CH628760A5 - Method of encrypting and then decrypting message signals - Google Patents

Description

628 760 2

PATENT CLAIMS correspond to the numerical sequence, so that the sub-frequency band

1. The method for obfuscation and subsequent Ent- time elements appear time-inverted at the signal output, blurring of message signals, characterized. 10. Method according to claim 5, characterized in that time scrambling and frequency band swapping that the storage of the sub-frequency band time elements are used together, that for this purpose the messages are changed once in their natural chronological order and then signals on the transmission side within a repeating time sequence.

cut into n time elements and within a frequency band 11. The method according to claim \, characterized in that the cut-out is divided into m sub-frequency bands, whereby in a first processing step n and m are natural numbers for each column / row, that by itself - The matrix from a predetermined amount of effective fre-fetching time period characterized block of messages an io quenzverwechsel / time scrambles each one selected (n • m) matrix with n • m sub-frequency band time elements, after which the elements of the respective column / row ent-that with the help of a quasi-random generator the individual parts are converted accordingly, that afterwards in a second frequency band time elements within the (n • m) matrix, quasi-processing step for each row / column of the resulting one changes randomly, whereby each of the n • m places only matrix also effective from one of the partial frequencies from a predetermined amount Frequency band time elements taken 15 time scrambling / frequency band swapping one can be interpreted that on the receiving side with the help of a glei- is selected, after which the elements of the respective line /

If the quasi-random generator exchanges the space within the column of the matrix, this double of the (n • m> matrix is undone and the transformation of the matrix for each message block a new natural message flow is selected. And that this twice reformed matrix is split

2. The method according to claim 1, characterized in that 20 is read out ten times.

that the message signals are divided into time elements of the same duration (T) 12. The method according to claim 11, characterized in that the time elements are divided into sub-frequency bands, that the matrix conversion is carried out several times, the same bandwidth (B), and that partial fre- 13 Claim 11, characterized in

quenz bands of several time elements simultaneously to transmit the matrix transformation carried out in one step. Turns 25.

3. The method according to claim 1, characterized in that the method according to claim 11, characterized in that the number m of the partial frequency bands is 5. that as an initial matrix for scrambling the next post

4. The method according to claim 1, characterized in that the end matrix of the preceding message aligns that the number n of time elements is equal to 8. blocks is used.

5. The method according to claim 1, characterized in 30 15. The method according to claim 11, characterized in that the message signal for decomposition into the sub-frequency that is newly selected for each message block, whether implemented in the band with the aid of several carrier frequencies, the first processing step Rows and in the second processing step, the respective sub-frequency band is exchanged by the same processing step, or vice versa. Filter is obtained in the same frequency position,

that the sub-frequency band is stored in a memory

is saved and, after being read out of the memory, is brought into a new frequency position by renewed frequency conversion with the aid of several carrier frequencies. For concealment and subsequent unveiling

6. The method according to claim 1, characterized by message signals, the methods of time discarding that the information content of the subbands for storage in 40 lung and the frequency band swapping are known.

digitized a memory and after reading from the. B. the transfer

Memory is converted back into an analog signal. bandwidth of the signals into a number of equally wide

7. The method according to claim 1, characterized in divided channels. By means of a quasi-statistical character string that the message signal is converted with the aid of an analog / digital converter by frequency converters at certain time intervals into digital values in sample values represented by dual numbers, the frequency places of the subchannels. It is established that the frequency conversion by multiplication interchanges the binary characters of the quasi-random generator of these sequences of numbers with samples of the corresponding fixed. The exchange at the receiving end of the

Numerical sequences representing carrier vibrations are carried out in their natural position by reversing the fact that digital reverse application of one of the transmission-side string iden filters is used to obtain the partial frequency bands, these partial frequency bands being a 50 table quasi-random sequence.

