fix: ensure session persistence on IOS (#1457)

* feat: update logo (#1454)

* fix: update keychain implementation to declear variables earlier during run

* feat: use struct for keychain utilities as opposed to class

---------

Co-authored-by: Rob <30500864+RobChangCA@users.noreply.github.com>

Author: iykazrji

account-kit/rn-signer/ios/implementation/KeychainHelper.swift

@@ -0,0 +1,58 @@
+import Foundation
+import Security
+import CryptoKit
+
+let ACCOUNT_KIT_EPHEMERAL_PRIVATE_KEY = "accountKitEphemeralPrivateKey"
+
+let save_ephemeral_private_key_query: [String: Any] = [
+    kSecClass as String: kSecClassGenericPassword,
+    kSecAttrAccount as String: ACCOUNT_KIT_EPHEMERAL_PRIVATE_KEY,
+    kSecAttrAccessible as String: kSecAttrAccessibleAfterFirstUnlock
+]
+ 
+let get_ephemeral_private_key_query: [String: Any] = [
+    kSecClass as String: kSecClassGenericPassword,
+    kSecAttrAccount as String: ACCOUNT_KIT_EPHEMERAL_PRIVATE_KEY,
+    kSecReturnData as String: true,
+    kSecMatchLimit as String: kSecMatchLimitOne
+]
+
+let delete_ephemeral_private_key_query: [String: Any] = [
+    kSecClass as String: kSecClassGenericPassword,
+    kSecAttrAccount as String: ACCOUNT_KIT_EPHEMERAL_PRIVATE_KEY
+]
+
+
+struct PrivateKeyChainUtilities {
+    @available(*, unavailable) private init() {}
+
+    static func savePrivateKeyToKeychain(_ privateKey: P256.KeyAgreement.PrivateKey) {
+        let keyData = privateKey.rawRepresentation
+        
+        var _saveEphemeralPrivateKeyQuery = save_ephemeral_private_key_query
+        _saveEphemeralPrivateKeyQuery.updateValue(keyData, forKey: kSecValueData as String)
+        
+        SecItemDelete(_saveEphemeralPrivateKeyQuery as CFDictionary)
+        SecItemAdd(_saveEphemeralPrivateKeyQuery as CFDictionary, nil)
+    }
+
+    static func getPrivateKeyFromKeychain() -> P256.KeyAgreement.PrivateKey? {
+        var result: AnyObject?
+        let status = SecItemCopyMatching(get_ephemeral_private_key_query as CFDictionary, &result)
+
+        if status == errSecSuccess, let keyData = result as? Data {
+            do {
+                return try P256.KeyAgreement.PrivateKey(rawRepresentation: keyData)
+            } catch {
+                print("❌ Failed to decode private key: \(error)")
+                return nil
+            }
+        }
+
+        return nil
+    }
+
+    static func deletePrivateKeyFromKeychain() {
+        SecItemDelete(delete_ephemeral_private_key_query as CFDictionary)
+    }
+}

account-kit/rn-signer/ios/implementation/NativeTEKStamperImpl.swift

@@ -1,3 +1,4 @@
+
 import CryptoKit
 import Foundation
 
@@ -11,22 +12,28 @@ enum StamperError: Error {
 @objc public class NativeTEKStamperImpl: NSObject {
     // TODO: we probably want to keep this longer term somewhere, because the RN session manager will
     // hold on to the bundle and try to recreate a session if a user is still logged in
-    var ephemeralPrivateKey: P256.KeyAgreement.PrivateKey? = nil;
+    var ephemeralPrivateKey: P256.KeyAgreement.PrivateKey? = nil
 
     // These can be ephemeral and held in memory because the session manager will handle re-authenticating
     var apiPublicKey: P256.Signing.PublicKey? = nil;
     var apiPrivateKey: P256.Signing.PrivateKey? = nil;
 
     @objc public func create() async throws -> NSString {
-        if (ephemeralPrivateKey == nil) {
-            ephemeralPrivateKey = P256.KeyAgreement.PrivateKey()
-        }
-        let targetPublicKey = try ephemeralPrivateKey!.publicKey.toString(representation: .x963)
+        var _ephemeralPrivateKey: P256.KeyAgreement.PrivateKey? = PrivateKeyChainUtilities.getPrivateKeyFromKeychain()
 
+        if (_ephemeralPrivateKey == nil) {
+            _ephemeralPrivateKey = P256.KeyAgreement.PrivateKey()
+            PrivateKeyChainUtilities.savePrivateKeyToKeychain(_ephemeralPrivateKey!)
+        }
+
+        let targetPublicKey = try _ephemeralPrivateKey!.publicKey.toString(representation: .x963)
+        ephemeralPrivateKey = _ephemeralPrivateKey
+
         return NSString(string: targetPublicKey)
     }
 
     @objc public func clear() {
+        PrivateKeyChainUtilities.deletePrivateKeyFromKeychain()
         ephemeralPrivateKey = nil
         apiPublicKey = nil
         apiPrivateKey = nil
@@ -41,18 +48,17 @@ enum StamperError: Error {
         }
     }
 
-    @objc public func injectCredentialBundle(bundle: NSString) async throws -> ObjCBool {
-        if let ephemeralPrivateKey = ephemeralPrivateKey {
-            let (bundlePrivateKey, bundlePublicKey) = try AuthManager.decryptBundle(encryptedBundle: bundle as String, ephemeralPrivateKey: ephemeralPrivateKey)
+     @objc public func injectCredentialBundle(bundle: NSString) async throws -> ObjCBool {
+       if let ephemeralPrivateKey = ephemeralPrivateKey {
+       let (bundlePrivateKey, bundlePublicKey) = try AuthManager.decryptBundle(encryptedBundle: bundle as String, ephemeralPrivateKey: ephemeralPrivateKey)
+               apiPublicKey = bundlePublicKey
+               apiPrivateKey = bundlePrivateKey
 
-            apiPublicKey = bundlePublicKey
-            apiPrivateKey = bundlePrivateKey
-            
-            return true;
-        } else {
-            throw StamperError.notInitialized
-        }
-    }
+               return true       
+       } else {
+           throw StamperError.notInitialized
+       }
+   }
 
     // TODO: we should use the turnkey stamper for all of this, but we need it published as a pod
     // and it shouldn't require use_frameworks!
@@ -70,7 +76,6 @@ enum StamperError: Error {
 
             let signatureHex = signature.derRepresentation.toHexString()
 
-            print(apiPublicKey.compressedRepresentation.toHexString())
             let stamp: [String: Any] = [
               "publicKey": apiPublicKey.compressedRepresentation.toHexString(),
               "scheme": "SIGNATURE_SCHEME_TK_API_P256",