Linguistic Steganography: Information Hiding in Text sc609/talks/  · PDF fileLinguistic Steganography: Information Hiding in Text Stephen Clark and Ching-Yun (Frannie) Chang University

Linguistic Steganography: Information Hiding in Text

Stephen Clark and Ching-Yun (Frannie) ChangUniversity of Cambridge Computer Laboratory

Edinburgh, May 2012

Intro Ling Steg Lex Sub 2

Information Hiding

My friend Bob, until yesterday I was using binoculars for stargazing.Today, I decided to try my new telescope. The galaxies in Leo andUrsa Major were unbelievable! Next, I plan to check out some nebulasand then prepare to take a few snapshots of the new comet. AlthoughI am satisfied with the telescope, I think I need to purchase lightpollution filters to block the xenon lights from a nearby highway toimprove the quality of my pictures. Cheers, Alice.

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 3

Information Hiding

My friend Bob, until yesterday I was using binoculars for stargazing.Today, I decided to try my new telescope. The galaxies in Leo andUrsa Major were unbelievable! Next, I plan to check out some nebulasand then prepare to take a few snapshots of the new comet. AlthoughI am satisfied with the telescope, I think I need to purchase lightpollution filters to block the xenon lights from a nearby highway toimprove the quality of my pictures. Cheers, Alice.

mfbuyiwubfstidttmnttgilaumwuniptcosnatpttafsotncaiaswttitintplpftbtxlfanhtitqompca

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 4

Information Hiding

My friend Bob, until yesterday I was using binoculars for stargazing.Today, I decided to try my new telescope. The galaxies in Leo andUrsa Major were unbelievable! Next, I plan to check out some nebulasand then prepare to take a few snapshots of the new comet. AlthoughI am satisfied with the telescope, I think I need to purchase lightpollution filters to block the xenon lights from a nearby highway toimprove the quality of my pictures. Cheers, Alice.

mfbuyiwubfstidttmnttgilaumwuniptcosnatpttafsotncaiaswttitintplpftbtxlfanhtitqompca

= 3.141592653589793 . . .

buubdlupnpsspx

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 5

Information Hiding [Fridrich, 2010]

My friend Bob, until yesterday I was using binoculars for stargazing.Today, I decided to try my new telescope. The galaxies in Leo andUrsa Major were unbelievable! Next, I plan to check out some nebulasand then prepare to take a few snapshots of the new comet. AlthoughI am satisfied with the telescope, I think I need to purchase lightpollution filters to block the xenon lights from a nearby highway toimprove the quality of my pictures. Cheers, Alice.

mfbuyiwubfstidttmnttgilaumwuniptcosnatpttafsotncaiaswttitintplpftbtxlfanhtitqompca

= 3.141592653589793 . . .

buubdlupnpsspxattack tomorrow

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 6

Steganography

Steganography is a branch of security concerned with hidinginformation in some cover medium

Use of images for hiding information has been extensively studied

Make changes to an image so that the changes are imperceptibleto an observer

The resulting image encodes the message

A related area is watermarking, which is concerned with hidinginformation for the purposes of identification (e.g. copyright)

or e.g. identifying Google translations

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 6

Steganography

Steganography is a branch of security concerned with hidinginformation in some cover medium

Use of images for hiding information has been extensively studied

Make changes to an image so that the changes are imperceptibleto an observer

The resulting image encodes the message A related area is watermarking, which is concerned with hiding

information for the purposes of identification (e.g. copyright) or e.g. identifying Google translations

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 7

The Cover Medium

Advantages of images

local changes can maintain global properties of the image easy to make changes which are imperceptible to a human

Disadvantages of images

sender needs an image sender needs to transmit image to the receiver

Text is everywhere - why not conceal information in a cover text?