The sequence of samples results in the form of dual numbers. With time scrambling methods, individual time elements are stored within a period in which the sub-frequency bands are exchanged in a periodic period so that the sub-frequency bands are read out from the memory according to the instructions of a quasi-random generator Multiplication with swaps and swapped back at the receiving end. Binary number sequences representing carrier vibrations are reversed. A major disadvantage of the known obfuscation is that the partial methods available as binary number sequences consist in the relatively easy detectable frequency bands, and their sum in one unit of the plain text from the disguised signal. Digital / analog converter back into an analog signal. This is especially true when converting in a narrowband that is transmitted to the receiver. gen transmission channel must be transmitted, because here the

8. The method according to claim 5, characterized in that the number of subchannels cannot be selected to be sufficiently large that the subfrequency band time elements can be stored. In the case of time scrambling, the still reasonable intermediate memory address control of a monotonically increasing memory storage time sets the number of time elements to a clear natural sequence of numbers, so that the partial frequency limit.

band time elements in a natural temporal sequence on The task leading to the invention was to develop a

Signal output appear. 65 for the obfuscation of messages and subsequent

9. The method according to claim 5, characterized in that the haze indicates that the two previously known methods — that drive when storing the sub-frequency band time elements, time scrambling and frequency band interchangeability — combine the memory address control of a monotonously falling natural type with one another in multiples safety

3,628,760

against unauthorized unveiling. log demultiplexer ADMX runs synchronously with the analog

The problem is solved as in claim 1 plexer AMX and carries the samples to the partial frequency

described. Appropriate designs are described in the band passports BFA1 to BFAm assigned to them, to which they are described. downstream are the ring modulators MAI to MAm,

Embodiments of the output-side summary of the starting point of the method according to the invention are explained in more detail below with the aid of the figures. The transmission signal generates a low pass in the transmission part, gen: A transmission signal generated in this way is now generated in reception mode

Figure 1 a, the possible division of another device to be transmitted fed in point E, the signal message in n time elements of duration T and m the same partial frequency processing as in transmission mode, except that the quasi-frequency bands of bandwidth B in the Frequency-time level. io random generator of the receiver instead of the exchange

FIG. 1b shows the possible scrambling of the (n * m) partial fre-matrix according to FIG. 1c, the inverse for this purpose, which quenzband time elements are delayed by an intermediate storage step when the time is used successively (with respect to scrambling and frequency band swapping. - against transmission) Addressing the message

1 c controls the possible scrambling of the (n • m> partial memory). In reception mode, the two quenz band time elements are to be switched to FIG. 2 according to the Veris switch according to the invention, and it must also be assumed that the quasi-random number generators are used synchronous

Figure 2 shows schematically a not fully digital working. This is e.g. B. caused by a preamble synchronization in leadership example of a concealment device after inventing every change of direction.

mixing process according to the invention, which can be used for sending and receiving by appropriate address inversion on the message. 20 buffers and by switching the carrier

FIG. 3 schematically a fully digitally working embodiment of the ring modulators, it is also possible to send out a tape inversion example of a concealment device according to the invented and time-inverted message elements, the mixing method according to the invention, which uses the inventive embodiments shown in FIG. 3 for sending and receiving can be. Example of an encryption device after the mixing

If a message block according to FIG. 1 a and 25 are now moved, the result does not differ from the device shown in the time scrambling method and then the device shown in FIG. The implementation uses quenzband swapping here or vice versa, so instead of individual ring modulators and bandpasses of a digital one, the transformed post-multiplier ME that is being transmitted speaks and a digital low-pass filter DTP1, which block in the illustration in FIG. 1 b. All band elements half of the analog / digital converter AID immediately following within a time element of the duration T are connected according to the 30 th analogue input low-pass TPE again band elements this, although it is time. The multiplier ME serves as a modulator on which of the scrambled time element. An exchange of the band elements digital low pass DTP1 is connected. The digital realization with such other time elements does not take place, conditional has the advantage that the mixer ME and the digital low due to the additive superimposition of both processes. pass DTP1 can be used multiple times in time multiplex,

The method according to the invention achieves a complete scrambling of the partial frequency band time elements within frequency bands in time division multiplex in the same frequency position before the message block at the output of the digital low pass DTP1. The disadvantage of the additive. The individual digitized carriers for the multiplier ven superposition (FIG. 1b) are stored in the sin / cos table SCT by the advantageous full ME.

constant mixing replaced, as shown in Figure 1 c. The cos table is required because the implementation of the

