Implement Signal Protocol

frontend/src/core/api/account/index.ts

@@ -127,6 +127,7 @@ export async function deriveAuthSecret(username: string, password: string): Prom
     return b64(derived);
 }
 
+
 export async function ensureKeysOnLogin(password: string, token: string): Promise<UserKeyPairMemory> {
 	// Try to restore from backup
 	const blobJson = await fetchBackupBlob(token);

frontend/src/core/api/crypto.ts

@@ -2,6 +2,7 @@ import { API_BASE_URL } from "@/core/config";
 import { getAuthHeaders } from "./account";
 import type { UploadPublicKeyRequest, BackupBlob } from "@/core/types";
 import { b64, ub64 } from "@/utils/utils";
+import type { PreKeyBundleData } from "@/utils/crypto/signalProtocol";
 
 /**
  * Fetches the current user's public key
@@ -74,3 +75,32 @@ export async function uploadBackupBlob(blobJson: string, token: string): Promise
     if (!res.ok) throw new Error("Failed to upload backup blob");
 }
 
+/**
+ * Uploads Signal Protocol prekey bundle for the current user
+ */
+export async function uploadPreKeyBundle(bundle: PreKeyBundleData, token: string): Promise<void> {
+    const payload = { bundle };
+
+    const headers = getAuthHeaders(token, true);
+    const res = await fetch(`${API_BASE_URL}/crypto/signal/prekey-bundle`, {
+        method: "POST",
+        headers,
+        body: JSON.stringify(payload)
+    });
+    if (!res.ok) throw new Error("Failed to upload prekey bundle");
+}
+
+/**
+ * Fetches Signal Protocol prekey bundle for another user
+ */
+export async function fetchPreKeyBundle(userId: number, token: string): Promise<any | null> {
+    const headers = getAuthHeaders(token, true);
+    const res = await fetch(`${API_BASE_URL}/crypto/signal/prekey-bundle/of/${userId}`, {
+        method: "GET",
+        headers
+    });
+    if (!res.ok) return null;
+    const data = await res.json();
+    return data.bundle || null;
+}
+

frontend/src/core/api/dm.ts

@@ -1,178 +1,16 @@
-import { API_BASE_URL } from "@/core/config";
-import { getAuthHeaders } from "./account";
-import { ecdhSharedSecret, deriveWrappingKey } from "@/utils/crypto/asymmetric";
-import { importAesGcmKey, aesGcmEncrypt, aesGcmDecrypt } from "@/utils/crypto/symmetric";
-import { randomBytes } from "@/utils/crypto/kdf";
-import { getCurrentKeys } from "./account";
-import { request } from "@/core/websocket";
-import type { SendDMRequest, DmEnvelope, DMEditRequest, DmEncryptedJSON, BaseDmEnvelope, User } from "@/core/types";
-import { b64, ub64 } from "@/utils/utils";
-import { fetchUserPublicKey } from "./crypto";
-import { fetchUsers, searchUsers } from "./users";
+// Re-export from dmApi.ts which has Signal Protocol support
+export {
+    decryptDm,
+    fetchDMHistory,
+    sendDMViaWebSocket,
+    sendDmWithFiles,
+    editDmEnvelope,
+    deleteDmEnvelope,
+    fetchDMConversations,
+    fetchUsers,
+    searchUsers,
+    fetchUserPublicKey
+} from "./dmApi";
 
