<?xml version="1.0" encoding="utf-8" ?> <codesnippets xmlns="http://schemas.microsoft.com/VisualStudio/2005/CodeSnippet"> <codesnippet format="1.0.0"> <header> <title>Implementing Simple Encryption and Decryption with ProtectedData Class</title> <shortcut>protecteddata</shortcut> <description>Demonstrates how to implement simple encryption and decryption of data such as database strings with the new ProtectedData class.</description> <author>C# .Net Fun - http://www.dotnetfun.com - Michael G.</author> </header> <snippet> <declarations> <literal> <id>strDBString</id> <type>System.String</type> <tooltip>The database string to encrypt.</tooltip> <default>"Data Source=localhost; User ID=sa; Password=somepassword;"</default> </literal> <literal> <id>strFileName</id> <type>System.String</type> <tooltip>The file name to which encrypted data is saved and read from during decryption.</tooltip> <default>"ENCDBSTR.bin"</default> </literal> </declarations> <code language="CSharp"> <![CDATA[ // NOTE: This code snippet is designed for VS.NET 2005 or later. // Additional reference: System.Security.dll // using using System.Security.Cryptography; // using System.IO; // This is a button click event - to encrypt the DB string to disk: private void btnEncrypt_Click(object sender, EventArgs e) { // The DB string that we want to encrypt/decrypt: String strConnectionString = $strDBString$; // Call the custom method for encrypting the string: this.EncryptDBString(strConnectionString); } // This is a button click event - to unencrypt the saved DB string: private void btnDecrypt_Click(object sender, EventArgs e) { String strConnectionString = this.DecryptDBString(); // Do something with the unencrypted DB string ... MessageBox.Show(strConnectionString); } // This method will encrypt the provided DB string to disk private void EncryptDBString(String DBString) { /**************** Encrypt/Protect Database String ****************/ // Convert the string to a byte array: byte[] arrDBString = System.Text.Encoding.Unicode.GetBytes(DBString); // Provide additional protection via entropy with another byte array: byte[] arrEntropy = { 4, 5, 7, 9, 4, 5, 7, 9 }; // Save this for unprotecting later // Encrypt/protect the DB string: byte[] arrEncryptedDBString = ProtectedData.Protect(arrDBString, arrEntropy, DataProtectionScope.CurrentUser); // Write the encrypted DB string to disk: using (FileStream fs = new FileStream($strFileName$, FileMode.OpenOrCreate)) { fs.Write(arrEncryptedDBString, 0, arrEncryptedDBString.Length); } } // This method will decrypt the saved encrypted DB string private String DecryptDBString() { /**************** Decrypt/Unprotect Database String ****************/ // Setup the unencrypted DB string to return: String strUnencryptedDBString = null; // Provide additional protection via entropy with another byte array: byte[] arrEntropy = { 4, 5, 7, 9, 4, 5, 7, 9 }; // Save this for protecting later // Setup the byte array that will hold the encrypted DB string: byte[] arrEncryptedDBString = new byte[0]; // Read the encrypted DB string from disk: if (File.Exists($strFileName$)) { using (FileStream fs = new FileStream($strFileName$, FileMode.Open)) { // Reset the byte array's length based on read length: arrEncryptedDBString = new byte[fs.Length]; // Read the encrypted file into the byte array: fs.Read(arrEncryptedDBString, 0, (int) fs.Length); } } if (arrEncryptedDBString.Length > 0) { // Decrypt/unprotect the DB string: byte[] arrUnencryptedDBString = ProtectedData.Unprotect(arrEncryptedDBString, arrEntropy, DataProtectionScope.CurrentUser); // Convert the byte array to a string: strUnencryptedDBString = System.Text.Encoding.Unicode.GetString(arrUnencryptedDBString); } // Return the unencrypted DB string: return strUnencryptedDBString; } ]> </code> </snippet> </codesnippet> </codesnippets>