I'd like get username/password out of my keychain. for this I followed this guide:
Simple iPhone Keychain Access
But this part is not allowed with ARC:
NSData *result = nil;
OSStatus status = SecItemCopyMatching(
(CFDictionaryRef)searchDictionary,
(CFTypeRef *)&result);
What can I do?
ARC only manages Objective-C types. If you cast to Core Foundation types you have to tell ARC who owns the variable by using __bridge, __bridge_retained or __bridge_transfer.
Here's Apple's official documentation on toll-free bridging under ARC, or see this blog post (scroll down to Toll-Free Bridging) for a great overview.
For example:
NSData *inData = nil;
CFTypeRef inTypeRef = (__bridge CFTypeRef)inData;
OSStatus status = SecItemCopyMatching(
(__bridge CFDictionaryRef)searchDictionary,
&inTypeRef);
CFTypeRef inData = NULL;
OSStatus status = SecItemCopyMatching(
(__bridge CFDictionaryRef)searchDictionary,
& inData);
NSData *data = (__bridge NSData *)inData;
Related
I'm developing a react-native app using https://github.com/oblador/react-native-keychain to save and get things from keychain.
The things stored in keychain (and some other things) should be accessible from all our apps. So in xcode under capabilities I have activated an app-group "group.something.test".
I'm using setGenericPassword function of react-native-keychain like this:
await Keychain.setGenericPassword(
'a username',
'a password',
{
service: 'a userId',
accessible: Keychain.ACCESSIBLE.ALWAYS,
accessGroup: 'group.something.test',
accessControl: Keychain.ACCESS_CONTROL.DEVICE_PASSCODE
}
);
In the native module this will store it to the keychain something like this:
SecAccessControlRef sacRef = SecAccessControlCreateWithFlags(kCFAllocatorDefault,
kSecAttrAccessibleAlways,
kSecAccessControlDevicePasscode,
&error);
NSDictionary *attributes = attributes = #{
(__bridge NSString *)kSecClass: (__bridge id)(kSecClassGenericPassword),
(__bridge NSString *)kSecAttrService: service,
(__bridge NSString *)kSecAttrAccount: username,
(__bridge NSString *)kSecValueData: [password dataUsingEncoding:NSUTF8StringEncoding],
(__bridge NSString *)kSecAttrAccessControl] = (__bridge id)sacRef,
(__bridge NSString *)kSecAttrAccessGroup] = accessGroup;
};
...
OSStatus osStatus = SecItemAdd((__bridge CFDictionaryRef) attributes, NULL);
...
And keychain items are retrieved in the following way:
await Keychain.getGenericPassword({ service: 'a userId' });
Which will will run the following native code:
NSDictionary *query = #{
(__bridge NSString *)kSecClass: (__bridge id)(kSecClassGenericPassword),
(__bridge NSString *)kSecAttrService: service,
(__bridge NSString *)kSecReturnAttributes: (__bridge id)kCFBooleanTrue,
(__bridge NSString *)kSecReturnData: (__bridge id)kCFBooleanTrue,
(__bridge NSString *)kSecMatchLimit: (__bridge NSString *)kSecMatchLimitOne,
(__bridge NSString *)kSecUseOperationPrompt:#"Authenticate to retrieve secret"
};
CFTypeRef foundTypeRef = NULL;
OSStatus osStatus = SecItemCopyMatching((__bridge CFDictionaryRef) query, (CFTypeRef*)&foundTypeRef);
This works fine in the first app, I can store and retrieve an item from the keychain.
When I deploy a second app through xcode by just changing Display name and Bundle identifier to something different it also works. I can retrieve the key saved by the first app.
However if I now go back to the first app and try to retrieve the keychain item osStatus is -25308 (errSecInteractionNotAllowed).
If I uninstall the second app, it will start working in the first app again.
What am I doing wrong? Is there something more I need to do in the project settings?
I have also tried with keychain group capability, having the same keychain group as the first index in the keychain groups array, using that id as kSecAttrAccessGroup.
To generate key pair I am using Secure Enclave (kSecAttrTokenIDSecureEnclave). When trying to access generated key pair, iOS system, asks for TouchID. Below is code snapshot how I am generating and accessing key pair.
Is here a way to setup properties/attributes, that Secure Enclave functionality will be able to use without TouchID and Passcode?
