diff options
Diffstat (limited to 'comm/third_party/botan/src/lib/math/numbertheory/pow_mod.h')
-rw-r--r-- | comm/third_party/botan/src/lib/math/numbertheory/pow_mod.h | 122 |
1 files changed, 122 insertions, 0 deletions
diff --git a/comm/third_party/botan/src/lib/math/numbertheory/pow_mod.h b/comm/third_party/botan/src/lib/math/numbertheory/pow_mod.h new file mode 100644 index 0000000000..b465013e55 --- /dev/null +++ b/comm/third_party/botan/src/lib/math/numbertheory/pow_mod.h @@ -0,0 +1,122 @@ +/* +* Modular Exponentiator +* (C) 1999-2007 Jack Lloyd +* +* Botan is released under the Simplified BSD License (see license.txt) +*/ + +#ifndef BOTAN_POWER_MOD_H_ +#define BOTAN_POWER_MOD_H_ + +#include <botan/bigint.h> + +BOTAN_FUTURE_INTERNAL_HEADER(pow_mod.h) + +namespace Botan { + +class Modular_Exponentiator; + +/** +* Modular Exponentiator Proxy +*/ +class BOTAN_PUBLIC_API(2,0) Power_Mod + { + public: + + 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 + }; + + /* + * Try to choose a good window size + */ + static size_t window_bits(size_t exp_bits, size_t base_bits, + Power_Mod::Usage_Hints hints); + + /** + * @param modulus the modulus + * @param hints Passed to set_modulus if modulus > 0 + * @param disable_montgomery_arith Disables use of Montgomery + * representation. Likely only useful for testing. + */ + void set_modulus(const BigInt& modulus, + Usage_Hints hints = NO_HINTS, + bool disable_montgomery_arith = false) const; + + /** + * Set the base + */ + void set_base(const BigInt& base) const; + + /** + * Set the exponent + */ + void set_exponent(const BigInt& exponent) const; + + /** + * All three of the above functions must have already been called. + * @return result of g^x%p + */ + BigInt execute() const; + + Power_Mod& operator=(const Power_Mod&); + + /** + * @param modulus Optionally call set_modulus + * @param hints Passed to set_modulus if modulus > 0 + * @param disable_montgomery_arith Disables use of Montgomery + * representation. Likely only useful for testing. + */ + Power_Mod(const BigInt& modulus = 0, + Usage_Hints hints = NO_HINTS, + bool disable_montgomery_arith = false); + Power_Mod(const Power_Mod&); + virtual ~Power_Mod(); + private: + mutable std::unique_ptr<Modular_Exponentiator> m_core; + }; + +/** +* Fixed Exponent Modular Exponentiator Proxy +*/ +class BOTAN_PUBLIC_API(2,0) Fixed_Exponent_Power_Mod final : public Power_Mod + { + public: + BigInt operator()(const BigInt& b) const + { set_base(b); return execute(); } + + Fixed_Exponent_Power_Mod() = default; + + Fixed_Exponent_Power_Mod(const BigInt& exponent, + const BigInt& modulus, + Usage_Hints hints = NO_HINTS); + }; + +/** +* Fixed Base Modular Exponentiator Proxy +*/ +class BOTAN_PUBLIC_API(2,0) Fixed_Base_Power_Mod final : public Power_Mod + { + public: + BigInt operator()(const BigInt& e) const + { set_exponent(e); return execute(); } + + Fixed_Base_Power_Mod() = default; + + Fixed_Base_Power_Mod(const BigInt& base, + const BigInt& modulus, + Usage_Hints hints = NO_HINTS); + }; + +} + +#endif |