From 8c6823c4639f1bfcac774ee2870610a14f4d5cac Mon Sep 17 00:00:00 2001
From: Kyle Spearrin <kyle.spearrin@gmail.com>
Date: Mon, 8 Apr 2019 21:23:16 -0400
Subject: [PATCH] key chain storage service

---
 .../Services/PreferencesStorageService.cs     |   3 +-
 src/Core/Services/SecureStorageService.cs     |   8 +-
 src/iOS/Services/KeyChainStorageService.cs    | 127 ++++++++++++++++++
 src/iOS/iOS.csproj                            |   1 +
 4 files changed, 132 insertions(+), 7 deletions(-)
 create mode 100644 src/iOS/Services/KeyChainStorageService.cs

diff --git a/src/Core/Services/PreferencesStorageService.cs b/src/Core/Services/PreferencesStorageService.cs
index bfc7e4f86..3cf7d397e 100644
--- a/src/Core/Services/PreferencesStorageService.cs
+++ b/src/Core/Services/PreferencesStorageService.cs
@@ -8,8 +8,7 @@ namespace Bit.Core.Services
 {
     public class PreferencesStorageService : IStorageService
     {
-        private string _keyFormat = "bwPreferencesStorage:{0}";
-
+        private readonly string _keyFormat = "bwPreferencesStorage:{0}";
         private readonly string _sharedName;
         private readonly JsonSerializerSettings _jsonSettings = new JsonSerializerSettings
         {
diff --git a/src/Core/Services/SecureStorageService.cs b/src/Core/Services/SecureStorageService.cs
index f4a01aabf..a79c5a33c 100644
--- a/src/Core/Services/SecureStorageService.cs
+++ b/src/Core/Services/SecureStorageService.cs
@@ -7,7 +7,7 @@ namespace Bit.Core.Services
 {
     public class SecureStorageService : IStorageService
     {
-        private string _keyFormat = "bwSecureStorage:{0}";
+        private readonly string _keyFormat = "bwSecureStorage:{0}";
         private readonly JsonSerializerSettings _jsonSettings = new JsonSerializerSettings
         {
             ContractResolver = new CamelCasePropertyNamesContractResolver()
@@ -17,8 +17,7 @@ namespace Bit.Core.Services
         {
             var formattedKey = string.Format(_keyFormat, key);
             var val = await Xamarin.Essentials.SecureStorage.GetAsync(formattedKey);
-            var objType = typeof(T);
-            if(objType == typeof(string))
+            if(typeof(T) == typeof(string))
             {
                 return (T)(object)val;
             }
@@ -36,8 +35,7 @@ namespace Bit.Core.Services
                 return;
             }
             var formattedKey = string.Format(_keyFormat, key);
-            var objType = typeof(T);
-            if(objType == typeof(string))
+            if(typeof(T) == typeof(string))
             {
                 await Xamarin.Essentials.SecureStorage.SetAsync(formattedKey, obj as string);
             }
diff --git a/src/iOS/Services/KeyChainStorageService.cs b/src/iOS/Services/KeyChainStorageService.cs
new file mode 100644
index 000000000..fa44bbce9
--- /dev/null
+++ b/src/iOS/Services/KeyChainStorageService.cs
@@ -0,0 +1,127 @@
+using System;
+using System.Runtime.CompilerServices;
+using System.Text;
+using System.Threading.Tasks;
+using Bit.Core.Abstractions;
+using Foundation;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
+using Security;
+
+namespace Bit.iOS.Services
+{
+    public class KeyChainStorageService : IStorageService
+    {
+        private readonly string _keyFormat = "bwKeyChainStorage:{0}";
+        private readonly string _service;
+        private readonly string _group;
+        private readonly JsonSerializerSettings _jsonSettings = new JsonSerializerSettings
+        {
+            ContractResolver = new CamelCasePropertyNamesContractResolver()
+        };
+
+        public KeyChainStorageService(string service, string group)
+        {
+            _service = service;
+            _group = group;
+        }
+
+        public Task<T> GetAsync<T>(string key)
+        {
+            var formattedKey = string.Format(_keyFormat, key);
+            byte[] dataBytes = null;
+            using(var existingRecord = GetKeyRecord(formattedKey))
+            using(var record = SecKeyChain.QueryAsRecord(existingRecord, out SecStatusCode resultCode))
+            {
+                if(resultCode == SecStatusCode.ItemNotFound)
+                {
+                    return Task.FromResult((T)(object)null);
+                }
+
+                CheckError(resultCode);
+                dataBytes = record.Generic.ToArray();
+            }
+
+            var dataString = Encoding.UTF8.GetString(dataBytes);
+            if(typeof(T) == typeof(string))
+            {
+                return Task.FromResult((T)(object)dataString);
+            }
+            else
+            {
+                return Task.FromResult(JsonConvert.DeserializeObject<T>(dataString, _jsonSettings));
+            }
+        }
+
+        public async Task SaveAsync<T>(string key, T obj)
+        {
+            if(obj == null)
+            {
+                await RemoveAsync(key);
+                return;
+            }
+
+            string dataString = null;
+            if(typeof(T) == typeof(string))
+            {
+                dataString = obj as string;
+            }
+            else
+            {
+                dataString = JsonConvert.SerializeObject(obj, _jsonSettings);
+            }
+
+            var formattedKey = string.Format(_keyFormat, key);
+            var dataBytes = Encoding.UTF8.GetBytes(dataString);
+            using(var data = NSData.FromArray(dataBytes))
+            using(var newRecord = GetKeyRecord(formattedKey, data))
+            {
+                await RemoveAsync(formattedKey);
+                CheckError(SecKeyChain.Add(newRecord));
+            }
+        }
+
+        public Task RemoveAsync(string key)
+        {
+            var formattedKey = string.Format(_keyFormat, key);
+            using(var record = GetExistingRecord(formattedKey))
+            {
+                if(record != null)
+                {
+                    CheckError(SecKeyChain.Remove(record));
+                }
+            }
+            return Task.FromResult(0);
+        }
+
+        private SecRecord GetKeyRecord(string key, NSData data = null)
+        {
+            var record = new SecRecord(SecKind.GenericPassword)
+            {
+                Service = _service,
+                Account = key,
+                AccessGroup = _group
+            };
+            if(data != null)
+            {
+                record.Generic = data;
+            }
+            return record;
+        }
+
+        private SecRecord GetExistingRecord(string key)
+        {
+            var existingRecord = GetKeyRecord(key);
+            SecKeyChain.QueryAsRecord(existingRecord, out SecStatusCode resultCode);
+            return resultCode == SecStatusCode.Success ? existingRecord : null;
+        }
+
+        private void CheckError(SecStatusCode resultCode, [CallerMemberName] string caller = null)
+        {
+            if(resultCode != SecStatusCode.Success)
+            {
+                throw new Exception(string.Format("Failed to execute {0}. Result code: {1}", caller, resultCode));
+            }
+        }
+    }
+}
diff --git a/src/iOS/iOS.csproj b/src/iOS/iOS.csproj
index d166cb296..9ba949d92 100644
--- a/src/iOS/iOS.csproj
+++ b/src/iOS/iOS.csproj
@@ -93,6 +93,7 @@
     <Compile Include="Main.cs" />
     <Compile Include="AppDelegate.cs" />
     <Compile Include="Services\CryptoPrimitiveService.cs" />
+    <Compile Include="Services\KeyChainStorageService.cs" />
     <None Include="Entitlements.plist" />
     <None Include="Info.plist" />
     <Compile Include="Properties\AssemblyInfo.cs" />