Generate key pair:
SecAccessControlRef sacObject = SecAccessControlCreateWithFlags(kCFAllocatorDefault,
kSecAttrAccessibleWhenUnlocked,
kSecAccessControlUserPresence | kSecAccessControlPrivateKeyUsage, &error);
NSDictionary *parameters = #{
(__bridge id)kSecAttrTokenID: (__bridge id)kSecAttrTokenIDSecureEnclave,
(__bridge id)kSecAttrKeyType: (__bridge id)kSecAttrKeyTypeEC,
(__bridge id)kSecAttrKeySizeInBits: #256,
(__bridge id)kSecPrivateKeyAttrs: #{
(__bridge id)kSecAttrAccessControl: (__bridge_transfer id)sacObject,
(__bridge id)kSecAttrIsPermanent: #YES,
(__bridge id)kSecAttrLabel: #“SecKey”,
},
};
SStatus status = SecKeyGeneratePair((__bridge CFDictionaryRef)parameters, &publicKey, &privateKey);
Access key pair:
NSDictionary *query = #{
(__bridge id)kSecClass: (__bridge id)kSecClassKey,
(__bridge id)kSecAttrKeyClass: (__bridge id)kSecAttrKeyClassPrivate,
(__bridge id)kSecAttrLabel: #"SecKey",
(__bridge id)kSecReturnRef: #YES
};
OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef)query, (CFTypeRef *)&privateKey);
This code is taken form Apple examples KeychainTouchID. By removing kSecAccessControlTouchIDAny it is possible to generate private key inside secure enclave and later use it without entering a passcode.
SecAccessControlRef sacObject;
// Should be the secret invalidated when passcode is removed? If not then use `kSecAttrAccessibleWhenUnlocked`.
sacObject = SecAccessControlCreateWithFlags(kCFAllocatorDefault,
kSecAttrAccessibleWhenPasscodeSetThisDeviceOnly,
/*kSecAccessControlTouchIDAny |*/ kSecAccessControlPrivateKeyUsage, &error);
// Create parameters dictionary for key generation.
NSDictionary *parameters = #{
(__bridge id)kSecAttrTokenID: (__bridge id)kSecAttrTokenIDSecureEnclave,
(__bridge id)kSecAttrKeyType: (__bridge id)kSecAttrKeyTypeEC,
(__bridge id)kSecAttrKeySizeInBits: #256,
(__bridge id)kSecPrivateKeyAttrs: #{
(__bridge id)kSecAttrAccessControl: (__bridge_transfer id)sacObject,
(__bridge id)kSecAttrIsPermanent: #YES,
(__bridge id)kSecAttrLabel: #"my-se-key",
},
};
I'm struggling with iOS keychain and i can't seem to find any good documentation.
Anyway, I have two apps, and basically all i want to do is share some data in the keychain and keep some data private so that the other app cannot access it.
I've tried to implement the KeychainItemWrapper provided by Apple, but this is simply not working. I have no issue sharing data, but if i don't set an access group, the data is still shared. I working with a device not the simulator, which could lead to the same problems.
Here is my code
App 1 :
KeychainItemWrapper *item = [[KeychainItemWrapper alloc] initWithIdentifier:#"SharedKeyChainApp" accessGroup:nil];
[item setObject:#"MyAccount" forKey:(__bridge id)kSecAttrAccount];
[item setObject:#"SecureValue" forKey:(__bridge id)kSecValueData];
App 2 :
KeychainItemWrapper *keychain = [[KeychainItemWrapper alloc] initWithIdentifier:#"SharedKeyChainApp" accessGroup:nil];
NSString *data = [keychain objectForKey:(__bridge id)kSecValueData];
NSLog(#"data is : %#",data); //Prints "data is : SecureValue"
If I remove in project properties my keychain group in one or the other app, it won't print anything. But obviously i'm not able to share data between those two apps anymore.
Thanks
If it's a shared keychain then it's shared. All the data in it will be accessible to any other app which can access the keychain.
You could:
Create 2 keychain. One shared and one private. Sharable stuff goes in shared, private stuff goes in private.
Encrypt data you won't want to to share with others.
I'd probably go with the first. IMHO, KeychainItemWrapper is pretty poor as grab and use code. It's old code which provides little in the way of functionality. I'm attaching a quick and dirty bit of code I wrote to play with and test out using the key chain functionality without KeychainItemWrapper. In this case I was playing with items both in "app" and "Security" to create some shared and non-shared items. You can't really tell that here since it's just some test code and sharing is under Targets->Capabilities->Keychain Sharing.
