SFHFKeychainUtils. iOS keychain. ARC compatible

Question

I was wondering if anyone that was using the SFHFKeychainUtils managed to modify them to be compatible for ARC. More exactly the

NSDictionary *attributeResult = NULL;
NSMutableDictionary *attributeQuery = [query mutableCopy];
[attributeQuery setObject: (id) kCFBooleanTrue forKey:(__bridge id) kSecReturnAttributes];
OSStatus status = SecItemCopyMatching((CFDictionaryRef) attributeQuery,(CFTypeRef *)(attributeResult));

I tried

OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef) attributeQuery,(CFTypeRef *)(attributeResult));

also

CFTypeRef subAttributeResult = (CFTypeRef *)(objc_unretainedPointer(attributeResult));
OSStatus status = SecItemCopyMatching((__bridge CFDictionaryRef) attributeQuery,(CFTypeRef *)(subAttributeResult));

These 2 being the only 2 approaches I managed to get no errors for. Any other approach by adding objc_XXX instead of CFTypeRef here and there gets me errors(from implicit conversions from obj-c pointer to CFTypeRef is disallowed in ARC, to passing x parameter to y parameter discards qualifiers). Obviously the first snip of code gives an error too. Although I get no errors when building, app crashes with EXC_BAD_ACCESS when reaching this part of code.

The link for the full SFHFKeychainUtils: https://github.com/ldandersen/scifihifi-iphone/tree/master/security

Any help, please? Thank you.

Desdee

Answer 1

here is the ARC compatible SFHFKeychainUtils,

SFHFKeychainUtils.h

//
//  SFHFKeychainUtils.h
//
//  Created by Buzz Andersen on 10/20/08.
//  Based partly on code by Jonathan Wight, Jon Crosby, and Mike Malone.
//  Copyright 2008 Sci-Fi Hi-Fi. All rights reserved.
//
//  Permission is hereby granted, free of charge, to any person
//  obtaining a copy of this software and associated documentation
//  files (the "Software"), to deal in the Software without
//  restriction, including without limitation the rights to use,
//  copy, modify, merge, publish, distribute, sublicense, and/or sell
//  copies of the Software, and to permit persons to whom the
//  Software is furnished to do so, subject to the following
//  conditions:
//
//  The above copyright notice and this permission notice shall be
//  included in all copies or substantial portions of the Software.
//
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
//  OTHER DEALINGS IN THE SOFTWARE.
//

#import <UIKit/UIKit.h>


@interface SFHFKeychainUtils : NSObject {

}

+ (NSString *) getPasswordForUsername: (NSString *) username andServiceName: (NSString *) serviceName error: (NSError **) error;
+ (BOOL) storeUsername: (NSString *) username andPassword: (NSString *) password forServiceName: (NSString *) serviceName updateExisting: (BOOL) updateExisting error: (NSError **) error;
+ (BOOL) deleteItemForUsername: (NSString *) username andServiceName: (NSString *) serviceName error: (NSError **) error;

@end

SFHFKeychainUtils.m

//  
//  SFHFKeychainUtils.m 
//

//  Created by Buzz Andersen on 10/20/08.   
//  Based partly on code by Jonathan Wight, Jon Crosby, and Mike Malone.    
//  Copyright 2008 Sci-Fi Hi-Fi. All rights reserved.   
//

//  Permission is hereby granted, free of charge, to any person 
//  obtaining a copy of this software and associated documentation  
//  files (the "Software"), to deal in the Software without 
//  restriction, including without limitation the rights to use,    
//  copy, modify, merge, publish, distribute, sublicense, and/or sell   
//  copies of the Software, and to permit persons to whom the   
//  Software is furnished to do so, subject to the following    
//  conditions: 
//

//  The above copyright notice and this permission notice shall be  
//  included in all copies or substantial portions of the Software. 
//  
//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
//  EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES 
//  OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND    
//  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT 
//  HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,    
//  WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING    
//  FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR   
//  OTHER DEALINGS IN THE SOFTWARE. 
//

#import "SFHFKeychainUtils.h"   
#import <Security/Security.h>   


static NSString *SFHFKeychainUtilsErrorDomain = @"SFHFKeychainUtilsErrorDomain";

