Разработка распределенных приложений в Microsoft.NET Framework


Пример III1


// Файл SevaSecurityCipher.cs using System; using System.IO; using System.Security.Cryptography; namespace Seva.Security.Encryption { public class SymmetricEncryptor { public const int KeySize = 32; public const int BlockSize = 32; RijndaelManaged cipher = null; public byte[] Key { get { return cipher.Key; } set { cipher.Key = value; } } public SymmetricEncryptor() { cipher = CreateCipher(); cipher.GenerateKey(); } public SymmetricEncryptor(byte[] key) { cipher = CreateCipher(); cipher.Key = key; } public void SaveKey(string fileName) { using (FileStream file = new FileStream(fileName, FileMode.Create, FileAccess.Write)) { file.Write(Key, 0, Key.Length); } } public void LoadKey(string fileName) { byte[] buffer = new byte[KeySize]; using (FileStream file = new FileStream(fileName, FileMode.Open, FileAccess.Read)) { file.Read(buffer, 0, KeySize); } Key = buffer; } public byte[] CreateEmptyIv() { return new byte[SymmetricEncryptor.BlockSize]; } public byte[] EncryptMessage(byte[] plainText, out byte[] iv) { cipher.GenerateIV(); iv = cipher.IV; ICryptoTransform transform = cipher.CreateEncryptor(); byte[] cipherText = transform.TransformFinalBlock(plainText, 0, plainText.Length); return cipherText; } public byte[] DecryptMessage(byte[] cipherText, byte[] iv) { cipher.IV = iv; ICryptoTransform transform = cipher.CreateDecryptor(); byte[] plainText = transform.TransformFinalBlock(cipherText, 0, cipherText.Length); return plainText; } public void Encrypt(Stream input, Stream output) { byte[] iv = null; byte[] buffer = new byte[input.Length]; input.Read(buffer, 0, buffer.Length); buffer = EncryptMessage(buffer, out iv); // output.Write(iv, 0, iv.Length); output.Write(buffer, 0, buffer.Length); } public void Decrypt(Stream input, Stream output) { byte[] iv = CreateEmptyIv(); byte[] buffer = new byte[input.Length-iv.Length]; input.Read(iv, 0, iv.Length); input.Read(buffer, 0, buffer.Length); // buffer = DecryptMessage(buffer, iv); output.Write(buffer, 0, buffer.Length); } private RijndaelManaged CreateCipher() { RijndaelManaged cipher = new RijndaelManaged(); cipher.KeySize = KeySize * 8; cipher.BlockSize = BlockSize * 8; cipher.Mode = CipherMode.CBC; cipher.Padding = PaddingMode.PKCS7; return cipher; } } } // SevaSecurityCipher.cs
Листинг III.1.
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