1. Giới thiệu
Ngày nay chúng ta thường nghe nói đến Steganography. Đó là một hình thức che dấu sự tồn tại của thông điệp. Khác với Cryptography thì Steganography ẩn đi các thông tin cần giữ bí mật trong các dữ liệu vô hại để đối phương không thể biết được sự hiện diện của thông điệp. Thực chất Steganography đã được con người biết tới từ rất lâu rồi. Năm 440 trước công nguyên, người Herodotus (Người Hy Lạp xa xưa) đã cạo trọc đầu các nô lệ tin cậy rồi xăm lên đó các thông điệp và chờ tóc mọc lại. Mục đích của việc này là nhằm gửi tin đi trong cuộc chiến tranh giữa người Herodotus và Persians (Người Ba Tư). Trong cuộc cách mạng của Mỹ, mực không màu cũng được sử dụng để trao đổi thông điệp giữa người Mỹ và người Anh. Trong các cuộc chiến tranh thế giới, Steganography cũng được sử dụng. Người Đức đã sử dụng mực không màu để viết các dấu chấm nhỏ lên phía trên và dưới các chữ cái bằng cách thay đổi chiều cao các chữ trong đoạn văn bản. Trong chiến tranh thế giới thứ nhất, các tù nhân cũng sử dụng mã Morse để gửi thư về nhà bằng cách viết các dấu chấm và gạch ngang lên các chữ cái i,j,t,f. Trong chiến tranh thế giới thứ 2, các gián điệp của Đức đã sử dụng đoạn văn bản sau:“Apparently neutral’s protest is thoroughly discounted and ignored. Isman hard hit. Blockade issue affects for pretext embargo on by-products, ejecting suets and vegetable oils.”Bằng cách đọc những chữ thứ 2 của các từ ta sẽ được đoạn thông điệp sau:
“Pershing sails for NY June 1”.Ngày nay trên mạng có rất nhiều đoạn nhạc hay các bức hình tưởng chừng như bình thường nhưng nó lại chứa các thông tin hoàn toàn bí mật. Điều này càng làm cho Steganography càng trở nên phổ biến. Dưới đây là hình ảnh minh họa cho điều này:
2. Quá trình mã hóa và giải mã của Stegranography
Tiếp theo ta sẽ cùng tìm hiểu về ẩn thông tin trong Steganography. Đầu tiên, thông điệp và bức ảnh ban đầu sẽ được đưa vào trong bộ mã hóa (encoder). Trong bộ mã hóa, một bộ giao thức sẽ được thực thi để nhúng thông điệp vào trong bức ảnh. Kiểu của giao thức sẽ phụ thuộc vào kiểu của thông điệp và cách ta nhúng. Ví dụ hình dưới đây sẽ cho ta thấy giao thức để ẩn thông điệp trong các bức ảnh.
3. Một số cơ chế trong Stegranography
3.1 Cơ chế ẩn thông điệp trong văn bản hoặc đoạn ký tự Đối với các tài liệu giấy thì khi bạn copy, bạn có thể sẽ không vi phạm bản quyền vì chất lượng của các tài liệu này khác nhau. Tuy nhiên đối với các tài liệu trên máy tính thì các bản copy sẽ giống hệt các bản gốc nên bạn rất dễ vi phạm bản quyền. Sở dĩ có thể biết được là do trong các tài liệu này đã được chèn thêm vào một số đoạn text để đánh dấu. Những đoạn này là ẩn với người dùng và bằng mắt thường khó có thể nhận biết được. Chúng ta chỉ có thể giải mã nhờ máy tính thì mới có thể nhìn thấy được.