-export async function decryptDm(envelope: DmEnvelope, senderPublicKeyB64: string): Promise<string> {
-    const keys = getCurrentKeys();
-    if (!keys) throw new Error("Keys not initialized");
-
-    // Obtain the key
-    const shared = ecdhSharedSecret(keys.privateKey, ub64(senderPublicKeyB64));
-    const wkRaw = await deriveWrappingKey(shared, ub64(envelope.salt), new Uint8Array([1]));
-    const wk = await importAesGcmKey(wkRaw);
-    const mk = await aesGcmDecrypt(wk, ub64(envelope.iv2), ub64(envelope.wrappedMk));
-
-    // Decrypt
-    const msg = await aesGcmDecrypt(await importAesGcmKey(mk), ub64(envelope.iv), ub64(envelope.ciphertext));
-    return new TextDecoder().decode(msg);
-}
-
-export async function fetchDMHistory(userId: number, token: string, limit: number = 50): Promise<DmEnvelope[]> {
-    const response = await fetch(`${API_BASE_URL}/dm/history/${userId}?limit=${limit}`, {
-        headers: getAuthHeaders(token, true)
-    });
-    if (!response.ok) return [];
-    const data = await response.json();
-    return data.messages || [];
-}
-
-// Re-export user functions for convenience
-export { fetchUsers, searchUsers, fetchUserPublicKey };
-
-export async function sendDMViaWebSocket(recipientId: number, recipientPublicKeyB64: string, plaintext: string, authToken: string, replyToId?: number): Promise<void> {
-    const keys = getCurrentKeys();
-    if (!keys) throw new Error("Keys not initialized");
-
-    // Encryption key
-    const mk = randomBytes(32);
-    const wkSalt = randomBytes(16);
-    const shared = ecdhSharedSecret(keys.privateKey, ub64(recipientPublicKeyB64));
-    const wkRaw = await deriveWrappingKey(shared, wkSalt, new Uint8Array([1]));
-    const wk = await importAesGcmKey(wkRaw);
-
-    // Encrypt the message
-    const encMsg = await aesGcmEncrypt(await importAesGcmKey(mk), new TextEncoder().encode(plaintext));
-    const wrap = await aesGcmEncrypt(wk, mk);
-
-    const payload: SendDMRequest = {
-        recipientId: recipientId,
-        iv: b64(encMsg.iv),
-        ciphertext: b64(encMsg.ciphertext),
-        salt: b64(wkSalt),
-        iv2: b64(wrap.iv),
-        wrappedMk: b64(wrap.ciphertext)
-    };
-    if (replyToId) payload.replyToId = replyToId;
-
-    await request({
-        type: "dmSend",
-        credentials: {
-            scheme: "Bearer",
-            credentials: authToken
-        },
-        data: payload
-    });
-}
-
-export async function sendDmWithFiles(recipientId: number, recipientPublicKeyB64: string, plaintextJson: string, files: File[], token: string): Promise<void> {
-    const keys = getCurrentKeys();
-    if (!keys) throw new Error("Keys not initialized");
-
-    const mk = randomBytes(32);
-    const wkSalt = randomBytes(16);
-    const shared = await ecdhSharedSecret(keys.privateKey, ub64(recipientPublicKeyB64));
-    const wkRaw = await deriveWrappingKey(shared, wkSalt, new Uint8Array([1]));
-    const wk = await importAesGcmKey(wkRaw);
-
-    const wrap = await aesGcmEncrypt(wk, mk);
-
-    const form = new FormData();
-    const names: string[] = [];
-    function sliceBuffer(u8: Uint8Array): ArrayBuffer {
-        return (u8.buffer as ArrayBuffer).slice(u8.byteOffset, u8.byteOffset + u8.byteLength);
-    }
-
-    for (const f of files) {
-        // Encrypt file with same mk
-        const data = new Uint8Array(await f.arrayBuffer());
-        const enc = await aesGcmEncrypt(await importAesGcmKey(mk), data);
-        const blob = new Blob([sliceBuffer(enc.iv), sliceBuffer(enc.ciphertext)], { type: "application/octet-stream" });
-        const serverName = f.name; // server uses provided name
-        names.push(serverName);
-        form.append("files", new File([blob], serverName));
-    }
-    form.append("fileNames", JSON.stringify(names));
-
-    // Merge files metadata into plaintext JSON and encrypt
-    let obj: DmEncryptedJSON;
-    try {
-        obj = JSON.parse(plaintextJson);
-    } catch {
-        obj = { type: "text", data: { content: String(plaintextJson) } };
-    }
-
-    const encMsg = await aesGcmEncrypt(await importAesGcmKey(mk), new TextEncoder().encode(JSON.stringify(obj)));
-    form.append("dm_payload", JSON.stringify({
-        recipientId: recipientId,
-        iv: b64(encMsg.iv),
-        ciphertext: b64(encMsg.ciphertext),
-        salt: b64(wkSalt),
-        iv2: b64(wrap.iv),
-        wrappedMk: b64(wrap.ciphertext)
-    } satisfies BaseDmEnvelope));
-
-    await fetch(`${API_BASE_URL}/dm/send`, {
-        method: "POST",
-        headers: getAuthHeaders(token, false),
-        body: form
-    });
-}
-
-export async function editDmEnvelope(id: number, recipientPublicKeyB64: string, newPlaintextJson: string, authToken: string): Promise<void> {
-    const keys = getCurrentKeys();
-    if (!keys) throw new Error("Keys not initialized");
-
-    // We cannot reuse the old mk safely without knowing it; generate a fresh mk and wrap
-    const mk = randomBytes(32);
-    const wkSalt = randomBytes(16);
-    const shared = await ecdhSharedSecret(keys.privateKey, ub64(recipientPublicKeyB64));
-    const wkRaw = await deriveWrappingKey(shared, wkSalt, new Uint8Array([1]));
-    const wk = await importAesGcmKey(wkRaw);
-    const encMsg = await aesGcmEncrypt(await importAesGcmKey(mk), new TextEncoder().encode(newPlaintextJson));
-    const wrap = await aesGcmEncrypt(wk, mk);
-
-    await request({
-        type: "dmEdit",
-        credentials: { scheme: "Bearer", credentials: authToken },
-        data: {
-            id,
-            iv: b64(encMsg.iv),
-            ciphertext: b64(encMsg.ciphertext),
-            iv2: b64(wrap.iv),
-            wrappedMk: b64(wrap.ciphertext),
-            salt: b64(wkSalt)
-        }
-    } as DMEditRequest);
-}
-
-export async function deleteDmEnvelope(id: number, recipientId: number, authToken: string): Promise<void> {
-    await request({
-        type: "dmDelete",
-        credentials: { scheme: "Bearer", credentials: authToken },
-        data: { id, recipientId }
-    });
-}
-
-export interface DMConversationResponse {
-    user: User;
-    lastMessage: DmEnvelope;
-    unreadCount: number;
-}
-
-export async function fetchDMConversations(token: string): Promise<DMConversationResponse[]> {
-    const res = await fetch(`${API_BASE_URL}/dm/conversations`, {
-        headers: getAuthHeaders(token, true)
-    });
-    if (!res.ok) return [];
-    const data = await res.json();
-    return data.conversations || [];
-}
+export type { DMConversationResponse } from "./dmApi";
 

