/**
 * @author: Jeff Thompson
 * See COPYING for copyright and distribution information.
 */

#include <stdexcept>
#include <openssl/ssl.h>
#include <openssl/rsa.h>
#include "c/encoding/binary-xml-data.h"
#include "encoding/binary-xml-encoder.hpp"
#include "key-chain.hpp"

using namespace std;

namespace ndn {

static unsigned char DEFAULT_PUBLIC_KEY_DER[] = {
0x30, 0x81, 0x9F, 0x30, 0x0D, 0x06, 0x09, 0x2A, 0x86, 0x48, 0x86, 0xF7, 0x0D, 0x01, 0x01, 0x01, 0x05, 0x00, 0x03, 0x81,
0x8D, 0x00, 0x30, 0x81, 0x89, 0x02, 0x81, 0x81, 0x00, 0xE1, 0x7D, 0x30, 0xA7, 0xD8, 0x28, 0xAB, 0x1B, 0x84, 0x0B, 0x17,
0x54, 0x2D, 0xCA, 0xF6, 0x20, 0x7A, 0xFD, 0x22, 0x1E, 0x08, 0x6B, 0x2A, 0x60, 0xD1, 0x6C, 0xB7, 0xF5, 0x44, 0x48, 0xBA,
0x9F, 0x3F, 0x08, 0xBC, 0xD0, 0x99, 0xDB, 0x21, 0xDD, 0x16, 0x2A, 0x77, 0x9E, 0x61, 0xAA, 0x89, 0xEE, 0xE5, 0x54, 0xD3,
0xA4, 0x7D, 0xE2, 0x30, 0xBC, 0x7A, 0xC5, 0x90, 0xD5, 0x24, 0x06, 0x7C, 0x38, 0x98, 0xBB, 0xA6, 0xF5, 0xDC, 0x43, 0x60,
0xB8, 0x45, 0xED, 0xA4, 0x8C, 0xBD, 0x9C, 0xF1, 0x26, 0xA7, 0x23, 0x44, 0x5F, 0x0E, 0x19, 0x52, 0xD7, 0x32, 0x5A, 0x75,
0xFA, 0xF5, 0x56, 0x14, 0x4F, 0x9A, 0x98, 0xAF, 0x71, 0x86, 0xB0, 0x27, 0x86, 0x85, 0xB8, 0xE2, 0xC0, 0x8B, 0xEA, 0x87,
0x17, 0x1B, 0x4D, 0xEE, 0x58, 0x5C, 0x18, 0x28, 0x29, 0x5B, 0x53, 0x95, 0xEB, 0x4A, 0x17, 0x77, 0x9F, 0x02, 0x03, 0x01,
0x00, 01  
};

