# data[].attributes.body
* people committing cyber crimes don't fit a single profile or motivation
* Larger countries have cyber army
* Virus is an executable program that is installed that harms the user and their computer
* virus can spread to other computers
* when a virus is on file it can steal , delete, control programs and remotely control computers
*botnet is a hackers army
*DDOS= distributed denial of service
* Phishing scam is when you get a trust worthy email asking you to login into your accounts
* clicking emails take to fake website

# data[].attributes.attachment_link.description
Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.

# data[].attributes.body
*Encryption is scrambling or changing a message to hide it
* Decryption is unscrambling the message to make it readable
*  Key allows  reader to unlock message
* Secure communications are encrypted using 256 bit keys
* using a larger key does not make encrypting hard just exponentially increases the number of guesses.
* Symmetric Encryption is when the same key is used to encrypt and decrypt
* Computers use asymmetric encryption a public key that can be exchanged with anybody and  and a private key
* anyone can encrypt with a public key
* A private key can only be used to decrypted by a computer with access
*

# data[].attributes.attachment_link.readable_text
(energetic music) - Hi. My name is Mia Gil Epner. I'm majoring in Computer Science at UC Berkeley and I work for the Department of Defense where I try to keep information safe. The internet is an open and public system. We all send and receive information over shared wires and connections. Even though it's an open system, we still exchange a lot of private data, things like credit card numbers, bank information, passwords, and emails. So how is all this private stuff kept secret? Data of any kind can be kept secret through a process known as encryption, descrambling or changing of the message to hide the original text. Now, decryption is the process of unscrambling that message to make it readable. This is a simple idea, and people have been doing it for centuries. One of the first well-known methods of encryption was Caesar's cipher, named after Julius Caesar, a Roman general who encrypted his military commands to make sure that if a message was intercepted by enemies, they wouldn't be able to read it. Caesar's cipher is an algorithm that substitutes each letter in the original message with a letter a certain number of steps down the alphabet. If the number is something only the sender and receiver know, then it's called the key. It allows the reader to unlock the secret message. For example, if your original message is, "Hello", then, using the Caesar's cipher algorithm with a key of five, the encrypted message would be this. (typrwriter keys clacking) (computer chime) To decrypt the message, the recipient would simply use the key to reverse the process. But there's a big problem with Caesar's cipher. Anybody can easily break or crack the encrypted message by trying every possible key. In the English alphabet, there are only 26 letters, which means you'd only need to try, at most, 26 keys to decrypt the message. Now, trying 26 possible keys isn't very hard. It would take, at most, an hour to do. So let's make it harder. Instead of shifting every letter by the same amount, let's shift each letter by a different amount. In this example, a 10 digit key shows how many positions each successive letter will be changed to encrypt a longer message. (typewriter keys clacking) Guessing this key would be really hard. Using 10 digit encryption, there could be 10 billion possible key solutions. Obviously, that's more than any human could ever solve. It would take many centuries, but an average computer today would take just a few seconds to try all 10 billion possibilities. So in a modern world, where the bad guys are armed with computers instead of pencils, how can you encrypt messages so securely that they're too hard to crack? Now, "too hard" means that there are too many possibilities to compute in a reasonable amount of time. Today's secure communications are encrypted using 256 bit keys. That means a bad guy's computer that intercepts your message, would need to try this many possible options until they discover the key and crack the message. (robot bleeps and beeps) (energetic music) Even if you had a hundred thousand super computers, and each of them was able to try a million billion keys every second, it would take trillions of trillions of trillions of years to try every option, just to crack a single message protected with 256 bit encryption. Of course, computer chips get twice as fast, then half the size every year or so. If that pace of exponential progress continues, today's impossible problems will be solvable just a few hundred years in the future, and 256 bits won't be enough to be safe. In fact, we've already had to increase the standard key length to keep up with the speed of computers. The good news is, using a longer key doesn't make encrypting messages much harder, but it exponentially increases the number of guesses that it would to crack a cipher. When the sender and the receiver share the same key to scramble and unscramble a message, it's called symmetric encryption. With symmetric encryption, like Caesar's cipher, the secret key has to be agreed on ahead of time by two people in private. That's great for people, but the internet is open and public, so it's impossible for two computers to meet in private to agree on a secret key. Instead, computers use asymmetric keys, a public key that can be exchanged with anybody and a private key that is not shared. The public key is used to encrypt data and anybody can use it to create a secret message, but the secret can only be decrypted by a computer with access to the private key. How it works is with some math that we won't get into right now. Think of it this way, imagine that you have a personal mailbox where anybody can deposit mail, but they need a key to do it. Now, you could make many copies of the deposit key, and send one to your friend or even just make it publicly available. Your friend, or even a stranger, can use the public key to access your deposit slot and drop a message in, but only you can open the mailbox with your private key to access all of the secret messages you've received. You can send a secure message back to your friend by using the public deposit key to their mailbox. This way, people can exchange secure messages without ever needing to agree on a private key. Public key cryptography is the foundation of all secure messaging on the open internet including security protocols known as SSL and TLS which protect us when we're browsing the web. Your computer uses this today. Any time you see the little lock or the letters https in your browser's address bar, this means your computer is using public key encryption to exchange data securely with the website you're on. (energetic music) As more and more people get on the internet, more and more private data will be transmitted, and the need to secure that data will be even more important. As computers become faster and faster, we'll have to develop new ways to make encryption too hard for computers to break. This is what I do with my work, and it's always changing. (energetic music)

