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POUnable to create CryptoStream to read from - System.NotSupportedException
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copied!<p>There is really simple code to decrypt file (triple des encryption):</p> <pre><code> FileStream fin = new FileStream(FilePath, FileMode.Open, FileAccess.Read); TripleDES tdes = new TripleDESCryptoServiceProvider(); CryptoStream cs = new CryptoStream(fin, tdes.CreateDecryptor(key, iv),CryptoStreamMode.Read); //<---- Exceptions </code></pre> <p>And it does not work. 'cs' is invalid and it's impossible to read from it. There are some exceptions while creating CryptoStream:</p> <pre><code>Length = 'cs.Length' threw an exception of type 'System.NotSupportedException' base {System.SystemException} = {"Stream does not support seeking."} </code></pre> <p>Why I can't create crypto stream and read from it and how to fix this issue?</p> <p>[added]</p> <p>Thanks for responses, now it's more clear for me. But - still, this is impossible to read from 'cs'. </p> <p>Encryption:</p> <pre><code>FileStream fout = new FileStream(FilePath, FileMode.OpenOrCreate, FileAccess.Write); TripleDES tdes = new TripleDESCryptoServiceProvider(); CryptoStream cs = new CryptoStream(fout, tdes.CreateEncryptor(key, iv), CryptoStreamMode.Write); byte[] d = Encoding.ASCII.GetBytes(Data); cs.Write(d, 0, d.Length); cs.WriteByte(0); cs.Close(); fout.Close(); </code></pre> <p>There is iv and key defined somewhere else. And, decryption - entire method:</p> <pre><code> FileStream fin = new FileStream(FilePath, FileMode.Open, FileAccess.Read); TripleDES tdes = new TripleDESCryptoServiceProvider(); CryptoStream cs = new CryptoStream(fin, tdes.CreateDecryptor(key, iv),CryptoStreamMode.Read); StringBuilder SB = new StringBuilder(); int ch; for (int i = 0; i < fin.Length; i++) { ch = cs.ReadByte(); //Exception - CryptographicException: Bad data if (ch == 0) break; SB.Append(Convert.ToChar(ch)); } cs.Close(); fin.Close(); </code></pre> <p>As you can see, there is the same key and iv like in encryption code. But it' still impossible to read from 'cs' stream -exception is thrown. How do you think - what's wrong here?</p> <p>This is my key and iv used:</p> <pre><code>public static byte[] key = { 21, 10, 64, 10, 100, 40, 200, 4, 21, 54, 65, 246, 5, 62, 1, 54, 54, 6, 8, 9, 65, 4, 65, 9}; private static byte[] iv = { 0, 0, 0, 0, 0, 0, 0, 0 }; </code></pre>

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