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 8

Example using Lexical Substitution

Cover text:

Which is why, some would say, its slightly odd that when no less anauthority than the chairman of the Financial Services Authority, LordTurner, questions the social utility of much activity in financialmarkets, and also suggests that it might be no bad thing to levy a tinyTobin tax on all this frenetic trading in electrons, well its curious thatthe chancellor of the exchequer (who could use a bob or two) doesntlick his chops and demand a bit of that.

Secret bitstring: 0 1 1 0 0 0 1 0

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 9

Example using Lexical Substitution

Data Embedding:

Which is why, some would say, its fairly odd that when no less anauthority than the chairman of the Financial Services Authority, LordTurner, questions the social utility of much activity in financialmarkets, and also suggests that it might be no bad thing to levy a tinyTobin tax on all this frenetic trading in electrons, well its curious thatthe chancellor of the exchequer (who could use a bob or two) doesntlick his chops and demand a bit of that.

Secret bitstring: 0 1 1 0 0 0 1 0

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 10

Example using Lexical Substitution

Data Embedding:

Which is why, some would say, its fairly odd that when no less anauthority than the president of the Financial Services Authority, LordTurner, questions the social utility of much activity in financialmarkets, and also suggests that it might be no bad thing to levy a tinyTobin tax on all this frenetic trading in electrons, well its curious thatthe chancellor of the exchequer (who could use a bob or two) doesntlick his chops and demand a bit of that.

Secret bitstring: 0 1 1 0 0 0 1 0

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 11

Example using Lexical Substitution

Data Embedding:

Which is why, some would say, its fairly odd that when no less anauthority than the president of the Financial Services Authority, LordTurner, questions the social usefulness of much activity in financialmarkets, and also suggests that it might be no bad thing to levy a tinyTobin tax on all this frenetic trading in electrons, well its curious thatthe chancellor of the exchequer (who could use a bob or two) doesntlick his chops and demand a bit of that.

Secret bitstring: 0 1 1 0 0 0 1 0

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 12

Example using Lexical Substitution

Data Embedding:

Which is why, some would say, its fairly odd that when no less anauthority than the president of the Financial Services Authority, LordTurner, questions the social usefulness of much activity in financialmarkets, and also suggests that it might be no bad thing to levy a tinyTobin tax on all this frenetic trading in electrons, well its curious thatthe chancellor of the exchequer (who could use a bob or two) doesntlick his chops and demand a bit of that.

Secret bitstring: 0 1 1 0 0 0 1 0

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 13

Example using Lexical Substitution

Data Embedding:

Which is why, some would say, its fairly odd that when no less anauthority than the president of the Financial Services Authority, LordTurner, questions the social usefulness of much activity in financialmarkets, and also suggests that it might be no bad thing to levy a tinyTobin tax on all this frenetic trading in electrons, well its strange thatthe chancellor of the exchequer (who could use a bob or two) doesntlick his chops and demand a bit of that.

Secret bitstring: 0 1 1 0 0 0 1 0

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 14

Example using Lexical Substitution

Data Embedding:

Which is why, some would say, its fairly odd that when no less anauthority than the president of the Financial Services Authority, LordTurner, questions the social usefulness of much activity in financialmarkets, and also suggests that it might be no bad thing to levy a tinyTobin tax on all this frenetic trading in electrons, well its strangethat the chancellor of the exchequer (who could use a bob or two)doesnt lick his lips and demand a bit of that.

Secret bitstring: 0 1 1 0 0 0 1 0

Stephen Clark Linguistic Steganography Edinburgh, May 2012

Intro Ling Steg Lex Sub 15

Example using Lexical Substitution

Data Embedding:

Which is why, some would say, its fairly odd that when no less anauthority than the president of the Financial Services Authority, LordTurner, questions the social usefulness of much activity in financialmarkets, and also suggests that it might be no bad thing to levy a tinyTobin tax on all this frenetic trading in electrons, well its strangethat the chancellor of the exchequer (who could use a bob or two)doesnt lick his lips and demand a piece of that.

Secret bitstring: 0 1 1 0 0 0 1 0

Stephen Clark Linguistic Steganography Edinburg