public Captcha GenerateCaptcha()
{
const string dicString = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz";
var random = new Random();
var text = new char[4];
for (var i = 0; i < 4; ++i)
{
text[i] = dicString[random.Next(0, dicString.Length - 1)];
}
var captchaId = Guid.NewGuid();
MemoryCacheUtil.SetItem(captchaId.ToString(), text);
return(new Captcha
{
Id = captchaId,
Image = Convert.ToBase64String(CaptchaUtil.CreateCaptcha(new string(text)))
});
}