ecdsa_sig.cpp

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/*
* ECDSA Signature
* (C) 2007 Falko Strenzke, FlexSecure GmbH
* (C) 2008-2010 Jack Lloyd
*
* Distributed under the terms of the Botan license
*/
 
#include <botan/ecdsa_sig.h>
 
namespace Botan {
 
ECDSA_Signature::ECDSA_Signature(const MemoryRegion<byte>& ber)
   {
   BER_Decoder(ber)
      .start_cons(SEQUENCE)
         .decode(m_r)
         .decode(m_s)
      .end_cons()
      .verify_end();
   }
 
MemoryVector<byte> ECDSA_Signature::DER_encode() const
   {
   return DER_Encoder()
      .start_cons(SEQUENCE)
        .encode(get_r())
        .encode(get_s())
      .end_cons()
      .get_contents();
   }
 
MemoryVector<byte> ECDSA_Signature::get_concatenation() const
   {
   // use the larger
   const size_t enc_len = m_r > m_s ? m_r.bytes() : m_s.bytes();
 
   SecureVector<byte> sv_r = BigInt::encode_1363(m_r, enc_len);
   SecureVector<byte> sv_s = BigInt::encode_1363(m_s, enc_len);
 
   SecureVector<byte> result(sv_r);
   result += sv_s;
   return result;
   }
 
ECDSA_Signature decode_concatenation(const MemoryRegion<byte>& concat)
   {
   if(concat.size() % 2 != 0)
      throw Invalid_Argument("Erroneous length of signature");
 
   const size_t rs_len = concat.size() / 2;
 
   BigInt r = BigInt::decode(&concat[0], rs_len);
   BigInt s = BigInt::decode(&concat[rs_len], rs_len);
 
   return ECDSA_Signature(r, s);
   }
 
}