Encryption

Overview

Symmetric Encryption

Introduction

• Symmetric encryption is a type of encryption where only one key (a secret key) is used to both encrypt and decrypt electronic data. The entities communicating via symmetric encryption must exchange the key so that it can be used in the decryption process.

Cipher

• Algorithm of executing encryption and decryption based on key

• Examples of symmetric ciphers are Advanced Encryption Standard (AES), Data Encryption Standard (DES), Blowfish, and International Data Encryption Algorithm (IDEA).

• IV (initialization vector) can be used to add randomness and unpredictability to the encryption process, which makes it more difficult for an attacker to decrypt the data.

Asymmetric Encryption

Introduction

• In an asymmetric key encryption scheme, anyone can encrypt messages using a public key, but only the holder of the paired private key can decrypt such a message. The security of the system depends on the secrecy of the private key, which must not become known to any other.

Cipher

• Algorithm of executing encryption and decryption based on key

• Examples of asymmetric ciphers are RSA

Comparison

1. Speed: Symmetric encryption is generally faster than asymmetric encryption, as it requires less computational power, making it suitable for encrypting large amounts of data.

2. Key distribution: In symmetric encryption, secure key distribution is crucial, as the same key is used for both encryption and decryption. Asymmetric encryption simplifies key distribution, as only the public key needs to be shared, while the private key remains confidential.

3. Key usage: Symmetric encryption uses a single shared key for both encryption and decryption, while asymmetric encryption employs a pair of keys: a public key for encryption and a private key for decryption.

4. Use cases: Symmetric encryption is ideal for bulk data encryption and secure communication within closed systems, whereas asymmetric encryption is often used for secure key exchanges, digital signatures, and authentication in open systems.

5. Security: Asymmetric encryption is considered more secure due to the use of two separate keys, making it harder for attackers to compromise the system. However, symmetric encryption can still provide strong security when implemented correctly with strong key management practices.

HMAC

Introduction

• It is a message authentication code that uses a cryptographic hash function and a secret key to verify the authenticity and integrity of a message.

• It's assumed that the client and server have already agreed on a common hash function, for example SHA2

• In this method, the sender uses a secret key to generate a MAC (Message Authentication Code) for the message, which is sent along with the message.

• The receiver uses the same secret key and the same hash function to calculate the MAC for the received message and compares it with the MAC received from the sender.

• If the MACs match, the receiver can be sure that the message has not been tampered with or altered in transit.

Comparison with symmetric encryption

Similarity

• Both involve the shared key for validation

Difference

• Symmetric encryption aims is to focus on encryption and decryption of the content or message

• HMAC aims to focus on to verify the authenticity and integrity of a message to come up true or false