C++ BER_Decoder类代码示例

/*
* Decode BER encoded parameters
*/
void DL_Group::BER_decode(const std::vector<byte>& data,
                          Format format)
   {
   BigInt new_p, new_q, new_g;

   BER_Decoder decoder(data);
   BER_Decoder ber = decoder.start_cons(SEQUENCE);

   if(format == ANSI_X9_57)
      {
      ber.decode(new_p)
         .decode(new_q)
         .decode(new_g)
         .verify_end();
      }
   else if(format == ANSI_X9_42)
      {
      ber.decode(new_p)
         .decode(new_g)
         .decode(new_q)
         .discard_remaining();
      }
   else if(format == PKCS_3)
      {
      ber.decode(new_p)
         .decode(new_g)
         .discard_remaining();
      }
   else
      throw Invalid_Argument("Unknown DL_Group encoding " + std::to_string(format));

   initialize(new_p, new_q, new_g);
   }

/*
* Decode a BER encoded DistinguishedName
*/
void X509_DN::decode_from(BER_Decoder& source)
   {
   MemoryVector<byte> bits;

   source.start_cons(SEQUENCE)
      .raw_bytes(bits)
   .end_cons();

   BER_Decoder sequence(bits);

   while(sequence.more_items())
      {
      BER_Decoder rdn = sequence.start_cons(SET);

      while(rdn.more_items())
         {
         OID oid;
         ASN1_String str;

         rdn.start_cons(SEQUENCE)
            .decode(oid)
            .decode(str)
            .verify_end()
        .end_cons();

         add_attribute(oid, str.value());
         }
      }

   dn_bits = bits;
   }

Response::Response(const uint8_t response_bits[], size_t response_bits_len) :
   m_response_bits(response_bits, response_bits + response_bits_len)
   {
   m_dummy_response_status = Certificate_Status_Code::OCSP_RESPONSE_INVALID;

   BER_Decoder response_outer = BER_Decoder(m_response_bits).start_cons(SEQUENCE);

   size_t resp_status = 0;

   response_outer.decode(resp_status, ENUMERATED, UNIVERSAL);

   if(resp_status != 0)
      throw Exception("OCSP response status " + std::to_string(resp_status));

   if(response_outer.more_items())
      {
      BER_Decoder response_bytes =
         response_outer.start_cons(ASN1_Tag(0), CONTEXT_SPECIFIC).start_cons(SEQUENCE);

      response_bytes.decode_and_check(OID("1.3.6.1.5.5.7.48.1.1"),
                                      "Unknown response type in OCSP response");

      BER_Decoder basicresponse =
         BER_Decoder(response_bytes.get_next_octet_string()).start_cons(SEQUENCE);

      basicresponse.start_cons(SEQUENCE)
           .raw_bytes(m_tbs_bits)
         .end_cons()
         .decode(m_sig_algo)
         .decode(m_signature, BIT_STRING);
      decode_optional_list(basicresponse, ASN1_Tag(0), m_certs);

      size_t responsedata_version = 0;
      Extensions extensions;

      BER_Decoder(m_tbs_bits)
         .decode_optional(responsedata_version, ASN1_Tag(0),
                          ASN1_Tag(CONSTRUCTED | CONTEXT_SPECIFIC))

         .decode_optional(m_signer_name, ASN1_Tag(1),
                          ASN1_Tag(CONSTRUCTED | CONTEXT_SPECIFIC))

         .decode_optional_string(m_key_hash, OCTET_STRING, 2,
                                 ASN1_Tag(CONSTRUCTED | CONTEXT_SPECIFIC))

         .decode(m_produced_at)

         .decode_list(m_responses)

         .decode_optional(extensions, ASN1_Tag(1),
                          ASN1_Tag(CONSTRUCTED | CONTEXT_SPECIFIC));
      }

   response_outer.end_cons();
   }

/*
* Decode a BER encoded ASN1_EAC_String
*/
void ASN1_EAC_String::decode_from(BER_Decoder& source)
   {
   BER_Object obj = source.get_next_object();

   if(obj.type_tag != this->tag)
      {
      std::stringstream ss;

      ss << "ASN1_EAC_String tag mismatch, tag was "
         << std::hex << obj.type_tag
         << " expected "
         << std::hex << this->tag;

      throw Decoding_Error(ss.str());
      }

   Character_Set charset_is;
   charset_is = LATIN1_CHARSET;

   try
      {
      *this = ASN1_EAC_String(
         Charset::transcode(ASN1::to_string(obj), charset_is, LOCAL_CHARSET),
         obj.type_tag);
      }
   catch(Invalid_Argument inv_arg)
      {
      throw Decoding_Error(std::string("ASN1_EAC_String decoding failed: ") +
                           inv_arg.what());
      }
   }

