Botan::RW_Signature_Operation Class Reference

#include <rw.h>

Inheritance diagram for Botan::RW_Signature_Operation:

Public Member Functions
size_t	max_input_bits () const
virtual size_t	message_part_size () const
virtual size_t	message_parts () const
	RW_Signature_Operation (const RW_PrivateKey &rw)
SecureVector< byte >	sign (const byte msg[], size_t msg_len, RandomNumberGenerator &rng)

Detailed Description

Rabin-Williams Signature Operation

Definition at line 65 of file rw.h.

Constructor & Destructor Documentation

RW_Signature_Operation()

Botan::RW_Signature_Operation::RW_Signature_Operation

(

const RW_PrivateKey &

rw

)

Definition at line 62 of file rw.cpp.

                                                                      :
   n(rw.get_n()),
   e(rw.get_e()),
   q(rw.get_q()),
   c(rw.get_c()),
   powermod_d1_p(rw.get_d1(), rw.get_p()),
   powermod_d2_q(rw.get_d2(), rw.get_q()),
   mod_p(rw.get_p())
   {
   }

Referenced by Botan::Core_Engine::get_signature_op().

Member Function Documentation

max_input_bits()

size_t Botan::RW_Signature_Operation::max_input_bits ( ) const

inlinevirtual

Get the maximum message size in bits supported by this public key.

Returns

maximum message in bits

Implements Botan::PK_Ops::Signature.

Definition at line 70 of file rw.h.

{ return (n.bits() - 1); }

message_part_size()

virtual size_t Botan::PK_Ops::Signature::message_part_size ( ) const

inlinevirtualinherited

Find out the message part size supported by this scheme/key.

Returns

size of the message parts

Reimplemented in Botan::DSA_Signature_Operation, Botan::ECDSA_Signature_Operation, and Botan::NR_Signature_Operation.

Definition at line 62 of file pk_ops.h.

{ return 0; }

message_parts()

virtual size_t Botan::PK_Ops::Signature::message_parts ( ) const

inlinevirtualinherited

Find out the number of message parts supported by this scheme.

Returns

number of message parts

Reimplemented in Botan::DSA_Signature_Operation, Botan::ECDSA_Signature_Operation, and Botan::NR_Signature_Operation.

Definition at line 56 of file pk_ops.h.

{ return 1; }

sign()

SecureVector< byte > Botan::RW_Signature_Operation::sign ( const byte msg[], size_t msg_len, RandomNumberGenerator & rng )

virtual

Implements Botan::PK_Ops::Signature.

Definition at line 74 of file rw.cpp.

   {
   if(!blinder.initialized())
      {
      BigInt k(rng, n.bits() / 2);
      blinder = Blinder(power_mod(k, e, n), inverse_mod(k, n), n);
      }
 
   BigInt i(msg, msg_len);
 
   if(i >= n || i % 16 != 12)
      throw Invalid_Argument("Rabin-Williams: invalid input");
 
   if(jacobi(i, n) != 1)
      i >>= 1;
 
   i = blinder.blind(i);
 
   BigInt j1 = powermod_d1_p(i);
   BigInt j2 = powermod_d2_q(i);
   j1 = mod_p.reduce(sub_mul(j1, j2, c));
 
   BigInt r = blinder.unblind(mul_add(j1, q, j2));
 
   r = std::min(r, n - r);
 
   return BigInt::encode_1363(r, n.bytes());
   }

References Botan::Blinder::Blinder(), Botan::BigInt::bytes(), Botan::BigInt::encode_1363(), Botan::inverse_mod(), Botan::jacobi(), Botan::mul_add(), Botan::power_mod(), and Botan::sub_mul().

---

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

• src/pubkey/rw/rw.h
• src/pubkey/rw/rw.cpp