How do I create an MD5 Hash of a string in Cocoa?

Question

I know SHA-1 is preferred, but this project requires I use MD5.

#include 

- (NSString*) MD5Hasher: (NSString*) query {
    NSData* hash         


        

Answer 1

The MD5 function does not return a C string, it returns a pointer to some bytes. You can't treat it as a string.

If you want to create a string, you need to build a string using the hex values of those bytes. Here is one way to do it as a category on NSData:

#import 
@implementation NSData (MMAdditions)
- (NSString*)md5String
{
    unsigned char md5[CC_MD5_DIGEST_LENGTH];
    CC_MD5([self bytes], [self length], md5);
    return [NSString stringWithFormat: @"%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x%02x",
            md5[0], md5[1],
            md5[2], md5[3],
            md5[4], md5[5],
            md5[6], md5[7],
            md5[8], md5[9],
            md5[10], md5[11],
            md5[12], md5[13],
            md5[14], md5[15]
            ];
}
@end