mirror of
https://github.com/DorkSquadRR/DorkNet.git
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Alexa
891ec89899
- Data-protection keys are encrypted (AES-256-GCM, key derived from the server secret) before they reach the DataProtectionKeys table. - /link only follows local return paths and keeps the form when a signed-in visitor has an identity waiting to be linked. - A failed sign-out says so instead of reloading as if it worked.
68 lines
3.2 KiB
C#
68 lines
3.2 KiB
C#
using System.Security.Cryptography;
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using System.Text;
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using System.Xml.Linq;
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using Microsoft.AspNetCore.DataProtection.XmlEncryption;
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using Microsoft.Extensions.DependencyInjection;
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namespace DorkNet.Server.Services;
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/// <summary>
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/// Encrypts the data-protection key ring (the keys behind the sign-in
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/// cookies) before it is stored in the <c>DataProtectionKeys</c> table:
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/// AES-256-GCM under a key derived (HKDF-SHA256) from the server secret.
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/// The secret comes from the environment, not the database, so a database
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/// backup alone holds no usable keys. Changing the secret makes the stored
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/// keys unreadable: the server then creates a new key and everyone signs in
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/// again.
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/// </summary>
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public sealed class DataProtectionKeyEncryption : IXmlEncryptor
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{
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private const int NonceSize = 12;
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private const int TagSize = 16;
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private static readonly byte[] Info = Encoding.UTF8.GetBytes("DorkNet.DataProtectionKeys.v1");
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private static readonly XName Root = "dorknetEncryptedKey";
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private readonly byte[] _key;
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public DataProtectionKeyEncryption(string secret)
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{
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if (string.IsNullOrEmpty(secret))
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throw new InvalidOperationException("The server secret is required to encrypt the data-protection keys.");
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_key = HKDF.DeriveKey(HashAlgorithmName.SHA256, Encoding.UTF8.GetBytes(secret), 32, salt: null, info: Info);
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}
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public EncryptedXmlInfo Encrypt(XElement plaintextElement)
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{
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var plaintext = Encoding.UTF8.GetBytes(plaintextElement.ToString(SaveOptions.DisableFormatting));
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var payload = new byte[NonceSize + TagSize + plaintext.Length];
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var nonce = payload.AsSpan(0, NonceSize);
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RandomNumberGenerator.Fill(nonce);
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using (var aes = new AesGcm(_key, TagSize))
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aes.Encrypt(nonce, plaintext, payload.AsSpan(NonceSize + TagSize), payload.AsSpan(NonceSize, TagSize));
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return new EncryptedXmlInfo(
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new XElement(Root, new XAttribute("version", "1"), Convert.ToBase64String(payload)),
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typeof(Decryptor));
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}
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public XElement DecryptElement(XElement encrypted)
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{
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if (encrypted.Name != Root || (string?)encrypted.Attribute("version") != "1")
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throw new CryptographicException("Unrecognised encrypted data-protection key.");
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var payload = Convert.FromBase64String(encrypted.Value);
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if (payload.Length < NonceSize + TagSize)
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throw new CryptographicException("Encrypted data-protection key is truncated.");
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var plaintext = new byte[payload.Length - NonceSize - TagSize];
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using (var aes = new AesGcm(_key, TagSize))
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aes.Decrypt(payload.AsSpan(0, NonceSize), payload.AsSpan(NonceSize + TagSize),
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payload.AsSpan(NonceSize, TagSize), plaintext);
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return XElement.Parse(Encoding.UTF8.GetString(plaintext));
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}
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/// <summary>Created by the data-protection system from the stored type
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/// name, with the app's service provider.</summary>
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public sealed class Decryptor(IServiceProvider services) : IXmlDecryptor
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{
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public XElement Decrypt(XElement encryptedElement) =>
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services.GetRequiredService<DataProtectionKeyEncryption>().DecryptElement(encryptedElement);
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}
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}
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