![]() Like many other areas of software engineering, the development of encryption mechanisms is based on the assumption that open source doesn’t compromise the security. This theory remains basically unchanged today. As early as 1883, Auguste Kerckhoffs formulated one of the principles of modern cryptography: To encrypt a plaintext reliably, all you really need is to do is provide a well-known mathematical method with secret parameters. The secrecy of an encryption process is rather counterproductive for its security.Īccording to Kerckhoffs’ principle, the security of a cryptosystem is not based on the secrecy of the algorithm, but on the key. Another approach is focused on so-called side channel attacks that target the implementation of a cryptosystem in a device or software. Instead, code-crackers look for weaknesses in the algorithm that make it possible to reduce the computation time for decrypting the encrypted data. According to the EE Times, it would take a supercomputer 1 billion billion years to crack a 128-bit AES key, which is more than the age of the universe.īecause of the long key lengths, brute force attacks against modern encryption methods are no longer a threat. With today’s technology, brute force attacks on the AES key length are simply not practical. Even with the appropriate technical equipment, it would take an eternity to try out all of the possible combinations. If AES works with 256 bits, the number of possible key is more than 115 quattuorvigintillion (or 10 75). These correspond to more than 240 sextillion possible key combinations. The key length of this method is accordingly large, as a result.Įven with 128-bit encryption, 2 128 conditions can be mapped. ![]() The Advanced Encryption Standard ( AES), for example, offers the possibility to select key lengths of either 128, 192, or 256 bits. ![]() ![]() Modern encryption methods, on the other hand, use keys which can provide significantly more defense. A code-cracker only needs to try 25 combinations in order to decipher the plaintext, so encryption using the Caesar cipher doesn’t constitute a serious obstacle. Its key space is 25 – which corresponds to a key length of less than 5 bits. To explain brute force attacks, we’ll use the Caesar cipher as an example. The bigger the key space, the more resilient the encryption will be against brute force attacks – a cracking method based on testing all possible combinations. It is also referred to in such as case as key space. This specifies the logarithmic units for the number of possible key combinations. An essential criteria for the security of the encryption is the key length in bits. Modern cipher methods use digital keys in the form of bit sequences. The resulting encryption code went as follows: To protect his military correspondence from enemy spies, the emperor shifted the letters of each word by three steps in the alphabet. The so-called Caesar cipher is based on monoalphabetic substitution. One of the first and easiest encryption methods of this type goes all the way back to Julius Caesar. Substitution methods are based on a tabular assignment of plaintext characters and ciphers in the form of a secret code book. To rewrite a transposed ciphertext into plaintext, you have to either know or reconstruct the transposition matrix. Permutations in the context of transposition methods are usually carried out using a matrix. To be able to decode such an encrypted text, the recipient needs to know the rule used to encrypt it. Individual characters of plaintext, words, or entire sentences within the message are rearranged ( transposition) or replaced by alternative character combinations ( substitution). In ancient times, simple encryption methods were used which were primarily restricted to coding the information that was to be protected. In addition to text messages, modern encryption methods can also be applied to other electronically transmitted information such as voice messages, image files, or program code.Įncryption is used to protect files, drives, or directories from unwanted access or to transmit data confidentially. The terms “plaintext” and “ciphertext” have historically been used when talking about encryption. In the best case scenario, the content of the encrypted text is only accessible to the user who has the key to read it. The word encryption refers to a method by which plain text is converted into an incomprehensible sequence using a key.
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