/*************************************************
* PKCS #5 PBES1 Source File                      *
* (C) 1999-2006 The Botan Project                *
*************************************************/

#include <botan/pbe_pkcs.h>
#include <botan/der_enc.h>
#include <botan/ber_dec.h>
#include <botan/parsing.h>
#include <botan/lookup.h>
#include <botan/rng.h>
#include <algorithm>
#include <memory>

namespace Botan {

/*************************************************
* Encrypt some bytes using PBES1                 *
*************************************************/
void PBE_PKCS5v15::write(const byte input[], u32bit length)
   {
   while(length)
      {
      u32bit put = std::min(DEFAULT_BUFFERSIZE, length);
      pipe.write(input, length);
      flush_pipe(true);
      length -= put;
      }
   }

/*************************************************
* Start encrypting with PBES1                    *
*************************************************/
void PBE_PKCS5v15::start_msg()
   {
   pipe.append(get_cipher(cipher, key, iv, direction));
   pipe.start_msg();
   if(pipe.message_count() > 1)
      pipe.set_default_msg(pipe.default_msg() + 1);
   }

/*************************************************
* Finish encrypting with PBES1                   *
*************************************************/
void PBE_PKCS5v15::end_msg()
   {
   pipe.end_msg();
   flush_pipe(false);
   pipe.reset();
   }

/*************************************************
* Flush the pipe                                 *
*************************************************/
void PBE_PKCS5v15::flush_pipe(bool safe_to_skip)
   {
   if(safe_to_skip && pipe.remaining() < 64)
      return;

   SecureVector<byte> buffer(DEFAULT_BUFFERSIZE);
   while(pipe.remaining())
      {
      u32bit got = pipe.read(buffer, buffer.size());
      send(buffer, got);
      }
   }

/*************************************************
* Set the passphrase to use                      *
*************************************************/
void PBE_PKCS5v15::set_key(const std::string& passphrase)
   {
   std::auto_ptr<S2K> pbkdf(get_s2k("PBKDF1(" + digest + ")"));
   pbkdf->set_iterations(iterations);
   pbkdf->change_salt(salt, salt.size());
   SymmetricKey key_and_iv = pbkdf->derive_key(16, passphrase);

   key.set(key_and_iv.begin(), 8);
   iv.set(key_and_iv.begin() + 8, 8);
   }

/*************************************************
* Create a new set of PBES1 parameters           *
*************************************************/
void PBE_PKCS5v15::new_params()
   {
   iterations = 2048;
   salt.create(8);
   Global_RNG::randomize(salt, salt.size());
   }

/*************************************************
* Encode PKCS#5 PBES1 parameters                 *
*************************************************/
MemoryVector<byte> PBE_PKCS5v15::encode_params() const
   {
   return DER_Encoder()
      .start_cons(SEQUENCE)
         .encode(salt, OCTET_STRING)
         .encode(iterations)
      .end_cons()
   .get_contents();
   }

/*************************************************
* Decode PKCS#5 PBES1 parameters                 *
*************************************************/
void PBE_PKCS5v15::decode_params(DataSource& source)
   {
   BER_Decoder(source)
      .start_cons(SEQUENCE)
         .decode(salt, OCTET_STRING)
         .decode(iterations)
         .verify_end()
      .end_cons();

   if(salt.size() != 8)
      throw Decoding_Error("PBES1: Encoded salt is not 8 octets");
   }

/*************************************************
* Return an OID for this PBES1 type              *
*************************************************/
OID PBE_PKCS5v15::get_oid() const
   {
   const OID base_pbes1_oid("1.2.840.113549.1.5");
   if(cipher == "DES/CBC" && digest == "MD2")
      return (base_pbes1_oid + 1);
   else if(cipher == "DES/CBC" && digest == "MD5")
      return (base_pbes1_oid + 3);
   else if(cipher == "DES/CBC" && digest == "SHA-160")
      return (base_pbes1_oid + 10);
   else if(cipher == "RC2/CBC" && digest == "MD2")
      return (base_pbes1_oid + 4);
   else if(cipher == "RC2/CBC" && digest == "MD5")
      return (base_pbes1_oid + 6);
   else if(cipher == "RC2/CBC" && digest == "SHA-160")
      return (base_pbes1_oid + 11);
   else
      throw Internal_Error("PBE-PKCS5 v1.5: get_oid() has run out of options");
   }

/*************************************************
* PKCS#5 v1.5 PBE Constructor                    *
*************************************************/
PBE_PKCS5v15::PBE_PKCS5v15(const std::string& d_algo,
                           const std::string& c_algo, Cipher_Dir dir) :
   direction(dir), digest(deref_alias(d_algo)), cipher(c_algo)
   {
   std::vector<std::string> cipher_spec = split_on(c_algo, '/');
   if(cipher_spec.size() != 2)
      throw Invalid_Argument("PBE-PKCS5 v1.5: Invalid cipher spec " + c_algo);
   const std::string cipher_algo = deref_alias(cipher_spec[0]);
   const std::string cipher_mode = cipher_spec[1];

   if(!have_block_cipher(cipher_algo))
      throw Algorithm_Not_Found(cipher_algo);
   if(!have_hash(digest))
      throw Algorithm_Not_Found(digest);

   if((cipher_algo != "DES" && cipher_algo != "RC2") || (cipher_mode != "CBC"))
      throw Invalid_Argument("PBE-PKCS5 v1.5: Invalid cipher " + cipher);
   if(digest != "MD2" && digest != "MD5" && digest != "SHA-160")
      throw Invalid_Argument("PBE-PKCS5 v1.5: Invalid digest " + digest);
   }

}