Encyption Key- THIS first part IS A REPEAT OF THE Transmission... PAGE.
Definition of encryption - the process of encoding/scrambling messages so that it cannot be properly read. Encryption does not of itself prevent interception, but since the message is scrambled in some way the interceptor cannot properly interpret what is being communicated. In internet banking, all of the transactions need to be encrypted so that sensitive financial data cannot be read; this includes information that could be used for fraud attempts, such as user name and password.
(This example happens to be symmetrical encryption.)
From: http://www.howtogeek.com/howto/33949/htg-explains-what-is-encryption-and-how-does-it-work/
Definition of an encryption key - An encryption key is a variable value that is applied using an algorithm to a string or block of unencrypted text to produce encrypted text, or to decrypt encrypted text. The length of the key is a factor in considering how difficult it will be to decrypt the text in a given message.
To understand what encryption keys are, here are two simple examples of encryption:
Example 1 - Caeser Cypher, in which each letter is shifted by a certain number, so 3, for example:
ABCDEFGHIJKLMNOPQRSTUVWXYZis shifted 3 places to
DEFGHIJKLMNOPQRSTUVWXYZABCIn which JOHN would be encrypted to MRKQ, and then decrypted back to JOHN.
In this case, the encryption key is: 3
Example 2 - Substitution Cypher:
plain alphabet : abcdefghijklmnopqrstuvwxyz cipher alphabet: phqgiumeaylnofdxjkrcvstzwbAn example encryption using the above key:
plaintext : defend the east wall of the castle ciphertext: giuifg cei iprc tpnn du cei qprcniSo in this case the key is: phqgiumeaylnofdxjkrcvstzwb
Brute Force Decryption Techniques-
Brute force is a way to crack an encryption key; i.e. to try to guess it. By brute force, you try every combination of characters until you find that it works.
If you were trying to guess an encryption key that was only one lower case letter, would maximum have to try 26 times. If two case letters, then you would have to try 26 x 26 times. And so on. So the longer the encryption key, the more time it would take to brute force decrypt it.
But's not just trying every combination of characters, but running a "Word List", too which are most likely words to try.
This video just shows a kid just running a brute force program:
https://www.youtube.com/watch?v=jR7ut-q3JJA
2048-length Encryption Key-
So the point is that with each additional bit, the time needed for brute force decryption increases by 2. But this is exponential, so if it takes one day to brute force crack a certain level of encryption, then with, for example, 64 more bits, that's, 2 ^ 64 times more time, or 18,000,000,000,000,000,000 days.
A bit more detail if you wish:
https://blog.cloudflare.com/why-are-some-keys-small/
Backdoor Methods -
The whole idea here is like how if a castle has lots of walls and moats and so on that make it seem secure, but if there's a "back door" into the kitchen for example through which someone can slip in, all the walls and moats don't mean much.
An organization has some sort of knowlege of the encryption method, for example, something like, AES has a backdoor for the NSA giving them access to 49 of the 2048 bits. So their brute force will need trillions and trillions of less tries to crack the encryption than normal.
Governments often will covertly require this of service providers or encryption standards agencies etc. so that they can monitor all activity, looking for possible criminal/terrorist activity. Edward Snowden's revelations revealed that the NSA had many backdoors to present encryption technology.
What about the Heartbleed bug last year on Linux? Was that an NSA backdoor??? We'll likely never know...