Keychain

keychain.m

- (BOOL)checkKeychainForAuthCredentials
{
    NSMutableDictionary *keychainQuery = [self keychainSearchDictionary];
    
    // Fire off the query
    OSStatus keychainErr = noErr;
    
    CFDictionaryRef outDictionary;
    keychainErr = SecItemCopyMatching((__bridge CFDictionaryRef)keychainQuery, (CFTypeRef *)&outDictionary);
    
    if (keychainErr == noErr && outDictionary != NULL)
    {
        // Query the keychain again for the password data
        [keychainQuery setObject:(id)kCFBooleanTrue forKey:(__bridge id)kSecReturnData];
        [keychainQuery removeObjectForKey:(__bridge id)kSecReturnAttributes];
        
        CFDataRef passwordData = NULL;
        
        keychainErr = SecItemCopyMatching((__bridge CFDictionaryRef)keychainQuery, (CFTypeRef *)&passwordData);
        
        if (keychainErr == noErr)
        {
            NSString *username = [((__bridge NSDictionary *)outDictionary) objectForKey:(__bridge id)kSecAttrAccount];
            
            // Convert the password to an NSString and add it to the return dictionary
            NSString *password = [[NSString alloc] initWithBytes:[(__bridge NSData *)passwordData bytes]
                                                          length:[(__bridge NSData *)passwordData length]
                                                        encoding:NSUTF8StringEncoding];
            
            NSLog(@"Username: %@ || Password: %@", username, password);
            
            // TODO: Validate the credentials?
        }
        else if (keychainErr == errSecItemNotFound)
        {
            // TODO: Anything?
        }
    }
    else if (keychainErr == errSecItemNotFound)
    {
        // TODO: Anything?
    }
    
    return NO;
}

- (BOOL)saveAuthCredentialsToKeychain:(NSDictionary *)credentials
{
    NSMutableDictionary *keychainQuery = [self keychainSearchDictionary];
    
    // Fire off the query
    OSErr keychainErr = noErr;
    
    // Try to find an existing item
    CFDictionaryRef outDictionary;
    keychainErr = SecItemCopyMatching((__bridge CFDictionaryRef)keychainQuery, (CFTypeRef *)&outDictionary);
    
    NSString *username = [credentials objectForKey:@"username"];
    NSData *passwordData = [[credentials objectForKey:@"password"] dataUsingEncoding:NSUTF8StringEncoding];
    
    if (keychainErr == errSecSuccess)
    {
        // Update the item (via the response we got back from the call to SecItemCopyMatching)
        NSDictionary *updatedCredentials = @{ (__bridge id)kSecAttrAccount : username, (__bridge id)kSecValueData : passwordData };
        keychainErr = SecItemUpdate(outDictionary, (__bridge CFDictionaryRef)updatedCredentials);
        
        return (keychainErr == noErr);
    }
    else
    {
        // Create the item
        [keychainQuery setObject:username forKey:(__bridge id)kSecAttrAccount];
        [keychainQuery setObject:passwordData forKey:(__bridge id)kSecValueData];
        keychainErr = SecItemAdd((__bridge CFDictionaryRef)keychainQuery, NULL);
        
        return (keychainErr == noErr);
    }
}

- (NSMutableDictionary *)keychainSearchDictionary
{
    NSMutableDictionary *keychainQuery = [@{ } mutableCopy];
    
    // We're looking for a generic password
    [keychainQuery setObject:(__bridge id)kSecClassGenericPassword forKey:(__bridge id)kSecClass];
    
    // For the Fly Delta app
    [keychainQuery setObject:@"My Awesome Service" forKey:(__bridge id)kSecAttrService];
    
    // We only want the first match
    [keychainQuery setObject:(__bridge id)kSecMatchLimitOne forKey:(__bridge id)kSecMatchLimit];
    
    // Return the attributes of the keychain item (if found)
    [keychainQuery setObject:(id)kCFBooleanTrue forKey:(__bridge id)kSecReturnAttributes];
    
    return keychainQuery;
}