frontend/src/core/api/dmApi.ts

@@ -1,28 +1,33 @@
 import { API_BASE_URL } from "@/core/config";
 import { getAuthHeaders } from "./account";
-import { ecdhSharedSecret, deriveWrappingKey } from "@/utils/crypto/asymmetric";
-import { importAesGcmKey, aesGcmEncrypt, aesGcmDecrypt } from "@/utils/crypto/symmetric";
+import { importAesGcmKey, aesGcmEncrypt } from "@/utils/crypto/symmetric";
 import { randomBytes } from "@/utils/crypto/kdf";
 import { getCurrentKeys } from "./account";
 import { request } from "@/core/websocket";
 import type { SendDMRequest, DmEnvelope, DMEditRequest, DmEncryptedJSON, BaseDmEnvelope, User } from "@/core/types";
 import { b64, ub64 } from "@/utils/utils";
-import { fetchUserPublicKey } from "./crypto";
+import { fetchUserPublicKey, fetchPreKeyBundle } from "./crypto";
 import { fetchUsers, searchUsers } from "./users";
+import { SignalProtocolService } from "@/utils/crypto/signalProtocol";
+import { useUserStore } from "@/state/user";
+import { ecdhSharedSecret, deriveWrappingKey } from "@/utils/crypto/asymmetric";
 
-export async function decryptDm(envelope: DmEnvelope, senderPublicKeyB64: string): Promise<string> {
-    const keys = getCurrentKeys();
-    if (!keys) throw new Error("Keys not initialized");
+export async function decryptDm(envelope: DmEnvelope, senderId: number): Promise<string> {
+    const user = useUserStore.getState().user.currentUser;
+    if (!user?.id) {
+        throw new Error("User not authenticated");
+    }
 