# data[].attributes.attachment_link.title
Encryption and public keys (video) | Khan Academy

# data[].attributes.attachment_link.description
(energetic music) - Hi. My name is Mia Gil Epner. I'm majoring in Computer Science at UC Berkeley and I work for the Department of Defense where I try to keep information safe. The internet is an open and public system. We all send and receive information over shared wires and connections.

# data[].attributes.body
* URL= Uniform Resource Locator
* Computer language is HTTP
* HTTP = Hypertext Transfer Protocol
* Web servers are made up of "GET" request
* HTML= Hyper Text Markup Language
* cookie data is an ID number
* Digital certificates authorities safe passage into websites

# data[].attributes.attachment_link.description
Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.

# data[].attributes.body
* if the internet was made of Direct Dedicated Connections it would be impossible for things to keep working.
* Data travels in an indirect fashion
*Information does not follow a fixed path
* Info travels through a packet
*  router act like traffic monitors.
*  often the best rout for data to travel is not the most direct
* Fault Tolerant keep  sending packets
*  TCP- Transmission Control Protocol
* TCP manages the sending and reviving of all data as packets
* TCP+ Router systems is scalable
* More router the more reliability the internet is.

# data[].attributes.attachment_link.description
Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.

# data[].attributes.body
* In 1970 no standard method for networks to communicate
* Vint Cerf and Bob Kahn invented the Internetworking Protocol
* Internet is a network of networks
* The internet is a design pholophies
* Internet Protocol = IP address
*  organize in a hierarchy
*IPv4 is when IP address is broken up
* IPv6 uses 128 bits
*Domain NAme System + DNS
* DNS looks up names associated with IP address
* DNS Servers are connected in a distributed hierarchy and are dived into zones
* DNS was created to be open to public
DNS Spoofing lets hackers to change names to go to a different IP address

# data[].attributes.attachment_link.description
Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.

# data[].attributes.body
* the Internet ships binary info
*info is made of bits
*A bit is any pair of opposites
* 1 = on
* 0= off
* 8 bits =1 Byte
* 1000 bytes = 1 kilo byte
* 1000 kilo bytes= 1 mega bytes
* Send bites by electricity , light ,and radio waves
*  Band width= transmission capacity, measured by bitrate
* Bitrate = number of bits per second a system can transmit
* Lantency= time it takes for a bit to travel from sender to receiver.
*  Ethernet wire is found in homes, see signal lost over a few hundred feet
* Fiber optic cable is a thread of glass that reflects light
* Light bounces in the wire, depending on the bounce multiply bit at  the same time, at the speed of light
* Fiber optic cables allow internet to go across oceans
*  wire less machines use radio waves to send bits
* The machines have to translate the ones and zeros in to radio waves of different frequencies
* Receiving machines reverse the process and turn it back to binary on computers
* Radio does not travel far
*
*

# data[].attributes.attachment_link.description
Learn for free about math, art, computer programming, economics, physics, chemistry, biology, medicine, finance, history, and more. Khan Academy is a nonprofit with the mission of providing a free, world-class education for anyone, anywhere.