce_below(), Botan::CurveGFp_Repr::curve_mul(), Botan::CurveGFp_Repr::curve_sqr(), Botan::divide(), encode_words(), Botan::Montgomery_Int::fix_size(), is_equal(), is_less_than(), mod_add(), mod_sub(), Botan::Modular_Reducer::Modular_Reducer(), Botan::Montgomery_Params::Montgomery_Params(), Botan::Montgomery_Params::mul(), mul(), Botan::mul_add(), Botan::Montgomery_Params::mul_by(), Botan::operator%(), operator%=(), Botan::operator*(), Botan::operator+(), operator+=(), Botan::operator-(), operator-=(), Botan::operator/(), operator/=(), Botan::operator<<(), operator<<=(), Botan::operator>>(), Botan::Modular_Reducer::reduce(), reduce_below(), rev_sub(), Botan::Montgomery_Params::sqr(), square(), Botan::Montgomery_Params::square_this(), and top_bits_free().

        {
        return m_data.sig_words();
        }

Sign Botan::BigInt::sign ( ) const

inline

Return the sign of the integer

Returns

the sign of the integer

Definition at line 537 of file bigint.h.

Referenced by add(), add2(), cond_flip_sign(), ct_cond_assign(), is_equal(), mul(), Botan::mul_add(), Botan::operator%(), operator%=(), Botan::operator*(), Botan::operator+(), operator+=(), operator-=(), Botan::operator<<(), Botan::operator>>(), and rev_sub().

{ return (m_signedness); }

size_t Botan::BigInt::size ( ) const

inline

Give size of internal register

Returns

size of internal register in words

Definition at line 578 of file bigint.h.

Referenced by Botan::PointGFp::add(), add(), Botan::PointGFp::add_affine(), clear_bit(), cmp(), const_time_lookup(), ct_cond_assign(), ct_cond_swap(), Botan::ct_divide(), Botan::ct_modulo(), ct_reduce_below(), Botan::CurveGFp_Repr::curve_mul(), Botan::CurveGFp_Repr::curve_sqr(), Botan::low_zero_bits(), Botan::Montgomery_Params::mul(), mul(), Botan::mul_add(), Botan::Montgomery_Params::mul_by(), Botan::operator*(), operator*=(), operator<<=(), Botan::redc_p192(), Botan::redc_p224(), Botan::redc_p256(), Botan::redc_p384(), Botan::redc_p521(), Botan::Modular_Reducer::reduce(), reduce_below(), Botan::Montgomery_Params::sqr(), square(), and Botan::Montgomery_Params::square_this().

{ return m_data.size(); }

BigInt & Botan::BigInt::square

(

secure_vector< word > &

ws

)

Square value of *this

Parameters

ws	a temp workspace

Definition at line 216 of file big_ops2.cpp.

References Botan::bigint_sqr(), data(), Positive, set_sign(), sig_words(), size(), and swap_reg().

Referenced by Botan::square().

   {
   const size_t sw = sig_words();

   secure_vector<word> z(2*sw);
   ws.resize(z.size());

   bigint_sqr(z.data(), z.size(),
              data(), size(), sw,
              ws.data(), ws.size());

   swap_reg(z);
   set_sign(BigInt::Positive);

   return (*this);
   }

BigInt& Botan::BigInt::sub ( const word  y[], size_t  y_words, Sign  sign  )

inline

Definition at line 285 of file bigint.h.

        {
        return add(y, y_words, sign == Positive ? Negative : Positive);
        }

void Botan::BigInt::swap ( BigInt &  other )

inline

Swap this value with another

Parameters

other

BigInt to swap values with

Definition at line 159 of file bigint.h.

Referenced by Botan::PointGFp::add_affine(), botan_mp_swap(), Botan::PointGFp::mult2(), and Botan::PointGFp::swap().

        {
        m_data.swap(other.m_data);
        std::swap(m_signedness, other.m_signedness);
        }

void Botan::BigInt::swap_reg ( secure_vector< word > &  reg )

inline

Definition at line 165 of file bigint.h.