/*
* Decode a BER encoded AlgorithmIdentifier
*/
void AlgorithmIdentifier::decode_from(BER_Decoder& codec)
   {
   codec.start_cons(SEQUENCE)
      .decode(oid)
      .raw_bytes(parameters)
   .end_cons();
   }

/*
* Decode a BER encoded EAC_Time
*/
void EAC_Time::decode_from(BER_Decoder& source)
   {
   BER_Object obj = source.get_next_object();

   if(obj.type_tag != this->tag)
      throw BER_Decoding_Error("Tag mismatch when decoding");

   if(obj.value.size() != 6)
      {
      throw Decoding_Error("EAC_Time decoding failed");
      }

   try
      {
      u32bit tmp_year = dec_two_digit(obj.value[0], obj.value[1]);
      u32bit tmp_mon = dec_two_digit(obj.value[2], obj.value[3]);
      u32bit tmp_day = dec_two_digit(obj.value[4], obj.value[5]);
      year = tmp_year + 2000;
      month = tmp_mon;
      day = tmp_day;
      }
   catch (Invalid_Argument)
      {
      throw Decoding_Error("EAC_Time decoding failed");
      }

   }

/*
* Decompress a message
*/
void CMS_Decoder::decompress(BER_Decoder& decoder)
   {
   size_t version;
   AlgorithmIdentifier comp_algo;

   BER_Decoder comp_info = decoder.start_cons(SEQUENCE);

   comp_info.decode(version);
   if(version != 0)
      throw Decoding_Error("CMS: Unknown version for CompressedData");

   comp_info.decode(comp_algo);
   read_econtent(comp_info);
   comp_info.end_cons();

   Filter* decompressor = 0;

   info = comp_algo.oid.as_string();

#if defined(BOTAN_HAS_COMPRESSOR_ZLIB)
   if(comp_algo.oid == OIDS::lookup("Compression.Zlib"))
      {
      decompressor = new Zlib_Decompression;
      info = "Zlib";
      }
#endif

   if(!decompressor)
      status = FAILURE;

   Pipe pipe(decompressor);
   pipe.process_msg(data);
   data = pipe.read_all();
   }

/*
* Decode a BER encoded Attribute
*/
void Attribute::decode_from(BER_Decoder& codec)
   {
   codec.start_cons(SEQUENCE)
      .decode(oid)
      .start_cons(SET)
         .raw_bytes(parameters)
      .end_cons()
   .end_cons();
   }

void X509_Time::decode_from(BER_Decoder& source)
   {
   BER_Object ber_time = source.get_next_object();

   set_to(Charset::transcode(ASN1::to_string(ber_time),
                             LATIN1_CHARSET,
                             LOCAL_CHARSET),
          ber_time.type_tag);
   }

/*
* Decode a BER encoded CRL_Entry
*/
void CRL_Entry::decode_from(BER_Decoder& source)
   {
   BigInt serial_number_bn;

   source.start_cons(SEQUENCE)
      .decode(serial_number_bn)
      .decode(time);

   if(source.more_items())
      {
      Extensions extensions(throw_on_unknown_critical);
      source.decode(extensions);
      Data_Store info;
      extensions.contents_to(info, info);
      reason = CRL_Code(info.get1_u32bit("X509v3.CRLReasonCode"));
      }

   serial = BigInt::encode(serial_number_bn);
   }

/*
* Decode a BER encoded CRL_Entry
*/
void CRL_Entry::decode_from(BER_Decoder& source)
   {
   BigInt serial_number_bn;

   std::unique_ptr<CRL_Entry_Data> data(new CRL_Entry_Data);

   BER_Decoder entry = source.start_cons(SEQUENCE);

   entry.decode(serial_number_bn).decode(data->m_time);
   data->m_serial = BigInt::encode(serial_number_bn);

   if(entry.more_items())
      {
      entry.decode(data->m_extensions);
      if(auto ext = data->m_extensions.get_extension_object_as<Cert_Extension::CRL_ReasonCode>())
         {
         data->m_reason = ext->get_reason();
         }
      else
         {
         data->m_reason = UNSPECIFIED;
         }
      }

   entry.end_cons();

   m_data.reset(data.release());
   }

/*
* Decode a BER encoded ASN1_String
*/
void ASN1_String::decode_from(BER_Decoder& source)
{
    BER_Object obj = source.get_next_object();

