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lihansani
270
DCIT.Core/Utilities/HashUtility.cs
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270
DCIT.Core/Utilities/HashUtility.cs
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using System;
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using System.IO;
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using System.Security.Cryptography;
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using System.Text;
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namespace DCIT.Core.Utilities
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{
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public static class HashUtility
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{
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private static readonly byte[] EncryptionKey = ComputeSha256Bytes("DCIT::DiffEncryptionKey::20260424");
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private static readonly byte[] TamperKey = ComputeSha256Bytes("DCIT::TamperProtectionKey::20260424");
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public static string ComputeSha256Base64(byte[] bytes)
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{
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using (var sha = SHA256.Create())
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{
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return Convert.ToBase64String(sha.ComputeHash(bytes ?? new byte[0]));
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}
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}
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public static string ComputeSha256Base64(string value)
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{
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return ComputeSha256Base64(Encoding.UTF8.GetBytes(value ?? string.Empty));
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}
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public static string ComputeFileSha256Base64(string path)
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{
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using (var stream = File.OpenRead(path))
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using (var sha = SHA256.Create())
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{
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return Convert.ToBase64String(sha.ComputeHash(stream));
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}
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}
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public static string ComputeHmacBase64(byte[] bytes)
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{
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using (var hmac = new HMACSHA256(TamperKey))
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{
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return Convert.ToBase64String(hmac.ComputeHash(bytes ?? new byte[0]));
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}
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}
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public static string ComputeFileHmacBase64(string path)
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{
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using (var stream = File.OpenRead(path))
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using (var hmac = new HMACSHA256(TamperKey))
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{
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return Convert.ToBase64String(hmac.ComputeHash(stream));
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}
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}
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public static EncryptedPayload Encrypt(byte[] plaintextBytes)
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{
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var iv = new byte[16];
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using (var rng = RandomNumberGenerator.Create())
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{
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rng.GetBytes(iv);
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}
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byte[] cipherBytes;
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using (var aes = Aes.Create())
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{
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aes.Key = EncryptionKey;
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aes.IV = iv;
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aes.Mode = CipherMode.CBC;
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aes.Padding = PaddingMode.PKCS7;
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using (var encryptor = aes.CreateEncryptor())
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{
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cipherBytes = encryptor.TransformFinalBlock(plaintextBytes ?? new byte[0], 0, (plaintextBytes ?? new byte[0]).Length);
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}
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}
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var tagInput = Combine(iv, cipherBytes);
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using (var hmac = new HMACSHA256(TamperKey))
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{
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return new EncryptedPayload
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{
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CiphertextBase64 = Convert.ToBase64String(cipherBytes),
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NonceBase64 = Convert.ToBase64String(iv),
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TagBase64 = Convert.ToBase64String(hmac.ComputeHash(tagInput)),
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};
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}
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}
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public static EncryptedPayloadHeader EncryptStream(Stream plaintextStream, Stream ciphertextStream)
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{
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if (plaintextStream == null)
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{
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throw new ArgumentNullException("plaintextStream");
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}
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if (ciphertextStream == null)
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{
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throw new ArgumentNullException("ciphertextStream");
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}
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if (!ciphertextStream.CanSeek)
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{
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throw new ArgumentException("密文流必须支持 Seek 以便计算防篡改标签。", "ciphertextStream");
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}
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var iv = new byte[16];
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using (var rng = RandomNumberGenerator.Create())
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{
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rng.GetBytes(iv);
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}
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using (var aes = Aes.Create())
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{
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aes.Key = EncryptionKey;
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aes.IV = iv;
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aes.Mode = CipherMode.CBC;
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aes.Padding = PaddingMode.PKCS7;
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using (var encryptor = aes.CreateEncryptor())
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using (var cryptoStream = new CryptoStream(ciphertextStream, encryptor, CryptoStreamMode.Write, leaveOpen: true))
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{
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plaintextStream.CopyTo(cryptoStream);
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cryptoStream.FlushFinalBlock();
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}
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}
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ciphertextStream.Position = 0;
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using (var hmac = new HMACSHA256(TamperKey))
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{
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hmac.TransformBlock(iv, 0, iv.Length, iv, 0);
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var buffer = new byte[65536];
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int read;
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while ((read = ciphertextStream.Read(buffer, 0, buffer.Length)) > 0)
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{
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hmac.TransformBlock(buffer, 0, read, buffer, 0);