#if __IPHONE_OS_VERSION_MIN_REQUIRED < 30000 && TARGET_IPHONE_SIMULATOR

@interface SFHFKeychainUtils (PrivateMethods)   
(SecKeychainItemRef) getKeychainItemReferenceForUsername: (NSString *) username andServiceName: (NSString *) serviceName error: (NSError **) error; 
@end

#endif

@implementation SFHFKeychainUtils

#if __IPHONE_OS_VERSION_MIN_REQUIRED < 30000 && TARGET_IPHONE_SIMULATOR

 +(NSString *) getPasswordForUsername: (NSString *) username andServiceName: (NSString *) serviceName error: (NSError **) error {       
      if (!username || !serviceName) {          
           *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: -2000 userInfo: nil];          
            return nil;         
          }      

      SecKeychainItemRef item = [SFHFKeychainUtils getKeychainItemReferenceForUsername: username andServiceName: serviceName error: error];
      if (*error || !item) {            
            return nil;         
          }

      // from Advanced Mac OS X Programming, ch. 16     
      UInt32 length;        
      char *password;       
      SecKeychainAttribute attributes[8];       
      SecKeychainAttributeList list;
      attributes[0].tag = kSecAccountItemAttr;      
      attributes[1].tag = kSecDescriptionItemAttr;      
      attributes[2].tag = kSecLabelItemAttr;
      attributes[3].tag = kSecModDateItemAttr;
      list.count = 4;       
      list.attr = attributes;
     OSStatus status = SecKeychainItemCopyContent(item, NULL, &list, &length, (void **)&password);
      if (status != noErr) {            
            *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: status userInfo: nil];            
            return nil;         
          }
     NSString *passwordString = nil;
     if (password != NULL) {        
           char passwordBuffer[1024];
            if (length > 1023) {                
                 length = 1023;             
                }           
            strncpy(passwordBuffer, password, length);
            passwordBuffer[length] = '\0';          
            passwordString = [NSString stringWithCString:passwordBuffer];           
          }
      SecKeychainItemFreeContent(&list, password);
      CFRelease(item);
      return passwordString;        
    }

+ (void) storeUsername: (NSString *) username andPassword: (NSString *) password forServiceName: (NSString *) serviceName updateExisting: (BOOL) updateExisting error: (NSError **) error {  

      if (!username || !password || !serviceName) {         
            *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: -2000 userInfo: nil];         
            return;         
          }
      OSStatus status = noErr;
      SecKeychainItemRef item = [SFHFKeychainUtils getKeychainItemReferenceForUsername: username andServiceName: serviceName error: error];
      if (*error && [*error code] != noErr) {           
            return;         
          }
      *error = nil;     

      if (item) {           
            status = SecKeychainItemModifyAttributesAndData(item,NULL,strlen([password UTF8String]),[password UTF8String]);
            CFRelease(item);            
          }     
      else {            
            status = SecKeychainAddGenericPassword(NULL,strlen([serviceName UTF8String]),[serviceName UTF8String],strlen([username UTF8String]),[username UTF8String],strlen([password UTF8String]),[password UTF8String],NULL);

          }
      if (status != noErr) {            
            *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: status userInfo: nil];            
          }     
    }

+ (void) deleteItemForUsername: (NSString *) username andServiceName: (NSString *) serviceName error: (NSError **) error {    
      if (!username || !serviceName) {          
            *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: 2000 userInfo: nil];          
            return;        
          }

      *error = nil;

      SecKeychainItemRef item = [SFHFKeychainUtils getKeychainItemReferenceForUsername: username andServiceName: serviceName error: error];
      if (*error && [*error code] != noErr) {        
          return;           
          }

      OSStatus status;    
      if (item) {        
           status = SecKeychainItemDelete(item);            
            CFRelease(item);        
          }

      if (status != noErr) {            
            *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: status userInfo: nil];            
          }     
    }

+ (SecKeychainItemRef) getKeychainItemReferenceForUsername: (NSString *) username andServiceName: (NSString *) serviceName error: (NSError **) error {    
      if (!username || !serviceName) {          
            *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: -2000 userInfo: nil];        
            return nil;         
          }