-    // Obtain the key
-    const shared = ecdhSharedSecret(keys.privateKey, ub64(senderPublicKeyB64));
-    const wkRaw = await deriveWrappingKey(shared, ub64(envelope.salt), new Uint8Array([1]));
-    const wk = await importAesGcmKey(wkRaw);
-    const mk = await aesGcmDecrypt(wk, ub64(envelope.iv2), ub64(envelope.wrappedMk));
-
-    // Decrypt
-    const msg = await aesGcmDecrypt(await importAesGcmKey(mk), ub64(envelope.iv), ub64(envelope.ciphertext));
-    return new TextDecoder().decode(msg);
+    const signalService = new SignalProtocolService(user.id.toString());
+    
+    // Parse Signal Protocol message
+    const signalCiphertext = JSON.parse(envelope.ciphertext);
+    if (!signalCiphertext.type || !signalCiphertext.body) {
+        throw new Error("Invalid Signal Protocol message format");
+    }
+    
+    const plaintext = await signalService.decryptMessage(senderId, signalCiphertext);
+    return plaintext;
 }
 
 export async function fetchDMHistory(userId: number, token: string, limit: number = 50): Promise<DmEnvelope[]> {
@@ -34,31 +39,36 @@ export async function fetchDMHistory(userId: number, token: string, limit: numbe
     return data.messages || [];
 }
 
-// Re-export user functions for convenience
-export { fetchUsers, searchUsers, fetchUserPublicKey };
 
-export async function sendDMViaWebSocket(recipientId: number, recipientPublicKeyB64: string, plaintext: string, authToken: string, replyToId?: number): Promise<void> {
-    const keys = getCurrentKeys();
-    if (!keys) throw new Error("Keys not initialized");
-
-    // Encryption key
-    const mk = randomBytes(32);
-    const wkSalt = randomBytes(16);
-    const shared = ecdhSharedSecret(keys.privateKey, ub64(recipientPublicKeyB64));
-    const wkRaw = await deriveWrappingKey(shared, wkSalt, new Uint8Array([1]));
-    const wk = await importAesGcmKey(wkRaw);
-
-    // Encrypt the message
-    const encMsg = await aesGcmEncrypt(await importAesGcmKey(mk), new TextEncoder().encode(plaintext));
-    const wrap = await aesGcmEncrypt(wk, mk);
+export async function sendDMViaWebSocket(recipientId: number, plaintext: string, authToken: string, replyToId?: number): Promise<void> {
+    const user = useUserStore.getState().user.currentUser;
+    if (!user?.id) {
+        throw new Error("User not authenticated");
+    }
 
+    const signalService = new SignalProtocolService(user.id.toString());
+    
+    // Check if we have a session, if not, fetch prekey bundle and establish one
+    const hasSession = await signalService.hasSession(recipientId);
+    if (!hasSession) {
+        // Fetch prekey bundle from server
+        const bundle = await fetchPreKeyBundle(recipientId, authToken);
+        if (!bundle) {
+            throw new Error("No Signal Protocol prekey bundle available for recipient");
+        }
+        await signalService.processPreKeyBundle(recipientId, bundle);
+    }
+    
+    // Encrypt with Signal Protocol
+    const ciphertext = await signalService.encryptMessage(recipientId, plaintext);
+    
     const payload: SendDMRequest = {
         recipientId: recipientId,
-        iv: b64(encMsg.iv),
-        ciphertext: b64(encMsg.ciphertext),
-        salt: b64(wkSalt),
-        iv2: b64(wrap.iv),
-        wrappedMk: b64(wrap.ciphertext)
+        iv: "", // Not used for Signal Protocol
+        ciphertext: JSON.stringify(ciphertext), // Store Signal Protocol message as JSON
+        salt: "", // Not used for Signal Protocol
+        iv2: "", // Not used for Signal Protocol
+        wrappedMk: "" // Not used for Signal Protocol
     };
     if (replyToId) payload.replyToId = replyToId;
 
@@ -78,7 +88,7 @@ export async function sendDmWithFiles(recipientId: number, recipientPublicKeyB64
 
     const mk = randomBytes(32);
     const wkSalt = randomBytes(16);
-    const shared = await ecdhSharedSecret(keys.privateKey, ub64(recipientPublicKeyB64));
+    const shared = ecdhSharedSecret(keys.privateKey, ub64(recipientPublicKeyB64));
     const wkRaw = await deriveWrappingKey(shared, wkSalt, new Uint8Array([1]));
     const wk = await importAesGcmKey(wkRaw);
 
