Trying to Write NSString sha1 function, but it's returning null

Question

I have the following Objective-C function:

+(NSString *)stringToSha1:(NSString *)str{
    NSMutableData *dataToHash = [[NSMutableData alloc] init];
    [data         


        

Answer 1

Short answer: turn on gcc warnings (-Wall).

Long answer:

NSMutableData *dataToHash = [[NSMutableData alloc] init];
[dataToHash appendData:[str dataUsingEncoding:NSUTF8StringEncoding]];

is broken: You try to use a C string where an NSData argument is expected. Use

NSMutableData *dataToHash = [str dataUsingEncoding:NSUTF8StringEncoding];

instead.

The rest of the method takes the SHA1 buffer and tries interpret this data as an UTF-8 C string, which might crash or give any unexpected result. First, the buffer is not a UTF-8 string. Secondly, it's not null terminated.

What you want is to convert the SHA1 to a base 64 or similar string. Here's a nice post about how to do that.