EXC_BAD_ACCESS when using string declared in header file - iphone

Question

I've declared a string in my header file like so:
#property (nonatomic, retain) NSString *resultOfHash;
I call my getHash method like so:
NSString *hash = [self getHash];
My getHash method is:
-(NSString *) getHash
{
//Get username form Keychain
KeychainItemWrapper *keyChain = [[KeychainItemWrapper alloc] initWithIdentifier:KeyChainName accessGroup:nil];
username = [keyChain objectForKey:(__bridge id)kSecAttrAccount];
//get token from NSUserDefauls
NSString *token = [[NSUserDefaults standardUserDefaults]objectForKey:#"Token"];
NSString *toHash = [[username stringByAppendingString:HashExtra] stringByAppendingString:token];
const char *s = [toHash cStringUsingEncoding:NSASCIIStringEncoding];
NSData *keyData = [NSData dataWithBytes:s length:strlen(s)];
uint8_t digest[CC_SHA1_DIGEST_LENGTH] = {0};
CC_SHA512(keyData.bytes, keyData.length, digest);
NSData *out = [NSData dataWithBytes:digest length:CC_SHA1_DIGEST_LENGTH];
//convert to string
resultOfHash = [out description];
//App crashed out above
// get rid of unwanted characters
resultOfHash = [resultOfHash stringByReplacingOccurrencesOfString:#" " withString:#""];
resultOfHash = [resultOfHash stringByReplacingOccurrencesOfString:#"<" withString:#""];
resultOfHash = [resultOfHash stringByReplacingOccurrencesOfString:#">" withString:#""];
//log to make sure it works
NSLog(#"hash is: %#", resultOfHash);
return resultOfHash;
}
My code crashes out at the line: ResultOfHash = [out description]; but I'm not sure why.
When I use a local variable the conversion works fine but then I cannot return the local variable from the getHash method. Example:
Replace ResultOfHash = [out description];
with
NSString *local = [out description];
return local;
and the conversion works fine and when I debug line by line, the debugger will go to my closing bracket on my method and then produce the EXC_BAD_ACCESS error.
I've tried running NSZombie but that didn't find anything at all.
Any help in trying to sort this out would be greatly appreciated.

Answer 1

Have a look at the answer in this question. Try converting to NSString using
[NSString *local = [[[NSString alloc] initWithData:out encoding:NSASCIIStringEncoding];
I haven't tested this code with this encoding, but it's similar to something I already use.
Update -
I corrected an error in the code above. I somehow left the method signiture out in a distracted copy and paste.

Answer 2

I think the problem is here:
uint8_t digest[CC_SHA1_DIGEST_LENGTH] = {0};
CC_SHA512(keyData.bytes, keyData.length, digest);
NSData *out = [NSData dataWithBytes:digest length:CC_SHA1_DIGEST_LENGTH];
You are using CC_SHA512, but only allocate array of size CC_SHA1_DIGEST_LENGTH, which is smaller and will lead to the buffer overrunning.
To correct this, you should use CC_SHA512_DIGEST_LENGTH instead.

Answer 3

It's crashing because out is unretained. You should add retain:
resultOfHash = [[out description] retain];
or use retained property:
self.resultOfHash = [out description];
Check this, it should be work.

Answer 4

You probably need to use an NSMutableString.