@@ -133,7 +143,7 @@ export async function editDmEnvelope(id: number, recipientPublicKeyB64: string,
     // We cannot reuse the old mk safely without knowing it; generate a fresh mk and wrap
     const mk = randomBytes(32);
     const wkSalt = randomBytes(16);
-    const shared = await ecdhSharedSecret(keys.privateKey, ub64(recipientPublicKeyB64));
+    const shared = ecdhSharedSecret(keys.privateKey, ub64(recipientPublicKeyB64));
     const wkRaw = await deriveWrappingKey(shared, wkSalt, new Uint8Array([1]));
     const wk = await importAesGcmKey(wkRaw);
     const encMsg = await aesGcmEncrypt(await importAesGcmKey(mk), new TextEncoder().encode(newPlaintextJson));
@@ -167,6 +177,9 @@ export interface DMConversationResponse {
     unreadCount: number;
 }
 
+// Re-export for convenience
+export { fetchUsers, searchUsers, fetchUserPublicKey };
+
 export async function fetchDMConversations(token: string): Promise<DMConversationResponse[]> {
     const res = await fetch(`${API_BASE_URL}/dm/conversations`, {
         headers: getAuthHeaders(token, true)

frontend/src/core/calls/encryption.ts

@@ -1,29 +1,15 @@
-import { importAesGcmKey, aesGcmEncrypt, aesGcmDecrypt } from "@/utils/crypto/symmetric";
 import { randomBytes } from "@/utils/crypto/kdf";
 import { b64, ub64 } from "@/utils/utils";
-import { ecdhSharedSecret, deriveWrappingKey } from "@/utils/crypto/asymmetric";
-import api from "@/core/api";
-import type { WrappedSessionKeyPayload } from "@/core/types";
+import { SignalProtocolService } from "@/utils/crypto/signalProtocol";
+import { useUserStore } from "@/state/user";
+import { fetchPreKeyBundle } from "@/core/api/crypto";
+import { getAuthToken } from "@/core/api/account";
 
 export interface CallSessionKey {
     key: Uint8Array;
     hash: string; // For emoji display
 }
 
-export interface CallKeyExchange {
-    type: "call_key_exchange";
-    sessionKeyHash: string;
-    encryptedSessionKey: EncryptedCallMessage;
-}
-
-export interface EncryptedCallMessage {
-    iv: string;
-    ciphertext: string;
-    salt: string;
-    iv2: string;
-    wrappedSessionKey: string;
-}
-
 /**
  * Generates a new call session key for end-to-end encryption
  * @returns Promise that resolves to a session key with its hash for display
@@ -60,97 +46,6 @@ export async function rotateCallSessionKey(): Promise<CallSessionKey> {
     };
 }
 
