Botan::ECDSA_Signature_Operation Class Reference

#include <ecdsa.h>

Inheritance diagram for Botan::ECDSA_Signature_Operation:

Public Member Functions
	ECDSA_Signature_Operation (const ECDSA_PrivateKey &ecdsa)
size_t	max_input_bits () const
size_t	message_part_size () const
size_t	message_parts () const
SecureVector< byte >	sign (const byte msg[], size_t msg_len, RandomNumberGenerator &rng)

Detailed Description

ECDSA signature operation

Definition at line 95 of file ecdsa.h.

Constructor & Destructor Documentation

ECDSA_Signature_Operation()

Botan::ECDSA_Signature_Operation::ECDSA_Signature_Operation

(

const ECDSA_PrivateKey &

ecdsa

)

Definition at line 27 of file ecdsa.cpp.

                                                                                  :
   base_point(ecdsa.domain().get_base_point()),
   order(ecdsa.domain().get_order()),
   x(ecdsa.private_value()),
   mod_order(order)
   {
   }

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

Member Function Documentation

max_input_bits()

size_t Botan::ECDSA_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 105 of file ecdsa.h.

{ return order.bits(); }

message_part_size()

size_t Botan::ECDSA_Signature_Operation::message_part_size ( ) const

inlinevirtual

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

Returns

size of the message parts

Reimplemented from Botan::PK_Ops::Signature.

Definition at line 104 of file ecdsa.h.

{ return order.bytes(); }

message_parts()

size_t Botan::ECDSA_Signature_Operation::message_parts ( ) const

inlinevirtual

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

Returns

number of message parts

Reimplemented from Botan::PK_Ops::Signature.

Definition at line 103 of file ecdsa.h.

{ return 2; }

sign()

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

virtual

Implements Botan::PK_Ops::Signature.

Definition at line 36 of file ecdsa.cpp.

   {
   rng.add_entropy(msg, msg_len);
 
   BigInt m(msg, msg_len);
 
   BigInt r = 0, s = 0;
 
   while(r == 0 || s == 0)
      {
      // This contortion is necessary for the tests
      BigInt k;
      k.randomize(rng, order.bits());
 
      while(k >= order)
         k.randomize(rng, order.bits() - 1);
 
      PointGFp k_times_P = base_point * k;
      r = mod_order.reduce(k_times_P.get_affine_x());
      s = mod_order.multiply(inverse_mod(k, order), mul_add(x, r, m));
      }
 
   SecureVector<byte> output(2*order.bytes());
   r.binary_encode(&output[output.size() / 2 - r.bytes()]);
   s.binary_encode(&output[output.size() - s.bytes()]);
   return output;
   }

References Botan::RandomNumberGenerator::add_entropy(), Botan::BigInt::binary_encode(), Botan::BigInt::bytes(), Botan::PointGFp::get_affine_x(), Botan::inverse_mod(), Botan::mul_add(), Botan::BigInt::randomize(), and Botan::MemoryRegion< T >::size().

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

• src/pubkey/ecdsa/ecdsa.h
• src/pubkey/ecdsa/ecdsa.cpp