DE1083308B - Method and device for checking the punched strips produced by a cube punch for a random distribution of the hole combinations - Google Patents

Description

GERMAN

kl. 21 a * 21

INTERNAT. KL. H 04 k

PATENT OFFICE

St 14508 VIIIa / 21a ¹

A N M E L D E T A G: NOVEMBER 29, 1958

NOTICE
LOGIN
AND ISSUE OF THE
FROM LE GE S CHRIFT: JUNE 15, 1960

Will be used for telex encryption purposes Key combination sequences or punched tape required, which the individual hole combinations in completely random arrangement included. All possible combinations of holes within the code used must, as they say, be distributed in the punched tape in a purely statistical manner. In special cases Punched tape required, the only twenty-six telex combinations corresponding to the twenty-six Contain letters of the alphabet or ten combinations corresponding to the numbers from 0 to 9, also statistically distributed.

Such so-called key strips are produced by a hole punch with an upstream one Random generator. The combination of both devices is called a dice punch.

It is now an important task to either constantly or but at least randomly to the random distribution of the punched key combinations check. Permanent or temporary failure of the dice punch would if the failure went unnoticed could question the confidentiality of a message.

There is already a test facility for encryption and decryption systems for telex characters Completeness of the elements become known, in which the plain text arriving from the line or the encrypted characters with their character and separating current pulses at the same time with a train of pulses that consists of the code elements of the first category of telex characters is formed and by appropriate conversion consists only of character current pulses, with two additional pulses on a negatively biased one Act on the grid of an electron tube in such a way that ζ. B. if a current step pulse fails in the pulse train the negative grid bias on the grid of the electron tube with simultaneous occurrence a separation current step in a teletype code character of the second category no longer compensated and so the impulse train from a telex character of the second category for completeness is checked.

Furthermore, arrangements for monitoring encryption systems for Hellschreiber are known, in which the quality of the encryption of the characters sent by difference formation through the determination the current surge frequency of the characters transmitted by the transmitter is continuously checked. When falling below a certain frequency an alarm signal or the shutdown of the broadcast is automatic triggered.

It has also been customary to carry out a statistical check during the punching process Procedure and establishment

for checking the from a dice punch

generated punched tape on the random distribution of the hole combinations

Applicant:

Standard electrical system Lorenz

Corporation,

Stuttgart-Zuffenhausen,

Hellmuth-Hirth-Str. 42

Dr. rer. nat. Werner Schiebeier, Eutingen (Bad.), Has been named as the inventor '

and using mechanical counters to count for each punch needle how many holes it is punching. Starting point for This type of test was the consideration that it must be sufficient to test each of the five rows of holes (accordingly the five punch needles and the 5 code) to check for the random distribution of perforations and non-perforations ... If the five rows of holes then diced and punched independently of one another, the resulting thirty-two would also have to be different hole combinations can be randomly distributed in the punched tape.

Closer checks have shown, however, that this independence of the dice for the five Rows of holes do not always have to be present. A mutual influence can e.g. by Couplings are electrical as well as mechanical. A very gross disturbance from mechanical Influence can easily be constructed in thought by assuming, for example, that two or also all five punch needles are rigidly coupled to one another by some erroneous influence. In this Case can be the hole distribution in the individual rows of holes remain entirely random, and an examination of the usual type does not reveal any errors. Nevertheless, the distribution of the thirty-two hole combinations in the entire strip is grossly wrong,

009 530/22 *

because some of the possible combinations are no longer punched at all.

The previously practiced type of control with counting the holes in the five rows of holes is now abandoned. According to the invention, the occurrence of all possible hole combinations within the code used is counted in these assigned counters , and after scanning a defined strip length in the counters in downstream evaluation circuits it is determined whether the counted number of each of the hole combinations is within the set safety limits. If the safety limits are exceeded or fallen short of in one or more meters, it is displayed for which hole combination this is the case, and at the same time a general warning signal is triggered.

In order to be able to make these counts and evaluations, it is either possible directly to electrically connect the five magnets of the hole to a decoder with thirty-two outputs, which converts the telex code into 1-out-of-32, or this decoder to a to connect a separate reading or scanning device. In the latter case, the punched tape is no longer with the perforation itself checked, but only at a later point in time, whereby you can use the punched tape Scan and check speed considerably higher than the original punching speed can.

For the counts, thirty-two counters are connected to the thirty-two outputs of the decoder. These counters can be mechanical or electronic, they can count in decimal, dual or another number system. You can also display the numbers optically or just evaluate them statistically in a mechanical, electrical or electronic manner. According to the invention, however, in addition to a possibly optical display, a statistical evaluation of the strip is carried out automatically, this evaluation according to the invention being based on a certain predetermined and possibly adjustable strip length and thus a defined number of hole combinations.

