## KS3 Encryption Algorithms (14-16 years)

- An editable PowerPoint lesson presentation
- Editable revision handouts
- A glossary which covers the key terminologies of the module
- Topic mindmaps for visualising the key concepts
- Printable flashcards to help students engage active recall and confidence-based repetition
- A quiz with accompanying answer key to test knowledge and understanding of the module

## A-Level Compression, Encryption and Hashing (16-18 years)

- An editable PowerPoint lesson presentation
- Editable revision handouts
- A glossary which covers the key terminologies of the module
- Topic mindmaps for visualising the key concepts
- Printable flashcards to help students engage active recall and confidence-based repetition
- A quiz with accompanying answer key to test knowledge and understanding of the module

**Symmetric encryption** is a form of encryption whereby the same key is used to encrypt and decrypt the message. This is different from asymmetric or public-key encryption, which uses one key to encrypt a message and another key to decrypt the message.

Symmetric encryption is a kind of computerised cryptography, which uses a particular encryption key to conceal the contents of an electronic message. Its data conversion utilises a mathematical procedure along with a private key, which results in the potential failure to make sense of a message for somebody who doesn’t have the right tools to decrypt it. Symmetric encryption is a two-way algorithm because the mathematical procedure is turned back when decrypting the message, along with using the same private key.

Symmetric encryption is also referred to as *private-key* encryption and *secure-key* encryption.

This is the most straightforward form of encryption, comprising only one private key to cipher and decipher information. Symmetrical encryption is an old and well-known practice. It uses a private key that can either be a number, a word, or a string of random letters. It is mixed with the plain text of a message to alter the content in a certain way. The sender and the recipient should know the private key that is used to cipher and decipher all the messages.

### Examples of Symmetric Encryption

- Blowfish
- AES (Advanced Encryption Standard)
- RC4 (Rivest Cipher 4)
- DES (Data Encryption Standard)
- RC5 (Rivest Cipher 5)
- RC6 (Rivest Cipher 6)

The most commonly used symmetric algorithms are AES-128, AES-192, and AES-256.

The main drawback of the symmetric key encryption is that all individuals engaged in the activity have to exchange the key used to encrypt the data before they can decrypt it, which isn’t always convenient.

### Types of Symmetric Encryption

**Block algorithms**are used to encrypt blocks of electronic data. Specified set lengths of bits are altered, while continuing to use the designated private key. This key is then used for each block. When network stream data is being encrypted, the encryption system retains the data in its memory components while waiting for the complete blocks. The time in which the system waits can lead to a certain security gap, and may undermine data security and integrity. The solution to the problem includes a process where the block of data can be decreased and merged with preceding encrypted data block contents, until the rest of the blocks arrive. This process is known as feedback. When the entire block is received, only then is it encrypted.**Stream algorithms**are not retained in the encryption system’s memory, but arrive in data stream algorithms. This type of procedure is considered somewhat safer, since a disk or system is not retaining the data without encryption in the memory components.

### Difference Between Symmetric and Asymmetric Encryption

- Symmetric encryption uses a single key that must be shared among the people who need to receive the message, while asymmetrical encryption uses a pair—consisting of a public key and a private key—to encrypt and decrypt messages when communicating.
- Symmetric encryption is an old practice, while asymmetric encryption is relatively new.
- Asymmetric encryption was brought in to fix the problem of the necessity of sharing the key in the symmetric encryption model, removing the need to share the key by using in its stead a pair of public-private keys.
- Asymmetric encryption eats up more time than the symmetric encryption.

When it comes to encryption, the latest systems may often be the best fit. You should always use the appropriate encryption procedure which is applicable for the task at hand. As a matter of fact, as cryptography evolves in a new direction, new procedures are being established in a bid to catch up with would-be hackers, and to protect information in order to improve privacy. Hackers are destined to make it hard for experts in the coming years, so we can safely expect more innovations to come from the cryptographic community.