-/**
- * Create session key from hash (for backward compatibility)
- * @deprecated Use deriveCallSessionKeyFromSharedSecret instead
- */
-export async function createCallSessionKeyFromHash(hash: string): Promise<CallSessionKey> {
-    // For backward compatibility, generate a deterministic key from the hash
-    const hashBytes = ub64(hash);
-    const sessionKey = new Uint8Array(32);
-
-    // Repeat the hash bytes to fill 32 bytes
-    for (let i = 0; i < 32; i++) {
-        sessionKey[i] = hashBytes[i % hashBytes.length];
-    }
-
-    return {
-        key: sessionKey,
-        hash
-    };
-}
-
-/**
- * Derive session key from ECDH shared secret and session key hash
- * This creates a deterministic but cryptographically secure key
- */
-export async function deriveCallSessionKeyFromSharedSecret(
-    sharedSecret: Uint8Array,
-    sessionKeyHash: string,
-    isInitiator: boolean
-): Promise<CallSessionKey> {
-    // Use HKDF to derive the session key from the shared secret
-    // Include the session key hash and role to ensure uniqueness
-    const info = new TextEncoder().encode(`call-session-${sessionKeyHash}-${isInitiator ? 'initiator' : 'receiver'}`);
-    const salt = new Uint8Array(32); // Zero salt for deterministic derivation
-
-    // Import the shared secret as a raw key for HKDF
-    const sharedKey = await crypto.subtle.importKey(
-        'raw',
-        sharedSecret.buffer as ArrayBuffer,
-        { name: 'HKDF' },
-        false,
-        ['deriveKey']
-    );
-
-    // Derive the session key using HKDF
-    const sessionKey = await crypto.subtle.deriveKey(
-        {
-            name: 'HKDF',
-            hash: 'SHA-256',
-            salt: salt,
-            info: info
-        },
-        sharedKey,
-        { name: 'AES-GCM', length: 256 },
-        true, // Make the key extractable so we can export it
-        ['encrypt', 'decrypt']
-    );
-
-    // Export the raw key material
-    const sessionKeyMaterial = await crypto.subtle.exportKey('raw', sessionKey);
-
-    return {
-        key: new Uint8Array(sessionKeyMaterial),
-        hash: sessionKeyHash
-    };
-}
-
-/**
- * Encrypt a call signaling message with the session key
- */
-export async function encryptCallMessage(message: Record<string, unknown>, sessionKey: Uint8Array): Promise<EncryptedCallMessage> {
-    const messageKey = await importAesGcmKey(sessionKey);
-    const encrypted = await aesGcmEncrypt(messageKey, new TextEncoder().encode(JSON.stringify(message)));
-
-    return {
-        iv: b64(encrypted.iv),
-        ciphertext: b64(encrypted.ciphertext),
-        salt: "", // Not used for message encryption, only for key wrapping
-        iv2: "",
-        wrappedSessionKey: ""
-    };
-}
-
-/**
- * Decrypt a call signaling message
- */
-export async function decryptCallMessage(encryptedMessage: EncryptedCallMessage, sessionKey: Uint8Array): Promise<Record<string, unknown>> {
-    const messageKey = await importAesGcmKey(sessionKey);
-    const decrypted = await aesGcmDecrypt(messageKey, ub64(encryptedMessage.iv), ub64(encryptedMessage.ciphertext));
-    return JSON.parse(new TextDecoder().decode(decrypted));
-}
-
 /**
  * Generate 4 emojis representing the call session key
  */
@@ -176,63 +71,65 @@ export function generateCallEmojis(sessionKeyHash: string): string[] {
     return emojis;
 }
 
-// HKDF info for CALL key wrapping (distinct from DM's info)
-const CALL_INFO = new Uint8Array([2]);
-
 /**
- * Wraps a call session key for a specific recipient using ECDH key exchange
- * @param recipientPublicKeyB64 - The recipient's public key in base64 format
- * @param sessionKey - The session key to wrap
- * @returns Promise that resolves to the wrapped session key payload
+ * Encrypts a call session key using Signal Protocol
+ * @param recipientId - The recipient's user ID
+ * @param sessionKey - The session key to encrypt
+ * @returns Promise that resolves to encrypted session key data
  */
-export async function wrapCallSessionKeyForRecipient(recipientPublicKeyB64: string, sessionKey: Uint8Array): Promise<WrappedSessionKeyPayload> {
-    const keys = api.user.auth.getCurrentKeys();
-    if (!keys) throw new Error("Keys not initialized");
+export async function encryptCallSessionKey(recipientId: number, sessionKey: Uint8Array): Promise<{ type: number; body: string }> {
+    const user = useUserStore.getState().user.currentUser;
+    if (!user?.id) {
+        throw new Error("User not authenticated");
+    }
 
-    const salt = randomBytes(16);
-    const shared = ecdhSharedSecret(keys.privateKey, ub64(recipientPublicKeyB64));
-    const wkRaw = await deriveWrappingKey(shared, salt, CALL_INFO);
-    const wk = await importAesGcmKey(wkRaw);
-    const wrap = await aesGcmEncrypt(wk, sessionKey);
-    return {
-        salt: b64(salt),
-        iv2: b64(wrap.iv),
-        wrapped: b64(wrap.ciphertext)
-    };
+    const signalService = new SignalProtocolService(user.id.toString());
+    
+    // Ensure we have a session with the recipient
+    const hasSession = await signalService.hasSession(recipientId);
+    if (!hasSession) {
+        // Fetch prekey bundle and establish session
+        const token = getAuthToken();
+        if (!token) {
+            throw new Error("No auth token");
+        }
+        
+        const bundle = await fetchPreKeyBundle(recipientId, token);
+        if (!bundle) {
+            throw new Error("No prekey bundle available for recipient");
+        }
+        
+        await signalService.processPreKeyBundle(recipientId, bundle);
+    }
+    
+    // Encrypt the session key using Signal Protocol
+    const sessionKeyString = b64(sessionKey);
+    const encrypted = await signalService.encryptMessage(recipientId, sessionKeyString);
+    
+    return encrypted;
 }
 
