In this article I will explain with an example, how to use encryption and decryption (Cryptography) in ASP.Net Core (.Net Core 8) Razor Pages.
This article makes use of Symmetric (Same) key AES Algorithm for encryption and decryption process.
Note: For beginners in ASP.Net Core (.Net Core 8) Razor Pages, please refer my article ASP.Net Core 8 Razor Pages: Hello World Tutorial with Sample Program example.
 
 

Namespaces

You will need to import the following namespaces.
using System.IO;
using System.Text;
using System.Security.Cryptography;
 
 

Index PageModel (Code-Behind)

The PageModel consists of following Handler methods.

Handler method for handling GET operation

This Handler method handles the GET calls, for this particular example it is not required and hence left empty.
 

Handler method for handling Encrypt POST operation

Note: For Encryption and Decryption AES encryption algorithm will be used, where a Symmetric (Same) key will be used for encryption and decryption process.
 
This Handler method gets called when the Encrypt button is clicked.
Inside this Handler method, the original text i.e. clear text is converted into bytes using the GetBytes method of Encoding class and then for the AES algorithm to perform encryption Key and IV is generated using the derived bytes and the symmetric key.
Then, using MemoryStream and CryptoStream the clear text is encrypted and written to byte array and the byte array is converted to Base64String.
Finally, the encrypted text is set in TempData object.
 

Handler method for handling Decrypt POST operation

This Handler method gets called when the Decrypt button is clicked.
Inside this Handler method, the encrypted text i.e. cipher text is converted into bytes and then similar to the encryption process a Key and IV is generated using the derived bytes and the symmetric key.
Then, using MemoryStream and CryptoStream the cipher text is decrypted and written to byte array and the byte array is converted to string.
Finally, the decrypted text is set in TempData object.
public class IndexModel : PageModel
{
    public void OnGet()
    {
 
    }
 
    public void OnPostEncrypt(string clearText)
    {
        string encryptionKey = "MAKV2SPBNI99212";
        byte[] clearBytes = Encoding.Unicode.GetBytes(clearText);
        using (Aes encryptor = Aes.Create())
        {
            Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(encryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
            encryptor.Key = pdb.GetBytes(32);
            encryptor.IV = pdb.GetBytes(16);
            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateEncryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(clearBytes, 0, clearBytes.Length);
                    cs.Close();
                }
                TempData["EncryptedText"] = Convert.ToBase64String(ms.ToArray());
            }
        }
    }
 
    public void OnPostDecrypt(string cipherText)
    {
        string encryptionKey = "MAKV2SPBNI99212";
        byte[] cipherBytes = Convert.FromBase64String(cipherText);
        using (Aes encryptor = Aes.Create())
        {
            Rfc2898DeriveBytes pdb = new Rfc2898DeriveBytes(encryptionKey, new byte[] { 0x49, 0x76, 0x61, 0x6e, 0x20, 0x4d, 0x65, 0x64, 0x76, 0x65, 0x64, 0x65, 0x76 });
            encryptor.Key = pdb.GetBytes(32);
            encryptor.IV = pdb.GetBytes(16);
            using (MemoryStream ms = new MemoryStream())
            {
                using (CryptoStream cs = new CryptoStream(ms, encryptor.CreateDecryptor(), CryptoStreamMode.Write))
                {
                    cs.Write(cipherBytes, 0, cipherBytes.Length);
                    cs.Close();
                }
                TempData["DecryptedText"] = Encoding.Unicode.GetString(ms.ToArray());
            }
        }
    }
}
 
 

Razor Page (HTML)

HTML Markup

Inside the Razor Page, the ASP.Net TagHelpers is inherited.
The HTML of Razor Page consists of an HTML Form which has been created using following attribute.
method – It specifies the Form Method i.e. GET or POST. In this case it will be set to POST.
The Form consists of two HTML Input TextBox elements to accept inputs for encryption and decryption, two Input Submit Button elements and two SPAN elements for displaying encrypted and decrypted text.
The Submit Buttons has been set with the POST Handler method using the asp-page-handler attribute.
Note: For more details on using Multiple Submit buttons refer my article, ASP.Net Core: Using Multiple Submit Buttons in Razor Pages.
 
When the Submit Button is clicked, the encrypted and decrypted TempData object is displayed in the respective SPAN element.
Finally, after the TempData object value is read, the Keep function is called which will preserve the value in TempData object.
@page
@model Encrypt_Decrypt_Razor_Core.Pages.IndexModel
@addTagHelper*,Microsoft.AspNetCore.Mvc.TagHelpers
@{
Layout = null;
}
 
<!DOCTYPE html>
 
<html>
<head>
    <meta name="viewport" content="width=device-width" />
    <title>Index</title>
</head>
<body>
    <form method="post">
        <u>Encrypt</u><br /><br />
        <span>Original Text:</span>
        <input type="text" name="clearText" />
        <br /><br />
        <span>Encrypted Text:</span>
        <span>@TempData["EncryptedText"]</span>
        <br /><br />
        <input type="submit" value="Encrypt" asp-page-handler="Encrypt" />
        <hr />
        <u>Decrypt</u><br /><br />
        <span>Encrypted Text:</span>
        <input type="text" name="cipherText" />
        <br /><br />
        <span>Decrypted Text:</span>
        <span>@TempData["DecryptedText"]</span>
        <br /><br />
        <input type="submit" value="Decrypt" asp-page-handler="Decrypt" />
    </form>
    @{
        TempData.Keep("EncryptedText");
    }
</body>
</html>
 
 

Screenshot

ASP.Net Core Razor Pages: AES Encryption Decryption (Cryptography) Tutorial with example
 
 

Downloads

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