One embodiment can operate as follows. A first counter counts the total number of punched combinations. When a previously set number is reached, for example JV = 32,000, the counter readings% of the thirty-two remaining counters are queried and evaluated, which individually count the thirty-two hole combinations that occur. Since with random generation of the holes the probability of the occurrence of a certain hole combination is p - - ^ , the thirty-two counters will show on average a number of n = f · JV = 1000 (the numerical value according to the assumed example).

But it is in the nature of chance that large and large deviations (n _t —n) can also occur. The decision as to where the limit of chance lies is at one's own discretion.

It has proven to be useful to choose this limit so that about 5 or 3% of the samples are not within the specified limits. This means that 5 or 3% (depending on the definition) of all punched tapes tested as "suspicious" through an evaluation according to the method according to the invention recognized and then eliminated, even though the appearance of the streak was purely coincidental.

But shouldn't random (i.e. systematic) factors in the combination distribution on the Perforated tapes play a role, so naturally increases the rate of testing and evaluation discarded punched tape. Such values of 5 and 3% as given above are referred to as critical probabilities or safety thresholds, the following is intended in the broader sense below the safety threshold, however, also the value

ίο An = \ ni — n \ , which with a certain assumed critical probability is just permissible as a deviation from η without the perforated tape having to be separated out.

With reference to Fig. 1 is to be explained how a punched tape check and evaluation according to the above Embodiments according to the invention can be made:

The transistors 10 to 17 are pairs of four bistable. Multivibrators (flip-flop) interconnected. The four flip-flops form a dual counter that can count up to 15 in the simplified form assumed. A lamp 5, 6, 7, 8 is inserted in each of the left collector branches to display the counter reading. The transistors 18 and 19 form a flip-flop with which the permitted limit values (in this assumed case according to FIG. 1, these are the values 8 and 11) are determined. The transistors 20 and 21 form a flip-flop which, if the limit values are not complied with, delivers a warning signal after evaluation of the hole mark, in this case it causes its warning lamp 9 to light up. The diodes 32 to 38 form coincidence circuits, the function of which will be explained later. The mode of operation of the circuit according to FIG. 1 is as follows: A punched tape with a hole combination number of N = 304 is to be counted. For a certain combination, which is counted according to FIG. 1, one has in

304

Means a number of n = pN = - ^ --- - 9.5

wait. We allow 8 and 11 as permissible limit values for the evaluation, corresponding to an An = ± 1.5.

Before counting begins, key 31 is momentary

to press. As a result, all flip-flops are brought into the same starting position, in such a way that the transistors on the right are conductive in each case. The pulses to be counted (according to the respective occurrence of the associated combination) are now transferred from the output of the decoder (not shown) to the input of the counter via terminal 2. Each pulse at terminal 2 advances the entire counter by one number, with the first flip-flop counting the ones, the second the two, the third the four and the fourth the eight. The eighth pulse at terminal 2 blocks transistor 17. The resistor 41 is thus no longer connected to ground via the diode 35 and the transistor 17. A negative pulse is sent to the flip-flop 18/19 via the diode 36 and the capacitor 28 . The flip-flop toggles, with the transistor 18 opening. Before the number 12 has now entered the counter of FIG. 1, the strip evaluation is carried out. At the moment when the specified three hundred and four hole combinations have run through the scanning device, a positive pulse (evaluation pulse) reaches terminal 4 from a circuit not shown. The transistor 22 blocks as a result for a short time. However, since the transistor 18 is open, a coincidence at the diodes 37 and 38 is not fulfilled. As a result, no pulse is given to the flip-flop 20/21 via the capacitor 30.

The warning lamp 9 does not light up, and so does the punched tape is found to be good.

However, if the strip evaluation is carried out after the number 12 (or before the number 8) has entered the counter , the function looks different. When the number 12 arrives, the flip-flop 14/15 flips over. The transistors 15 and 17 are now both blocked. The diodes 32 and 33 are therefore both no longer connected to ground (occurrence of coincidence). As a result, a negative pulse is sent to the flip-flop 18/19 via the diode 34 and the capacitor 27. The flip-flop flips and the transistor 18 blocks. Another entry of numbers into the counter no longer affects the flip-flop 18/19.

If the positive evaluation pulse now arrives via terminal 4 and briefly blocks transistor22, so the coincidence at diodes 37 and 38 is fulfilled (both no longer connected to ground). Above the capacitor 30 is given a negative pulse to the flip-flop 20/21. The transistor 20 becomes conductive, and the warning lamp 9 lights up. The punched tape is thus recognized as "suspicious" and can be weeded out.

