Botan  1.11.15
Public Types | Public Member Functions | Static Public Member Functions
Botan::Fixed_Base_Power_Mod Class Reference

#include <pow_mod.h>

Inheritance diagram for Botan::Fixed_Base_Power_Mod:
Botan::Power_Mod

List of all members.

Public Types

enum  Usage_Hints {
  NO_HINTS = 0x0000, BASE_IS_FIXED = 0x0001, BASE_IS_SMALL = 0x0002, BASE_IS_LARGE = 0x0004,
  BASE_IS_2 = 0x0008, EXP_IS_FIXED = 0x0100, EXP_IS_SMALL = 0x0200, EXP_IS_LARGE = 0x0400
}

Public Member Functions

BigInt execute () const
 Fixed_Base_Power_Mod ()
 Fixed_Base_Power_Mod (const BigInt &base, const BigInt &modulus, Usage_Hints hints=NO_HINTS)
BigInt operator() (const BigInt &e) const
void set_base (const BigInt &) const
void set_exponent (const BigInt &) const
void set_modulus (const BigInt &, Usage_Hints=NO_HINTS) const

Static Public Member Functions

static size_t window_bits (size_t exp_bits, size_t base_bits, Power_Mod::Usage_Hints hints)

Detailed Description

Fixed Base Modular Exponentiator Proxy

Definition at line 88 of file pow_mod.h.


Member Enumeration Documentation

Enumerator:
NO_HINTS 
BASE_IS_FIXED 
BASE_IS_SMALL 
BASE_IS_LARGE 
BASE_IS_2 
EXP_IS_FIXED 
EXP_IS_SMALL 
EXP_IS_LARGE 

Definition at line 35 of file pow_mod.h.

                       {
         NO_HINTS        = 0x0000,

         BASE_IS_FIXED   = 0x0001,
         BASE_IS_SMALL   = 0x0002,
         BASE_IS_LARGE   = 0x0004,
         BASE_IS_2       = 0x0008,

         EXP_IS_FIXED    = 0x0100,
         EXP_IS_SMALL    = 0x0200,
         EXP_IS_LARGE    = 0x0400
      };

Constructor & Destructor Documentation

Definition at line 94 of file pow_mod.h.

{}
Botan::Fixed_Base_Power_Mod::Fixed_Base_Power_Mod ( const BigInt base,
const BigInt modulus,
Usage_Hints  hints = NO_HINTS 
)

Definition at line 192 of file pow_mod.cpp.

References Botan::Power_Mod::set_base().

                                                              :
   Power_Mod(n, Usage_Hints(hints | BASE_IS_FIXED | choose_base_hints(b, n)))
   {
   set_base(b);
   }

Member Function Documentation

BigInt Botan::Power_Mod::execute ( ) const [inherited]

Definition at line 95 of file pow_mod.cpp.

References Botan::Modular_Exponentiator::execute().

Referenced by Botan::power_mod().

   {
   if(!core)
      throw Internal_Error("Power_Mod::execute: core was NULL");
   return core->execute();
   }
BigInt Botan::Fixed_Base_Power_Mod::operator() ( const BigInt e) const [inline]

Definition at line 91 of file pow_mod.h.

         { set_exponent(e); return execute(); }
void Botan::Power_Mod::set_base ( const BigInt b) const [inherited]

Definition at line 69 of file pow_mod.cpp.

References Botan::BigInt::is_negative(), Botan::BigInt::is_zero(), and Botan::Modular_Exponentiator::set_base().

Referenced by Fixed_Base_Power_Mod(), and Botan::power_mod().

   {
   if(b.is_zero() || b.is_negative())
      throw Invalid_Argument("Power_Mod::set_base: arg must be > 0");

   if(!core)
      throw Internal_Error("Power_Mod::set_base: core was NULL");
   core->set_base(b);
   }
void Botan::Power_Mod::set_exponent ( const BigInt e) const [inherited]

Definition at line 82 of file pow_mod.cpp.

References Botan::BigInt::is_negative(), and Botan::Modular_Exponentiator::set_exponent().

Referenced by Botan::Fixed_Exponent_Power_Mod::Fixed_Exponent_Power_Mod(), and Botan::power_mod().

   {
   if(e.is_negative())
      throw Invalid_Argument("Power_Mod::set_exponent: arg must be > 0");

   if(!core)
      throw Internal_Error("Power_Mod::set_exponent: core was NULL");
   core->set_exponent(e);
   }
void Botan::Power_Mod::set_modulus ( const BigInt n,
Usage_Hints  hints = NO_HINTS 
) const [inherited]

Definition at line 56 of file pow_mod.cpp.

References Botan::BigInt::is_odd().

Referenced by Botan::Power_Mod::Power_Mod().

   {
   delete core;

   if(n.is_odd())
      core = new Montgomery_Exponentiator(n, hints);
   else if(n != 0)
      core = new Fixed_Window_Exponentiator(n, hints);
   }
size_t Botan::Power_Mod::window_bits ( size_t  exp_bits,
size_t  base_bits,
Power_Mod::Usage_Hints  hints 
) [static, inherited]

Definition at line 105 of file pow_mod.cpp.

References Botan::Power_Mod::BASE_IS_FIXED, and Botan::Power_Mod::EXP_IS_LARGE.

Referenced by Botan::Fixed_Window_Exponentiator::set_base(), and Botan::Montgomery_Exponentiator::set_base().

   {
   static const size_t wsize[][2] = {
      { 1434, 7 },
      {  539, 6 },
      {  197, 4 },
      {   70, 3 },
      {   25, 2 },
      {    0, 0 }
   };

   size_t window_bits = 1;

   if(exp_bits)
      {
      for(size_t j = 0; wsize[j][0]; ++j)
         {
         if(exp_bits >= wsize[j][0])
            {
            window_bits += wsize[j][1];
            break;
            }
         }
      }

   if(hints & Power_Mod::BASE_IS_FIXED)
      window_bits += 2;
   if(hints & Power_Mod::EXP_IS_LARGE)
      ++window_bits;

   return window_bits;
   }

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