Re: MD5 encryption?

[Richard Frith-Macdonald]

On Thursday, January 17, 2002, at 12:07 PM, <anstouh@yahoo.com.au> wrote:

> I was just wondering how I could encrypt a string given an MD5 hash from
> within a GNUstep program (written in Objective C)? I would prefer it if
> the response was detailed; I'm not all that familiar with Obj-C.

I'm not sure what you mean ...

If you want to generate the MD5 hash of a string I'd use some C library
(such as openssl) to do it (unless you want to write the MD5 support 
yourself).

Since the MD5 stuff works on raw data, you would generally pass a 
pointer to
the data and a length as arguments to the hashing function.

If you are working with unicode strings, you would do something like -

NSData  *data = [theString dataUsingEncoding: NSUnicodeStringEncoding];

/*
 * Call some hashing function passing it a pointer to the data to be 
hashed,
 * the length of that data, and a pointer to a buffer in which the hash 
is
 * to be stored.
 */
md5hash([data bytes], [data length], theHash);

If your string is plain ascii, you would use
[theString dataUsingEncoding: NSASCIIStringEncoding]

etc.