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By Sergey Lozhkin, Kaspersky Lab Technology Evangelist
The process of converting data into an unreadable form in order to conceal it from unauthorised parties and, at the same time, granting access to those who are authorised - encryption is a very simple and extremely safe concept. If there is no way to read a piece of data, it becomes worthless.
Information that can only be viewed by authorised users is of no use to anyone else and therefore has no value. In other words, there's no point in expending resources to gain access to it.
The history of encryption
Encryption used to be the exclusive prerogative of the military. The need to transfer orders and strategies, to agree alliances etc., without the information falling into the wrong hands, led to the appearance of steganography.
Steganography appeared around 440 BC, with the first encryption device being invented in Sparta. A piece of parchment was rolled over a stick with a particular diameter and a message was written along the axis of the stick. A stick of the same diameter was needed to read the text. This method is called a simple substitution cipher.
The appearance of computers in the post-World War Two period was the catalyst for the development of modern encryption. In the 1960s various block ciphers were created, which were cryptographically stronger than rotor machines. However, they required the use of digital electronics, signalling the end of manual and mechanical encryption methods.
The benchmark of modern encryption technologies was the creation of the Data Encryption Standard (DES) - a symmetric encryption algorithm developed by IBM and approved by the US government in 1977 as the official standard.
Types of encryption
Encryption is used to securely store and transfer sensitive data through insecure channels. Transferring this sort of data involves two inverse processes. First, data must be encrypted before being placed in storage or transferred via communication channels. To restore the source data the encrypted material has to be decrypted.
Initially, encryption was only used to transfer sensitive data, and only later to store it securely. A couple of algorithms, known as the cipher, carry out the conversions mentioned above. These algorithms are implemented using a key.
Encryption and decryption keys may differ, though they can also be the same. The secrecy of the second key (decryption key) makes the data inaccessible for unauthorised viewing, and the secrecy of the first one makes it impossible to corrupt data.
The first encryption methods used the same keys, but in 1976 algorithms for different keys were developed. Keeping those keys secret, and making sure they were distributed properly, was critical for ensuring sensitive data remained confidential when being transferred and kept. This task falls under encryption key management theory - also referred to as secret sharing.
Encryption technologies can also be divided according to the systematic approach to the process. For instance, when it comes to encryption on computers and other devices such as laptops, smartphones, tablets, etc., these methods can be divided into full-disk encryption and file-level encryption.
Full-disk encryption (FDE) technology is a special method of data protection that involves encrypting all the hard drive sectors, i.e. all the data stored on a hard drive is protected using FDE: swap space, system files, page files, hibernation files, and all temporary files.
