#### Topic: To distinguish the oblate data from the ciphered?

Who clever, prompt Subj. At least  archivers (and formats with the built in compression), but without the analysis of titles etc., only on character of the data. Except attempt to compress all given/is casual selected pieces an arithmetical compression - it is more than nothing on mind goes.

#### Re: To distinguish the oblate data from the ciphered?

Hello, IID, you wrote: IID> Except attempt to compress all given/is casual selected pieces an arithmetical compression - it is more than nothing on mind goes. And attempts to compress the ciphered data in what do not result.

#### Re: To distinguish the oblate data from the ciphered?

Hello, Nik, you wrote: N> Hello, IID, you wrote: IID>> Except attempt to compress all given/is casual selected pieces an arithmetical compression - it is more than nothing on mind goes. N> and attempts to compress the ciphered data in what do not result. If the data before compression had  a type, this method that does not give.

#### Re: To distinguish the oblate data from the ciphered?

Hello, Nik, you wrote: IID>> Except attempt to compress all given/is casual selected pieces an arithmetical compression - it is more than nothing on mind goes. N> and attempts to compress the ciphered data in what do not result. And compressed by normal algorithms - though it is a little, but . Since arithmetics closely costs to theoretical to a limit for compression, and to it nobody presses, because of it .

#### Re: To distinguish the oblate data from the ciphered?

Hello, Qulac, you wrote: Q> If the data before compression had  a type, this method that does not give. Erratic actuating on such data - not a problem. We can suppose with confidence that the data interesting us - not noise.

#### Re: To distinguish the oblate data from the ciphered?

Hello, IID, you wrote: IID> Hello, Qulac, you wrote: Q>> If the data before compression had  a type, this method that does not give. IID> erratic actuating on such data - not a problem. IID> we can suppose with confidence that the data interesting us - not noise. Well still it is possible to add what be methods of static analysis, type here it: Testing of pseudorandom sequences

#### Re: To distinguish the oblate data from the ciphered?

IID> At least  archivers (and formats with the built in compression), but without the analysis of titles etc., only on character of the data. Zip-archiving is an enciphering by means of variable length codes of Haffmena.

#### Re: To distinguish the oblate data from the ciphered?

Hello, IID, you wrote: IID> At least  archivers (and formats with the built in compression), but without the analysis of titles etc., only on character of the data. I think that if to apply to the data any statistical techniques the ciphered data will be more similar on casual, than archived. But the difference will be not so great.

#### Re: To distinguish the oblate data from the ciphered?

Hello, Pzz, you wrote: Pzz> I think that if to apply to the data any statistical techniques Is is more specific... Pzz> the ciphered data will be more similar on casual, than archived. But the difference will be not so great. In it and a problem

#### Re: To distinguish the oblate data from the ciphered?

Hello, IID, you wrote: IID> And compressed by normal algorithms - though it is a little, but . Since arithmetics closely costs to theoretical to a limit for compression, And paternal there is a confidence, what ? Arithmetics is a method of entropy encoding. And that compression worked before it there should be a unit predicting probabilities. And this unit knows a lot of very important about the nature of the initial input data. That is in practice it select a miscellaneous at coding, for example, audio, the text or the machine code. But what character the data before enciphering/compression had it is not known, and without it it is necessary to use only the general methods of a prediction like PPM. But they simply will not have length of already oblate data that will be trained to predict something acceptable. Well that is even if to go on this way arithmetical coding here as though appears superfluous: After all simply enough to launch PPM on sequence and to look at the found regularities (if they are - the sequence means more likely it is not ciphered, and on the contrary). And to launch compression through arithmetics it is not so necessary. IID> and to it nobody presses, because of it . Well in itself arithmetics not so slow. It is quite comparable with the same classical coding of Haffmana. It is unpopular more likely for the historical reasons: for example because of problems with patents in some countries.

#### Re: To distinguish the oblate data from the ciphered?

Hello, IID, you wrote: IID> At least  archivers (and formats with the built in compression), but without the analysis of titles etc., only on character of the data. IID> except attempt to compress all given/is casual selected pieces an arithmetical compression - it is more than nothing on mind goes. Generally in any way. It is possible to try all possible , and then to look, it will be unpacked or not, and if yes that turns out.

#### Re: To distinguish the oblate data from the ciphered?

Hello, IID, you wrote: IID> At least  archivers (and formats with the built in compression), but without the analysis of titles etc., only on character of the data. Normally  the histogram of a section of the data if there are no selected values that the data are packed or ciphered. Other variant entropy to count S =-sum (p [i] *ln (p [i])). Archives have areas where the data is predicted, any tables and tables of contents as a variant to search for entropy dips in a flow  at the scrambled dips will not be. Other variant under signatures if there are the characteristic sequences. It is possible to select a row of characteristics of a data stream and   on test dial-ups. But 100 % of a variant will not be anyway.

#### Re: To distinguish the oblate data from the ciphered?

Hello, kov_serg, you wrote: _> Hello, IID, you wrote: _> Other variant entropy to count S =-sum (p [i] *ln (p [i])). Archives have areas where the data is predicted, any tables and tables of contents as a variant to search for entropy dips in a flow  at the scrambled dips will not be. More likely on the contrary, entropy at oblate files will be more less identical in the field of the data, and at scrambled dips since at the scrambled data repetitions of sequence byte are possible are possible, at compressed such possibility is extremely small.

#### Re: To distinguish the oblate data from the ciphered?

Hello, vladimir.romin, you wrote: VR> Hello, kov_serg, you wrote: _>> Hello, IID, you wrote: _>> Other variant entropy to count S =-sum (p [i] *ln (p [i])). Archives have areas where the data is predicted, any tables and tables of contents as a variant to search for entropy dips in a flow  at the scrambled dips will not be. VR> is faster on the contrary, entropy at oblate files will be more less identical in the field of the data, and at scrambled dips since at the scrambled data repetitions of sequence byte are possible are possible, at compressed such possibility is extremely small. Simply try on the real data.

#### Re: To distinguish the oblate data from the ciphered?

Hello, vladimir.romin, you wrote: VR> and at scrambled dips since at the scrambled data repetitions of sequence byte In practice such only at ECB are possible are possible it is possible to meet. That, really, it is visually possible to see on an example of enciphering of pictures: https://en.wikipedia.org/wiki/Block_cip … _.28ECB.29 That is so feeble ciphers will be defined only: well who, seriously, will cipher small units in mode ECB?

#### Re: To distinguish the oblate data from the ciphered?

Hello, watchmaker, you wrote: W> Hello, vladimir.romin, you wrote: VR>> and at scrambled dips since at the scrambled data repetitions of sequence byte W> In practice such only at ECB are possible are possible it is possible to meet. That, really, it is visually possible to see on an example of enciphering of pictures: https://en.wikipedia.org/wiki/Block_cip … _.28ECB.29 W> That is so feeble ciphers will be defined only: well who, seriously, will cipher small units in mode ECB? ... Generally all not so is simple. For example if we cipher sequence of zero algorithm with a key finite are long, we receive periodic sequence, after all differently at us would be then the ideal generator of random numbers.