Khi đó ta được email sau:
Dear Friend , Especially for you – this breath-taking news ! If you no longer wish to receive our publications simply reply with a Subject: of “REMOVE” and you will immediately be removed from our database . This mail is being sent in compliance with Senate bill 2116 , Title 8 ; Section 309 . This is not multi-level marketing . Why work for somebody else when you can become rich within 65 weeks ! Have you ever noticed how many people you know are on the Internet & society seems to be moving faster and faster . Well, now is your chance to capitalize on this ! We will help you turn your business into an E-BUSINESS and decrease perceived waiting time by 150% ! You are guaranteed to succeed because we take all the risk ! But don’t believe us . Mr Ames of Iowa tried us and says “Now I’m rich, Rich, RICH” . This offer is 100% legal ! We beseech you – act now ! Sign up a friend and you get half off ! God Bless ! Dear Friend ; This letter was specially selected to be sent to you . This is a one time mailing there is no need to request removal if you won’t want any more . This mail is being sent in compliance with Senate bill 1620 , Title 9 , Section 302 . THIS IS NOT MULTI-LEVEL MARKETING . Why work for somebody else when you can become rich in 41 DAYS . Have you ever noticed people love convenience plus most everyone has a cellphone . Well, now is your chance to capitalize on this . We will help you deliver goods right to the customer’s doorstep & turn your business into an E-BUSINESS . The best thing about our system is that it is absolutely risk free for you ! But don’t believe us . Ms Anderson of Hawaii tried us and says “I was skeptical but it worked for me” ! We are licensed to operate in all states ! We BESEECH you – act now ! Sign up a friend and you get half off ! God Bless .
3.2 Cơ chế ẩn thông điệp trong tệp tin âm thanh
Định dạng MP3 là định dạng phổ biến của các file nhạc.Do đó ta có thể sử dụng chúng để ẩn các đoạn text trong đó.Có nhiều công cụ có thể giúp bạn ẩn thông tin trong file .MP3 và MP3Stego là một chương trình trong số đó. Dưới đây là giao diện của chương trình này:
Còn đây là giao diện khi bạn muốn giải mã:
- Steganography and Digital Watermarking
- https://en.wikipedia.org/wiki/Steganography
- Một số tài liệu khác trên Internet.
[…] Source : https://securitydaily.net/gioi-thieu-ky-thuat-giau-tin-trong-anh-steganography/ […]
coach outlet online
I must voice my admiration for your generosity supporting individuals that need assistance with that study. Your very own commitment to getting the message all around appeared to be surprisingly functional and have always enabled girls just like me to…
kyrie 6 shoes
I intended to draft you that tiny word so as to say thanks a lot yet again with the pretty suggestions you have shared on this website. This has been really extremely open-handed of you to deliver unhampered what a few individuals would’ve advertised…
yeezy shoes
I precisely needed to appreciate you once more. I’m not certain what I would have made to happen in the absence of those ways documented by you about this area. It truly was a daunting scenario in my opinion, however , finding out the well-written sty…
calvin klein underwear
My husband and i got really excited that Jordan managed to complete his studies using the precious recommendations he had out of your weblog. It’s not at all simplistic to simply choose to be giving for free techniques which most people may have been…
kyrie 3 shoes
Thanks a lot for giving everyone an extremely splendid possiblity to read articles and blog posts from this web site. It is often so cool and also stuffed with a good time for me personally and my office mates to search the blog minimum three times eve…
hermes handbags
I really wanted to make a small note to thank you for those magnificent strategies you are showing here. My time intensive internet research has finally been honored with excellent ideas to write about with my good friends. I would claim that we visito…
adidas nmd
I wanted to make a simple word so as to appreciate you for the stunning ways you are giving here. My considerable internet search has at the end been paid with good quality facts and techniques to write about with my friends and classmates. I would exp…
supreme
I happen to be writing to make you be aware of what a useful experience my cousin’s girl undergone reading the blog. She discovered plenty of pieces, including how it is like to have a great teaching style to let folks without difficulty master specif…
nike shoes for women
I needed to post you that little word so as to say thanks a lot once again considering the pleasing methods you have shown in this case. It has been generous of you to deliver unreservedly what exactly a lot of people would’ve distributed as an e book…
ferragamo belt
I have to show some thanks to this writer just for bailing me out of this type of instance. Because of looking through the the net and coming across principles which were not beneficial, I believed my life was gone. Existing without the presence of sol…
curry 5
You made some decent factors there. I appeared on the web for the difficulty and located most people will go together with together with your website.
michael kors
I抦 impressed, I must say. Really not often do I encounter a weblog that抯 both educative and entertaining, and let me let you know, you have hit the nail on the head. Your idea is outstanding; the problem is something that not enough persons are speakin…
air max 270
I was very happy to search out this net-site.I needed to thanks for your time for this wonderful learn!! I positively enjoying every little bit of it and I’ve you bookmarked to check out new stuff you blog post.
