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Alhamdulillah, sekarang penulis mau sedikit berbagi ilmu yang berkaitan dengan keamanan data (security).Bagi orang-orang yang sering berkecimpung di dunia informatika / komputer insya Allah sering mendengar istilah enkripsi ada juga yang pernah mendengar istilah encode, begitu juga istilah kripografi.
Tujuan sebenarnya teknik-teknik dengan istilah-istilah di atas adalah untuk menyamarkan data asli menjadi data baru dalam bentuk atau format lain, supaya orang lain selain si pemilik hak akses ke data tersebut tidak bisa melihat atau mengaksesnya.
Biasanya digunakan untuk mengamankan data, jaga-jaga kalau data tersebut jatuh ke tangan orang lain yang tidak berhak. Baik itu untuk disimpan sendiri maupun untuk tujuan pengiriman data ke orang lain.
Anda masih ingat ketika belajar pramuka, kita dulu belajar sandi rumput, bunyi, dan lain-lain.
Nah, sandi-sandi tersebut hanya bisa dipecahkan atau diterjemahkan oleh orang yang sudah paham tentang sandi tersebut dan cara menerjemahkannya.
Karena sifatnya umum, sandi-sandi tersebut (dalam pramuka) bisa dipelajari oleh semua orang, jadi kalau Anda punya data atau kalimat yang disandikan dengan menggunakan sandi publik tersebut, kemungkinan besar masih bisa diterjemahkan oleh orang lain, sehingga terlihatlah data atau kalimat aslinya.
Begitu juga dalam ilmu atau teknik penyandian data di dunia komputer, ada yang bisa diterjemahkan ke bentuk aslinya ada juga yang tidak.
Ilmu penyandian ini juga disebut dengan cipher
Ilustrasi penyandian yang bisa diterjemahkan balik dan yang tidak.
Misal kita punya sebuah data X, kita sandikan menggunakan teknik penyandian F, maka akan dihasilkan data baru (sudah tersamarkan) yaitu Z.
F
X ---> Z
X ---> Z
Sedangkan untuk membalikkan ke bentuk asli atau dikenal dengan dekripsi adalah tinggal membalik fungsi penyandian tersebut, ilustrasi sederhananya adalah:
-F
X <--- Z
X <--- Z
Baiklah, studi kasus...
Kita punya huruf abjad:
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
B C D E F G H I J K L M N O P Q R S T U V W X Y Z A
Susunan karakter berikut adalah metode enkripsi atau penyamarannya, Anda bisa menebaknya bukan?
Betul sekali. Sedikit kita ulas tentang fungsi dalam matematika:
Z = X + 1 (Jadi, fungsi penyandinya adalah karakter asli di tambah satu)
Contoh, kita punya kalimat: G A L I H H E R M AWA N
Dengan menggunakan fungsi: H B M J I I F S N B X B O
Bagaimana, mudah kan? Lalu bagaimana membaliknya ke bentuk aslinya?
OK. Kita sudah tahu rumusnya, bahwa:
KARAKTER BARU = KARAKTER LAMA + 1
Untuk membalik berarti:
KARAKTER LAMA = KARAKTER BARU - 1
Fungsi: X = Z - 1
Memang rumus ini terlalu mudah, namun tidak apa-apa, supaya membantu kita, terutama bagi yang belum paham apa itu enkripsi dan bagaimana cara kerjanya.
Beberapa metode penyandian (alias algoritma enkripsi) yang bisa digunakan di antaranya:- RC2
- RC5
- RC6
- SAFER
- dll
Sedangkan berikut ini contoh algoritma yang tidak ada fungsi pembalik atau penerjemah ke bentuk aslinya
- HAVAL
- MD4
- MD5
- SHA-0
- SHA-1
- WHIRLPOOL
- dll
Nah, khusus untuk algoritma yang tidak ada fungsi pembaliknya, para decryptor (orang yang suka atau ada keperluan mendekripsi suatu sandi), mereka suka menggunakan teknikBrute Force Attack. [indo wiki]
Untuk penjelasan mengenai brute force attack dan cara implementasinya menyusul pada tulisan berikutnya.
Thanx.
1.mngkn mas salah tulis, cipher jd chiper..
2. sistem sandi yang mas tulis tu CAESAR.tulis ja istilahnya, biar temen2 pada tw.