      *error = nil;    
      SecKeychainItemRef item;   
      OSStatus status = SecKeychainFindGenericPassword(NULL,strlen([serviceName UTF8String]),[serviceName UTF8String],strlen([username UTF8String]),[username UTF8String], NULL,NULL,&item);

      if (status != noErr) {        
            if (status != errSecItemNotFound) {             
                  *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: status userInfo: nil];              
                }        
            return nil;         
          }
          return item;    
    }

#else

+ (NSString *) getPasswordForUsername: (NSString *) username andServiceName: (NSString *) serviceName error: (NSError **) error {

      if (!username || !serviceName) {          
            if (error != nil) {             
                  *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: -2000 userInfo: nil];           
                }           
            return nil;        
          }      

      if (error != nil) {           
            *error = nil;           
          }   
      // Set up a query dictionary with the base query attributes: item type (generic), username, and service    
     NSArray *keys = [[NSArray alloc] initWithObjects: (__bridge_transfer NSString *) kSecClass, kSecAttrAccount, kSecAttrService, nil];  
     NSArray *objects = [[NSArray alloc] initWithObjects: (__bridge_transfer NSString *) kSecClassGenericPassword, username, serviceName, nil];    
     NSMutableDictionary *query = [[NSMutableDictionary alloc] initWithObjects: objects forKeys: keys];    
      // First do a query for attributes, in case we already have a Keychain item with no password data set.    
      // One likely way such an incorrect item could have come about is due to the previous (incorrect)    
      // version of this code (which set the password as a generic attribute instead of password data).   
      NSMutableDictionary *attributeQuery = [query mutableCopy];   
      [attributeQuery setObject: (id) kCFBooleanTrue forKey:(__bridge_transfer id) kSecReturnAttributes];       
       CFTypeRef attrResult = NULL;  
      OSStatus status = SecItemCopyMatching((__bridge_retained CFDictionaryRef) attributeQuery, &attrResult);       
      //NSDictionary *attributeResult = (__bridge_transfer NSDictionary *)attrResult;   
      if (status != noErr) {        
            // No existing item found--simply return nil for the password           
           if (error != nil && status != errSecItemNotFound) {              
                  //Only return an error if a real exception happened--not simply for "not found."           
                  *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: status userInfo: nil];              
                }    
            return nil;         
          }

     // We have an existing item, now query for the password data associated with it.    
      NSMutableDictionary *passwordQuery = [query mutableCopy];    
      [passwordQuery setObject: (id) kCFBooleanTrue forKey: (__bridge_transfer id) kSecReturnData];     
        CFTypeRef resData = NULL;       
      status = SecItemCopyMatching((__bridge_retained CFDictionaryRef) passwordQuery, (CFTypeRef *) &resData);      
      NSData *resultData = (__bridge_transfer NSData *)resData;    
      if (status != noErr) {       
            if (status == errSecItemNotFound) {            
                  // We found attributes for the item previously, but no password now, so return a special error.               
                  // Users of this API will probably want to detect this error and prompt the user to               
                  // re-enter their credentials.  When you attempt to store the re-entered credentials              
                  // using storeUsername:andPassword:forServiceName:updateExisting:error           
                  // the old, incorrect entry will be deleted and a new one with a properly encrypted               
                  // password will be added.

                  if (error != nil) {                   
                        *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: -1999 userInfo: nil];                 
                      }             
                }       
            else {              
                 // Something else went wrong. Simply return the normal Keychain API error code.            
                  if (error != nil) {                   
                        *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: status userInfo: nil];                    
                     }              
                }           
           return nil;          
          }   
      NSString *password = nil;     
     if (resultData) {          
            password = [[NSString alloc] initWithData: resultData encoding: NSUTF8StringEncoding];          
          } 
      else {        
            // There is an existing item, but we weren't able to get password data for it for some reason,          
            // Possibly as a result of an item being incorrectly entered by the previous code.          
            // Set the -1999 error so the code above us can prompt the user again.

           if (error != nil) {      
                  *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: -1999 userInfo: nil];               
                }           
          }     
      return password;      
    }

+ (BOOL) storeUsername: (NSString *) username andPassword: (NSString *) password forServiceName: (NSString *) serviceName updateExisting: (BOOL) updateExisting error: (NSError **) error 

{           
     if (!username || !password || !serviceName)

          {            
                if (error != nil)                   
                    {                       
                         *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: -2000 userInfo: nil];                    
                 }              
                return NO;          
              }

    // See if we already have a password entered for these credentials.

