From msuinfo!agate!howland.reston.ans.net!usenet.ins.cwru.edu!ns.mcs.kent.edu!kira.cc.uakron.edu!malgudi.oar.net!chemabs!usenet Wed May 4 12:11:27 1994 Newsgroups: sci.crypt Path: msuinfo!agate!howland.reston.ans.net!usenet.ins.cwru.edu!ns.mcs.kent.edu!kira.cc.uakron.edu!malgudi.oar.net!chemabs!usenet From: jac55@cas.org () Subject: WWII book cipher - description Message-ID: <1994May4.112838.16775@chemabs.uucp> Sender: usenet@chemabs.uucp Reply-To: jac55@cas.org Organization: Chemical Abstracts Service Date: Wed, 4 May 1994 11:28:38 GMT Lines: 235 This is the description of the book cipher used by Alexander Foote to communicate with the Soviets in WWII. It is from Foote's book "Handbook for Spies" (Doubleday, Garden City, N.Y., 1949). It is reprinted without permission solely for the sake of information and in response to a number of requests. I think it's a pretty strong field cipher, but informed criticism welcome. A challenge cipher encoded by this method will be posted separately. Alec Chambers. ==============Begin included text============================ The process of enciphering messages for the Centre was divided into two parts. The first stage is comparatively simple and can be carried in the head, and as I have stated, I frequently made notes in this First Stage Cipher for ease and convenience. The second stage involves the "closing" of the first simple encipherment against the text of a code book. (In this case, a "code book" is any ordinary published book that may be selected.) The first stage of an encipherment is based on a keyword, which must have six letters and which is changed at intervals by the Centre. In the example to follow the key word is PLAYER. This is written out horizontally, and below ii - in line - the remainder of the alphabet is written (in the case of PLAYER in groups of six) together with a symbol for "signal (@) and Full Stop. "Signal" means that the message changes over from letters to numbers. (***NOTE: I have changed @ to comma because there are no numbers in the passages used. Otherwise, everything is as described by Foote.***) At this stage the "pattern" looks like this: P L A Y E R B C D F G H I J K M N O Q S T U V W X Z @ . It is now necessary to assign a number to each letter, and for this purpose the numbers 1-9, 00-09, and 40-49 are used. (In the first set of numbers the figure 4 is omitted as it would lead to confusion with the double numbers beginning with 40.) Those letters which are changed into single figures (1-9) are ASINTOER (arranged in this order for mnemonic purposes), the numbers being assigned to the relevant letters as they occur reading vertically 3 6 8 P L A Y E R B C D F G H 1 7 9 I J K M N O 2 5 Q S T U V W X Z @ . To this pattern are now added the double number (00-09, 40-49), starting from the top left corner and going down the columns consecutively filling in the blanks. With all the numbers inserted, the diagram now looks like this: 00 04 3 41 6 8 P L A Y E R 01 05 08 42 46 48 B C D F G H 1 06 09 43 7 9 I J K M N O 02 2 5 44 47 49 Q S T U V W 03 07 40 45 X Z @ . (This pattern is, of course, changed occasionally by the Centre by allocating a different "mnemonic" or by changing the code word or both.) A message enciphered in the first stage would look like this. (After a change from words to numerals, indicated by the symbol "signal," the numerals are each repeated three times.) 08 1 8 6 05 5 9 8 45 48 3 47 6 8 6 05 6 1 47 6 08 D I R E C T O R . H A V E R E C E I V E D 41 9 44 8 7 8 2 45 40 666 888 45 666 999 45 777 000 Y O U R N R S . @ 6 8 . 6 9 . 7 0 40 45 06 1 43 45 7 8 45 40 444 111 40 45 @ . J I M . N R . @ 4 1 @ . These figures are then split into five figure groups, the third and antepenultimate groups being left blank to take "recognition groups." At this stage the message begins to look like a ciphered message, but it is by no means secure and would present no difficulties to a cryptographer. Here it is with the blanks left for the recognition groups and the last group made up with noughts to complete a five-figure group. 