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- 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
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