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}
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hmac.TransformFinalBlock(new byte[0], 0, 0);
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return new EncryptedPayloadHeader
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{
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NonceBase64 = Convert.ToBase64String(iv),
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TagBase64 = Convert.ToBase64String(hmac.Hash),
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};
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}
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}
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public static byte[] Decrypt(string ciphertextBase64, string nonceBase64, string tagBase64)
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{
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var cipherBytes = Convert.FromBase64String(ciphertextBase64 ?? string.Empty);
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var iv = Convert.FromBase64String(nonceBase64 ?? string.Empty);
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var providedTag = Convert.FromBase64String(tagBase64 ?? string.Empty);
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var expectedTag = Convert.FromBase64String(ComputeHmacBase64(Combine(iv, cipherBytes)));
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if (!FixedTimeEquals(providedTag, expectedTag))
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{
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throw new CryptographicException("差异载荷验证失败。");
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}
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using (var aes = Aes.Create())
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{
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aes.Key = EncryptionKey;
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aes.IV = iv;
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aes.Mode = CipherMode.CBC;
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aes.Padding = PaddingMode.PKCS7;
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using (var decryptor = aes.CreateDecryptor())
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{
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return decryptor.TransformFinalBlock(cipherBytes, 0, cipherBytes.Length);
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}
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}
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}
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public static void DecryptStream(Stream cipherStream, Stream plaintextStream, byte[] iv, byte[] expectedTag)
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{
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if (cipherStream == null)
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{
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throw new ArgumentNullException("cipherStream");
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}
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if (plaintextStream == null)
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{
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throw new ArgumentNullException("plaintextStream");
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}
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if (!cipherStream.CanSeek)
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{
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throw new ArgumentException("密文流必须支持 Seek 以便校验防篡改标签。", "cipherStream");
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}
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using (var hmac = new HMACSHA256(TamperKey))
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{
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hmac.TransformBlock(iv ?? new byte[0], 0, (iv ?? new byte[0]).Length, iv ?? new byte[0], 0);
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cipherStream.Position = 0;
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var buffer = new byte[65536];
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int read;
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while ((read = cipherStream.Read(buffer, 0, buffer.Length)) > 0)
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{
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hmac.TransformBlock(buffer, 0, read, buffer, 0);
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}
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hmac.TransformFinalBlock(new byte[0], 0, 0);
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if (!FixedTimeEquals(hmac.Hash, expectedTag ?? new byte[0]))
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{
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throw new CryptographicException("差异载荷防篡改校验失败。");
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}
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}
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cipherStream.Position = 0;
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using (var aes = Aes.Create())
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{
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aes.Key = EncryptionKey;
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aes.IV = iv;
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aes.Mode = CipherMode.CBC;
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aes.Padding = PaddingMode.PKCS7;
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using (var decryptor = aes.CreateDecryptor())
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using (var cryptoStream = new CryptoStream(cipherStream, decryptor, CryptoStreamMode.Read, leaveOpen: true))
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{
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cryptoStream.CopyTo(plaintextStream);
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}
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}
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}
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private static byte[] ComputeSha256Bytes(string value)
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{
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using (var sha = SHA256.Create())
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{
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return sha.ComputeHash(Encoding.UTF8.GetBytes(value ?? string.Empty));
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}
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}
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private static bool FixedTimeEquals(byte[] left, byte[] right)
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{
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if (left == null || right == null || left.Length != right.Length)
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{
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return false;
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}
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var diff = 0;
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for (var index = 0; index < left.Length; index++)
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{
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diff |= left[index] ^ right[index];
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}
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return diff == 0;
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}
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private static byte[] Combine(byte[] left, byte[] right)
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{
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left = left ?? new byte[0];
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right = right ?? new byte[0];
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var bytes = new byte[left.Length + right.Length];
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Buffer.BlockCopy(left, 0, bytes, 0, left.Length);
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Buffer.BlockCopy(right, 0, bytes, left.Length, right.Length);
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return bytes;
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}
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}
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public class EncryptedPayload
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{
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public string CiphertextBase64 { get; set; }
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public string NonceBase64 { get; set; }
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public string TagBase64 { get; set; }
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}
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public class EncryptedPayloadHeader
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{
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public string NonceBase64 { get; set; }
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public string TagBase64 { get; set; }
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}
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}
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