static unsigned char DEFAULT_PRIVATE_KEY_DER[] = {
0x30, 0x82, 0x02, 0x5d, 0x02, 0x01, 0x00, 0x02, 0x81, 0x81, 0x00, 0xe1, 0x7d, 0x30, 0xa7, 0xd8, 0x28, 0xab, 0x1b, 0x84,
0x0b, 0x17, 0x54, 0x2d, 0xca, 0xf6, 0x20, 0x7a, 0xfd, 0x22, 0x1e, 0x08, 0x6b, 0x2a, 0x60, 0xd1, 0x6c, 0xb7, 0xf5, 0x44,
0x48, 0xba, 0x9f, 0x3f, 0x08, 0xbc, 0xd0, 0x99, 0xdb, 0x21, 0xdd, 0x16, 0x2a, 0x77, 0x9e, 0x61, 0xaa, 0x89, 0xee, 0xe5,
0x54, 0xd3, 0xa4, 0x7d, 0xe2, 0x30, 0xbc, 0x7a, 0xc5, 0x90, 0xd5, 0x24, 0x06, 0x7c, 0x38, 0x98, 0xbb, 0xa6, 0xf5, 0xdc,
0x43, 0x60, 0xb8, 0x45, 0xed, 0xa4, 0x8c, 0xbd, 0x9c, 0xf1, 0x26, 0xa7, 0x23, 0x44, 0x5f, 0x0e, 0x19, 0x52, 0xd7, 0x32,
0x5a, 0x75, 0xfa, 0xf5, 0x56, 0x14, 0x4f, 0x9a, 0x98, 0xaf, 0x71, 0x86, 0xb0, 0x27, 0x86, 0x85, 0xb8, 0xe2, 0xc0, 0x8b,
0xea, 0x87, 0x17, 0x1b, 0x4d, 0xee, 0x58, 0x5c, 0x18, 0x28, 0x29, 0x5b, 0x53, 0x95, 0xeb, 0x4a, 0x17, 0x77, 0x9f, 0x02,
0x03, 0x01, 0x00, 0x01, 0x02, 0x81, 0x80, 0x1a, 0x4b, 0xfa, 0x4f, 0xa8, 0xc2, 0xdd, 0x69, 0xa1, 0x15, 0x96, 0x0b, 0xe8,
0x27, 0x42, 0x5a, 0xf9, 0x5c, 0xea, 0x0c, 0xac, 0x98, 0xaa, 0xe1, 0x8d, 0xaa, 0xeb, 0x2d, 0x3c, 0x60, 0x6a, 0xfb, 0x45,
0x63, 0xa4, 0x79, 0x83, 0x67, 0xed, 0xe4, 0x15, 0xc0, 0xb0, 0x20, 0x95, 0x6d, 0x49, 0x16, 0xc6, 0x42, 0x05, 0x48, 0xaa,
0xb1, 0xa5, 0x53, 0x65, 0xd2, 0x02, 0x99, 0x08, 0xd1, 0x84, 0xcc, 0xf0, 0xcd, 0xea, 0x61, 0xc9, 0x39, 0x02, 0x3f, 0x87,
0x4a, 0xe5, 0xc4, 0xd2, 0x07, 0x02, 0xe1, 0x9f, 0xa0, 0x06, 0xc2, 0xcc, 0x02, 0xe7, 0xaa, 0x6c, 0x99, 0x8a, 0xf8, 0x49,
0x00, 0xf1, 0xa2, 0x8c, 0x0c, 0x8a, 0xb9, 0x4f, 0x6d, 0x73, 0x3b, 0x2c, 0xb7, 0x9f, 0x8a, 0xa6, 0x7f, 0x9b, 0x9f, 0xb7,
0xa1, 0xcc, 0x74, 0x2e, 0x8f, 0xb8, 0xb0, 0x26, 0x89, 0xd2, 0xe5, 0x66, 0xe8, 0x8e, 0xa1, 0x02, 0x41, 0x00, 0xfc, 0xe7,
0x52, 0xbc, 0x4e, 0x95, 0xb6, 0x1a, 0xb4, 0x62, 0xcc, 0xd8, 0x06, 0xe1, 0xdc, 0x7a, 0xa2, 0xb6, 0x71, 0x01, 0xaa, 0x27,
0xfc, 0x99, 0xe5, 0xf2, 0x54, 0xbb, 0xb2, 0x85, 0xe1, 0x96, 0x54, 0x2d, 0xcb, 0xba, 0x86, 0xfa, 0x80, 0xdf, 0xcf, 0x39,
0xe6, 0x74, 0xcb, 0x22, 0xce, 0x70, 0xaa, 0x10, 0x00, 0x73, 0x1d, 0x45, 0x0a, 0x39, 0x51, 0x84, 0xf5, 0x15, 0x8f, 0x37,
0x76, 0x91, 0x02, 0x41, 0x00, 0xe4, 0x3f, 0xf0, 0xf4, 0xde, 0x79, 0x77, 0x48, 0x9b, 0x9c, 0x28, 0x45, 0x26, 0x57, 0x3c,
0x71, 0x40, 0x28, 0x6a, 0xa1, 0xfe, 0xc3, 0xe5, 0x37, 0xa1, 0x03, 0xf6, 0x2d, 0xbe, 0x80, 0x64, 0x72, 0x69, 0x2e, 0x9b,
0x4d, 0xe3, 0x2e, 0x1b, 0xfe, 0xe7, 0xf9, 0x77, 0x8c, 0x18, 0x53, 0x9f, 0xe2, 0xfe, 0x00, 0xbb, 0x49, 0x20, 0x47, 0xdf,
0x01, 0x61, 0x87, 0xd6, 0xe3, 0x44, 0xb5, 0x03, 0x2f, 0x02, 0x40, 0x54, 0xec, 0x7c, 0xbc, 0xdd, 0x0a, 0xaa, 0xde, 0xe6,
0xc9, 0xf2, 0x8d, 0x6c, 0x2a, 0x35, 0xf6, 0x3c, 0x63, 0x55, 0x29, 0x40, 0xf1, 0x32, 0x82, 0x9f, 0x53, 0xb3, 0x9e, 0x5f,
0xc1, 0x53, 0x52, 0x3e, 0xac, 0x2e, 0x28, 0x51, 0xa1, 0x16, 0xdb, 0x90, 0xe3, 0x99, 0x7e, 0x88, 0xa4, 0x04, 0x7c, 0x92,
0xae, 0xd2, 0xe7, 0xd4, 0xe1, 0x55, 0x20, 0x90, 0x3e, 0x3c, 0x6a, 0x63, 0xf0, 0x34, 0xf1, 0x02, 0x41, 0x00, 0x84, 0x5a,
0x17, 0x6c, 0xc6, 0x3c, 0x84, 0xd0, 0x93, 0x7a, 0xff, 0x56, 0xe9, 0x9e, 0x98, 0x2b, 0xcb, 0x5a, 0x24, 0x4a, 0xff, 0x21,
0xb4, 0x9e, 0x87, 0x3d, 0x76, 0xd8, 0x9b, 0xa8, 0x73, 0x96, 0x6c, 0x2b, 0x5c, 0x5e, 0xd3, 0xa6, 0xff, 0x10, 0xd6, 0x8e,
0xaf, 0xa5, 0x8a, 0xcd, 0xa2, 0xde, 0xcb, 0x0e, 0xbd, 0x8a, 0xef, 0xae, 0xfd, 0x3f, 0x1d, 0xc0, 0xd8, 0xf8, 0x3b, 0xf5,
0x02, 0x7d, 0x02, 0x41, 0x00, 0x8b, 0x26, 0xd3, 0x2c, 0x7d, 0x28, 0x38, 0x92, 0xf1, 0xbf, 0x15, 0x16, 0x39, 0x50, 0xc8,
0x6d, 0x32, 0xec, 0x28, 0xf2, 0x8b, 0xd8, 0x70, 0xc5, 0xed, 0xe1, 0x7b, 0xff, 0x2d, 0x66, 0x8c, 0x86, 0x77, 0x43, 0xeb,
0xb6, 0xf6, 0x50, 0x66, 0xb0, 0x40, 0x24, 0x6a, 0xaf, 0x98, 0x21, 0x45, 0x30, 0x01, 0x59, 0xd0, 0xc3, 0xfc, 0x7b, 0xae,
0x30, 0x18, 0xeb, 0x90, 0xfb, 0x17, 0xd3, 0xce, 0xb5
};