louboutin
It抯 hard to search out educated folks on this matter, but you sound like you understand what you抮e speaking about! Thanks
nike vapormax
An attention-grabbing discussion is value comment. I feel that you need to write more on this subject, it might not be a taboo subject but usually people are not sufficient to talk on such topics. To the next. Cheers
golden goose
I found your blog site on google and check a couple of of your early posts. Continue to keep up the very good operate. I simply extra up your RSS feed to my MSN News Reader. In search of forward to reading extra from you afterward!?
michael kors handbags
There are certainly lots of particulars like that to take into consideration. That could be a great level to convey up. I offer the thoughts above as general inspiration but clearly there are questions just like the one you deliver up where crucial thi…
vans outlet
The following time I learn a blog, I hope that it doesnt disappoint me as a lot as this one. I imply, I do know it was my choice to read, however I actually thought youd have one thing interesting to say. All I hear is a bunch of whining about somethin…
yeezy
There are actually loads of particulars like that to take into consideration. That could be a nice point to convey up. I offer the thoughts above as general inspiration but clearly there are questions just like the one you convey up where the most impo…
jordans
Nice post. I study something more challenging on different blogs everyday. It is going to always be stimulating to learn content material from other writers and practice a little bit one thing from their store. I抎 choose to use some with the content ma…
vans outlet
Youre so cool! I dont suppose Ive read something like this before. So good to search out somebody with some unique ideas on this subject. realy thank you for beginning this up. this website is one thing that is needed on the web, somebody with a bit of…
ultra boost
This actually answered my problem, thanks!
balenciaga shoes
An interesting discussion is price comment. I feel that it’s best to write more on this topic, it may not be a taboo topic however typically persons are not enough to talk on such topics. To the next. Cheers
outlet golden goose
There are some attention-grabbing points in time in this article however I don抰 know if I see all of them center to heart. There is some validity however I’ll take maintain opinion till I look into it further. Good article , thanks and we wish more! A…
michael kors handbags
There are certainly plenty of details like that to take into consideration. That is a great level to convey up. I provide the thoughts above as normal inspiration however clearly there are questions like the one you bring up where the most important th…
air max 2017
An attention-grabbing discussion is worth comment. I think that you must write extra on this subject, it might not be a taboo topic however generally individuals are not sufficient to speak on such topics. To the next. Cheers
balenciaga shoes
There are some fascinating deadlines on this article but I don抰 know if I see all of them center to heart. There is some validity but I’ll take hold opinion until I look into it further. Good article , thanks and we wish extra! Added to FeedBurner as…
yeezy boost 350
WONDERFUL Post.thanks for share..more wait .. ?
jordan retro
Youre so cool! I dont suppose Ive learn anything like this before. So nice to find any individual with some authentic thoughts on this subject. realy thank you for beginning this up. this web site is something that is wanted on the web, someone with so…
off white hoodie
When I initially commented I clicked the -Notify me when new feedback are added- checkbox and now each time a remark is added I get 4 emails with the identical comment. Is there any method you possibly can take away me from that service? Thanks!
curry 6
Spot on with this write-up, I actually think this web site needs far more consideration. I抣l probably be once more to learn far more, thanks for that info.
golden goose outlet
After I originally commented I clicked the -Notify me when new comments are added- checkbox and now each time a comment is added I get four emails with the same comment. Is there any way you can take away me from that service? Thanks!
supreme new york
Good post. I learn one thing more challenging on totally different blogs everyday. It should always be stimulating to learn content from other writers and apply a bit one thing from their store. I抎 choose to make use of some with the content on my webl…
nike shox
Spot on with this write-up, I truly suppose this web site wants rather more consideration. I抣l probably be again to read much more, thanks for that info.
adidas flux
Your place is valueble for me. Thanks!?
off white jordan 1
It抯 laborious to seek out knowledgeable folks on this matter, however you sound like you understand what you抮e talking about! Thanks
kyrie shoes
WONDERFUL Post.thanks for share..extra wait .. ?
