Category that implements MD5

NSString+MD5.m

#import "NSString+MD5.h"
#import <CommonCrypto/CommonDigest.h>

@implementation NSString (MD5)
- (NSString *)MD5String {
    const char *cstr = [self UTF8String];
    unsigned char result[16];
    CC_MD5(cstr, strlen(cstr), result);

    return [NSString stringWithFormat:
            @"%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X%02X",
            result[0], result[1], result[2], result[3],
            result[4], result[5], result[6], result[7],
            result[8], result[9], result[10], result[11],
            result[12], result[13], result[14], result[15]
            ];  
}
@end