/**
 * Compute the sha-256 digest of data.
 * @param data Pointer to the input byte array.
 * @param dataLength The length of data.
 * @param digest A pointer to a buffer of size SHA256_DIGEST_LENGTH to receive the data.
 */
static void digestSha256(const unsigned char *data, unsigned int dataLength, unsigned char *digest)
{
  SHA256_CTX sha256;
  SHA256_Init(&sha256);
  SHA256_Update(&sha256, data, dataLength);
  SHA256_Final(digest, &sha256);
}

/**
 * Call digestSha256 and set the digest vector to the result.
 * @param data
 * @param dataLength
 * @param digest
 */
static void setSha256(const unsigned char *data, unsigned int dataLength, vector<unsigned char> &digest)
{
  unsigned char digestBuffer[SHA256_DIGEST_LENGTH];
  digestSha256(data, dataLength, digestBuffer);
  setVector(digest, digestBuffer, sizeof(digestBuffer));
}

/**
 * Encode the fields of the Data object and set digest to the sha-256 digest.
 * @param data The Data object with the fields to digest.
 * @param digest A pointer to a buffer of size SHA256_DIGEST_LENGTH to receive the data.
 */
static void digestDataFieldsSha256(const Data &data, unsigned char *digest)
{
  // Imitate BinaryXmlWireFormat::encodeData.
  struct ndn_NameComponent nameComponents[100];
  struct ndn_Data dataStruct;
  ndn_Data_init(&dataStruct, nameComponents, sizeof(nameComponents) / sizeof(nameComponents[0]));
  data.get(dataStruct);

