Your SlideShare is downloading. ×
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Steganography
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Steganography

517

Published on

Published in: Technology
0 Comments
0 Likes
Statistics
Notes
  • Be the first to comment

  • Be the first to like this

No Downloads
Views
Total Views
517
On Slideshare
0
From Embeds
0
Number of Embeds
0
Actions
Shares
0
Downloads
67
Comments
0
Likes
0
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Simple Overview ofSteganographyDecember 2012Ashenafi Ethio1
  • 2. What is Steganography?It is the art and science of writing hiddenmessages in such a way that no one apart fromthe intended recipient knows of the existence ofthe message.steganographysteganóscoveredgraptoswritingThe art of secret (hidden) writing2
  • 3. History of SteganographyAn ancient Greek named Histaiaeus wasfomenting revolt against the king of Persia andneeded to pass along a message secretly.3
  • 4. History of SteganographyIn 5th century B.C. an exiled Greek namedDemaratus wrote a warning that the Persiansplanned to attack Sparta.4
  • 5. History of Steganography When the USS Pueblo was captured by North Korea in1968, the crew was forced to pose for propagandaphotos to demonstrate they were being well treated.Their finger gestures are a form of steganography thatsends a message AmericansFdfdsfFdfdsfDfdfdDsfdsfDsfds5
  • 6. Steganography Vs. CryptographyBoth have been used as means to protectinformationCryptographic techniques "scramble" messages soif intercepted, the messages cannot beunderstood.Steganography, in an essence, "cover-ups" amessage to hide its existence and make it seem"invisible" thus concealing the fact that a messageis being sent altogether.6
  • 7. Steganography Vs. CryptographyOriginal Message: Start Attacking at 11:00 Pm.Steganography: Hiding messages within carrier objectsCryptography: Encrypting messages[k>>4]*2^k*257/8,s[j]=k^(k&k*2&34)7
  • 8. Steganography and cryptography can becombinedThe message can also be encrypted before it ishidden inside a cover message. This providesa double layer of protection.Encryption will make the existence of themessage more difficult to detect, due to thefact that some encryption techniques causethe patterns of the characters in theencrypted version to be more random than inthe original version.8
  • 9. A practical comparison of steganography andcryptographyPurchasing some books online Order the books online to pay for the books by supplying our credit cardnumber(we check to make certain that our browserhas switched into the secure mode) Sending our credit number should be secret and it isour hope that the transmission is encrypted by thebrowser. Vendor can decrypt the message and read our creditcard number.In this case, there is no need for steganography becausethere is no need to hide the existence of the message.9
  • 10. A romantic trystLet’s assume that you are sending a messageto Alice (your best friends wife) to arrange aromantic tryst.In this case, you would probably prefer thatneither your wife nor your best friend knowthe existence of the message.(If they learn the secret message, they may notcontinue to be your wife and your best friend forvery much longer)10
  • 11. A romantic trystUse some form of steganography to hide theexistence of the secret message.It also wouldnt hurt to encrypt the messageusing Alices public key That way, even if the existence of themessage is detected, it wouldnt be possiblefor your wife or your best friend to read it.(That may increase your chances of survival evenif the existence of the message is detected)11
  • 12. How to send the message to AliceWe can use SteganographyWe have different forms of Steganography tohide the existence of the message.The easiest way would be to send his latestset of digital vacation photos to Alice and herhusband by embedding the message in one ofthe photos.12
  • 13. How to send the message to AliceAlice could extract and read your message. Alices husband would probably see a set ofvacation photos. The existence of a secretmessage would certainly not be obvious inviewing the photos.Alice could embed her answer in a digital photoof her graduation. She could send that picture to you and yourwife. You could extract and read the message. Your wife could say congratulations to Alice.13
  • 14. How to send the message to AliceYou and Alice could continue to secretlycommunicate in this manner for as long as youcould come up with reasons to exchangesdigital photos.(That approach might get stale after a while andyou would need to come up with some otherform of steganography to continue the dialog)14
  • 15. How Steganography works15
  • 16. Cover is the original picture, audio or video file. Emb is the message to be embeded.Key is the parameter which controls the hidingprocess of the secret messageStego is the resultant file that contains the hiddenmessage.(We have to be careful that how much informationwe try to conceal within the carrier. The longer themessage, the larger the modification of the carrierimage and the higher the probability that themodifications can be statistically detected )16
  • 17. Common techniques in SteganographyModern day steganography mainly deals withhiding information within other files such asImage, Audio, Video files. These files can “containperceptually irrelevant or redundant informationthat can be substituted for hidden messagesThere are three common techniques in use today:SubstitutionInjectionGeneration of new files17
  • 18. I. SubstitutionEvery file that is created will contain unused orinsignificant areas of data. These areas can bereplaced without any visible changes to thevisual or audio clarity of the file.This enables one to conceal sensitiveinformation within the file and still have thefile appear as though it is the same as theoriginal unmodified version.18
  • 19. I. SubstitutionAlso called the Least Significant Bit (LSB) methodwhich replaces the last bit in an 8 bit byte.E.g. 10010110 01101010 11100101If we change the most significant bit it would belikely have a significant effect on the picture andbe easily seen by the naked eye. However, if wechange the last bit (1) in the last byte thenchances are that this change would not benoticeable.19
  • 20. I. SubstitutionLSB works best in files that have a lot of ‘noise’i.e. Pictures that have many colors and shapesor audio files that have a lot of differentsounds and effects such as echoes.Substitution method generally does notincrease the size of the file but depending onthe size of the hidden message, it caneventually cause a noticeable change from theunmodified version.20
  • 21. II. InjectionInjection involves embedding the secretmessage directly into the carrier object.The problem with this approach is that itgenerally makes the file larger than theoriginal unmodified file.21
  • 22. II. Generation of New FilesThis technique involves taking your message andusing this to generate a new file from scratch.22
  • 23. Choice of CarrierWhat digital format should we choose toconceal our private message?Steganography can be used in just about anytype of file. The most common methods usedarea. Imagesb. Audioc. Video23
  • 24. Detecting the use of SteganographySteganalysis is identifying the existence of ahidden message in Steganography.There are two types of attacksActiveThis involves destroying the hidden messagePassiveDetecting the use of steganography and is anintroduction to actually deciphering the hiddenmessage.Viewing the fileListening to the file24
  • 25. Advantages of SteganographySecurely storing sensitive data, such ashiding system passwords or keys within otherfiles.Difficult to detect.Network surveillance and monitoringsystems will not flag messages or files thatcontain Steganography data.25
  • 26. Disadvantages of Steganographyif someone knows the message is there, themessage can be easily read.If you want to send large file like book, its prettyhard to hide with steganographyNetwork surveillance and monitoring systems willnot flag messages or files that containsteganographic data. Therefore, if someoneattempted to steal confidential data, they couldconceal it within another file and send it in aninnocent looking email.26
  • 27. 27
  • 28. Conclusionsteganography as a tool to conceal highlysensitive information with other digitalinformation. It is not a replacement forcryptography but it is other form of hidinginformation.28
  • 29. Thank You!29

×