Analogous to that. Explained, takes place the evaluation instead of when the number 8 has not yet entered the counter. The warning lamp also lights up then 9 on.

If numbers other than 8 and 12 are to be specified as limit values for the evaluation, they are To switch coincidence circuits at the resistors 39 and 41 differently. After adding more Any number between 1 and 15 can be switched as a limit value for diodes.

It remains to be mentioned that the dual counter in FIG. 1 can of course be expanded as desired can and can therefore also allow higher numbers than 15 as a limit value.

Evaluation circuits for any other counter (decimal counter, mechanical Counter).

In the methods described so far, only the statistical evaluation of the thirty-two possible hole combinations is carried out. The method should be modified accordingly if, as already mentioned, there are only 26 or 10 different combinations of holes in the punched tape. However, this does not reveal any periodicity in the punched tape that could possibly be of a very coarse nature. Imagine a punched tape that may periodically contain the hole combinations from 1 to 32 in the same order or alternating from period to period. Such a strip is found to be flawless after the test described so far, because all thirty-two counters show An = O. Nevertheless, the hole combination distribution is not nearly statistical either.

In order to uncover such rough periodicities and also other "accidental deficiencies", according to a Further development of the invention installed a further test circuit with a connected counter. She checks and counts the occurrence of immediate repetitions of the same combinations of holes, so-called "Follow" on the punched tape.

In the case constructed above, a sequence of identical hole combinations does not occur at all. It but it is in the nature of chance that the hole combination a is followed by a one or more times can. These repetitions, also called "sequences", are counted. A hole combination series of, for example

rzykkacccqxbbzzz

contains six sequences and results in six counting pulses that are sent to a counter. These counts can either be obtained by always having two when scanning the punched tape Sign read and match at the same time

ίο be checked, or by storing the w-th hole combinations either before or after decoding until the new (n + l-th) hole combination arrives and the saved w-th and new incoming (fz. + 1- te) hole combination must be checked for conformity. In both cases, each match results in a count. According to a further embodiment of the invention, the counting pulses for the sequences are checked and evaluated in exactly the same way as the pulses for each of the thirty-two hole combinations.

The sequence counter with test circuit can thus again be constructed according to FIG. 1, for example operate.

After the entire perforated tape has been scanned, an electronic check is carried out again to determine whether the number of sequences recorded is within the limits set by the safety threshold, and if necessary a signal is given by the warning lamp9. The probability of a sequence occurring is p = -.

The mean value of all occurring frequencies of sequences is η = φ N.

By checking the sequence of identical hole combinations, not only are rough periodicities (which will hardly occur in practice) uncovered, but the cube punch supplying the paper tape is examined above all to see whether it does not have the property of following the occurrence of a certain one Hole combination with a greater probability than p = —to punch the same hole combination again, or whether this probability is smaller than -. So you check at

the dice-punch something that can be described as "perseverance".

In the case of a punched tape with usually around a hundred thousand hole combinations, it is quite possible that happens to be a relatively long sequence of

so the same hole combinations occurs. So it can happen that five or six times in a row the hole combinations a or Bu are punched. This case can not only be random, but can also be caused by a short-term disruption of the dice punch. Be it that punch needles for a short time jam or that any electrical voltage is temporarily absent as a result of loose contact.

If such a peculiarity, be it accidental, be it due to interference with the dice punch, one or the other occurs twice in the whole punched tape, it will not be avoided by the test methods described so far uncovered. Nor does it have to be revealed because it does not necessarily contradict a random distribution.

Nevertheless, the occurrence of longer consequences in the punched tape for the secrecy of the to be encrypted Message extremely harmful.

Assume that Bu is punched ten times in a row in the punched tape (and Bu is the worst case), then the encrypted one

The message can be read in plain text at this point. One finds unauthorized in a series of "meaningless" letters Readers ten at a time. Letters that make sense, that are legible. If this readable If a piece of the message just contains an important word, the effects can be unpleasant. Does the assumed sequence of identical hole combinations consist not of ten times Bu, but for example from ten times x, the encrypted text is not immediately readable at this point, but can be made immediately legible by recoding the entire ciphertext with the hole combination χ will. In an emergency one would have to have a captured secret message, if the one just described Deficiency of the perforated tape is suspected, try to re-code with all thirty-two hole combinations one after the other and check each time, whether some areas of the message have not become readable.

