In this article I will explain with an example, how to use encryption and decryption (Cryptography) in ASP.Net using C# and VB.Net.
This article makes use of System.Security.Cryptography class and AES algorithm for encryption and decryption in ASP.Net.
HTML Markup
The HTML Markup consists of following controls:
TextBox – For capturing plain text to be encrypted.
Label – For displaying encrypted and decrypted text.
Button – For performing encrypting and decrypting function.
The Buttons have been assigned with an OnClick event handler.
Plain Text:
<asp:TextBox ID="txtPlain" runat="server"></asp:TextBox>
<asp:Button ID="btnEncrypt" runat="server" Text="Encrypt" OnClick="OnEncrypt" />
<br />
Encrypted Text:<asp:Label ID="lblEncrypted" runat="server"></asp:Label>
<hr />
<asp:Button ID="btnDecrypt" runat="server" Text="Decrypt" OnClick="OnDecrypt" />
<br />
<br />
Decrypted Value: <asp:Label ID="lblDecrypted" runat="server"></asp:Label>
Namespaces
You will need to import the following namespaces.
C#
using System.Text;
using System.Security.Cryptography;
VB.Net
Imports System.Text
Imports System.Security.Cryptography
Encrypting Plain Text using C# and VB.Net
When Encrypt button is clicked, the plain text is captured from the TextBox and passed as parameter to Encrypt method.
Encrypt
Inside the Encrypt method, first the secret key is defined for the encryption and converted into a BYTE array using GetBytes method of the Encoding class.
And the plain text captured from the TextBox is also converted into a BYTE array.
Note: For Encryption and Decryption, AES encryption algorithm will be used, where a Symmetric (Same) key will be used for encryption and decryption process.
Then, an object of AES class (AES Symmetric key algorithm) is created for performing encryption and its necessary properties are set.
Key – For defining the EncryptionKey.
Mode – It defines the mode of the operation. Here it is CipherMode.ECB (Electronic Codebook).
Padding – It specifies padding mode.
After that, an object of ICryptoTransform is created and CreateEncryptor method of AES class (AES Symmetric key algorithm) is called.
Then, using TransformFinalBlock method of ICryptoTransform class object the plain text is encrypted and stored as BYTE array.
Finally, the BYTE array is converted into a BASE64 string and string value is returned and displayed using Label control
C#
protected void OnEncrypt(object sender, EventArgs e)
{
lblEncrypted.Text = this.Encrypt(txtPlain.Text.Trim());
}
private string Encrypt(string plainText)
{
//Secret Key.
string secretKey = "$ASPcAwSNIgcPPEoTSa0ODw#";
//Secret Bytes.
byte[] secretBytes = Encoding.UTF8.GetBytes(secretKey);
//Plain Text Bytes.
byte[] plainTextBytes = Encoding.UTF8.GetBytes(plainText);
//Encrypt with AES Alogorithm using Secret Key.
using (Aes aes = Aes.Create())
{
aes.Key = secretBytes;
aes.Mode = CipherMode.ECB;
aes.Padding = PaddingMode.PKCS7;
byte[] encryptedBytes = null;
using (ICryptoTransform encryptor = aes.CreateEncryptor())
{
encryptedBytes = encryptor.TransformFinalBlock(plainTextBytes, 0, plainTextBytes.Length);
}
return Convert.ToBase64String(encryptedBytes);
}
}
VB.Net
Protected Sub OnEncrypt(ByVal sender As Object, ByVal e As EventArgs)
lblEncrypted.Text = Me.Encrypt(txtPlain.Text.Trim())
End Sub
Private Function Encrypt(ByVal plainText As String) As String
'Secret Key.
Dim secretKey As String = "$ASPcAwSNIgcPPEoTSa0ODw#"
'Secret Bytes.
Dim secretBytes As Byte() = Encoding.UTF8.GetBytes(secretKey)
'Plain Text Bytes.
Dim plainTextBytes As Byte() = Encoding.UTF8.GetBytes(plainText)
'Encrypt with AES Alogorithm using Secret Key.