Referenced by mod_sub(), mul(), reduce_below(), rev_sub(), and square().

        {
        m_data.swap(reg);
        // sign left unchanged
        }

std::string Botan::BigInt::to_dec_string

(

)

const

Convert this value to a decimal string. Warning: decimal conversions are relatively slow

Definition at line 15 of file big_code.cpp.

References Botan::ct_divide_u8(), Botan::Charset::digit2char(), Positive, and set_sign().

Referenced by encode(), encode_locked(), and Botan::operator<<().

   {
   BigInt copy = *this;
   copy.set_sign(Positive);

   uint8_t remainder;
   std::vector<uint8_t> digits;

   while(copy > 0)
      {
      ct_divide_u8(copy, 10, copy, remainder);
      digits.push_back(remainder);
      }

   std::string s;

   for(auto i = digits.rbegin(); i != digits.rend(); ++i)
      {
      s.push_back(Charset::digit2char(*i));
      }

   if(s.empty())
      s += "0";

   return s;
   }

std::string Botan::BigInt::to_hex_string

(

)

const

Convert this value to a hexadecimal string.

Definition at line 42 of file big_code.cpp.

References bits(), encode(), and Botan::hex_encode().

Referenced by botan_mp_to_hex(), encode(), encode_locked(), and Botan::operator<<().

   {
   const std::vector<uint8_t> bits = BigInt::encode(*this);
   if(bits.empty())
      return "00";
   else
      return hex_encode(bits);
   }

uint32_t Botan::BigInt::to_u32bit

(

)

const

Convert this value into a uint32_t, if it is in the range [0 ... 2**32-1], or otherwise throw an exception.

Returns

the value as a uint32_t if conversion is possible

Definition at line 236 of file bigint.cpp.

References bits(), byte_at(), and is_negative().

Referenced by botan_mp_to_uint32().

   {
   if(is_negative())
      throw Encoding_Error("BigInt::to_u32bit: Number is negative");
   if(bits() > 32)
      throw Encoding_Error("BigInt::to_u32bit: Number is too big to convert");

   uint32_t out = 0;
   for(size_t i = 0; i != 4; ++i)
      out = (out << 8) | byte_at(3-i);
   return out;
   }

size_t Botan::BigInt::top_bits_free

(

)

const

Get the number of high bits unset in the top (allocated) word of this integer. Returns BOTAN_MP_WORD_BITS only iff *this is zero. Ignores sign.

Definition at line 278 of file bigint.cpp.

References Botan::high_bit(), sig_words(), Botan::CT::unpoison(), and word_at().

Referenced by bits(), Botan::divide(), and operator<<=().

   {
   const size_t words = sig_words();

   const word top_word = word_at(words - 1);
   const size_t bits_used = high_bit(top_word);
   CT::unpoison(bits_used);
   return BOTAN_MP_WORD_BITS - bits_used;
   }

word Botan::BigInt::word_at ( size_t  n ) const

inline

Return the word at a specified position of the internal register

Parameters

n	position in the register

Returns

value at position n

Definition at line 506 of file bigint.h.

Referenced by binary_encode(), byte_at(), clear_bit(), conditionally_set_bit(), ct_cond_assign(), Botan::divide(), Botan::is_prime(), Botan::low_zero_bits(), Botan::Montgomery_Params::Montgomery_Params(), mul(), Botan::operator%(), operator%=(), Botan::operator*(), Botan::operator/(), operator/=(), Botan::redc_p521(), and top_bits_free().

        {
        return m_data.get_word_at(n);
        }

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

• src/lib/math/bigint/bigint.h
• src/lib/math/bigint/big_code.cpp
• src/lib/math/bigint/big_ops2.cpp
• src/lib/math/bigint/big_ops3.cpp
• src/lib/math/bigint/big_rand.cpp
• src/lib/math/bigint/bigint.cpp