      NSError *getError = nil;      
      NSString *existingPassword = [SFHFKeychainUtils getPasswordForUsername: username andServiceName: serviceName error:&getError];        

     if ([getError code] == -1999)     
          {            
                // There is an existing entry without a password properly stored (possibly as a result of the previous incorrect version of this code.

                // Delete the existing item before moving on entering a correct one.            
               getError = nil;          

                [self deleteItemForUsername: username andServiceName: serviceName error: &getError];            

                if ([getError code] != noErr)                 
                   {                   
                          if (error != nil)                         
                              {                            
                                    *error = getError;                           
                                 }                      
                          return NO;                        
                       }            
              }     
    else if ([getError code] != noErr)      
          {           
                if (error != nil)                   
                    {                       
                          *error = getError;                    
                        }               
                return NO;          
              }     
     if (error != nil)          
          {          
                *error = nil;               
              }

      OSStatus status = noErr;

      if (existingPassword)         
          {

                // We have an existing, properly entered item with a password.        
                // Update the existing item.            

               if (![existingPassword isEqualToString:password] && updateExisting)                
                    {                       
                          //Only update if we're allowed to update existing.  If not, simply do nothing.

                          NSArray *keys = [[NSArray alloc] initWithObjects: (__bridge_transfer NSString *) kSecClass,kSecAttrService,kSecAttrLabel,kSecAttrAccount,nil];

                          NSArray *objects = [[NSArray alloc] initWithObjects: (__bridge_transfer NSString *) kSecClassGenericPassword,serviceName,serviceName,username,nil];

                          NSDictionary *query = [[NSDictionary alloc] initWithObjects: objects forKeys: keys];      

                          status = SecItemUpdate((__bridge_retained CFDictionaryRef) query, (__bridge_retained CFDictionaryRef) [NSDictionary dictionaryWithObject: [password dataUsingEncoding: NSUTF8StringEncoding] forKey: (__bridge_transfer NSString *) kSecValueData]);                      
                        }               
              }     
      else      
          {             
               // No existing entry (or an existing, improperly entered, and therefore now

                // deleted, entry).  Create a new entry.


                NSArray *keys = [[NSArray alloc] initWithObjects: (__bridge_transfer NSString *) kSecClass,kSecAttrService,kSecAttrLabel,kSecAttrAccount,kSecValueData,nil];

                NSArray *objects = [[NSArray alloc] initWithObjects: (__bridge_transfer NSString *) kSecClassGenericPassword,serviceName,serviceName,username,[password dataUsingEncoding: NSUTF8StringEncoding],nil];

                NSDictionary *query = [[NSDictionary alloc] initWithObjects: objects forKeys: keys];            

                status = SecItemAdd((__bridge_retained CFDictionaryRef) query, NULL);               
              }     
      if (error != nil && status != noErr)          
          {            
                // Something went wrong with adding the new item. Return the Keychain error code.               
                *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: status userInfo: nil];                
                return NO;            
              }     
      return YES;       
    }

+ (BOOL) deleteItemForUsername: (NSString *) username andServiceName: (NSString *) serviceName error: (NSError **) error    
{       
      if (!username || !serviceName)        
          {            
                if (error != nil)                   
                   {                        
                          *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: -2000 userInfo: nil];                       
                        }            
                return NO;          
              }     
      if (error != nil)       
          {             
               *error = nil;            
              }     
      NSArray *keys = [[NSArray alloc] initWithObjects: (__bridge_transfer NSString *) kSecClass, kSecAttrAccount, kSecAttrService, kSecReturnAttributes, nil];     
      NSArray *objects = [[NSArray alloc] initWithObjects: (__bridge_transfer NSString *) kSecClassGenericPassword, username, serviceName, kCFBooleanTrue, nil];        
      NSDictionary *query = [[NSDictionary alloc] initWithObjects: objects forKeys: keys];      
      OSStatus status = SecItemDelete((__bridge_retained CFDictionaryRef) query);       

      if (error != nil && status != noErr)        
          {           
                *error = [NSError errorWithDomain: SFHFKeychainUtilsErrorDomain code: status userInfo: nil];            
                return NO;           
              }    
      return YES;    
    }
#endif
@end

