Computer Systems and Security Module Assignment Sample

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Introduction to Computer Systems And Security Module Assignment

Cryptography is widely known as an essential component of the modern information security provision and mechanism. This paper focuses on hands-on applications of the three main cryptographic algorithms: DES, RSA, and MD5 with use of CrypTool 2. These algorithms serve distinct purposes: DES for symmetric, RSA for asymmetric and MD for hashing. All of these tasks were designed to provide an understanding of the capabilities and limitations and uses of these approaches for professional applications. Thus, through the analyses of these algorithms, the report shows how data confidentiality, integrity, and secure communication can be achieved and how cryptographic practices dictate and apply these theoretical notions.

Computer Systems and Security Module Assignment Sample

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All of these tasks were designed to provide a clear understanding of the capabilities, limitations, and practical uses of these approaches for academic and professional applications. Through the analysis of these algorithms, the report demonstrates how data confidentiality, integrity, and secure communication can be achieved, and how cryptographic practices translate theoretical concepts into real-world implementation-supporting students and professionals seeking reliable Assignment Help in cryptography and information security.

DES

Data Encryption Standard or DES is a symmetrical key algorithm that was initially designed in 1970 s and was later officially accepted as a standard by NIST is 1977. DES has the capability to work only on 64-bit plain text and has 8-bit key for encryption and decryption. The described algorithm is based on Feistel structure in which input data are divided into two equal halves which are transformed with the help of permutation and substitution stages and rounds. DES includes 16 rounds of operations, which take place in round each, depending on the key and then the sequence of the bitwise operations are performed. Another distinctive subkey is created for each round with the help of initial 56-bit key by means of key-scheduling (Schmidbauer et al. 2022). Within the rounds or before executing the rounds or after the rounds there is a permutation that is initialized permutation (IP) and the last permutation which is final permutation (FP) which forms the ciphertext.

RSA

The RSA is the cryptosystem developed by Rivest, Shamir, and Adleman hence the initials, and is the most common public-key algorithm widely used in information security. Unlike symmetric encryption, RSA relies on two distinct keys: an encryption key, which can be used by the receiver, and a decryption key used by the sender. This asymmetry makes it possible to have a secure conversation without having to exchange a secret key in the process. RSA is basically and fundamentally based on the property of prime numbers and modular arithmetic. However, the security of the algorithm lies with the possibility of factoring the product of two big prime numbers, otherwise known as integer factorization. The main generation process includes choosing two big prime numbers pp and q, and calculating their product n = p × q which form the modulus (Mohamed, 2022). The public key consists of n with the help of two values, n and e, where e is a number that is relatively prime to (p-1)(q-1). Using the inverse of ee modulus (p-1)(q-1) refer to as the modular multiplicative inverse the private key is obtained.

Encryption in RSA is performed using the formula:

sets up where “M” represents the plain text message, “C” represents the cipher text, and “e” and “n” makes up the public key.

Decryption uses the formula:

where d is the private key.

MD5

MD5 is short for Message Digest Algorithm 5; the cryptographic hash is a function which is developed by Ronald Rivest in the year 1991. It generates a determinate and predetermined number of 128 bits hash value for every input string. The use of hashing is such that it is a one way function and it is virtually impossible to deduce the hashing key from the hash. As an instance, MD5 takes 512 bits of data and passes the input through pre-processing and initialization before alternatively compressing it (Kim et al. 2021). The input message is first filled up such that it has modulo 512 equal to 448 Finally a 64—bit representation of the length of the original input message is added on the input message.

The padded message is split into blocks of 512-bits, each the size of one block being processed independently of the neighbors. The algorithm begins a 128-bit state split into A, B, C, and A, B, C, D registers all with constants(Ispahany et al. 2024). Each block goes through 64 rounds, which are subdivided into four classes each containing non-linear transformation, modular addition and bitwise operation.

Task 1

a) Objective

It was aimed at this particular task to exhibit how DES algorithm can be implemented for securing data. DES is One way encryption which uses 64 bits of block cipher and 8 bytes key to encrypt and decrypt data. As was aimed the part of being able to completely disguise the input text whereby it was encrypted with a certain key had to be tested through successfully decrypting the ciphertext into its original form. This particular exercise makes a point of illustrating the significance of key management and goes further to show the basic cryptography algorithm known as DES.

b) Task Execution

The exercise entailed entering the text ‘This is the input data’ into the DES algorithm found in the CrypTool 2. An 8-byte hexadecimal key “A1 B2 C3 D4 E5 F6 78 90” was used for both the processes. The encryption phase change the input data to ciphertext, so that no one who is not supposed to access the information can in any way get a hold of it. Encryption was then done as earlier outlined followed by decryption with the same key resulting to the determination of the original plaintext (Bentley, 2023). A GUI component that allowed for easy choosing of DES, input of the key, and the operations with the data in sequence was included in the tool.

c) Observations

There was an expected performance of the encryption and decryption process. The plaintext made during the encryption stage was fully meaningless, and is proof of the security offered by DES. Upon the decryption of the letters some were shifted, but all the texts were perfectly retrieved revealing the actual and efficiency of the algorithm. However, the task showed that DES has the problem such as brute force attacks possible because of relatively small key size (Poudyal, 2021). This further justifies why DES has to a greater extent been replaced by more effective versions such as the AES interested in most cryptographic systems.