air max 2018
Nice post. I learn something more challenging on totally different blogs everyday. It’ll at all times be stimulating to learn content material from different writers and follow just a little something from their store. I抎 prefer to use some with the c…
bape hoodie
There are some interesting closing dates on this article but I don抰 know if I see all of them middle to heart. There’s some validity however I’ll take hold opinion until I look into it further. Good article , thanks and we want extra! Added to FeedBu…
kobe sneakers
A powerful share, I just given this onto a colleague who was doing somewhat analysis on this. And he in fact bought me breakfast because I found it for him.. smile. So let me reword that: Thnx for the deal with! However yeah Thnkx for spending the time…
yeezy
There are some attention-grabbing closing dates in this article but I don抰 know if I see all of them heart to heart. There may be some validity but I’ll take hold opinion till I look into it further. Good article , thanks and we would like more! Added…
nmd
This web page is known as a walk-through for all the info you wished about this and didn抰 know who to ask. Glimpse right here, and also you抣l definitely discover it.
yeezy boost 350 v2
I was very pleased to seek out this net-site.I wished to thanks for your time for this glorious read!! I positively enjoying each little bit of it and I have you bookmarked to check out new stuff you weblog post.
… [Trackback]
[…] There you will find 87855 more Infos: securitydaily.net/gioi-thieu-ky-thuat-giau-tin-trong-anh-steganography/ […]
air max 90
There are some interesting time limits in this article however I don抰 know if I see all of them heart to heart. There is some validity but I will take maintain opinion till I look into it further. Good article , thanks and we want more! Added to FeedBu…
100% real jordans for cheap
After study a few of the weblog posts in your web site now, and I actually like your way of blogging. I bookmarked it to my bookmark website list and can be checking back soon. Pls try my website as nicely and let me know what you think.
kd 11
Youre so cool! I dont suppose Ive learn something like this before. So nice to seek out somebody with some original thoughts on this subject. realy thank you for beginning this up. this web site is one thing that’s needed on the web, someone with slig…
golden goose sneakers
Aw, this was a very nice post. In concept I would like to put in writing like this moreover ?taking time and precise effort to make an excellent article?however what can I say?I procrastinate alot and under no circumstances seem to get one thing done.
nike air vapormax
WONDERFUL Post.thanks for share..more wait .. ?
hermes birkin
I used to be very happy to search out this net-site.I needed to thanks on your time for this wonderful learn!! I undoubtedly enjoying each little bit of it and I have you bookmarked to check out new stuff you weblog post.
kobe shoes
Spot on with this write-up, I truly assume this website needs rather more consideration. I抣l probably be again to read far more, thanks for that info.
yeezy boost 350
Aw, this was a really nice post. In concept I want to put in writing like this additionally ?taking time and actual effort to make a very good article?however what can I say?I procrastinate alot and under no circumstances seem to get something done.
christian louboutin
Oh my goodness! an incredible article dude. Thank you Nonetheless I’m experiencing subject with ur rss . Don抰 know why Unable to subscribe to it. Is there anyone getting equivalent rss downside? Anybody who is aware of kindly respond. Thnkx
russell westbrook shoes
It抯 hard to search out educated people on this subject, but you sound like you already know what you抮e talking about! Thanks
coach handbags
You made some first rate factors there. I seemed on the internet for the issue and found most people will go together with with your website.
lebron shoes
This web site is really a stroll-via for all of the info you wanted about this and didn抰 know who to ask. Glimpse right here, and also you抣l positively discover it.
balenciaga sneakers
This site can be a walk-via for all of the information you needed about this and didn抰 know who to ask. Glimpse here, and also you抣l definitely discover it.
jordan shoes
I抎 must examine with you here. Which isn’t one thing I often do! I enjoy studying a submit that may make people think. Also, thanks for permitting me to remark!
hermes online
This really answered my drawback, thanks!
nike huarache
You made some respectable points there. I seemed on the internet for the issue and found most individuals will go along with together with your website.
chrome hearts online
There are some fascinating points in time in this article however I don抰 know if I see all of them center to heart. There is some validity but I’ll take maintain opinion until I look into it further. Good article , thanks and we would like more! Added…
air jordans
Spot on with this write-up, I truly assume this website needs way more consideration. I抣l most likely be once more to read far more, thanks for that info.