Ciphers

What is symmetric encryption in cryptography?

When we talk about encryption in cryptography, we refer to procedures that encrypt information to keep it secret. A key concept within this field is symmetric encryption, where an algorithm converts plaintext into encrypted information and then uses the same process to decrypt the text and return to the original format. This back-and-forth mechanics defines the symmetric cipher and is thought of as a "little box" that transforms content from one side to the other.

How do block ciphers work?

A modern method of encryption is the block cipher. Here, the data goes through multiple rounds of encryption, i.e. the algorithm is applied repeatedly possibly using different keys. The idea is that each round of encryption wraps around the previous one, creating an additional layer of security. Block ciphers have modes of operation that determine how the data is processed. Examples include:

• Electronic Code Book (ECB): divides information into blocks and encrypts them individually.
• Other modes of operation increase security and have specific applications.

How does stream ciphering work?

In scenarios where the information is not completely known in advance, such as in audio or video streaming, streaming encryption is essential. This method uses a random number generator to encrypt data continuously. YouTube and Spotify are examples where each data stream is accompanied by random bits to keep the information secure.

Importance of the key and the unique number (nonce)

In stream ciphering, in addition to a key, a unique number, known as a nonce, is used to ensure that keys are not repeated and predictability in encryption is avoided. The key-non-repeat combination ensures protection and security against attacks.

Streaming architectures

In stream ciphering there are different architectures that define its operation:

1. State-based stream: uses internal memory updated with each encryption operation and functions as a second seed for the process.
2. Counter-based flow: Relies on an external counter that allows generating new keys for each flow, maintaining security as long as the counter is secure and not manipulable by attackers.

Each architecture offers advantages and is designed to improve encryption security, adapting to specific applications as needed.

Find inspiration for further learning

Knowing the difference between these two types of encryption and the accompanying modes of operation and architectures opens the door to delve deeper into the vast world of cryptography. Don't hesitate to investigate further and apply this knowledge in your projects to ensure greater data security. If you know examples of stream ciphers or modes of operation for block ciphers, please share them and continue exploring this fascinating topic!