What is encryption?
What is encryption? It is the ability to misconstrue or distort a message whilst it is transit. This to protect the contents from being intercepted
by an untrusted party. These methods were designed primarily for military operations when battle plans had to be communicated quickly but not fall into enemy hands. If a communique was intercepted, it took would be unintelligible to the reader as the contents would be disguised. Only the sender and the receiver would know the secret code that would unveil its hidden meaning. This could come in the form of a “Caesars scroll” (wrapping a message around a stick till only certain letters are displayed), the enigma machine (changing rotors on a machine to randomly move letters) or modern block chain (multiple levels of code) all protect the original message.
For the sender and recipient to decipher the message they must share a joint understanding of how unwind the cloak. This could be a shared method or code that both understand to unlock its meaning. If both parties use the same method, then they both share a “private key”. This they can share amongst themselves but then gets cumbersome if other parties become involved (chance of compromise but if situation changes all parties need to have updated keys). This is called symmetrical encryption is both keys share the same code.
Different methods of encryption.
Methods of mutating the original message could be as simple as substituting one letter for another. If we had the word “Like” and moved each letter 3 places along the alphabet we would get “OLNH” the latter being unintelligible unless the intended reader knew the formula to take it a step backwards. Transposition is a step on from this when letters are randomly jumped about so that the formula is harder to unwind. Random letters for “Like” could now be ZAUT but we would have to refer to a pre-agreed table to remember how it was jumbled up in the first place. Further permutations could be achieved by adding mathematical equations to jumble the results even further. These could go through multiple encryptions but then move the start point each time, which is known as the initialisation vector, and where we begin to get the concept of block chain.
Where is encryption used?
The official formal recognition for this came from the US government when they engaged the “Data Encryption Service” (DES) in 1977 to provide a benchmark for military, government and commercial purposes. This was contained in 64 bits split into 32-bit halves (for each key) then reduced to 56 bits so it could fit on to a chip. The basis of this is used in encrypting traffic between high speed destinations such as desktops to remote locations (IPsec) and ATM (asynchronous transfer mode) machines. It is the basis for many online transactions and connections such as VPN (Virtual Private Network).
With the advance in computing power the original DES was considered unsafe for some transactions, so a new method surprisingly called “Advanced Encryption Service” (AES) came into effect in 1997. It is 128-bit length and is a “block cypher” as it breaks down the communication into chunks of encrypted data. This is used in the 802.11i protocol for wireless internet and a version of it is used in Bluetooth technologies (Secure and Fast Encryption routine).
Issues with symmetrical encryption.
Although fast and effective it was not practical for some uses as although it kept the transfer of information safe it would not provide %100 proof that the message came from that originator as the one private key could be shared amongst a group for a purpose. If you had a problem with a key or it had been compromised that was shared between 10 individuals, then you would have to replace 45 keys. The resolution to this problem we shall look at next with asymmetrical encryption.