Using aes As Aes = Aes.Create()
aes.Key = secretBytes
aes.Mode = CipherMode.ECB
aes.Padding = PaddingMode.PKCS7
Dim encryptedBytes As Byte() = Nothing
Using encryptor As ICryptoTransform = aes.CreateEncryptor()
encryptedBytes = encryptor.TransformFinalBlock(plainTextBytes, 0, plainTextBytes.Length)
End Using
Return Convert.ToBase64String(encryptedBytes)
End Using
End Function
Decrypting Encrypted Text to Plain Text using C# and VB.Net
When Decrypt button is clicked, the encrypted text is captured from the Label and passed as parameter to Decrypt method.
Decrypt
Inside the Decrypt method, first the secret key is defined for the decryption and converted into a BYTE array using GetBytes method of the Encoding class.
And the encrypted text captured from the Label is also converted into a BYTE array.
Note: For Encryption and Decryption, AES encryption algorithm will be used, where a Symmetric (Same) key will be used for encryption and decryption process.
Then, an object of AES class (AES Symmetric key algorithm) is created for performing encryption and its necessary properties are set.
Key – For defining the EncryptionKey.
Mode – It defines the mode of the operation. Here it is CipherMode.ECB (Electronic Codebook).
Padding – It specifies padding mode.
After that, an object of ICryptoTransform is created and CreateDecryptor method of AES class (AES Symmetric key algorithm) is called.
Then, using TransformFinalBlock method of ICryptoTransform class object the encrypted text is decrypted and stored as BYTE array.
Finally, the BYTE array is converted into a BASE64 string and string value is returned and displayed using Label controls
C#
protected void OnDecrypt(object sender, EventArgs e)
{
lblDecrypted.Text = this.Decrypt(lblEncrypted.Text.Trim());
}
private string Decrypt(string encryptedText)
{
//Secret Key.
string secretKey = "$ASPcAwSNIgcPPEoTSa0ODw#";
//Secret Bytes.
byte[] secretBytes = Encoding.UTF8.GetBytes(secretKey);
//Encrypted Bytes.
byte[] encryptedBytes = Convert.FromBase64String(encryptedText);
//Decrypt with AES Alogorithm using Secret Key.
using (Aes aes = Aes.Create())
{
aes.Key = secretBytes;
aes.Mode = CipherMode.ECB;
aes.Padding = PaddingMode.PKCS7;
byte[] decryptedBytes = null;
using (ICryptoTransform decryptor = aes.CreateDecryptor())
{
decryptedBytes = decryptor.TransformFinalBlock(encryptedBytes, 0, encryptedBytes.Length);
}
return Encoding.UTF8.GetString(decryptedBytes);
}
}
VB.Net
Protected Sub OnDecrypt(ByVal sender As Object, ByVal e As EventArgs)
lblDecrypted.Text = Me.Decrypt(lblEncrypted.Text.Trim())
End Sub
Private Function Decrypt(ByVal encryptedText As String) As String
'Secret Key.
Dim secretKey As String = "$ASPcAwSNIgcPPEoTSa0ODw#"
'Secret Bytes.
Dim secretBytes As Byte() = Encoding.UTF8.GetBytes(secretKey)
'Encrypted Bytes.
Dim encryptedBytes As Byte() = Convert.FromBase64String(encryptedText)
'Decrypt with AES Alogorithm using Secret Key.
Using aes As Aes = Aes.Create()
aes.Key = secretBytes
aes.Mode = CipherMode.ECB
aes.Padding = PaddingMode.PKCS7
Dim decryptedBytes As Byte() = Nothing
Using decryptor As ICryptoTransform = aes.CreateDecryptor()
decryptedBytes = decryptor.TransformFinalBlock(encryptedBytes, 0, encryptedBytes.Length)
End Using
Return Encoding.UTF8.GetString(decryptedBytes)
End Using
End Function
Screenshot
![AES Encryption Decryption (Cryptography) Tutorial with example in ASP.Net using C# and VB.Net]()
Demo
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