In order to deactivate this possibility of partial deciphering in any case, according to a further embodiment of the invention, a circuit is inserted in front of the counter for the sequences of identical hole combinations, which gives a warning signal in the event of a longer sequence of identical hole combinations and immediately stops the punched tape in the scanner. The punched tape can then be sorted out. The test circuit can be dimensioned so that the warning signal is given after six or seven identical hole combinations. The warning signal should also appear if only a single change occurs in a hole combination sequence or if abnormal series of sequences arise at all, such as for example

aaaaraaaaa

aaaaccccckkk

35

A possible embodiment of the circuit will be discussed with reference to FIG.

The subsequent counting pulses are sent to transistor 4 via terminal 2 and resistor 17. In this they are amplified and differentiated by the capacitor 9 and the diodes 12 and 13 and converted into alternating current pulses. The negative sequence counting pulses charge the capacitor via the diode 13 10 on. At this occurs under the influence of the impulsive and continuous charging Discharge across the resistors 18 and 19 a sawtooth-shaped voltage curve. Behind the resistor 18 is followed by an emitter-coupled flip-flop circuit formed from the transistors 5 and 6, the acts as a trigger stage. The transistor 5 is normally blocked, the transistor 6 conductive. However, if the base of the transistor 5 is more negative than the associated emitter, the stage flips into the second stable state. This tilting can be caused by the tension on the Capacitor 10 exceeds a certain negative value. About the rheostat 19 can Height of the critical voltage value and also the Discharge time constant of the capacitor 10 can be set. You can do this by setting accordingly of the resistor 19 therefore determine after how many consecutive consecutive number pulses the trigger level should tilt 5/6. If the necessary number of impulses is not reached, it discharges the capacitor 10 again until it is charged again by renewed sequence counting pulses. Man can thus achieve by appropriately adjusting the resistance 19 that occurring in a certain way Clusters of the same hole combinations result in a reversal of the trigger level 5/6 and thus a Cause blocking of the transistor 6.

As soon as the transistor 6 blocks, a negative pulse is applied via the capacitor 11 and the diode 14 given the flip-flop 7/8.

The normal position of this flip-flop, which can be set by pressing key 16, is such that the transistor 7 is blocked and the warning lamp 15 does not light up.

If the negative sequence counting pulse arrives at the base of transistor 7, the flip-flop hits and the warning lamp 15 lights up. An electrical voltage can also be applied to terminal 21 to stop the scanner.

Claims (7)

Patent claims: 1. Procedure for checking the punched tape produced by a dice punch for random Distribution of hole combinations, characterized in that the occurrence of all within of the code used, possible combinations of holes is counted in these associated counters that after scanning a defined strip length in the counters in downstream evaluation circuits it is determined whether the counted number of each of the hole combinations is within the established safety limits, and that if the safety limits are exceeded or fallen below, displayed in one or more counters is used for which hole combination this is the case and at the same time triggers a general warning signal will. 2. The method according to claim 1, characterized in that, in addition, the immediate repetitions of the same hole combinations (sequences) are counted in a separate counter , that after scanning a defined strip length in an evaluation circuit connected to the counter it is determined whether the counted number of sequences within the safety limits and that a general warning signal is triggered if the safety limits are exceeded or not reached. 3. The method according to claim 1 and 2, characterized in that when ■ an ■ undesirable Accumulation of consequences a warning signal is triggered and / or the strip run in the scanning - facility is stopped. 4. A device for performing the method according to claim 1, characterized in that a counter is provided for each possible hole combination, to which a counting pulse is supplied when the associated hole combination occurs, that each counter when a determinable number is reached, an associated bistable switching element in the The working position tilts and when a determinable higher number is exceeded, the bistable switching element tilts back into the rest position, the numbers that are the same for all counters being determined as a function of the total number of hole combinations to be scanned, and that finally gate circuits are connected downstream of the bistable switching elements, via which a warning signal is triggered when the associated bistable switching element is in the rest position after passing through all the combinations of holes to be scanned. 5. Device for performing the method according to claim 1 and 2, using a counter with an assigned bistable switching element and a downstream gate circuit according to claim 4, characterized in that two reading heads are provided in the scanning device are that scan adjacent hole combinations on the punched tape, and that both Read heads are connected to a comparison circuit which, when the scanned hole combinations are identical each triggers a pulse, which are counted in the said counter. 6. Device according to claim 5, characterized in that instead of the second reading head a memory is provided in which a scanned combination of holes is compared with the subsequently sampled combination of holes is stored. 7. Device for performing the method according to claim 1 to 3, using a comparison device according to claim 5, characterized in that the output of the comparison device a counting capacitor is connected downstream, which is charged by successive counting pulses and between two counting pulses is continuously discharged and that a warning signal is given when the charge of the capacitor exceeds a certain value. Considered publications:
German patent specifications No. 855 876, 1 018 452. 1 sheet of drawings © 009 530/224 6.60