    Character_Set charset_is;

    if(obj.type_tag == BMP_STRING)
        charset_is = UCS2_CHARSET;
    else if(obj.type_tag == UTF8_STRING)
        charset_is = UTF8_CHARSET;
    else
        charset_is = LATIN1_CHARSET;

    *this = ASN1_String(
                Charset::transcode(ASN1::to_string(obj), charset_is, LOCAL_CHARSET),
                obj.type_tag);
}

/*
* Decode a BER encoded ASN1_EAC_String
*/
void ASN1_EAC_String::decode_from(BER_Decoder& source)
   {
   BER_Object obj = source.get_next_object();
   if (obj.type_tag != this->tag)
      {

      std::string message("decoding type mismatch for ASN1_EAC_String, tag is ");
      std::stringstream ss;
      std::string str_is;
      ss << std::hex << obj.type_tag;
      ss >> str_is;
      message.append(str_is);
      message.append(", while it should be ");
      std::stringstream ss2;
      std::string str_should;
      ss2 << std::hex << this->tag;
      ss2 >> str_should;
      message.append(str_should);
      throw Decoding_Error(message);
      }

/*
* Decode a BER encoded KeyUsage
*/
void decode(BER_Decoder& source, Key_Constraints& key_usage)
   {
   BER_Object obj = source.get_next_object();

   if(obj.type_tag != BIT_STRING || obj.class_tag != UNIVERSAL)
      throw BER_Bad_Tag("Bad tag for usage constraint",
                        obj.type_tag, obj.class_tag);
   if(obj.value.size() != 2 && obj.value.size() != 3)
      throw BER_Decoding_Error("Bad size for BITSTRING in usage constraint");
   if(obj.value[0] >= 8)
      throw BER_Decoding_Error("Invalid unused bits in usage constraint");

   const byte mask = (0xFF << obj.value[0]);
   obj.value[obj.value.size()-1] &= mask;

   u16bit usage = 0;
   for(u32bit j = 1; j != obj.value.size(); ++j)
      usage = (obj.value[j] << 8) | usage;

   key_usage = Key_Constraints(usage);
   }

bool ne7ssh_keys::getDSAKeys (char* buffer, uint32 size)
{
//  DataSource_Memory privKeyPEMSrc (privKeyPEMStr);
  const char* headerDSA = "-----BEGIN DSA PRIVATE KEY-----\n";
  const char* footerDSA = "-----END DSA PRIVATE KEY-----\n";
  SecureVector<Botan::byte> keyDataRaw;
  BigInt p, q, g, y, x;
  char *start;
  uint32 version;

  start = buffer + strlen(headerDSA);
  Pipe base64dec (new Base64_Decoder);
  base64dec.process_msg ((Botan::byte*)start, size - strlen(footerDSA) - strlen(headerDSA));
  keyDataRaw = base64dec.read_all (PIPE_DEFAULT_MESSAGE);

  BER_Decoder decoder (keyDataRaw);

#if BOTAN_PRE_15
  BER_Decoder sequence = BER::get_subsequence(decoder);
  BER::decode (sequence, version);
#else
  BER_Decoder sequence = decoder.start_cons (SEQUENCE);
  sequence.decode (version);
#endif

  if (version)
  {
    ne7ssh::errors()->push (-1, "Encountered unknown DSA key version.");
    return false;
  }

#if BOTAN_PRE_15
  BER::decode (sequence, p);
  BER::decode (sequence, q);
  BER::decode (sequence, g);
  BER::decode (sequence, y);
  BER::decode (sequence, x);
#else
  sequence.decode (p);
  sequence.decode (q);
  sequence.decode (g);
  sequence.decode (y);
  sequence.decode (x);
#endif


  sequence.discard_remaining();
  sequence.verify_end();

  if (p.is_zero() || q.is_zero() || g.is_zero() || y.is_zero() || x.is_zero())
  {
    ne7ssh::errors()->push (-1, "Could not decode the supplied DSA key.");
    return false;
  }

  DL_Group dsaGroup (p, q, g);

#if BOTAN_PRE_18 || BOTAN_PRE_15
  dsaPrivateKey = new DSA_PrivateKey (dsaGroup, x);
#else
  dsaPrivateKey = new DSA_PrivateKey (*ne7ssh::rng, dsaGroup, x);
#endif
  publicKeyBlob.clear();
  publicKeyBlob.addString ("ssh-dss");
  publicKeyBlob.addBigInt (p);
  publicKeyBlob.addBigInt (q);
  publicKeyBlob.addBigInt (g);
  publicKeyBlob.addBigInt (y);

  return true;

}