mirror of
https://github.com/hashcat/hashcat.git
synced 2024-11-26 18:08:20 +00:00
168 lines
7.0 KiB
Markdown
168 lines
7.0 KiB
Markdown
xxHash - Extremely fast hash algorithm
|
|
======================================
|
|
|
|
xxHash is an Extremely fast Hash algorithm, running at RAM speed limits.
|
|
It successfully completes the [SMHasher](http://code.google.com/p/smhasher/wiki/SMHasher) test suite
|
|
which evaluates collision, dispersion and randomness qualities of hash functions.
|
|
Code is highly portable, and hashes are identical on all platforms (little / big endian).
|
|
|
|
|Branch |Status |
|
|
|------------|---------|
|
|
|master | [](https://travis-ci.org/Cyan4973/xxHash?branch=master) |
|
|
|dev | [](https://travis-ci.org/Cyan4973/xxHash?branch=dev) |
|
|
|
|
|
|
|
|
Benchmarks
|
|
-------------------------
|
|
|
|
The benchmark uses SMHasher speed test, compiled with Visual 2010 on a Windows Seven 32-bit box.
|
|
The reference system uses a Core 2 Duo @3GHz
|
|
|
|
|
|
| Name | Speed | Quality | Author |
|
|
|---------------|----------|:-------:|------------------|
|
|
| [xxHash] | 5.4 GB/s | 10 | Y.C. |
|
|
| MurmurHash 3a | 2.7 GB/s | 10 | Austin Appleby |
|
|
| SBox | 1.4 GB/s | 9 | Bret Mulvey |
|
|
| Lookup3 | 1.2 GB/s | 9 | Bob Jenkins |
|
|
| CityHash64 | 1.05 GB/s| 10 | Pike & Alakuijala|
|
|
| FNV | 0.55 GB/s| 5 | Fowler, Noll, Vo |
|
|
| CRC32 | 0.43 GB/s| 9 | |
|
|
| MD5-32 | 0.33 GB/s| 10 | Ronald L.Rivest |
|
|
| SHA1-32 | 0.28 GB/s| 10 | |
|
|
|
|
[xxHash]: http://www.xxhash.com
|
|
|
|
Q.Score is a measure of quality of the hash function.
|
|
It depends on successfully passing SMHasher test set.
|
|
10 is a perfect score.
|
|
Algorithms with a score < 5 are not listed on this table.
|
|
|
|
A more recent version, XXH64, has been created thanks to [Mathias Westerdahl](https://github.com/JCash),
|
|
which offers superior speed and dispersion for 64-bit systems.
|
|
Note however that 32-bit applications will still run faster using the 32-bit version.
|
|
|
|
SMHasher speed test, compiled using GCC 4.8.2, on Linux Mint 64-bit.
|
|
The reference system uses a Core i5-3340M @2.7GHz
|
|
|
|
| Version | Speed on 64-bit | Speed on 32-bit |
|
|
|------------|------------------|------------------|
|
|
| XXH64 | 13.8 GB/s | 1.9 GB/s |
|
|
| XXH32 | 6.8 GB/s | 6.0 GB/s |
|
|
|
|
This project also includes a command line utility, named `xxhsum`, offering similar features as `md5sum`,
|
|
thanks to [Takayuki Matsuoka](https://github.com/t-mat) contributions.
|
|
|
|
|
|
### License
|
|
|
|
The library files `xxhash.c` and `xxhash.h` are BSD licensed.
|
|
The utility `xxhsum` is GPL licensed.
|
|
|
|
|
|
### Build modifiers
|
|
|
|
The following macros can be set at compilation time,
|
|
they modify xxhash behavior. They are all disabled by default.
|
|
|
|
- `XXH_INLINE_ALL` : Make all functions `inline`, with bodies directly included within `xxhash.h`.
|
|
There is no need for an `xxhash.o` module in this case.
|
|
Inlining functions is generally beneficial for speed on small keys.
|
|
It's especially effective when key length is a compile time constant,
|
|
with observed performance improvement in the +200% range .
|
|
See [this article](https://fastcompression.blogspot.com/2018/03/xxhash-for-small-keys-impressive-power.html) for details.
