Generate SHA256 String in Objective C [duplicate]

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Sha256 in Objective-C for iPhone

Greetings,

I'm having terrible trouble generating a SHA256 string in Objective C (probably because I'm so new to the language).

In jQuery, all I have to do is this:

var sha256String=$.sha256("Hello");

which produces the hash as expected.

But in Objective-C, I've tried the following to no avail:

NSString *pword=[[NSString alloc]
initWithString:login_pword.text];
unsigned char result[64];
CC_SHA256([pword UTF8String], [pword lengthOfBytesUsingEncoding:NSASCIIStringEncoding],result);
UIAlertView *msg=[[UIAlertView alloc] initWithTitle:@"Hi" message:result delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
[msg show];
[msg release];

Is there some function that I can call such as:

NSString *sha256String=[self getSHA256:pword];

This is what I'm trying to create and I'm finding it very difficult!

I hope someone can help.

Many thanks in advance,

---

After much playing around today, I finally came up with a function to get the SHA256:

-(NSString*) sha256:(NSString *)clear{
    const char *s=[clear cStringUsingEncoding:NSASCIIStringEncoding];
    NSData *keyData=[NSData dataWithBytes:s length:strlen(s)];

    uint8_t digest[CC_SHA256_DIGEST_LENGTH]={0};
    CC_SHA256(keyData.bytes, keyData.length, digest);
    NSData *out=[NSData dataWithBytes:digest length:CC_SHA256_DIGEST_LENGTH];
    NSString *hash=[out description];
    hash = [hash stringByReplacingOccurrencesOfString:@" " withString:@""];
    hash = [hash stringByReplacingOccurrencesOfString:@"<" withString:@""];
    hash = [hash stringByReplacingOccurrencesOfString:@">" withString:@""];
    return hash;
}

This gives the same output as PHP. It can easily be converted to SHA1 - just change 'SHA256' to 'SHA1'.

Hope it helps someone.

---

You are passing result into the UIAlertView's init method. result is a char[], and UIAlertView expects an NSString*. You need to convert your char[] to an NSString *.

Try this:

NSString *resultString = [NSString stringWithCString:result encoding:NSASCIIStringEncoding];
UIAlertView *msg=[[UIAlertView alloc] initWithTitle:@"Hi" message:resultString delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];

Also see this article on hashing on the iPhone.

---

You will need to use the OpenSSL C functions. See for example this question on how to do that. As input string, you'd use [myString UTFString] with length [myString lengthOfBytesUsingEncoding:NSUTF8StringEncoding].