Friday, December 18, 2009

Encryption & Decryption : ASCII encoding

The GetByteCount method determines how many bytes result in encoding a set of Unicode characters, and the GetBytes method performs the actual encoding.

Likewise, the GetCharCount method determines how many characters result in decoding a sequence of bytes, and the GetChars and GetString methods perform the actual decoding.

When selecting the ASCII encoding for your applications, consider the following:

    * The ASCII encoding is usually appropriate for protocols that require ASCII.
    * If your application requires 8-bit encoding, the UTF-8 encoding is recommended over the ASCII encoding. For the characters 0-7F, the results are identical, but use

of UTF-8 avoids data loss by allowing representation of all Unicode characters that are representable. Note that the ASCII encoding has an 8th bit ambiguity that can allow malicious use, but the UTF-8 encoding removes ambiguity about the 8th bit.

    * Previous versions of .NET Framework allowed spoofing by merely ignoring the 8th bit. The current version has been changed so that non-ASCII code points fall back during the decoding of bytes.

——————————————————————
Example of ASCII encoding
——————————————————————

SecurityClass.cs
————————–
public static string EnryptString(string strEncrypted)
{
byte[] b = System.Text.ASCIIEncoding.ASCII.GetBytes(strEncrypted);
string encryptedConnectionString = Convert.ToBase64String(b);
return encryptedConnectionString;
}

public static string DecryptString(string encrString)
{
byte[] b = Convert.FromBase64String(encrString);
string decryptedConnectionString = System.Text.ASCIIEncoding.ASCII.GetString(b);
return decryptedConnectionString;
}

Default.aspx.cs
———————
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
string Password = “SandeepMRamani”;
lblOriginal.Text = Password;
lblEncryption.Text = SecurityClass.EnryptString(Password);
lblDecryption.Text = SecurityClass.DecryptString(lblEncryption.Text);
}
}
Default.aspx
——————
<div align=”center” style=”font-size:xx-large;”>
<h1> Encryption / Decryption Example </h1>
<hr />

Original String :
<asp:Label ID=”lblOriginal” style=”font-weight:bolder;” runat=”server” Text=”"></asp:Label>
<br />
Encrypted Text :
<asp:Label ID=”lblEncryption” style=”font-weight:bolder;” runat=”server” Text=”"></asp:Label>
<br />
Decrypted Text :
<asp:Label ID=”lblDecryption” style=”font-weight:bolder;” runat=”server” Text=”"></asp:Label>
<hr />
</div>

--

Happy programming

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