08186 05598 45483 47686 05614 76084 19448 78245 40666 88845 66699 94577 70004 04506 14345 78454 04441 11404 50000 At this point the first stage of encipherment is complete. It is now necessary to "close" the message by reenciphering it against a selected portion of the "code book." In practice I used a Swiss book of trade statistics, but not having that by me now, I think it might be appropriate to take a passage at random from the report of the Royal Commission on the Canadian spy case (The defection of Gouzenko - jac). On page 77, line 14, is the following phrase: "that even if the adherent or member should refuse to engage in activities so clearly illegal and which constitute so clear a betrayal of his or her country." The enciphering phrase can be taken from anywhere in the book, starting at any word in any line. In this case, it starts at the fourth word of the line, i.e., "that." From here on, the key phrase is enciphered in exactly the same way as was the original message, and written out in five-figure groups, leaving here also the third and antipenultimate groups blank, as below: 54835 64767 14254 86308 48686 75984 36430 16824 89440 40886 42442 65967 46346 61730 55147 15162 29050 46380 44110 These groups are then added to the groups of the original ciphered message, the tens being ignored, and the final result is this: 08186 05598 45483 47686 05614 76084 54835 64767 14254 86308 48686 75984 ------------------------------------------ 52911 69255 59637 23984 43290 41968 19448 78245 40666 88845 66699 94577 70004 36430 16824 89440 40886 42442 65967 46346 ----------------------------------------- 45878 84069 29006 28621 08031 59434 16340 04506 14345 78454 04441 11404 50000 61730 55147 15162 29050 46380 44110 ----------------------------------------- 65236 69482 83516 23491 57784 94110 Now the message is complete save for the two recognition groups which enable the recipient to decipher message. These are made up-in different ways-from the "code book group", the "fixed group," and the "message group." The code book group is composed of the page number, line number, and word number of the key phrase. In this case, page 77, line 14, and word (from left) 4-77144. The fixed group-69696-is given by the Centre and changed only on orders from the Centre. The message group is, for the first recognition group, the fifth group of the message as enciphered so far, i.e. 43290; for the second recognition group, the fifth group from the end of the message as enciphered so far, i.e. 69482. Now in each case the code book group, the fixed group, and the message group are added together. Thus: Recognition 1 Recognition2 Code Book 77144 77144 Fixed Group 69696 69696 Message Group 43290 69482 ----- ----- 79920 95112 These two totals are now inserted into the appropriate spaces in the already enciphered message and the final result reads as follows: 52911 69255 79920 59637 23984 43290 41968 45878 84069 29006 28621 08031 59434 16340 65236 69482 83516 23491 95112 57784 94110 DECIPHERMENT In decipherment, naturally, the first essential is to unravel the components of the two recognition groups. To illustrate this process clearly, let us recapitulate how the two recognition groups were arrived at. The first recognition group was composed of the code book group (C), the fixed group (F), and the fifth group of the enciphered message (not counting the blank) (M1); the second recognition group was composed of the the code book group (C), the fixed recognition group (F) and the fifth group from the end of the enciphered message (not counting the blank)(M2). Therefore the first recognition group is made up of C+F+M1, and the second recognition group is made of C+F+M2. To break down the first recognition group, subtract