MD5加密

//md5 32位小写

+ (NSString *)md5:(NSString *)str

{

   const char *cStr = [strUTF8String];

   unsigned char result[16];

   CC_MD5(cStr, (CC_LONG)strlen(cStr), result);

   return [NSStringstringWithFormat:@"%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]

            ];

}