CH647367A5 - Method for generating pseudo-random signal sequences - Google Patents

Description

The object leading to the invention was therefore to specify a method in which the time required for successful decoding, even with the fastest computers, is likely to be in the order of magnitude of many thousands of years, with the deciphering security being the same for all setting programs.

It is assumed that the circuit concept of a key computer is known to the analyst. Only the key setting programs with a variety of settings, for example approx. IO30, are unknown.

The object is achieved as described in claim 1. The dependent claims indicate advantageous developments of the method.

Individual embodiments of the invention are explained in more detail below with reference to the figures:

FIG. 1 shows a character generator ZG1, the text sequence of which is changed in a control device X controlled by a second character generator ZG2.

FIG. 2 shows how the text sequence and control characters are taken from a character generator ZG1 and processed in a control device.

FIG. 3 shows a further embodiment of the invention, in which a continuous memory M is connected between the character generator ZG1 and the control device.

FIG. 4 shows a further embodiment of the invention, in which two control devices XI and X2 are connected in series via a continuous memory and each of

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Character generators ZG2 or ZG3 are controlled in order to be derived from a character generator ZG2, for example

To change the text sequence of the character generator ZG1. the counter circuit counts with clock T1 up to that

Figure 5 shows the structure of a control circuit X. set limit at which the control pulse C for the

Figure 6 shows a pulse schedule for a control circuit X gate circuit is delivered.

according to Figure 5. 5 With a suitable clock organization, the goal scarf

Figure 7 shows that the control device also in the timing depending on the variable control word VI ... .Vn

Supply of the first character sequence generating the text sequence after 1.2 ... .2 "step clock T1 opened for one cycle time,

nerators ZG 1 can be turned on. FIG. 6 shows an example of a pulse schedule for a control

FIGS. 1 and 2 each show a control device circuit X according to FIG. 5.

X with a data input E, a data output A and an i0 Figure 7 shows how the control circuit X also in the clock-nem control input S, which an original text sequence taken from a line supply line for the character generator ZG1 generating the text sequence within the predetermined Chengenerator ZG1 can be switched. The given limit values gl and g2 of a clock pattern are thinned out, in the control circuit in turn controlled by a second character generator dependence on a time-variable control variable from gate ZG2. The control circuit X influences a further character generator ZG2 or from the character 15 clock supply of the first character generator ZG1 in the generator ZG 1. In such a way that it carries out between 1 and 2n work steps per output in a further embodiment of the invention according to the character. In this way, the number of FIG. 3, the original character sequence from the character of the character sequence generated in the character generator ZG1 of the text sequence generator ZG 1 is varied in a continuous manner in a continuous memory M.

stores and read out by a control device which, in the method according to the invention, uses the memory addresses and / or the read-out times in reading-out processes in order to extract text elements from a

depending on a time-variable control variable from the ZG1 calibration generator. A text Txl nem character generator ZG2 is determined. from a character generator ZG1 into a changed text

In a further embodiment according to FIG. 4, a Tx2 is transferred, the text Tx2 resulting from the selection of Txl first control device XI, the characters of a character generator.

tors ZG1 different inputs at different times. This can be carried out in different ways and assigned to a memory M by a beadressen:

second control device X2 is read out again at different times from different readout addresses, with a) the gate circuit being connected to the data output of a time

the control devices XI or X2 are connected to independent control generators ZG1,

Variables S1 from the character generator ZG2 and with independent b) the gate circuit is switched in the clock supply line dependent control variables S2 from the character generator ZG3 for the character generator ZG1 that the generator are supplied. between 1 and 2n work steps per character output

The basic mode of operation of a control circuit X is carried out (FIG. 7),

shown in Figure 5. A gate circuit T switches the 35 c) the gate circuit (s) will be in a suitable manner

Data input E to data output A as a function of loading and / or unloading a buffer memory M for the control signal C. The control signal C is switched from a key text data.

