diff options
Diffstat (limited to 'crypt/README.ufc-crypt')
| -rw-r--r-- | crypt/README.ufc-crypt | 135 |
1 files changed, 135 insertions, 0 deletions
diff --git a/crypt/README.ufc-crypt b/crypt/README.ufc-crypt new file mode 100644 index 0000000000..74d81dd865 --- /dev/null +++ b/crypt/README.ufc-crypt @@ -0,0 +1,135 @@ +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 |