 /**
- * Create a shared secret and derive session key for the receiver
+ * Decrypts a call session key using Signal Protocol
+ * @param senderId - The sender's user ID
+ * @param encryptedKey - The encrypted session key data
+ * @returns Promise that resolves to the decrypted session key
  */
-export async function createSharedSecretAndDeriveSessionKey(
-    senderPublicKeyB64: string,
-    sessionKeyHash: string,
-    isInitiator: boolean
-): Promise<CallSessionKey> {
-    const keys = api.user.auth.getCurrentKeys();
-    if (!keys) throw new Error("Keys not initialized");
+export async function decryptCallSessionKey(senderId: number, encryptedKey: { type: number; body: string }): Promise<Uint8Array> {
+    const user = useUserStore.getState().user.currentUser;
+    if (!user?.id) {
+        throw new Error("User not authenticated");
+    }
 
-    // Create shared secret using ECDH
-    const sharedSecret = ecdhSharedSecret(keys.privateKey, ub64(senderPublicKeyB64));
-
-    // Derive the session key from the shared secret
-    return await deriveCallSessionKeyFromSharedSecret(sharedSecret, sessionKeyHash, isInitiator);
-}
-
-/**
- * Unwraps a call session key received from a sender using ECDH key exchange
- * @param senderPublicKeyB64 - The sender's public key in base64 format
- * @param payload - The wrapped session key payload
- * @returns Promise that resolves to the unwrapped session key
- */
-export async function unwrapCallSessionKeyFromSender(senderPublicKeyB64: string, payload: WrappedSessionKeyPayload): Promise<Uint8Array> {
-    const keys = api.user.auth.getCurrentKeys();
-    if (!keys) throw new Error("Keys not initialized");
-
-    const salt = ub64(payload.salt);
-    const shared = ecdhSharedSecret(keys.privateKey, ub64(senderPublicKeyB64));
-    const wkRaw = await deriveWrappingKey(shared, salt, CALL_INFO);
-    const wk = await importAesGcmKey(wkRaw);
-    const sessionKey = await aesGcmDecrypt(wk, ub64(payload.iv2), ub64(payload.wrapped));
-    return new Uint8Array(sessionKey);
+    const signalService = new SignalProtocolService(user.id.toString());
+    
+    // Decrypt using Signal Protocol
+    const decryptedString = await signalService.decryptMessage(senderId, encryptedKey);
+    
+    // Convert back to Uint8Array
+    const sessionKey = new Uint8Array(
+        atob(decryptedString).split("").map(c => c.charCodeAt(0))
+    );
+    
+    return sessionKey;
 }

frontend/src/core/calls/signaling.ts

@@ -1,4 +1,4 @@
-import type { CallSignalingMessage, CallAcceptData, CallRejectData, CallOfferData, CallAnswerData, CallIceCandidateData, CallEndData, CallVideoToggleData, CallScreenShareToggleData, CallInviteMessageData } from "@/core/types";
+import type { CallSignalingMessage, CallAcceptData, CallRejectData, CallOfferData, CallAnswerData, CallIceCandidateData, CallEndData, CallVideoToggleData, CallScreenShareToggleData, CallInviteMessageData, CallSessionKeyData } from "@/core/types";
 import * as WebRTC from "./webrtc";
 
 export interface CallState {
@@ -133,12 +133,16 @@ export class CallSignalingHandler {
 
     private handleCallSessionKey(message: CallSignalingMessage) {
         const state = this.getState();
-        const { sessionKeyHash, data } = message;
+        const { sessionKeyHash } = message;
+        const data = message.data as CallSessionKeyData;
+
         if (sessionKeyHash) {
             state.setCallSessionKeyHash(sessionKeyHash);
         }
-        if (data && 'wrappedSessionKey' in data && data.wrappedSessionKey && message.fromUserId) {
-            WebRTC.receiveWrappedSessionKey(message.fromUserId, data.wrappedSessionKey, sessionKeyHash);
+        
+        // Check if data is CallSessionKeyData and has encryptedSessionKey
+        if (data && data.encryptedSessionKey && message.fromUserId) {
+            WebRTC.receiveWrappedSessionKey(message.fromUserId, data.encryptedSessionKey);
         }
     }
 

