///
- (id)urlEncoded {
  CFStringRef cfUrlEncodedString = CFURLCreateStringByAddingPercentEscapes(NULL,
                                            (CFStringRef)self,NULL,
                                            (CFStringRef)@"!#$%&'()*+,/:;=?@[]",
                                            kCFStringEncodingUTF8);

  NSString *urlEncoded = [NSString stringWithString:(NSString *)cfUrlEncodedString];
  CFRelease(cfUrlEncodedString);
  return urlEncoded;

}

///
- (NSString*)md5Hash {
  return [[self dataUsingEncoding:NSUTF8StringEncoding] md5Hash];
}


///
- (NSString*)sha1Hash {
  return [[self dataUsingEncoding:NSUTF8StringEncoding] sha1Hash];
}

@implementation NSData (TTCategory)


///
- (NSString*)md5Hash {
  unsigned char result[CC_MD5_DIGEST_LENGTH];
  CC_MD5([self bytes], [self length], result);

  return [NSString stringWithFormat:
    @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
    result[0], result[1], result[2], result[3], result[4], result[5], result[6], result[7],
    result[8], result[9], result[10], result[11], result[12], result[13], result[14], result[15]
  ];
}


///
- (NSString*)sha1Hash {
  unsigned char result[CC_SHA1_DIGEST_LENGTH];
  CC_SHA1([self bytes], [self length], result);

  return [NSString stringWithFormat:
    @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
    result[0], result[1], result[2], result[3], result[4], result[5], result[6], result[7],
    result[8], result[9], result[10], result[11], result[12], result[13], result[14], result[15],
    result[16], result[17], result[18], result[19]
  ];
}

///
// base64 code found on http://www.cocoadev.com/index.pl?BaseSixtyFour
// where the poster released it to public domain
// style not exactly congruous with normal three20 style, but kept mostly intact with the original
static const char encodingTable[] =
                                 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

///
+ (NSData*)dataWithBase64EncodedString:(NSString *)string {
  if ([string length] == 0)
    return [NSData data];

  static char *decodingTable = NULL;
  if (decodingTable == NULL)
  {
    decodingTable = malloc(256);
    if (decodingTable == NULL)
      return nil;
    memset(decodingTable, CHAR_MAX, 256);
    NSUInteger i;
    for (i = 0; i < 64; i++)
      decodingTable[(short)encodingTable[i]] = i;
  }

  const char *characters = [string cStringUsingEncoding:NSASCIIStringEncoding];
  if (characters == NULL)     //  Not an ASCII string!
    return nil;
  char *bytes = malloc((([string length] + 3) / 4) * 3);
  if (bytes == NULL)
    return nil;
  NSUInteger length = 0;

  NSUInteger i = 0;
  while (YES)
  {
    char buffer[4];
    short bufferLength;
    for (bufferLength = 0; bufferLength < 4; i++)
    {
      if (characters[i] == '\0')
        break;
      if (isspace(characters[i]) || characters[i] == '=')
        continue;
      buffer[bufferLength] = decodingTable[(short)characters[i]];
      if (buffer[bufferLength++] == CHAR_MAX)      //  Illegal character!
      {
        free(bytes);
        return nil;
      }
    }

    if (bufferLength == 0)
      break;
    if (bufferLength == 1)      //  At least two characters are needed to produce one byte!
    {
      free(bytes);
      return nil;
    }

        //  Decode the characters in the buffer to bytes.
    bytes[length++] = (buffer[0] << 2) | (buffer[1] >> 4);
    if (bufferLength > 2)
      bytes[length++] = (buffer[1] << 4) | (buffer[2] >> 2);
    if (bufferLength > 3)
      bytes[length++] = (buffer[2] << 6) | buffer[3];
  }

  realloc(bytes, length);
  return [NSData dataWithBytesNoCopy:bytes length:length];
}

///
- (NSString *)base64Encoding {
  if ([self length] == 0)
    return @"";

  char *characters = malloc((([self length] + 2) / 3) * 4);
  if (characters == NULL)
    return nil;
  NSUInteger length = 0;

  NSUInteger i = 0;
  while (i < [self length])
  {
    char buffer[3] = {0,0,0};
    short bufferLength = 0;
    while (bufferLength < 3 && i < [self length])
      buffer[bufferLength++] = ((char *)[self bytes])[i++];

    // Encode the bytes in the buffer to four characters,
    // including padding "=" characters if necessary.
    characters[length++] = encodingTable[(buffer[0] & 0xFC) >> 2];
    characters[length++] = encodingTable[((buffer[0] & 0x03) << 4) | ((buffer[1] & 0xF0) >> 4)];
    if (bufferLength > 1)
      characters[length++] = encodingTable[((buffer[1] & 0x0F) << 2) | ((buffer[2] & 0xC0) >> 6)];
    else characters[length++] = '=';
    if (bufferLength > 2)
      characters[length++] = encodingTable[buffer[2] & 0x3F];
    else characters[length++] = '=';
  }

  return [[[NSString alloc] initWithBytesNoCopy:characters length:length
                                       encoding:NSASCIIStringEncoding freeWhenDone:YES]
          autorelease];
}
// end recycled base64 code
///

@end