In this blog post, I will talk about a few methods of encryption 🙂

Advanced Encryption Standard (AES)

AES was first published in 1998, and was developed by Joan Daemen and Vincent Rijmen. AES uses the same key to encrypt and decrypt information. It applies multiple rounds to encrypt, which is why AES is so difficult to break. AES is a block cipher, so it encrypts data using blocks rather than in a stream. There are three different lengths of possible keys, 128 bits, 196 bits, and 256 bits. 256 bit encryption is the strongest, though it requires a lot of energy to complete.

AES puts data into a 16 byte column, and puts it into a four by four. Of course if your data is more that 16 bytes, the rest of the data would go into the next column. A key is then created, and Rijndael’s key schedules is applied, making it look like a jumble of random numbers and letters. AES then adds the binary of the data and the original key (not the one that the key schedule was applied to). Then, bytes are substituted, and then shifted. A predefined matrix is multiplied by that matrix, and then that is added to the key matrix that was put through Rijndael’s key schedule. This is done multiple times to apply multiple rounds of encryption, which is what makes AES so secure (source).

AES is used in some messaging apps such as WhatsApp, programs like WinZip, even many government agencies such as the military utilize AES to send messages and such.

Twofish Encryption

Twofish was developed as an encryption method to replace DES, though AES was the ultimate replacement. Twofish is still secure, but AES was chosen over it because it’s faster. Twofish is also vulnerable to side channel attacks, due to tables often being pre-computed.

Twofish uses the same key to both encrypt and decrypt. Its keys are 128 bit or higher. In Twofish, every word is broken up into 4 bytes and those bytes are then sents to S boxes. The output bytes are then combined into a 32 bit word, using a Maximum Distance Separable matrix and combined into a 32 bit word. Then the two words are put into Pseudo Hadamard Transform (PHT) . These words are then added to round subkeys, and XORed (source).

Twofish can be used where keys are changed often and also where very little RAM is available.

Triple DES

Triple DES (3DES) is a cipher used to encrypt data. 3DES is based on a previous algorithm called DES, which was developed by IBM with the help of the NSA in the early 1970’s. 3DES was originally introduced in 1998 as a transitional algorithm between DES and AES, though the use of 3DES has decreased a lot (source). The use of 3DES will be disallowed after December 31, 2023, according to a document published by the NIST.

3DES works by encrypting with one key, decrypting by a second, and encrypting with a third. Decoding is just the reverse, so you decrypt with the third key, encrypt with the second, and then decrypt with the third again. This system is more secure than regular DES, though still not very secure (source).

Some old Microsoft programs utilize 3DES, and it may be used in some banking and finance.

Serpent

Serpent is a symmetric key block cipher, developed by Ross Anderson, Eli Biham, and Lars Knudsen. It was in the AES competition, and came in second behind Rijndael (what is now aka AES). Serpent is supposedly stronger than AES, though AES was chosen over it because it was faster. Serpent has a block size of 128 (four 32 bit words), and keys can be 128, 192 256. Serpent’s designed so operations can be executed in parallel (source).

There are 32 rounds. In each round a 4 bit by 4 bit S-box 32 times. The designers of Serpent have said that 16 rounds would likely be sufficient against all types of known attack. However, the extra 16 rounds are used as insurance for future development in cryptanalysis (source).