a. Codasys is an international company that provides network supports and troubleshooting services throughout the world. Their employees are working remotely and communicating with the headquarters using wireless mobile communication. In order for the employees to communicate with the headquarters, the communication must pass through the Internet. i. List any TWO (2) types of encryptions that can be used to secure data communications over the network for Codasys. [2 marks] ii. Discuss ONE (1) of the encryptions in part (a)(i) that could be implemented by Codasys to secure the communication between the employees and the headquarters. Include in your discussion the advantages and drawbacks of deploying the encryption. [8 marks] b. i. Decrypt the following ciphertext using CAESAR encryption given the decryption key=7: “SHCPLLUYVZL” [4 marks] ii. Explain how the same algorithm for Data Encryption System (DES) can be used in 3DES to produce a stronger encryption system.
The Correct Answer and Explanation is :
a. i. Types of Encryptions for Securing Data Communications:
Two types of encryptions that can be used to secure data communications over the network are:
- AES (Advanced Encryption Standard): This is a symmetric encryption algorithm widely used for securing sensitive data. It uses fixed-size keys (128, 192, or 256 bits) and performs multiple rounds of transformation to encrypt data.
- TLS (Transport Layer Security): This is a cryptographic protocol used to secure communication over a computer network, particularly in web communication. It provides encryption, authentication, and data integrity.
a. ii. Discussion on One Encryption: AES (Advanced Encryption Standard)
AES is one of the most commonly used encryption methods for securing communications. It is a symmetric encryption algorithm, meaning the same key is used for both encryption and decryption. Here are the advantages and drawbacks of deploying AES to secure communication:
Advantages:
- Strong Security: AES is considered highly secure and resistant to various types of cryptographic attacks. It uses different key lengths (128, 192, and 256 bits), with the larger key sizes offering increased security.
- Efficiency: AES is relatively fast in encrypting and decrypting data, making it suitable for high-performance applications, even on devices with limited resources.
- Widely Adopted: AES is used globally, both by the government and private sectors. Its widespread adoption ensures interoperability across different systems.
Drawbacks:
- Key Management: One potential challenge with AES is the management and protection of the encryption keys. If the key is compromised, the security of the entire communication is jeopardized.
- Performance Impact: While AES is fast, the process of encryption and decryption still adds some computational overhead, especially when encrypting large volumes of data. This can impact the performance of network devices.
- Vulnerability to Brute Force Attacks: Although AES is very secure, a brute-force attack (trying all possible keys) is theoretically possible. However, with long keys (such as 256-bit), this becomes computationally infeasible.
In conclusion, AES is an effective encryption method for securing communications, but Codasys should ensure proper key management and handle any potential performance impact carefully.
b. i. Decrypting the Ciphertext using Caesar Cipher with Key 7:
To decrypt the message “SHCPLLUYVZL” using Caesar cipher with a key of 7, you need to shift each letter of the ciphertext 7 positions backward in the alphabet.
Decryption process:
- S → L
- H → A
- C → V
- P → I
- L → E
- L → E
- U → N
- Y → R
- V → O
- Z → S
- L → E
Decrypted message: “LAVIEENROSE”
b. ii. How DES in 3DES Strengthens Encryption:
Data Encryption Standard (DES) is a symmetric-key algorithm used to encrypt data. However, DES has a relatively small key size (56 bits), which makes it vulnerable to brute-force attacks. To address this vulnerability, Triple DES (3DES) was introduced as a stronger encryption scheme.
3DES applies the DES algorithm three times to each data block, using different keys for each iteration. Here’s how it works:
- Encrypt the data with the first key (DES1).
- Decrypt the result from the first step using the second key (DES2).
- Encrypt the output from the second step with the third key (DES3).
This triple encryption approach significantly strengthens the encryption by effectively increasing the key length, making brute-force attacks more difficult.
Key Differences:
- Standard DES uses a single 56-bit key to encrypt data.
- 3DES uses either two or three different 56-bit keys (making it equivalent to a key size of 112 or 168 bits), which dramatically increases security.
Advantages of 3DES:
- Stronger Encryption: By applying DES three times, 3DES offers significantly stronger encryption than DES alone, especially with the use of three different keys.
- Backward Compatibility: 3DES is compatible with systems that originally used DES, making it an easy upgrade for legacy systems.
Drawbacks:
- Slower Performance: The multiple iterations of encryption and decryption can make 3DES slower compared to other encryption algorithms, such as AES.
- Decreased Efficiency: Although 3DES strengthens the security of DES, it is less efficient due to its triple encryption process, which is computationally expensive.
In summary, 3DES enhances the security of DES by applying the encryption process multiple times, making it more resistant to attacks, but at the cost of performance.