- (void)viewDidLoad {
[super viewDidLoad];
// [self removeKeychainItem];
// [self addKeychainItem];
[self searchForKeychainItems];
}
- (void)searchForKeychainItems {
[self log:#"\n\n EXISTING KEYCHAIN ITEM(S)"];
NSDictionary *query = #{(__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
(__bridge id)kSecMatchLimit: (__bridge id)kSecMatchLimitAll,
(__bridge id)kSecReturnData: (__bridge id)kCFBooleanTrue, // returns password
(__bridge id)kSecReturnAttributes: (__bridge id)kCFBooleanTrue, // returns rest of data
// (__bridge id)kSecAttrAccessGroup: #"AAAAAAAAAA.com.foo.Security"
// (__bridge id)kSecAttrAccessGroup: #"AAAAAAAAAA.com.foo.app"
};
OSStatus resultCode;
CFArrayRef *searchResults = nil;
resultCode = SecItemCopyMatching((__bridge CFDictionaryRef)query, (CFTypeRef *)&searchResults);
NSArray *foo = CFBridgingRelease(searchResults);
[self log:[NSString stringWithFormat:#"Search result code: %d", (int)resultCode]];
[self log:[NSString stringWithFormat:#"Search Results: %#", foo]];
NSDictionary *keychainItem = foo[0];
NSString *password = [[NSString alloc] initWithData:[keychainItem objectForKey:(__bridge id)kSecValueData] encoding:NSUTF8StringEncoding];
[self log:[NSString stringWithFormat:#"password is `%#`", password]];
}
- (void)addKeychainItem {
[self log:#"\n\n ADDING KEYCHAIN ITEM"];
NSDictionary *genericDataDictionary = #{#"authState": #"1",
#"lastAuthDate": #"2/11/2014",
#"otherCrap": #"poo"};
NSData *encodedGenericData = [NSKeyedArchiver archivedDataWithRootObject:genericDataDictionary];
NSData *encodedPassword = [#"secret" dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *query = #{(__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
(__bridge id)kSecAttrCreator: #"MyCom",
(__bridge id)kSecAttrComment: #"keychain tests",
(__bridge id)kSecAttrService: #"Credentials",
(__bridge id)kSecAttrAccount: #"username",
(__bridge id)kSecValueData: encodedPassword,
(__bridge id)kSecAttrGeneric: encodedGenericData,
(__bridge id)kSecAttrAccessGroup: #"AAAAAAAAAA.com.foo.Security"
};
OSStatus result;
result = SecItemAdd((__bridge CFDictionaryRef)query, NULL);
NSLog(#"Add status code: %d", (int)result);
}
- (void)removeKeychainItem {
[self log:#"\n\n REMOVING KEYCHAIN ITEM"];
NSDictionary *query = #{(__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
// (__bridge id)kSecAttrCreator: #"MyCom",
// (__bridge id)kSecAttrService: #"Credentials",
(__bridge id)kSecAttrComment: #"New Keychain standards Test Item",
// (__bridge id)kSecAttrAccount: #"username",
// (__bridge id)kSecValueData: [#"password" dataUsingEncoding:NSUTF8StringEncoding],
// (__bridge id)kSecAttrGeneric: encodedGenericData
// (__bridge id)kSecAttrAccessGroup: #"AAAAAAAAAA.com.foo.Security"
};
OSStatus resultsCode;
resultsCode = SecItemDelete((__bridge CFDictionaryRef)query);
NSLog(#"Delete results code: %d", (int)resultsCode);
}
- (void)log:(NSString *)text {
self.textView.text = [[self.textView.text stringByAppendingString:text] stringByAppendingString:#"\n"];
}
One thing to be aware of is that you need to add both a private and a shared access group. The private access group should match the app's bundle ID and come before the shared one.
<dict>
<key>keychain-access-groups</key>
<array>
<string>$(AppIdentifierPrefix)<APP BUNDLE ID></string>
<string>$(AppIdentifierPrefix)com.mybusiness.shared</string>
</array>
</dict>
If you only add a single named access group then this will be the default for all keychain items effectively sharing everything.
First off, I have watched the WWDC 2013 session on protecting secrets with the keychain. I want to do a basic passcode store. Watched the whole video, but found what I needed in the first 10 minutes of the video. It seems straightforward, but I don't completely understand how the data encoding and retrieval works.
PROBLEM: after secItemCopyMatching, I check my NSData object to make sure it is not nil before converting it to a NSString. Problem is, it is always nil. Below is how I'm saving the keychain entry or update, followed by how I'm retrieving it. Any help and explanation would be very much appreciated.
UPDATE (EDITED):
Fruity Geek, thanks for the response. I've updated my code below using __bridge. My problem now boils down to, am I storing and retrieving the password correctly? Have I got both wrong or just one or the other? My NSData instance is always nil. I am checking returns codes and my SecItemAdd and SecItemUpdate (when the keychaing entry exists) are working correctly. I can't seem to retrieve the string value of the data (passcode) stored to compare it with the passcode entered by the user. Appreciate the help guys and gals. Here is what I am doing now:
UPDATE #2: (Edited with Fruity Geek's answers and final working version. My edits only include changes to the code below.)