|
|
- `XXH_ACCEPT_NULL_INPUT_POINTER` : if set to `1`, when input is a null-pointer,
|
|
xxhash result is the same as a zero-length key
|
|
(instead of a dereference segfault).
|
|
- `XXH_FORCE_MEMORY_ACCESS` : default method `0` uses a portable `memcpy()` notation.
|
|
Method `1` uses a gcc-specific `packed` attribute, which can provide better performance for some targets.
|
|
Method `2` forces unaligned reads, which is not standard compliant, but might sometimes be the only way to extract better performance.
|
|
- `XXH_CPU_LITTLE_ENDIAN` : by default, endianess is determined at compile time.
|
|
It's possible to skip auto-detection and force format to little-endian, by setting this macro to 1.
|
|
Setting it to 0 forces big-endian.
|
|
- `XXH_FORCE_NATIVE_FORMAT` : on big-endian systems : use native number representation.
|
|
Breaks consistency with little-endian results.
|
|
- `XXH_PRIVATE_API` : same impact as `XXH_INLINE_ALL`.
|
|
Name underlines that symbols will not be published on library public interface.
|
|
- `XXH_NAMESPACE` : prefix all symbols with the value of `XXH_NAMESPACE`.
|
|
Useful to evade symbol naming collisions,
|
|
in case of multiple inclusions of xxHash source code.
|
|
Client applications can still use regular function name,
|
|
symbols are automatically translated through `xxhash.h`.
|
|
- `XXH_STATIC_LINKING_ONLY` : gives access to state declaration for static allocation.
|
|
Incompatible with dynamic linking, due to risks of ABI changes.
|
|
- `XXH_NO_LONG_LONG` : removes support for XXH64,
|
|
for targets without 64-bit support.
|
|
|
|
|
|
### Example
|
|
|
|
Calling xxhash 64-bit variant from a C program :
|
|
|
|
```
|
|
#include "xxhash.h"
|
|
|
|
unsigned long long calcul_hash(const void* buffer, size_t length)
|
|
{
|
|
unsigned long long const seed = 0; /* or any other value */
|
|
unsigned long long const hash = XXH64(buffer, length, seed);
|
|
return hash;
|
|
}
|
|
```
|
|
|
|
Using streaming variant is more involved, but makes it possible to provide data in multiple rounds :
|
|
```
|
|
#include "stdlib.h" /* abort() */
|
|
#include "xxhash.h"
|
|
|
|
|
|
unsigned long long calcul_hash_streaming(someCustomType handler)
|
|
{
|
|
XXH64_state_t* const state = XXH64_createState();
|
|
if (state==NULL) abort();
|
|
|
|
size_t const bufferSize = SOME_VALUE;
|
|
void* const buffer = malloc(bufferSize);
|
|
if (buffer==NULL) abort();
|
|
|
|
unsigned long long const seed = 0; /* or any other value */
|
|
XXH_errorcode const resetResult = XXH64_reset(state, seed);
|
|
if (resetResult == XXH_ERROR) abort();
|
|
|
|
(...)
|
|
while ( /* any condition */ ) {
|
|
size_t const length = get_more_data(buffer, bufferSize, handler); /* undescribed */
|
|
XXH_errorcode const addResult = XXH64_update(state, buffer, length);
|
|
if (addResult == XXH_ERROR) abort();
|
|
(...)
|
|
}
|
|
|
|
(...)
|
|
unsigned long long const hash = XXH64_digest(state);
|
|
|
|
free(buffer);
|
|
XXH64_freeState(state);
|
|
|
|
return hash;
|
|
}
|
|
```
|
|
|
|
|
|
### Other programming languages
|
|
|
|
Beyond the C reference version,
|
|
xxHash is also available on many programming languages,
|
|
thanks to great contributors.
|
|
They are [listed here](http://www.xxhash.com/#other-languages).
|
|
|
|
|
|
### Branch Policy
|
|
|
|
> - The "master" branch is considered stable, at all times.
|
|
> - The "dev" branch is the one where all contributions must be merged
|
|
before being promoted to master.
|
|
> + If you plan to propose a patch, please commit into the "dev" branch,
|
|
or its own feature branch.
|
|
Direct commit to "master" are not permitted.
|