frontend/src/core/calls/webrtc.ts

@@ -1,7 +1,7 @@
 import api from "@/core/api";
-import type { CallSignalingMessage, WrappedSessionKeyPayload } from "@/core/types";
+import type { CallSignalingMessage } from "@/core/types";
 import { request } from "@/core/websocket";
-import { wrapCallSessionKeyForRecipient, unwrapCallSessionKeyFromSender, rotateCallSessionKey } from "./encryption";
+import { encryptCallSessionKey, decryptCallSessionKey, rotateCallSessionKey } from "./encryption";
 import { importAesGcmKey } from "@/utils/crypto/symmetric";
 import E2EEWorker from "./e2eeWorker?worker";
 import { delay } from "@/utils/utils";
@@ -855,21 +855,18 @@ export async function sendCallSessionKey(userId: number, sessionKeyHash: string)
 
 export async function sendWrappedCallSessionKey(userId: number, sessionKey: Uint8Array, sessionKeyHash: string): Promise<void> {
     try {
-        const recipientPublicKey = await api.chats.dm.fetchUserPublicKey(userId, api.user.auth.getAuthToken()!);
-        if (!recipientPublicKey) {
-            console.warn("No recipient public key for", userId);
-            return;
-        }
-        const wrapped = await wrapCallSessionKeyForRecipient(recipientPublicKey, sessionKey);
+        // Encrypt session key using Signal Protocol
+        const encrypted = await encryptCallSessionKey(userId, sessionKey);
+        
         await sendSignalingMessage({
             type: "call_session_key",
             fromUserId: 0,
             toUserId: userId,
             sessionKeyHash,
-            data: { wrappedSessionKey: wrapped }
+            data: { encryptedSessionKey: encrypted }
         });
     } catch (e) {
-        console.error("Failed to send wrapped session key:", e);
+        console.error("Failed to send encrypted session key:", e);
     }
 }
 
@@ -886,31 +883,21 @@ export async function setSessionKey(userId: number, keyBytes: Uint8Array): Promi
 
 export async function receiveWrappedSessionKey(
     fromUserId: number,
-    wrappedPayload: WrappedSessionKeyPayload,
-    sessionKeyHash?: string
+    encryptedKey: { type: number; body: string }
 ): Promise<void> {
     try {
-        const senderPublicKey = await api.chats.dm.fetchUserPublicKey(fromUserId, api.user.auth.getAuthToken()!);
-        if (!senderPublicKey) {
-            console.error("Failed to get sender public key");
-            return;
-        }
-        if (!wrappedPayload || !sessionKeyHash) {
-            console.error("Missing wrapped payload or session key hash");
+        if (!encryptedKey) {
+            console.error("Missing encrypted session key");
             return;
         }
 
-        // Unwrap the session key from the encrypted payload
-        const unwrappedSessionKey = await unwrapCallSessionKeyFromSender(senderPublicKey, {
-            salt: wrappedPayload.salt,
-            iv2: wrappedPayload.iv2,
-            wrapped: wrappedPayload.wrapped
-        });
+        // Decrypt the session key using Signal Protocol
+        const sessionKey = await decryptCallSessionKey(fromUserId, encryptedKey);
 
-        // Use the unwrapped session key directly (both sides should have the same key)
-        await setSessionKey(fromUserId, unwrappedSessionKey);
+        // Use the decrypted session key for media encryption
+        await setSessionKey(fromUserId, sessionKey);
     } catch (e) {
-        console.error("Failed to unwrap session key:", e);
+        console.error("Failed to decrypt session key:", e);
     }
 }
 

frontend/src/core/types.d.ts

@@ -505,7 +505,7 @@ export interface CallEndData {
 }
 
 export interface CallSessionKeyData {
-    wrappedSessionKey?: WrappedSessionKeyPayload;
+    encryptedSessionKey: { type: number; body: string };
 }
 
 export interface CallVideoToggleData {
@@ -526,12 +526,6 @@ export interface CallScreenShareToggleMessageData {
     data: CallScreenShareToggleData;
 }
 
-export interface WrappedSessionKeyPayload {
-    salt: string;
-    iv2: string;
-    wrapped: string;
-}
-
 export interface CallVideoToggleMessage extends CallSignalingMessage {
     type: "call_video_toggle";
     data: CallVideoToggleData;