Add project files.

2026-06-20 09:31:59 -05:00
parent 9bb3f00d86
commit 4baa4ce8c0
346 changed files with 55751 additions and 0 deletions
@@ -0,0 +1,39 @@
+using System.Security.Cryptography;
+using Wingnal.Protocol.Curve;
+using Wingnal.Protocol.State;
+
+namespace Wingnal.Service.Keys;
+
+/// <summary>Generates the prekeys a freshly linked device must register with the server.</summary>
+public static class PreKeyHelper
+{
+    /// <summary>A 14-bit Signal registration id (1..16383).</summary>
+    public static uint GenerateRegistrationId() => (uint)RandomNumberGenerator.GetInt32(1, 16384);
+
+    /// <summary>A signed prekey whose public key is signed with the given identity private key.</summary>
+    public static SignedPreKeyRecord GenerateSignedPreKey(byte[] identityPrivateKey, uint id)
+    {
+        ECKeyPair keyPair = Curve25519.GenerateKeyPair();
+        byte[] signature = XEd25519.CalculateSignature(
+            identityPrivateKey, Curve25519.EncodePoint(keyPair.PublicKey), RandomNumberGenerator.GetBytes(64));
+        return new SignedPreKeyRecord(id, keyPair, signature, DateTimeOffset.UtcNow.ToUnixTimeMilliseconds());
+    }
+
+    /// <summary>A last-resort ML-KEM prekey signed with the given identity private key.</summary>
+    public static KyberPreKeyRecord GenerateKyberPreKey(byte[] identityPrivateKey, uint id)
+    {
+        KyberKeyPair keyPair = Kyber.GenerateKeyPair();
+        byte[] signature = XEd25519.CalculateSignature(
+            identityPrivateKey, KemKeySerialization.Serialize(keyPair.PublicKey), RandomNumberGenerator.GetBytes(64));
+        return new KyberPreKeyRecord(id, keyPair, signature, DateTimeOffset.UtcNow.ToUnixTimeMilliseconds());
+    }
+
+    /// <summary>A batch of one-time prekeys, ids starting at <paramref name="startId"/>.</summary>
+    public static List<PreKeyRecord> GenerateOneTimePreKeys(uint startId, int count)
+    {
+        var result = new List<PreKeyRecord>(count);
+        for (uint i = 0; i < count; i++)
+            result.Add(PreKeyRecord.Generate(startId + i));
+        return result;
+    }
+}