3. fungsi ga da pembalik (istilah kerennya, fungsi HASH), setau saya, ampe kapan juga memang g bisa didekripsi. qt cm bs menemukan collision-nya ja. pesan lain dengan nilai hash sama. klo g salah md5 dah ditemukan collisionnya pda 2 ^ 80.
maaf kalo saya da salah...
Memang tujuan awal dari artikel ini adalah untuk pemula, bukan khusus orang IT, so bahasa dibuat sesederhana mungkin dengan mengurangi beberapa istilah2 khusus di bidang kriptografi.
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If you feel curious then you can re-read the story by changing your selection. Then you will see a different story with the story that you have read previously. The question now is why is this so? Because the storyline will be varying according to your choice.
Based on the above, then you are faced with two choices. Are you interested in reading my story is? Or you are not interested at all. The choice is in your hands.
If you are interested then spread widely disseminated this article to your family, friends, neighbors, and relatives. You can also distribute it on facebook, twitter, goggle +, or other social media that this article be viral in the world. By doing so it is a new entertainment industry has been created.
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The full articles that talks about this:
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4. A story with tens of thousands of articles. http://richardnata.blogspot.com/2015/03/a-story-with-tens-of-thousands-of.html
5. A story with millions of choices in it. http://richardnata.blogspot.com/2015/03/a-story-with-millions-of-choices-in-it.html
15. Looking for investors for startup that produces millions to tens of millions of dollars annually. http://richardnata.blogspot.com/2015/02/looking-for-investors-for-startup-that.html
16. Open offer letter to investors. http://richardnata.blogspot.com/2015/04/open-offer-letter-to-investors.html
Are you interested in my offer?
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If yes, don't hesitate to contact me as soon as possible.
P.S. The offer letter I gave also to the hedge funds and venture capital and other major companies in the entire world. So who is fast then he will get it.
P.P.S. If you are not interested in my offer, it is a good idea to periodically review my blog to see the development of my blog. http://richardnata.blogspot.com
If I've made a story on my blog and get a multiplication of clicks then you should know that the readers liked my story.
A story with millions of choices in it.
Try to imagine this. When you're reading a story on the web or blog, you are given two choices. You can choose the next story based on your own choice. After selecting then you can continue reading the story. Shortly afterwards you will be presented back to the 2 other options. The next choice is up to you. Then you continue the story you are reading. After that you will be faced again with 2 choices. So onwards.
If you feel curious then you can re-read the story by changing your selection. Then you will see a different story with the story that you have read previously. The question now is why is this so? Because the storyline will be varying according to your choice.
If you feel curious then you can re-read the story by changing your selection. Then you will see a different story with the story that you have read previously. The question now is why is this so? Because the storyline will be varying according to your choice.
Based on the above, then you are faced with two choices. Are you interested in reading my story is? Or you are not interested at all. The choice is in your hands.
If you are interested then spread widely disseminated this article to your family, friends, neighbors, and relatives. You can also distribute it on facebook, twitter, goggle +, or other social media that this article be viral in the world. By doing so it is a new entertainment industry has been created.
Its creator named Richard Nata.
The full articles that talks about this:
1. A Story That Surprised The World. http://richardnata.blogspot.com/2015/03/a-story-that-surprised-world.html
4. A story with tens of thousands of articles. http://richardnata.blogspot.com/2015/03/a-story-with-tens-of-thousands-of.html
5. A story with millions of choices in it. http://richardnata.blogspot.com/2015/03/a-story-with-millions-of-choices-in-it.html
15. Looking for investors for startup that produces millions to tens of millions of dollars annually. http://richardnata.blogspot.com/2015/02/looking-for-investors-for-startup-that.html
16. Open offer letter to investors. http://richardnata.blogspot.com/2015/04/open-offer-letter-to-investors.html
Are you interested in my offer?
Do you want to be an investor in my startup?
If yes, don't hesitate to contact me as soon as possible.
If yes, don't hesitate to contact me as soon as possible.
P.S. The offer letter I gave also to the hedge funds and venture capital and other major companies in the entire world. So who is fast then he will get it.
P.P.S. If you are not interested in my offer, it is a good idea to periodically review my blog to see the development of my blog. http://richardnata.blogspot.com
If I've made a story on my blog and get a multiplication of clicks then you should know that the readers liked my story.
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