What are Cryptographic Techniques and Tools Global Knowledge?
Most people are familiarized with encryption and cryptography. For centuries, governments and militaries have used encryption to protect their secrets from prying eyes. Modern cryptography is vital to preserve our economy by securing transactions and validating online purchases. Cryptography is a key technology in the new world of internet communication. It is important to understand how encryption works and the basics of it.
While a detailed study of cryptography’s mathematics may take many years to complete, there are many useful concepts which will make cryptography accessible for non-technical users.
Substitutions and Ciphers
Cryptography is often associated with a magic tool that substitutes one type of letter for another according to a set rules. This substitution cipher isn’t very secure.
Analysts can use context information, letter frequency, and other data to make educated guesses about how to crack encrypted messages. Computer algorithms can make complex changes to messages quickly and with little “leakage”. Each character is made up of eight bits (ones or zeros).
The computer can process individual bits very fast, especially when using the Exclusive-Or operation (XOR). The XOR operation compares a string and a key. If the bits in a given position are different, a “one” is sent. In all other cases, a zero is sent. (“XOR” means “if one or both of these but not both”) If the encrypted information is sent through the XOR compare process again, the XOR operation can be reversed.
Cryptography can be discussed using many terms.
Plain Text: This is an original message that is not encrypted. It doesn’t have to be text. It can be images, sound, spreadsheets, or other types of information. It is what is readable.
Ciphertext is encrypted data that should not be readable or altered by unauthorized persons or computers.
Key: This magic string can be used to decode or encode plain text into ciphertext. It doesn’t have to be as long as the text. To replace long strings of text, a short key can be used iteratively. You can guess short keys by trial and error. It takes more effort and computing power to guess a long key.
Stream cipher algorithm is an algorithm which works over stream data as it passes through a system. It must be able keep up with the stream and not look ahead. A streaming cipher must also allow missing bits of data. These ciphers are often used for streaming voice and video.
Block cipher algorithm. This algorithm divides data into 64 bits and encodes the entire block at once. Some algorithms reverse the order in which bits are placed in a block, reordering them using diagonal codes. Block ciphers can be extremely fast and very secure.
There are two main types of encryption algorithms.
There are two types. One uses the keys and one uses streaming and block encryption. Symmetrical encryption algorithms work exactly the same way as you would expect. They use the same key for decoding and encryption. They are efficient, secure and fast.
The problem is that both the sender of encrypted information and the receiver must have the same key. It is not possible to send a key over the medium that the data will be using. An eavesdropper could easily capture the key and decode it as it passes. Over the years, systems have used different routes for sending keys and data. Some systems still do. Modern systems use an algorithmic trick to share a common key.