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POHow to encrypt and save a binary stream after serialization and read it back?
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copied!<p>I am having some problems in using CryptoStream when I want to encrypt a binary stream after binary serialization and save it to a file. I am getting the following exception</p> <pre><code>System.ArgumentException : Stream was not readable. </code></pre> <p>Can anybody please show me how to encrypt a binary stream and save it to a file and deserialize it back correctly?</p> <p>The code is as follows:</p> <pre><code>class Program { public static void Main(string[] args) { var b = new B {Name = "BB"}; WriteFile<B>(@"C:\test.bin", b, true); var bb = ReadFile<B>(@"C:\test.bin", true); Console.WriteLine(b.Name == bb.Name); Console.ReadLine(); } public static T ReadFile<T>(string file, bool decrypt) { T bObj = default(T); var _binaryFormatter = new BinaryFormatter(); Stream buffer = null; using (var stream = new FileStream(file, FileMode.OpenOrCreate)) { if(decrypt) { const string strEncrypt = "*#4$%^.++q~!cfr0(_!#$@$!&#&#*&@(7cy9rn8r265&$@&*E^184t44tq2cr9o3r6329"; byte[] dv = {0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF}; CryptoStream cs; DESCryptoServiceProvider des = null; var byKey = Encoding.UTF8.GetBytes(strEncrypt.Substring(0, 8)); using (des = new DESCryptoServiceProvider()) { cs = new CryptoStream(stream, des.CreateEncryptor(byKey, dv), CryptoStreamMode.Read); } buffer = cs; } else buffer = stream; try { bObj = (T) _binaryFormatter.Deserialize(buffer); } catch(SerializationException ex) { Console.WriteLine(ex.Message); } } return bObj; } public static void WriteFile<T>(string file, T bObj, bool encrypt) { var _binaryFormatter = new BinaryFormatter(); Stream buffer; using (var stream = new FileStream(file, FileMode.Create)) { try { if(encrypt) { const string strEncrypt = "*#4$%^.++q~!cfr0(_!#$@$!&#&#*&@(7cy9rn8r265&$@&*E^184t44tq2cr9o3r6329"; byte[] dv = {0x12, 0x34, 0x56, 0x78, 0x90, 0xAB, 0xCD, 0xEF}; CryptoStream cs; DESCryptoServiceProvider des = null; var byKey = Encoding.UTF8.GetBytes(strEncrypt.Substring(0, 8)); using (des = new DESCryptoServiceProvider()) { cs = new CryptoStream(stream, des.CreateEncryptor(byKey, dv), CryptoStreamMode.Write); buffer = cs; } } else buffer = stream; _binaryFormatter.Serialize(buffer, bObj); buffer.Flush(); } catch(SerializationException ex) { Console.WriteLine(ex.Message); } } } } [Serializable] public class B { public string Name {get; set;} } </code></pre> <p>It throws the serialization exception as follows</p> <p>The input stream is not a valid binary format. The starting contents (in bytes) are: 3F-17-2E-20-80-56-A3-2A-46-63-22-C4-49-56-22-B4-DA ...</p>

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