from it the fixed group (69696) already known by agreement (F) and the sixth group of the completed message (M1), thus leaving C. The second recognition group is really only a cross-check, for on subtracting frim it F and M2 the result should also be C. Once C is known, the corresponding passage in the book can be turned up, and the decipherment follows by using the reverse procedure of the encipherment. From msuinfo!agate!usenet.ins.cwru.edu!ns.mcs.kent.edu!kira.cc.uakron.edu!malgudi.oar.net!chemabs!usenet Wed May 4 12:11:41 1994 Newsgroups: sci.crypt Path: msuinfo!agate!usenet.ins.cwru.edu!ns.mcs.kent.edu!kira.cc.uakron.edu!malgudi.oar.net!chemabs!usenet From: jac55@cas.org () Subject: WWII book cipher challenge text Message-ID: <1994May4.113418.17071@chemabs.uucp> Sender: usenet@chemabs.uucp Reply-To: jac55@cas.org Organization: Chemical Abstracts Service Date: Wed, 4 May 1994 11:34:18 GMT Lines: 50 This is three paragraphs of Jane Austen encrypted by the book cipher described in my previous post. This was done by hand with the aid of a couple of bottles of Anchor Steam so there may be a couple of arithmetical and transcription errors, but I doubt that they will prevent solution. In addition, each paragraph is ended with the term "para." The message 2550 bytes, which is somewhat longer than most messages encrypted by this system. Alec 56003 79954 75718 54703 37301 48727 44690 79079 66196 20423 15912 35343 85848 86043 91439 98690 29186 07229 24829 09364 03137 48796 59337 78159 41151 00155 54124 54103 07659 81242 92939 81346 64432 39417 74897 04907 16182 27591 16506 84562 52525 53326 88601 30633 88000 29093 01756 92326 74079 70345 28009 28949 33819 77967 00289 83151 50710 01544 72001 41283 40000 49118 97836 87620 60558 07163 95596 35268 45705 78245 59436 05897 48738 16839 78804 23409 03289 96595 68418 13949 45846 72676 71214 70751 85650 87998 76059 55369 76815 11511 26561 42763 32809 96450 66444 92848 60269 46597 28852 45844 91488 39374 76672 63246 94051 07600 65026 78286 61709 02342 73828 36228 92998 62307 62163 04946 23555 46107 52629 89671 07637 45442 24314 99644 53629 79682 96218 01138 42977 14613 50172 85547 03407 94789 89795 24856 71725 76852 43871 62703 04683 68144 94088 11106 08156 10981 65314 00405 86418 78469 89113 57563 34890 18560 89793 54333 15825 88670 38796 30525 58916 46644 97441 93548 70827 15929 36846 51306 05387 15898 07381 49613 86947 71993 11873 16679 77443 95490 41928 34551 93838 74892 99123 69010 10576 73544 94251 19381 69577 41354 43453 31455 93802 61484 86784 79146 41590 75554 86130 90026 31803 62758 08156 56691 36556 04792 45048 76953 02576 30353 01051 94219 96161 22518 01786 19740 50494 19547 25414 63626 79181 31267 35152 30673 17651 29947 75032 70141 89689 23386 77116 89471 72034 73789 54169 97313 09289 21545 99747 29210 13629 30140 47073 42224 98974 03731 83930 51262 95043 78534 15416 95539 51605 16786 24701 51240 36755 52932 46191 80457 76011 01615 87488 17151 42045 72109 62909 48654 08694 78965 11341 26897 56517 52742 05209 09825 35795 87570 14877 36919 14357 71379 11529 85437 86738 14325 82892 74104 63644 64275 48035 50785 72946 17360 31980 69067 48778 14469 11069 69817 15220 54301 44005 61709 18616 89518 94147 99104 40664 57410 30514 83038 32828 36964 24111 16895 89329 35102 61912 34581 39021 78955 96488 77084 29484 48802 11727 20970 26058 12380 69504 74588 97165 66141 33983 87898 92237 96954 78650 02130 56444 27368 47941 81803 01561 90365 07767 83550 13446 44524 85705 87793 89102 79949 99031 09711 73780 16135 88146 05979 78276 02400 00322 46485 15921 72306 27113 11899 79089 05108 04975 34090 86208 92644 07146 82184 60628 97888 24466 57887 21275 40044 08339 11360 00260 53988 46479 00038 24040 30892 82142 31495 94963 10066 98768 82063 19580 32314 77991 93418 96631 34220 89924 51018 57011 85143 81289 75339 98525 88427 11257 14579 71148 13263 16726 18660 24438 65084 20743 39943 98581 14832 66134 13442 42320