Alexander

The bridge casts in this are all completely wrong. For example, (__bridge_transfer NSString *) kSecClass is wrong. __bridge_transfer means you own (i.e. retained) kSecClass, and are passing that ownership into ARC. However, you never retained kSecClass, therefore it is an over-release. And another example, (__bridge_retained CFDictionaryRef) passwordQuery is wrong. A __bridge_retained cast gives you ownership of the resulting CF object, i.e. it retains it for you. However, you are just passing it to a function. You never release it. This is a leak. – Butylene

@Butylene Thank you, very simple very clear explanations. – Elbertine

Answer 2

I had the same issue - and don't know who properly to credit this to - but the version of SFHFKeychainUtils in this github project works with ARC as a drop in replacement.

Cerveny

Answer 3

In case anybody lands on this page with the same question, I would recommend you have a look at Sam Soffes SSKeychain component.

Not only is it ARC compatible, its well documented, maintained and has more features than SFHFKeychainUtils.

Haggadist

Thanks so much, Emmanuel. Switching to SSKeychain eliminated all the memory leaks I encountered with the ARC version of SFHFKeychainUtils. – Limner

Answer 4

You can always make that one file non-ARC.

Marra

Yea, I realized that after I posted and so I did. But would be nice to know the solution to this, at least for future(or other similar problems) reference. Nonetheless, thanks for the answer ;) – Desdee

The ARC documentation does go through handling CFRefs, see ARCProgrammingGuide.pdf. Also Mike Ash just did a nice blog post on this: Automatic Reference Counting – Marra

That was a nice read, I'll keep the document bookmarked. Problem is, it didn't really help this particular issue, or I didn't really understand how to do it. I tried adding __bridge or __bridge_transfer or __bridge_retain to the attributeResult variable (should have mentioned from the start that adding __bridge to the attributeQuery variable gives no more errors) just like I did to the attributeQuery variable, but it still gives errors. :/ the declaration looks like "OSStatus SecItemCopyMatching(CFDictionaryRef query, CFTypeRef *result)". the one with pointer gives errors, the other doesn't. – Desdee

Sorry, I can't help beyond that, I have not used ARC except on small projects and not with CF. – Marra

Answer 5

I just moved another framework (MPOAuth) to ARC, this is how I solved this issue:

NSString *foundPassword = nil;
NSData *foundValue = nil;
CFTypeRef foundDict;
status = SecItemCopyMatching((__bridge CFDictionaryRef)attributeQuery, &foundDict);

if (status == noErr) {
    attributesDictionary = (__bridge_transfer NSDictionary *)foundDict;
    foundValue = [attributesDictionary objectForKey:(__bridge id)kSecValueData];
    if (foundValue) {
        foundPassword = [[NSString alloc] initWithData:foundValue
                                              encoding:NSUTF8StringEncoding];
    }
}

I'll have to verify whether this causes foundDict to leak or not..

Jenkins

Answer 6

See this question:

iPhone fetch data dictionary from keychain

I haven't tested it yet, but it sounds right. You won't need to disable ARC. It also has notes on how to get rid of the

Cast of an indirect pointer to an Objective-C pointer to 'CFTypeRef*' (aka 'const void**') is disallowed with ARC.

error.

Isolation

Answer 7

The developer specifically mentions in his Github page that SFHFKeychainUtils should be considered deprecated, and to look at STKeychain instead in STUtils:

https://github.com/ldandersen/STUtils/tree/master/Security

Glad

If you look at this implementation of the STUtils you'll notice it doesn't support ARC either. A quick search for "release" will show you that. – Harless

I thought it useful to bring up because one can just make an ARC-compatible version of SFUtils; the library author may have other reasons for deprecating SFHFKeychainUtils on which the accepted answer is based. Plus, the OP can simply flag this library with -fno-objc-arc, which is better than using a deprecated library. – Glad

STKeychain brings in a bunch of unrelated stuff as well, so it'd be nice to have a standalone implementation again. – Ribaldry