  BinaryXmlEncoder encoder;
  unsigned int signedFieldsBeginOffset, signedFieldsEndOffset;
  ndn_Error error;
  if ((error = ndn_encodeBinaryXmlData(&dataStruct, &signedFieldsBeginOffset, &signedFieldsEndOffset, &encoder)))
    throw std::runtime_error(ndn_getErrorString(error));
  
  digestSha256(&encoder.getOutput()->front() + signedFieldsBeginOffset, signedFieldsEndOffset - signedFieldsBeginOffset, digest);
}

void KeyChain::sign
  (Data &data, const unsigned char *publicKeyDer, unsigned int publicKeyDerLength, 
   const unsigned char *privateKeyDer, unsigned int privateKeyDerLength)
{
  // Set the public key.
  setSha256(publicKeyDer, publicKeyDerLength, data.getSignedInfo().getPublisherPublicKeyDigest().getPublisherPublicKeyDigest());
  data.getSignedInfo().getKeyLocator().setType(ndn_KeyLocatorType_KEY);
  data.getSignedInfo().getKeyLocator().setKeyOrCertificate(publicKeyDer, publicKeyDerLength);
  // Clear the signature so we don't encode it below.
  data.getSignature().clear();

  // Sign the fields.
  unsigned char dataFieldsDigest[SHA256_DIGEST_LENGTH];
  digestDataFieldsSha256(data, dataFieldsDigest);
  // TODO: use RSA_size to get the proper size of the signature buffer.
  unsigned char signature[1000];
  unsigned int signatureLength;
  // Use a temporary pointer since d2i updates it.
  const unsigned char *derPointer = privateKeyDer;
  RSA *privateKey = d2i_RSAPrivateKey(NULL, &derPointer, privateKeyDerLength);
  if (!privateKey)
    throw std::runtime_error("Error decoding private key in d2i_RSAPrivateKey");
  int success = RSA_sign(NID_sha256, dataFieldsDigest, sizeof(dataFieldsDigest), signature, &signatureLength, privateKey);
  // Free the private key before checking for success.
  RSA_free(privateKey);
  if (!success)
    throw std::runtime_error("Error in RSA_sign");
  
  data.getSignature().setSignature(signature, signatureLength);
}

void KeyChain::defaultSign(Data &data)
{
  sign(data, DEFAULT_PUBLIC_KEY_DER, sizeof(DEFAULT_PUBLIC_KEY_DER), DEFAULT_PRIVATE_KEY_DER, sizeof(DEFAULT_PRIVATE_KEY_DER));
}

bool KeyChain::selfVerifyData(const unsigned char *input, unsigned int inputLength, WireFormat &wireFormat)
{
  // Decode the data packet and digest the data fields.
  Data data;
  unsigned int signedFieldsBeginOffset, signedFieldsEndOffset;
  wireFormat.decodeData(data, input, inputLength, &signedFieldsBeginOffset, &signedFieldsEndOffset);
  if (data.getSignature().getDigestAlgorithm().size() != 0)
    // TODO: Allow a non-default digest algorithm.
    throw std::runtime_error("Cannot verify a data packet with a non-default digest algorithm");
  unsigned char dataFieldsDigest[SHA256_DIGEST_LENGTH];
  digestSha256(input + signedFieldsBeginOffset, signedFieldsEndOffset - signedFieldsBeginOffset, dataFieldsDigest);
  
  // Find the public key.
  const unsigned char *publicKeyDer;
  unsigned int publicKeyDerLength;
  if (data.getSignedInfo().getKeyLocator().getType() == ndn_KeyLocatorType_KEY) {
    publicKeyDer = &data.getSignedInfo().getKeyLocator().getKeyOrCertificate().front();
    publicKeyDerLength = data.getSignedInfo().getKeyLocator().getKeyOrCertificate().size();
  }
  else
    // Can't find a public key.
    return false;

  // Verify the dataFieldsDigest.
  // Use a temporary pointer since d2i updates it.
  const unsigned char *derPointer = publicKeyDer;
  RSA *publicKey = d2i_RSA_PUBKEY(NULL, &derPointer, publicKeyDerLength);
  if (!publicKey)
    throw std::runtime_error("Error decoding public key in d2i_RSAPublicKey");
  int success = RSA_verify
    (NID_sha256, dataFieldsDigest, sizeof(dataFieldsDigest), &data.getSignature().getSignature().front(), 
     data.getSignature().getSignature().size(), publicKey);
  // Free the public key before checking for success.
  RSA_free(publicKey);
  
  return (success == 1);
}

}