The method according to the invention will now be explained in more detail with reference to a single sideband extraction according to the phase method of the weaving exemplary embodiment according to FIG. 2. ver (D.K. Weaver jr .: «A third method of generation and detec-

The message signal to be transmitted is carried out in the device shown in FIG. Of single sideband signais, Proceedings of IRE, Dec. 1956, 2 at E (input low pass ETP (pages 1703 to 1705)). In this case, the signal to be implemented is routed and modulated on the output side to the inputs of the ring modulators MEI up to 45 of the same frequency that are in the middle of the band, which are required to form the m signal in two channels with one cos or sin oscillation sub-frequency bands. Forwarded from M Em. Each of the ring modulators is a band - the resulting modulation product is then followed by filters BFE1 to BFEm, as a result of which the m partial frequencies are removed by means of low-pass filters to remove the sum frequencies. The frequency bands in identical frequency position on m input line signals of these filters will then be applied with one gene each from an analog multiplexer AMX. At the output of the sin or cos oscillation of the same frequency, which up to now lies analog / digital 50 downstream of the analog multiplexer, in which the signal is converted by the converter A / D, the signal with the sampling frequency mul appears - should, modulated. The sum of the resulting modular time-division multiplex signal of the sub-frequency bands in digitization products finally represents the new frequency band, in a standardized form. In a first intermediate storage step, the original signal was converted, the message storage matrix according to FIG. 1 a is filled. If, in the modulation on the output side, the sin and a second buffering step for the next 55 cos oscillation are interchanged, the sum of the message block provides the buffering according to the new frequency band in the inverted frequency position.

Figure 1 c, before the writing into the memory cells, the adaptation of the bit rate to the message flow such content is queried and is passed on to the digital / analog converter D / A by storing at least every 'A-m-th. In the following buffer sample in the message memory matrix. Since this step is carried out again according to FIG. 1 a, then the sampling frequency is reduced to a new mix of the signal according to FIG. 1 c, etc., this must be done by restoring the

The read-in / read-out scheme according to FIG. C is reversed by a bit rate on the digital low-pass filter DTP2 who controls the quasi-random generator which quasi-coincident. The digital low-pass filter DTP2 is followed by the digital distribution of the sub-frequency band elements within the output multiplier MA, it multiplies the number matrix, which, in relation to the signal output, results in a full value of the digital low-pass filter DTP2 with the same numerical mixture of the methods Frequency band trust like the digital input multiplier. That leads to digital research and time scrambling. Output multiplier MA combines the following accumulator

The Ana- downstream of the digital / analog converter D / A, the subbands back to the "scrambled" or "descrambled"

628 760 4

»News channel, which is selected by the digital analogue. The elements of a row / column of the converter D / A and the subsequent analog low pass matrix are selected according to the order of the

TPA switched back as an analog signal in point A of the circuit. In a second processing

pending. The partial frequency band inversion occurs here in the training step by the key provider for the columns / rows

Contrary to the circuit example in FIG. 2, by backmixing the intermediate matrix, one frequency band swap / time

Calculation of the scrambling / multiplication of time bands stored in the digital multiplier by multiplication with digitized sin carriers from a predetermined set of effective partial frequency bands.

ME selected using digital cos carriers and vice versa in the digital gene. The elements of the columns / rows of the intermediate

Multiplier MA, what about the output control of the look-up matrix are according to the order of the

straightening memory matrix is easy to implement. All other io sought exchanges.

Considerations are analogous to the description of the implementation. If the frequency bands are exchanged in accordance with FIG. 2 and the time is exchanged in the second processing step. A further exemplary embodiment avoids the crypto-scrambling, results in a different matrix of gically ineffective interchanges that are pure with the abundance statically than in the reverse order of the processing steps, static interchanging of the elements of the (n • m) matrix even if the same frequency band interchanges and times could occur and thus the security of the scrambling was selected.

veil. Is used as the initial matrix for the scrambling

This improvement is achieved in that in one of the next message blocks the end matrix of the previous

first processing step from a key provider for each message block, then there is the advantage that

Row / column of the matrix each have a time scrambling / frequency 20 for the intermediate storage of the message elements only a band swapping from a predetermined amount of effective time scrambling / frequency band swapping required for the elements of a message block.

t

G

3 sheets of drawings