snow - vloženie správy do medzier v texte

8.3.2017 13:13 | Přečteno: 1999× | Linux | | poslední úprava: 9.3.2017 10:43

snow je šikovný nástroj ktorý slúži na ukrytie textovej správy do medzier textového súboru.

Tajná správa:

Zajtra zdraží pivo

Text s vloženou tajnou správou:

Obedové menu
Polievka 0,33 Hrachový krém s pažítkou 
Hlavné jedlo 120/200 Pleskavica z teľacieho mäsa
dusená ryža, peperonáta a smotanový dressing 
Ponuka ľahkých jedál 250 Miešaný zeleninový šalát,
grilované kuracie prsia, dressing 250 Mišaný zeleninový šalát, 
grilované kúsky lososa, dressing 120/200 Grilovaný losos, 
zemiaková kaša, restované fazuľkové kúsky, omáčka z lesných húb

Ako na to:

./snow -C -m "Zajtra zdraží pivo" -p "heslo" sprava.txt sprava.txt.snow

ukrytie tajnej správy do textového súboru sprava.txt 
sprava.txt.snow je textový súbor s vloženou tajnou správou
-C použije kompresiu
-m text tajnej správy ktorú chceme vložiť
-p použije heslo na zašifrovanie tajnej správy

./snow -C -p "heslo" sprava.txt.snow
Zajtra zdraží pivo
získanie ukrytej správy z textového súboru sprava.txt.snow

Balíčky .deb - ak použijeme deb balíček program snow má meno stegsnow
https://packages.debian.org/jessie/stegsnow

Webstránka snow programu
http://www.darkside.com.au/snow/

manual
http://www.darkside.com.au/snow/manual.html

man

snow [ -CQS ] [ -p passwd ] [ -l line-len ] [ -f file | -m message ] [ infile [ outfile ]] 

Description

snow is a program for concealing messages in text files by
 appending tabs and spaces on the end of lines, and for 
extracting messages from files containing hidden
 messages. Tabs and spaces are invisible to most text viewers hence the 
 steganographic nature of this encoding scheme.

The data is concealed in the text file by appending sequences of up to 7 spaces, 
 interspersed with tabs. This usually allows 3 bits to be stored every 8 columns. An 
 alternative encoding scheme, using alternating spaces and tabs to represent zeroes and ones, 
was rejected because, although it used fewer bytes, it required 

more columns per bit (4.5 vs 2.67).

The start of the data is indicated by an appended tab character, which allows the
 insertion of mail and news headers without corrupting the data.


snow provides rudimentary compression, using Huffman tables optimised for English
 text. However, if the data is not text, or if there is a lot of data, the use of the
 built-in compression is not recommended, since an external compression
 program such as compress or gzip will do a much better job.

Encryption is also provided, using the ICE encryption algorithm in 1-bit
 cipher-feedback (CFB) mode. Because of ICE's arbitrary key size, passwords of any length
 up to 1170 characters are supported (since only 7 bits of each character are used,
 keys up to 1024-bytes are supported).

If a message string or message file are specified on the command-line, snow will
 attempt to conceal the message in the file infile if specified, or standard input 
otherwise. The resulting file will be written to outfile if specified, or
 standard output if not.

If no message string is provided, snow attempts to extract a message from the input 
 file. The result is written to the output file or standard output.

Options

-C
    Compress the data if concealing, or uncompress it if extracting.

-Q
    Quiet mode. If not set, the program reports statistics such as compression
 percentages and amount of available storage space used.

-S
    Report on the approximate amount of space available for hidden message in the
 text file. Line length is taken into account, but other options are ignored.

-p password
    If this is set, the data will be encrypted with this password during concealment,
  or decrypted during extraction.

-l line-length
    When appending whitespace, snow will always produce lines shorter than this
 value. By default it is set to 80.

-f message-file
    The contents of this file will be concealed in the input text file.


-m message-string
    The contents of this string will be concealed in the input text file. Note that,
 unless a newline is somehow included in the string, a newline will not be
 printed when the message is extracted. 

Examples

The following command will conceal the message "I am lying" in the file infile, with
 compression, and encrypted with the password "hello world". The resulting
 text will be stored in outfile.

    snow -C -m "I am lying" -p "hello world" infile outfile 

To extract the message, the command would be

    snow -C -p "hello world" outfile 

Note that the resulting message will not be terminated by a newline.

To prevent line wrap if text with concealed whitespace is likely to be indented by
 mail or news readers, a line length of 72 or less can be used.

    snow -C -l 72 -m "I am lying" infile outfile 

The approximate storage capacity of a file can be determined with the -S option.

    snow -S -l 72 infile 

       

Komentáře

[Ladislav Hagara]

Steganografie v Linuxu (stránka 21)

[sk7]

Vďaka za odkaz ,pan Hagara

[Josef Kufner]

Tip: Než někam vykopíruješ man nebo něco podobného z terminálu, zúži okno na cca 50 znaků.

[Vilda]

grilované kúsky lososa

ti Slováci se vskutku zmáhají. Ještě před 30 lety taková zanedbaná země a dneska si dávají v restauraci lososa.

Ale jinak díky za zajímavou informaci.

[Peter Golis]

Pred tridsiatimi rokmi bolo Slovensko súčasťou Československej Socialistickej Republiky.

[._]

ano, jeji zaostalou, rozvojovou, z ceska dotovanou casti

[tomvec]

A teď jezdí Češi pracovat na Slovensko...

[._]

fakt, a proc je praha plna slovaku (hlavne za pokladnami supermarketu)?

[tomvec]

Protože tam studují a chodí si přivydělávat?

[Peter Golis]

Áno. A popri štúdiu si privyrobia tak, že ich nezruinuje v dnešnej dobe už bežné jedlo z lososa.