private void distortImage(IImageProcessingContext pc, string foreColor)
{
var degrees = _randomNumberProvider.NextNumber(1, 6);
pc.Skew(degrees, degrees);
pc.Vignette(Color.ParseHex(foreColor));
}
/// <summary>
/// Creates DNTCaptcha
/// </summary>
/// <param name="captchaAttributes">captcha attributes</param>
public DNTCaptchaApiResponse CreateDNTCaptcha(DNTCaptchaTagHelperHtmlAttributes captchaAttributes)
{
if (captchaAttributes == null)
{
throw new ArgumentNullException(nameof(captchaAttributes));
}
if (_httpContextAccessor.HttpContext == null)
{
throw new InvalidOperationException("`_httpContextAccessor.HttpContext` is null.");
}
var number = _randomNumberProvider.NextNumber(captchaAttributes.Min, captchaAttributes.Max);
var randomText = _captchaTextProvider(captchaAttributes.DisplayMode).GetText(number, captchaAttributes.Language);
var encryptedText = _captchaProtectionProvider.Encrypt(randomText);
var captchaImageUrl = getCaptchaImageUrl(captchaAttributes, encryptedText);
var captchaDivId = Invariant($"{_captchaOptions.CaptchaClass}{Guid.NewGuid():N}{_randomNumberProvider.NextNumber(captchaAttributes.Min, captchaAttributes.Max)}");
var cookieToken = $".{captchaDivId}";
var hiddenInputToken = _captchaProtectionProvider.Encrypt(cookieToken);
_captchaStorageProvider.Add(_httpContextAccessor.HttpContext, cookieToken, randomText);
return(new DNTCaptchaApiResponse
{
DntCaptchaImgUrl = captchaImageUrl,
DntCaptchaId = captchaDivId,
DntCaptchaTextValue = encryptedText,
DntCaptchaTokenValue = hiddenInputToken
});
}
/// <summary>
/// SumOfTwoNumbers Provider
/// </summary>
public SumOfTwoNumbersProvider(IRandomNumberProvider randomNumberProvider)
{
if (randomNumberProvider == null)
{
throw new ArgumentNullException(nameof(randomNumberProvider));
}
_randomNumber = randomNumberProvider.NextNumber(1, 7);
}
/// <summary>
/// SumOfTwoNumbersToWords Provider
/// </summary>
public SumOfTwoNumbersToWordsProvider(
IRandomNumberProvider randomNumberProvider,
HumanReadableIntegerProvider humanReadableIntegerProvider)
{
if (randomNumberProvider == null)
{
throw new ArgumentNullException(nameof(randomNumberProvider));
}
_randomNumber = randomNumberProvider.NextNumber(1, 7);
_humanReadableIntegerProvider = humanReadableIntegerProvider;
}
/// <summary>
/// The default captcha protection provider
/// </summary>
public CaptchaCryptoProvider(
IOptions <DNTCaptchaOptions> options,
IRandomNumberProvider randomNumberProvider,
ILogger <CaptchaCryptoProvider> logger)
{
_logger = logger;
if (randomNumberProvider == null)
{
throw new ArgumentNullException(nameof(randomNumberProvider));
}
if (options == null)
{
throw new ArgumentNullException(nameof(options));
}
_keyBytes = getDesKey(options.Value.EncryptionKey, randomNumberProvider.NextNumber().ToString(CultureInfo.InvariantCulture));
}
/// <summary>
/// Creates the captcha image.
/// </summary>
public byte[] DrawCaptcha(string message, string foreColor, float fontSize, string fontName)
{
return(useFont(fontName, fontSize, captchaFont =>
{
var fColor = ColorTranslator.FromHtml(foreColor);
message = message.Replace(",", string.Empty, StringComparison.Ordinal);
const int margin = 8;
var captchaSize = measureString(message, captchaFont);
var height = (int)captchaSize.Height + margin;
var width = (int)captchaSize.Width + margin;
using var pic = new Bitmap(width, height, PixelFormat.Format24bppRgb);
var data = pic.LockBits(new Rectangle(0, 0, pic.Width, pic.Height), ImageLockMode.WriteOnly, pic.PixelFormat);
var noise = new byte[data.Width * data.Height * 3];
_randomNumberProvider.NextBytes(noise);
Marshal.Copy(noise, 0, data.Scan0, noise.Length);
pic.UnlockBits(data);
using (var graphics = Graphics.FromImage(pic))
{
var stringFormat = new StringFormat
{
Alignment = StringAlignment.Center,
LineAlignment = StringAlignment.Center
};
graphics.DrawString(message, captchaFont, new SolidBrush(fColor), new RectangleF(0, 0, pic.Width, pic.Height), stringFormat);
for (var i = 0; i < 30; i++)
{
var x0 = _randomNumberProvider.NextNumber(0, width);
var y0 = _randomNumberProvider.NextNumber(0, height);
var x1 = _randomNumberProvider.NextNumber(0, width);
var y1 = _randomNumberProvider.NextNumber(0, height);
graphics.DrawLine(Pens.White, x0, y0, x1, y1);
}
}
using var stream = new MemoryStream();
distortImage(height, width, pic);
pic.Save(stream, ImageFormat.Png);
return stream.ToArray();
}));
}
/// <summary>
/// Process the taghelper and generate the output.
/// </summary>
public void Process(TagHelperContext context, TagHelperOutput output)
{
if (context == null)
{
throw new ArgumentNullException(nameof(context));
}
if (output == null)
{
throw new ArgumentNullException(nameof(output));
}
if (ViewContext == null)
{
throw new InvalidOperationException("`ViewContext` is null.");
}
setUrlHelper(ViewContext);
output.TagName = "div";
output.Attributes.Add("class", _captchaOptions.CaptchaClass);
var captchaDivId = Invariant($"{_captchaOptions.CaptchaClass}{context.UniqueId}{_randomNumberProvider.NextNumber(Min, Max)}");
output.Attributes.Add("id", captchaDivId);
output.TagMode = TagMode.StartTagAndEndTag;
var number = _randomNumberProvider.NextNumber(Min, Max);
var randomText = _captchaTextProvider(DisplayMode).GetText(number, Language);
var encryptedText = _captchaProtectionProvider.Encrypt(randomText);
var captchaImage = getCaptchaImageTagBuilder(ViewContext, encryptedText);
output.Content.AppendHtml(captchaImage);
var cookieToken = $".{captchaDivId}";
var refreshButton = getRefreshButtonTagBuilder(ViewContext, captchaDivId, cookieToken);
output.Content.AppendHtml(refreshButton);
var hiddenInput = getHiddenInputTagBuilder(encryptedText);
output.Content.AppendHtml(hiddenInput);
var textInput = getTextInputTagBuilder();
output.Content.AppendHtml($"{string.Format(CultureInfo.InvariantCulture, TextBoxTemplate, textInput.GetString())}");
var validationMessage = getValidationMessageTagBuilder(ViewContext);
output.Content.AppendHtml(validationMessage);
var hiddenInputToken = getHiddenInputTokenTagBuilder(_captchaProtectionProvider.Encrypt(cookieToken));
output.Content.AppendHtml(hiddenInputToken);
var dataAjaxBeginScript = getOnRefreshButtonDataAjaxBegin(ViewContext);
output.Content.AppendHtml(dataAjaxBeginScript);
_captchaStorageProvider.Add(ViewContext.HttpContext, cookieToken, randomText);
}
