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Cipher encryption is a variety of encryption where a key is used to safeguard the encoded information. In general, there are two methods of cipher encryption—the block and the stream method. These determine how the cipher is applied to the original message. In addition to those two methods, there are two styles as well. A cipher is either symmetrical or asymmetrical depending on whether the message requires the same or a different decryption cipher.
Encrypted messages have been a staple of human secrecy since early civilization. Methods have come and gone for keeping important missives safe, but most have been some sort of cipher encryption. Methods of using a predesigned key to encode and decode messages have occupied the lives of many people. In the early days, these keys were complex only by virtue of the user’s low technology; now there are supercomputers that do nothing but encrypt and decrypt messages.
Block ciphers and stream ciphers make up the majority of cipher types. A block cipher encodes information in predetermined block sizes. If a cipher is designed to encode 200 characters, then that is precisely what it does. If the message is longer, it needs to be broken into multiple pieces, and if it’s shorter, it requires padding characters. A padding character is a character that simply makes the message longer; it can be anything from a stream of single characters to a random assortment of letters and spaces.
Stream ciphers are an innovation of the computer age. This style of cipher encryption generates and adapts its encoding string as it works. This encryption method uses the current state of the machine performing the encryption to generate the cipher.
This method constantly changes to match the current state of the system. Stream ciphers are nearly unbreakable as long as two things don’t happen; the code can’t repeat itself and no one that intercepts the message can know any of its contents. If the code repeats, it is possible to crack the sequence with little effort due to markers left behind in the cipher. If an interceptor knows any of the message contents, they can modify the message without opening it.
In a symmetrical cipher, the key used to encode the message is the same as the key used to decode the message. These ciphers are simple and easy to create, but the key is in danger as it moves from location to location for decoding. In addition, if any of the key holding locations are compromised, then the entire cipher is ruined.
An asymmetrical cipher encryption uses two keys, one that encodes the message and one that decodes the message. This is the cornerstone of public key encryption. A message is made of two keys, a public one and a private one. In this case, the keys interact to allow a specific person to unlock a message without knowledge of the actual encryption key.