Initial commit: Bluetooth mesh chat app with end-to-end encryption

2026-07-27 01:05:20 +00:00 · 2025-07-02 19:18:35 +02:00
commit 7e90bf6369
41 changed files with 2000 additions and 0 deletions
@@ -0,0 +1,67 @@
+import Foundation
+import CryptoKit
+
+class EncryptionService {
+    private var privateKey: Curve25519.KeyAgreement.PrivateKey
+    public let publicKey: Curve25519.KeyAgreement.PublicKey
+    private var peerPublicKeys: [String: Curve25519.KeyAgreement.PublicKey] = [:]
+    private var sharedSecrets: [String: SymmetricKey] = [:]
+    
+    init() {
+        self.privateKey = Curve25519.KeyAgreement.PrivateKey()
+        self.publicKey = privateKey.publicKey
+    }
+    
+    func addPeerPublicKey(_ peerID: String, publicKeyData: Data) throws {
+        let publicKey = try Curve25519.KeyAgreement.PublicKey(rawRepresentation: publicKeyData)
+        peerPublicKeys[peerID] = publicKey
+        
+        let sharedSecret = try privateKey.sharedSecretFromKeyAgreement(with: publicKey)
+        let symmetricKey = sharedSecret.hkdfDerivedSymmetricKey(
+            using: SHA256.self,
+            salt: "bitchat-v1".data(using: .utf8)!,
+            sharedInfo: Data(),
+            outputByteCount: 32
+        )
+        sharedSecrets[peerID] = symmetricKey
+    }
+    
+    func encrypt(_ data: Data, for peerID: String) throws -> Data {
+        guard let symmetricKey = sharedSecrets[peerID] else {
+            throw EncryptionError.noSharedSecret
+        }
+        
+        let sealedBox = try AES.GCM.seal(data, using: symmetricKey)
+        return sealedBox.combined ?? Data()
+    }
+    
+    func decrypt(_ data: Data, from peerID: String) throws -> Data {
+        guard let symmetricKey = sharedSecrets[peerID] else {
+            throw EncryptionError.noSharedSecret
+        }
+        
+        let sealedBox = try AES.GCM.SealedBox(combined: data)
+        return try AES.GCM.open(sealedBox, using: symmetricKey)
+    }
+    
+    func sign(_ data: Data) throws -> Data {
+        let signingKey = try Curve25519.Signing.PrivateKey(rawRepresentation: privateKey.rawRepresentation)
+        return try signingKey.signature(for: data)
+    }
+    
+    func verify(_ signature: Data, for data: Data, from peerID: String) throws -> Bool {
+        guard let peerPublicKey = peerPublicKeys[peerID] else {
+            return false
+        }
+        
+        let verifyingKey = try Curve25519.Signing.PublicKey(rawRepresentation: peerPublicKey.rawRepresentation)
+        return verifyingKey.isValidSignature(signature, for: data)
+    }
+}
+
+enum EncryptionError: Error {
+    case noSharedSecret
+    case invalidPublicKey
+    case encryptionFailed
+    case decryptionFailed
+}