Botan::DSA_Verification_Operation Class Reference

#include <dsa.h>

Inheritance diagram for Botan::DSA_Verification_Operation:

Public Member Functions
	DSA_Verification_Operation (const DSA_PublicKey &dsa)
size_t	max_input_bits () const
size_t	message_part_size () const
size_t	message_parts () const
bool	verify (const byte msg[], size_t msg_len, const byte sig[], size_t sig_len)
virtual SecureVector< byte >	verify_mr (const byte[], size_t)
bool	with_recovery () const

Detailed Description

Object that can verify a DSA signature

Definition at line 84 of file dsa.h.

Constructor & Destructor Documentation

DSA_Verification_Operation()

Botan::DSA_Verification_Operation::DSA_Verification_Operation

(

const DSA_PublicKey &

dsa

)

Definition at line 102 of file dsa.cpp.

                                                                               :
   q(dsa.group_q()), y(dsa.get_y())
   {
   powermod_g_p = Fixed_Base_Power_Mod(dsa.group_g(), dsa.group_p());
   powermod_y_p = Fixed_Base_Power_Mod(y, dsa.group_p());
   mod_p = Modular_Reducer(dsa.group_p());
   mod_q = Modular_Reducer(dsa.group_q());
   }

References Botan::Fixed_Base_Power_Mod::Fixed_Base_Power_Mod(), Botan::DL_Scheme_PublicKey::group_g(), Botan::DL_Scheme_PublicKey::group_p(), Botan::DL_Scheme_PublicKey::group_q(), and Botan::Modular_Reducer::Modular_Reducer().

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

Member Function Documentation

max_input_bits()

size_t Botan::DSA_Verification_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::Verification.

Definition at line 91 of file dsa.h.

{ return q.bits(); }

message_part_size()

size_t Botan::DSA_Verification_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::Verification.

Definition at line 90 of file dsa.h.

{ return q.bytes(); }

message_parts()

size_t Botan::DSA_Verification_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::Verification.

Definition at line 89 of file dsa.h.

{ return 2; }

verify()

bool Botan::DSA_Verification_Operation::verify ( const byte msg[], size_t msg_len, const byte sig[], size_t sig_len )

virtual

Reimplemented from Botan::PK_Ops::Verification.

Definition at line 111 of file dsa.cpp.

   {
   const BigInt& q = mod_q.get_modulus();
 
   if(sig_len != 2*q.bytes() || msg_len > q.bytes())
      return false;
 
   BigInt r(sig, q.bytes());
   BigInt s(sig + q.bytes(), q.bytes());
   BigInt i(msg, msg_len);
 
   if(r <= 0 || r >= q || s <= 0 || s >= q)
      return false;
 
   s = inverse_mod(s, q);
   s = mod_p.multiply(powermod_g_p(mod_q.multiply(s, i)),
                      powermod_y_p(mod_q.multiply(s, r)));
 
   return (mod_q.reduce(s) == r);
   }

References Botan::inverse_mod().

verify_mr()

virtual SecureVector< byte > Botan::PK_Ops::Verification::verify_mr ( const byte [], size_t  )

inlinevirtualinherited

Reimplemented in Botan::NR_Verification_Operation, Botan::RSA_Public_Operation, and Botan::RW_Verification_Operation.

Definition at line 133 of file pk_ops.h.

         {
         throw Invalid_State("Message recovery not supported");
         }

with_recovery()

bool Botan::DSA_Verification_Operation::with_recovery ( ) const

inlinevirtual

Returns

boolean specifying if this key type supports message recovery and thus if you need to call verify() or verify_mr()

Implements Botan::PK_Ops::Verification.

Definition at line 93 of file dsa.h.

{ return false; }

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

• src/pubkey/dsa/dsa.h
• src/pubkey/dsa/dsa.cpp