mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-25 02:33:36 +08:00
63f791d303
* crypt/crypt.texi: Update documentation of US export restrictions to match the 14 Jan 2000 regulations. 2000-02-28 Geoff Keating <geoffk@cygnus.com> * Makeconfig (all-subdirs): Add 'crypt' subdirectory. * sysdeps/unix/sysv/linux/configure.in (inhibit_glue): Don't complain if there is no crypt add-on. * crypt/configure: Removed. * crypt/crypt.texi: Update documentation of US export restrictions to match the 14 Jan 2000 regulations. 2000-02-28 Geoff Keating <geoffk@cygnus.com> * crypt: New subdirectory, merged in from the crypt add-on.
136 lines
4.5 KiB
Plaintext
136 lines
4.5 KiB
Plaintext
The following is the README for UFC-crypt, with those portions deleted
|
|
that are known to be incorrect for the implementation used with the
|
|
GNU C library.
|
|
|
|
|
|
UFC-crypt: ultra fast 'crypt' implementation
|
|
============================================
|
|
|
|
@(#)README 2.27 11 Sep 1996
|
|
|
|
Design goals/non goals:
|
|
----------------------
|
|
|
|
- Crypt implementation plugin compatible with crypt(3)/fcrypt.
|
|
|
|
- High performance when used for password cracking.
|
|
|
|
- Portable to most 32/64 bit machines.
|
|
|
|
- Startup time/mixed salt performance not critical.
|
|
|
|
Features of the implementation:
|
|
------------------------------
|
|
|
|
- On most machines, UFC-crypt runs 30-60 times faster than crypt(3) when
|
|
invoked repeated times with the same salt and varying passwords.
|
|
|
|
- With mostly constant salts, performance is about two to three times
|
|
that of the default fcrypt implementation shipped with Alec
|
|
Muffets 'Crack' password cracker. For instructions on how to
|
|
plug UFC-crypt into 'Crack', see below.
|
|
|
|
- With alternating salts, performance is only about twice
|
|
that of crypt(3).
|
|
|
|
- Requires 165 kb for tables.
|
|
|
|
Author & licensing etc
|
|
----------------------
|
|
|
|
UFC-crypt is created by Michael Glad, email: glad@daimi.aau.dk, and has
|
|
been donated to the Free Software Foundation, Inc. It is covered by the
|
|
GNU library license version 2, see the file 'COPYING.LIB'.
|
|
|
|
NOTES FOR USERS OUTSIDE THE US:
|
|
------------------------------
|
|
|
|
The US government limits the export of DES based software/hardware.
|
|
This software is written in Aarhus, Denmark. It can therefore be retrieved
|
|
from ftp sites outside the US without breaking US law. Please do not
|
|
ftp it from american sites.
|
|
|
|
Benchmark table:
|
|
---------------
|
|
|
|
The table shows how many operations per second UFC-crypt can
|
|
do on various machines.
|
|
|
|
|--------------|-------------------------------------------|
|
|
|Machine | SUN* SUN* HP* DecStation HP |
|
|
| | 3/50 ELC 9000/425e 3100 9000/720 |
|
|
|--------------|-------------------------------------------|
|
|
| Crypt(3)/sec | 4.6 30 15 25 57 |
|
|
| Ufc/sec | 220 990 780 1015 3500 |
|
|
|--------------|-------------------------------------------|
|
|
| Speedup | 48 30 52 40 60 |
|
|
|--------------|-------------------------------------------|
|
|
|
|
*) Compiled using special assembly language support module.
|
|
|
|
It seems as if performance is limited by CPU bus and data cache capacity.
|
|
This also makes the benchmarks debatable compared to a real test with
|
|
UFC-crypt wired into Crack. However, the table gives an outline of
|
|
what can be expected.
|
|
|
|
Optimizations:
|
|
-------------
|
|
|
|
Here are the optimizations used relative to an ordinary implementation
|
|
such as the one said to be used in crypt(3).
|
|
|
|
Major optimizations
|
|
*******************
|
|
|
|
- Keep data packed as bits in integer variables -- allows for
|
|
fast permutations & parallel xor's in CPU hardware.
|
|
|
|
- Let adjacent final & initial permutations collapse.
|
|
|
|
- Keep working data in 'E expanded' format all the time.
|
|
|
|
- Implement DES 'f' function mostly by table lookup
|
|
|
|
- Calculate the above function on 12 bit basis rather than 6
|
|
as would be the most natural.
|
|
|
|
- Implement setup routines so that performance is limited by the DES
|
|
inner loops only.
|
|
|
|
- Instead of doing salting in the DES inner loops, modify the above tables
|
|
each time a new salt is seen. According to the BSD crypt code this is
|
|
ugly :-)
|
|
|
|
Minor (dirty) optimizations
|
|
***************************
|
|
|
|
- combine iterations of DES inner loop so that DES only loops
|
|
8 times. This saves a lot of variable swapping.
|
|
|
|
- Implement key access by a walking pointer rather than coding
|
|
as array indexing.
|
|
|
|
- As described, the table based f function uses a 3 dimensional array:
|
|
|
|
sb ['number of 12 bit segment']['12 bit index']['48 bit half index']
|
|
|
|
Code the routine with 4 (one dimensional) vectors.
|
|
|
|
- Design the internal data format & uglify the DES loops so that
|
|
the compiler does not need to do bit shifts when indexing vectors.
|
|
|
|
Revision history
|
|
****************
|
|
|
|
UFC patchlevel 0: base version; released to alt.sources on Sep 24 1991
|
|
UFC patchlevel 1: patch released to alt.sources on Sep 27 1991.
|
|
No longer rebuilds sb tables when seeing a new salt.
|
|
UFC-crypt pl0: Essentially UFC pl 1. Released to comp.sources.misc
|
|
on Oct 22 1991.
|
|
UFC-crypt pl1: Released to comp.sources.misc in march 1992
|
|
* setkey/encrypt routines added
|
|
* added validation/benchmarking programs
|
|
* reworked keyschedule setup code
|
|
* memory demands reduced
|
|
* 64 bit support added
|