Set keychain entry:
NSData *secret = [_backupPassword dataUsingEncoding:NSUTF8StringEncoding];
NSDictionary *query = #{
(__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
(__bridge id)kSecAttrService: twServiceName,
(__bridge id)kSecAttrAccount: twAccountName,
(__bridge id)kSecValueData: secret,
};
OSStatus status =
SecItemAdd((__bridge CFDictionaryRef)query, NULL);
if (status == errSecDuplicateItem) {
// this item exists in the keychain already, update it
query = #{
(__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
(__bridge id)kSecAttrService: twServiceName,
(__bridge id)kSecAttrAccount: twAccountName,
};
NSDictionary *changes = #{
(__bridge id)kSecValueData: secret,
};
status = SecItemUpdate((__bridge CFDictionaryRef)query, (__bridge CFDictionaryRef)changes);
}
Retrieve password from keychain:
NSDictionary *query = #{
(__bridge id)kSecClass: (__bridge id)kSecClassGenericPassword,
(__bridge id)kSecAttrService: twServiceName,
(__bridge id)kSecAttrAccount: twAccountName,
(__bridge id)kSecReturnData: #YES,
};
NSData *data = NULL;
CFTypeRef dataTypeRef = (__bridge CFTypeRef)data;
OSStatus status =
SecItemCopyMatching((__bridge CFDictionaryRef)query, &dataTypeRef);
NSData *data = (__bridge NSData *)dataTypeRef;
NSString *passcode = #"none";
if (status == errSecSuccess) {
// we found a keychain entry, set the passcode
if (data)
passcode = [NSString stringWithUTF8String:[data bytes]];
}
twServiceName and twAccountName are static NSStrings.
As I said, I don't quite what I am doing with __bridge or CFTypeRef. I looked through apples docs, numerous posts here and other sites, but keychain and these terms are brand new to me and I'm still trying to figure it out. Hoping someone here can point out my error and help me understand. Thanks in advance for the help.
iOS 7 / Xcode 5
You don't own any of the Core Foundation objects (you didn't create or copy them) and you don't want to retain or release them, so CFBridgingRelease and CFBridgingRetainis incorrect. Use (__bridge id) instead whenever you want to cast to an Objective-C object.
(__bridge id)kSecAttrService
when should you use __bridge vs. CFBridgingRelease/CFBridgingRetain?
Your data variable and dataTypeRef are two distinct pointers. Only the dataTypeRef was filled with data in SecItemCopyMatching. Cast your CFTypeRef to NSData after it has been populated by SecItemCopyMatching so your data isn't always nil
CFTypeRef dataTypeRef = NULL;
OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef)query, &dataTypeRef);
NSData *data = (__bridge NSData *)dataTypeRef;
You should look more closely at the OSStatus returned by all your SecItem functions calls. There are many possible return codes that are not success. In your case, you are detecting a duplicate item in SecItemAdd - then updating it to the exact same item (doing nothing). Instead, you should try retrieving it first using SecItemCopyMatching. If no match is found, use SecItemAdd. If a match was found, use SecItemUpdate.
The example code from Apple is terrible, not written for ARC and confusing, but it exists. In particular, the writeToKeychain method is what you need. https://developer.apple.com/library/ios/documentation/Security/Conceptual/keychainServConcepts/iPhoneTasks/iPhoneTasks.html#//apple_ref/doc/uid/TP30000897-CH208-SW1
I am having a problem in type conversion in ARC environment.If anyone would be kind enough to address it as well:
When i used this line of code:
NSData *resultData = nil;
NSMutableDictionary *passwordQuery = [query mutableCopy];
[passwordQuery setObject: (id) kCFBooleanTrue forKey: (__bridge id) kSecReturnData];
status = SecItemCopyMatching((__bridge CFDictionaryRef) passwordQuery, (CFTypeRef *) &resultData);
Then i am recieving an error:
Cast of an indirect pointer to an Objective C pointer to 'CFTypeRef*'(aka 'const void **')is disallowed with ARC.
Please suggest me any way to ressolve this..
Thanks in advance..
The result data type is merely a CFTypeRef until after the call to SecItemCopyMatching so start by passing in a CFTypeRef:
CFTypeRef resultData = nil;
status = SecItemCopyMatching((__bridge CFDictionaryRef) passwordQuery, &resultData);
Since the query specified that the resultData should be a CFDataRef the resultData is now a CFDataRef, and you can now cast it as such. then cast it further into an NSData.
CFDataRef resultCFData = (CFDataRef)resultData;
NSData *resultNSData = (__bridge NSData *)resultCFData;
Or in one line:
NSData *resultNSData = (__bridge NSData *)(CFDataRef)resultData;