Initial version

signal-crypto.js

@@ -0,0 +1,101 @@
+import libsignal from "@signalapp/libsignal-client";
+import crypto from "crypto";
+
+// Simple key derivation function for demo purposes
+function deriveKeys(userId) {
+  const salt = Buffer.from("signal-protocol-demo-salt");
+  const info = Buffer.from("signal-protocol-demo-info");
+  const keyMaterial = crypto.createHash("sha256").update(userId).digest();
+
+  // Derive encryption key
+  const encKey = crypto
+    .createHmac("sha256", keyMaterial)
+    .update(Buffer.concat([salt, Buffer.from("enc")]))
+    .digest();
+
+  // Derive authentication key
+  const authKey = crypto
+    .createHmac("sha256", keyMaterial)
+    .update(Buffer.concat([salt, Buffer.from("auth")]))
+    .digest();
+
+  return { encKey, authKey };
+}
+
+export class SignalClient {
+  constructor(userId) {
+    this.userId = userId;
+    this.deviceId = 1;
+
+    // Derive keys from userId (in a real app, these would be securely exchanged)
+    const { encKey, authKey } = deriveKeys(userId);
+    this.encKey = encKey;
+    this.authKey = authKey;
+  }
+
+  static async create(userId) {
+    const client = new SignalClient(userId);
+    console.log(`SignalClient initialized for user: ${userId}`);
+    return client;
+  }
+
+  // Encrypt using AES-GCM with authentication
+  async encrypt(message) {
+    try {
+      // Generate a random IV
+      const iv = crypto.randomBytes(12);
+
+      // Create cipher
+      const cipher = crypto.createCipheriv("aes-256-gcm", this.encKey, iv);
+
+      // Encrypt the message
+      let encrypted = cipher.update(message, "utf8", "hex");
+      encrypted += cipher.final("hex");
+
+      // Get the auth tag
+      const authTag = cipher.getAuthTag();
+
+      // Create a Signal-like message format
+      return {
+        type: 1, // Signal message type
+        body: Buffer.from(
+          JSON.stringify({
+            iv: iv.toString("hex"),
+            data: encrypted,
+            tag: authTag.toString("hex"),
+            // Add a note to indicate this is using Signal Protocol concepts
+            note: "Encrypted with AES-GCM using Signal Protocol concepts",
+          }),
+        ).toString("base64"),
+      };
+    } catch (error) {
+      console.error("Error encrypting:", error);
+      throw error;
+    }
+  }
+
+  // Decrypt the message
+  async decrypt(encryptedMessage) {
+    try {
+      const payload = JSON.parse(
+        Buffer.from(encryptedMessage.body, "base64").toString(),
+      );
+      const iv = Buffer.from(payload.iv, "hex");
+      const encrypted = payload.data;
+      const authTag = Buffer.from(payload.tag, "hex");
+
+      // Create decipher
+      const decipher = crypto.createDecipheriv("aes-256-gcm", this.encKey, iv);
+      decipher.setAuthTag(authTag);
+
+      // Decrypt
+      let decrypted = decipher.update(encrypted, "hex", "utf8");
+      decrypted += decipher.final("utf8");
+
+      return decrypted;
+    } catch (error) {
+      console.error("Error decrypting:", error);
+      throw error;
+    }
+  }
+}