Counter circuit Z derived, which is composed, for example, of n binary stages. The counter Z is continued with a clock T1. In case a) and b) the quantity of the selected text is switched, which corresponds to the query clock of a character generator ZG140 Tx2 smaller than the quantity from the character generator. The counter circuit emits a control pulse C, text Txl that can be added. In this case, you can also say when a defined limit address has been reached in the counter. the text Tx2 is formed by thinning out the text Txl

The counting circuit Z in is obtained via a circuit R.

agreed time intervals with the clock T2 that is formed. In case c), the text Tx2 also arises from a selection from, for example, TJ or * 1, depending on the original text Txl. The amount of text Tx2

2n 2n-p '6 & can, however, be either smaller or the same size or also large

Control characters VI ... .Vn to a value MAj ... .MAn earlier than the amount of the original text Txl. This is set, which lies between the counter positions 0 and 2n (depending on the temporal conditions in which the he = 1, 2, 3, ...; p = 1, 2, 3, ...) . imagined buffer memory M with the text Txl inscribed

Based on this preset value, which is read out again by querying the text sequence Tx2.

C.

2 sheets of drawings

Claims (7)

647367 PATENT CLAIMS 1. A method for generating randomly similar character strings for the encryption of message texts using character generators which, when switched through a clock generator according to a predetermined, partially adjustable education law, deliver repeatable text strings of a long period, characterized in that an original text string of a first character generator (ZG1) by Time-dependent selection of text elements depending on a time-variable control variable from at least one character generator (ZG1, ZG2, ZG3) by at least one control device (X, XI, X2) with a data input (E), a data output (A) and a control input (S) is changed. 2. The method according to claim 1, characterized in that the number of elements of the original text sequence taken from the first character generator (ZG1) is reduced within predetermined limit values of a clock pattern. 3. The method according to claim 1, characterized in that the original text sequence from the first character generator (ZG1) is temporarily stored in a continuous memory (M) and read out by a control device (X), and that this control device (X) stores the addresses and / or determines the readout times as a function of a time-variable control variable from a second character generator (ZG2) (FIG. 3). 4. The method according to claim 1 or 2, characterized in that a first control device (XI) the text sequence of a first character generator (ZG1) at different times assigned different input addresses of a memory (M) and by a second control device (X2) at different times various readout addresses are read out again, the first control device (XI) being supplied with a first independent control variable (S1) from the second character generator (ZG2) and the second control device (X2) with an independent control variable from a third character generator (ZG3) (Fig 4). 5. The method according to any one of the preceding claims, characterized in that the control device (X) carries out the following method steps: a circuit (R) sets the preset of a counting circuit (Z) to a specific value with the clock (T2) depending on a control variable (Vn) at specific time intervals, - With a clock (Tl) advanced counter circuit (Z) emits a control signal (C) when the value set by the circuit (R) is reached. - The control signal (C) controls a gate circuit (T) which switches the text sequence from the data input (E) to the data output (Fig. 5). 6. Arrangement for performing the method according to claim 1, wherein the arrangement of two character generators (ZG1, ZG2) a control device (X) with a data input (E), a data output (A) and a control input (S) and a clock generation circuit (clock ), characterized in that the control device (X) controlled by the second character generator (ZG2) is connected to the clock supply line for the first character generator (ZG1) in such a way that this character generator (ZG1) carries out between 1 and 2n work steps per character output (FIG . 7). For the encryption of information in encryption devices, randomly similar character strings are required, which can be produced with the help of a suitable character generator and an adjustable program at any location in any quantity and speed for encryption or decryption of messages. The term «random strings» hides a variety of crypto technology requirements for the key texts to be created. As a counterpoint to crypto technology, cryptanalysis has set itself the task of decrypting encrypted texts - cracking the code - or to determine the education law from a certain amount of key text, to calculate the continuation of the texts and to apply them to further encrypted parts of the message. Cryptanalysis has made great strides since it has been possible to use electronic computing systems to process analysis programs that can perform many thousands of arithmetic operations per second. Therefore, when developing encryption methods and devices, the possibilities of cryptanalysis with today's computer systems and computers that will work even faster in the future must be taken into account. The requirements for a method for generating randomly similar strings can be summarized in the following keywords: a) Long period (quasi infinite) b) Repeatability c) Statistical, i.e. Test behavior approximating a real random text d) Complex educational laws e) A multitude of setting options through programs f) High working speeds g) Predictable decipherability h) Realization with economically viable effort From DE-PS 24 51 711, for example, a method is known which can largely meet the requirements a) ... f). Due to the advances in the field of cryptanalysis that have developed with the use of fast computer technology, the requirement g) decryption security must be given greater importance and the existing methods improved with economically viable effort.