@ -482,6 +482,7 @@ This configuration item is a bitmask field and is very similar to the module_opt
* OPTS_TYPE_COPY_TMPS: This option tells the hashcat host binary to copy the `tmps` data structure from the compute device to the host in case a hash was cracked. In order to access this data, you need to implement and register the module function module_build_plain_postprocess(). There are several scenarios in which this can be useful. For instance, if you have a weak algorithm that could be exploited to leak portions of the password and you use this leaked data to speed up your attacks, you still need to know the leaked data on the host to copy it to the password buffer before printing it to the user. A good example for this is PKZIP `src/modules/module_20510.c` which leaks the first 6 bytes of the password. Another scenario is the PIM brute force in VeraCrypt. The PIM in this case can be seen as an additional numeric password. In case we crack it, the user needs to know both the password and the PIM in order to mount the volume.
* OPTS_TYPE_POTFILE_NOPASS: This option simply prevents the hashcat host binary from adding a cracked hash to the potfile. For instance, if a specific hashing algorithm is implemented with several hash formats and therefore your plugins hash format shares the same format with a different plugin hash format (think of it like a format clash where the potfile parser could not really decide if it is the correct hash format to accept). A good example is the WPA PMK, which cannot be used to login to a specific WPA network directly. There could be other reasons for not printing the cracked hashes to the potfile.
* OPTS_TYPE_DYNAMIC_SHARED: This is a very special option which tells the hashcat host binary to query the real available shared memory on a device for a particular kernel. In addition it will also register the queried amount of shared memory from the host. On NVIDIA, this allows us to use the full available shared memory (regions in the post 48k range), though we still need to prepare the kernel in order to make use of the dynamic allocated shared memory. A good example is the bcrypt kernel `OpenCL/m03200-pure.cl`.
* OPTS_TYPE_SELF_TEST_DISABLE: This option can be used if you want to disable the self-test functionality for your hash-mode. Valid reasons to disable this feature are: Your OpenCL kernel is using compile time optimizations such as fixed salts (like in DESCrypt), the hash primitive to be used has to be derived first from the target hash (like in JWT) or the hash-mode is so slow that it hurts startup time of hashcat (like in Ethereum Wallet SCRYPT). For the first two cases the problem is that hashcat would create a cached optimized OpenCL kernel with a configuration which is valid only for the self-test hash, but very likely the wrong ones for the real target hash. The real target hash would never crack.
Jens Steube
4 years ago