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POhow to encrypt/Decrypt .xlsx/.doc files with C#
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  1. POhow to encrypt/Decrypt .xlsx/.doc files with C#
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    copied!<p>I'm writing an application to Encrtpt/Decrypt files and using <a href="http://support.microsoft.com/kb/307010" rel="nofollow">DESCryptoServiceProvider</a> for this purpose. This seems to work for text files but when I use the same application for .xlsx file, the resulting encrypted file and the decrypted file get corrupted and I'm not able to open that any more. is there any way I can encryt / decrypt different kinds of file like .doc..xls etc.</p> <p>update : added code for encryption/decryption</p> <pre><code>public static void EncryptFile(string filepath,string fileOutput, string key) { FileStream fsInput = new FileStream(filepath, FileMode.Open, FileAccess.Read); FileStream fsEncrypted = new FileStream(fileOutput, FileMode.Create, FileAccess.Write); DESCryptoServiceProvider DESc = new DESCryptoServiceProvider(); DESc.Key = ASCIIEncoding.ASCII.GetBytes(key); DESc.IV = ASCIIEncoding.ASCII.GetBytes(key); ICryptoTransform desEncrypt = DESc.CreateEncryptor(); CryptoStream cryptoStream = new CryptoStream(fsEncrypted, desEncrypt, CryptoStreamMode.Write); byte[] byteArrayInput = new byte[fsInput.Length - 1]; fsInput.Read(byteArrayInput, 0, byteArrayInput.Length); cryptoStream.Write(byteArrayInput, 0, byteArrayInput.Length); cryptoStream.Close(); fsInput.Close(); fsEncrypted.Close(); } public static void DecryptFile(string filepath, string fileOutput, string key) { DESCryptoServiceProvider DESc = new DESCryptoServiceProvider(); DESc.Key = ASCIIEncoding.ASCII.GetBytes(key); DESc.IV = ASCIIEncoding.ASCII.GetBytes(key); FileStream fsread = new FileStream(filepath, FileMode.Open, FileAccess.Read); ICryptoTransform desDecrypt = DESc.CreateDecryptor(); CryptoStream cryptoStreamDcr = new CryptoStream(fsread, desDecrypt, CryptoStreamMode.Read); StreamWriter fsDecrypted = new StreamWriter(fileOutput); fsDecrypted.Write(new StreamReader(cryptoStreamDcr).ReadToEnd()); fsDecrypted.Flush(); fsDecrypted.Close(); } static void Main(string[] args) { EncryptFile(@"C:\test1.xlsx", @"c:\test2.xlsx", "ABCDEFGH"); DecryptFile(@"C:\test2.xlsx", @"c:\test3.xlsx", "ABCDEFGH"); } </code></pre>
 

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