DE-crypting (trivial case)
Fellow C'punks: I was wondering if anyone knew of software that does decryption of weakly encrypted messages, i.e., similar to ROT13, but perhaps ROT(x) where 0<x<26? Or maybe a bit more sophisticated, but not even at the single DES level? Also...anyone know of any histogram software? i.e., I input a file, it counts how many letters of each type, and outputs it in a table and/or a graph? If not, I'll have to (horrors!) write code! Kindest regards, Dave
David L Womack says:
Fellow C'punks:
I was wondering if anyone knew of software that does decryption of weakly encrypted messages, i.e., similar to ROT13, but perhaps ROT(x) where 0<x<26? Or maybe a bit more sophisticated, but not even at the single DES level?
Between Caesar ciphers and DES lies an enormous range of encryption systems -- much as an enormous range of transport options lie between crawling on hands and knees and flying a space shuttle. Single DES is an extremely sophisticated encryption system -- its just a bit out of date. Breaking Caesar ciphers can be done by hand by a child with no knowledge of statistics. Breaking the traffic from an M209 is quite doable, but not exactly something you could explain in five minutes to someone, or even necessarily an hour.
Also...anyone know of any histogram software? i.e., I input a file, it counts how many letters of each type, and outputs it in a table and/or a graph?
You can write that yourself in about three or four minutes in PERL. Just keep an array of N elements corresponding to each of the ASCII codes (or whatever) and count. Its between four and fifteen lines, depending on how fancy you want to get with the printout.
If not, I'll have to (horrors!) write code!
Probably good for your soul. Perry
-----BEGIN PGP SIGNED MESSAGE----- In list.cypherpunks you write:
Fellow C'punks:
I was wondering if anyone knew of software that does decryption of weakly encrypted messages, i.e., similar to ROT13, but perhaps ROT(x) where 0<x<26? Or maybe a bit more sophisticated, but not even at the single DES level?
Isn't rot13 a Caesar cypher? Mark Riordan's collection has Caesar decrypt by exhaustive search. Lots of other stuff, too: [Ono-Sendai 1]c:\user\request\mrrcip.z>unzip -v mrrcip.zip Length Method Size Ratio Date Time CRC-32 Name ("^" ==> case ------ ------ ---- ----- ---- ---- ------ ---- conversion) 23058 Implode 15186 34% 11-19-87 11:49 80e94a0c ^detran.exe 4383 Implode 1878 57% 10-26-87 13:04 5e4c0ecd ^detran.for 7053 Implode 2858 59% 04-16-88 23:21 5d9e3deb ^entran.c 9088 Implode 5760 37% 04-16-88 23:22 bd543440 ^entran.exe 21104 Implode 13890 34% 02-06-88 20:29 f1b7d492 ^mktrnkey.exe 3105 Implode 1387 55% 02-06-88 20:28 d88ca139 ^mktrnkey.for 7176 Implode 2708 62% 02-16-88 23:20 3c825831 ^mrrmkmon.c 5072 Implode 2954 42% 02-16-88 23:20 4efef3aa ^mrrmkmon.exe 24516 Implode 15845 35% 10-26-87 22:54 ac58ac41 ^playfair.exe 10392 Implode 3582 66% 10-26-87 22:59 2474a710 ^playfair.for 3100 Implode 1416 54% 10-11-88 22:20 959c6d8d ^smplsub.c 10365 Implode 6807 34% 10-11-88 22:20 b95448af ^smplsub.exe 3244 Implode 1348 58% 07-29-88 23:56 bc28efd4 ^stradalf.c 8715 Implode 5387 38% 07-29-88 23:56 c98651f0 ^stradalf.exe 6711 Implode 2259 66% 07-19-88 13:16 7c4bb388 ^straddle.c 16890 Implode 9681 43% 07-19-88 13:17 edf8e4e2 ^straddle.exe 1138 Implode 614 46% 07-02-88 15:46 acc7b6ea ^caesar.c 5737 Implode 3820 33% 07-02-88 15:46 6c62c135 ^caesar.exe 74 Shrunk 62 16% 02-03-91 17:25 b16f569d ^p.h 4379 Implode 1665 62% 09-05-88 21:24 e1cd6821 ^periodic.c 9981 Implode 6619 34% 01-19-91 16:08 014028fa ^periodic.exe 8156 Implode 2607 68% 07-30-88 13:00 3d2a271b ^phrase.c 10192 Implode 6382 37% 07-30-88 13:00 5ab75734 ^phrase.exe 7555 Implode 2878 62% 02-03-92 21:48 7e088b37 ^solvevig.c 12182 Implode 8672 29% 01-13-91 10:34 0fda5189 ^solvevig.exe 13455 Implode 4159 69% 07-02-88 15:01 50230126 ^subst.c 13376 Implode 8377 37% 07-02-88 15:01 3a501d94 ^subst.exe 461 Implode 266 42% 01-12-91 19:28 af329b77 ^usage.c 1007 Implode 606 40% 01-19-91 16:22 85025017 ^vigkey.c 6662 Implode 4862 27% 01-19-91 16:23 9dd763a4 ^vigkey.exe 1922 Implode 1052 45% 02-03-92 22:09 ff0d58ad ^readme ------ ------ --- ------- 260249 145587 44% 31 I found it on cpsr.org, somewhere in the Gopherspace.
Also...anyone know of any histogram software? i.e., I input a file, it counts how many letters of each type, and outputs it in a table and/or a graph?
If not, I'll have to (horrors!) write code!
Histogram for 256 values? Yikes, that could take all morning! ;-) #! /usr/bin/perl undef $/; grep($table[vec($_,0,8)]++,split(/ */,<>)); for($x=0;$x < 256;$x++) { print "$x : $table[$x]\n"; } (you'll need lots of memory for this one, though ;) - -- Roy M. Silvernail, writing from roy@sendai.cybrspc.mn.org "Anything but Nixon, man... a blender. Anything!" -- National Lampoon, when they were funny -----BEGIN PGP SIGNATURE----- Version: 2.6 iQCVAwUBLgdUHRvikii9febJAQFWZwP+L9b9ZXhbksQfWe9FS9VUt6r4+ZJhYffN DosXC85KcV9flTi1NzL/MMHfy7LTImbDswr24GLbMYqXx821jBGRiuljDbYGcs5g faZZ8G3Gcmhgkeo6HOpad32A6lbHo18Suz5Z6zIHznNYtBGvXDasocVkO9IlBd2o Loi3Y0I68l8= =z0st -----END PGP SIGNATURE-----
I was wondering if anyone knew of software that does decryption of weakly encrypted messages, i.e., similar to ROT13, but perhaps ROT(x) where 0<x<26? Or maybe a bit more sophisticated, but not even at the single DES level?
There is stuff to be had. Look on the ftp sites (especially ripem. msu.edu). crypt200 by John K. Taber helps solve transposition and substitution ciphers.
Also...anyone know of any histogram software? i.e., I input a file, it counts how many letters of each type, and outputs it in a table and/or a graph?
Again, lots of statistics gathering software in the crypt directories lying around the internet.
If not, I'll have to (horrors!) write code!
I have examined a couple of these software packages and found some of them very powerful. However, all I have seen are interactive. I want a pipe (ciphertext in; plaintext out). This is completely feasible for large classes of substitution/transposition ciphers. I have ideas and _some_ code. Some of the concepts to look for include isomorphisms and cross reduction. Good luck! Cort.
participants (4)
-
cort -
dwomack＠runner.utsa.edu -
Perry E. Metzger -
roy＠sendai.cybrspc.mn.org