Task 2

a) Objective

The goal of this task was to learn about the working of RSA algorithm for encryption and decryption with the help of CrypTool 2. RSA is block cipher algorithm that utilize the two keys; an encryption key that is available for public use and the decryption key, which is kept discreet. This task was designed to demonstrate how RSA can safely transfer data by making certain that only the intended recipient with the private key can understand the data. The exercise also sought to demonstrate the feasibility of using RSA when dealing with large input texts and the utilization of RSA to guarantee secure communication.

b) Task Execution

In this task, the input may consist in the following text: “This is a sample data input given. Yazid Qureshi Hi My name is Yazid Qureshi and I am putting this input as a sample to provide full use of the RSA system so that the full demonstration of the task can be given with the help of this system” was encrypted using RSA in CrypTool 2. In the tool context, a couple of public/private keys was created. The transformed input data into ciphertext then use the private keys to decrypt it back to its text form (Badal Batllori, 2024). During the process, a great deal of attention was paid to the choice of the key sizes in order to provide reliable security and high performance.

c) Observations

The RSA algorithm was able to encrypt and decrypt the input text efficiently and securely, affirming the methods effectiveness. The text encountered during the encryption was completely indiscernible, this proved a good work in protecting data. The decryption process, therefore, authentically reconstructed the text confirming validity of the decryption process. Hence, this task highlighted RSA’s major sell of guaranteeing a secure means of communicating (Thakur, 2025). But it also brought out the fact that RSA has a serious computational complexity issue with large inputs which makes it necessary to use suitably large key sizes to secure against today’s threats.

Task 3

a) Objective

The goal of this task was to investigate what the MD5 hashing algorithm is and learn how to compute its hash value on an input text. Hashing is a one way functions that take as input a string of data of arbitrarily length and produce as output a fixed size result or hash value, hash or digest. The task was to show how MD5 can be used to determine data integrity, by producing the digital fingerprint of the input text, which can then be used to check whether the data has changed during the transmission and storage.

b) Task Execution

In this task, the input text “Sample data” was hashed in MD5 algorithm in CrypTool 2. It was easy to input the choice in the tool by choosing the MD5 option from the menu alongside the input box. When performing the execution, the algorithm produced a 128-bits hash value and interpreted as a 32 hexadecimal characters value. This hash value was responsive to the input text and was presented in the output tabulation of the tool (Tolboom, 2023). The entire procedure was executed in some seconds, which proved the effectiveness of MD5 in getting hash value.

c) Observations

The MD5 hashing algorithm was able to get a new hash for the input text. The research included multiple executions of the same input and the output was the same each time this proven the deterministic nature of hashing algorithms. But the task revealed the weaknesses in MD5 that are well understood, for example, collision attacks in which two different inputs yield the same hash result (Hoa and Van On, 2025). Due to this, MD5 has been found unsuitable for cryptography security applications though it is fine for simple integrity checks a non-secure/basic level in its non-critical settings.

Task 4

a) Objective

The goal of this task was to run and review the results of three PowerShell commands which are used to obtain the information about the systems and processes. These commands were given with the purpose of demonstrating that PowerShell can output live system data including system configuration, amount of RAM and current processes information. Its is is was carried out in an effort to illustrate how PowerShell scripting is effective in regard to system ladmin as well as performance monitoring activities.

b) Task Execution

Three commands where run: “systeminfo” to obtain information about the systems, “Get-WmiObject Win32_OperatingSystem | Select-Object ‘Total Visible Memory Size’” to get total memory available, and “Get-Process | Sort-Object -Property WorkingSet -Descending | Select-Object ProcessName, WorkingSet | Select-Object -First 10” to list down the top ten processes which consume most memory. These commands were typed on PowerShell terminal and the results obtained as shown and analyzed (Viet et al. 2024). Both commands run without problem and generated in proper format the system and process information required.

c) Observations

The execution of the PowerShell commands described above was very useful to get more information available or not about the system configuration and its performance. The above given command “systeminfo” provided detailed information about the systems hardwares and software environment. The second command was helpful in the memory management analysis as it provided a total of the visible memory size. The result of the third command successfully executed displayed the list of the ten processes who took the most amount of memory with their working set size. These observations showed how PowerShell may be used to carry out system diagnostics as well as how subsequent administrative functions can be made more manageable by minimizing the number of commands necessary for execution.

Reference List

Journals

• Badal Batllori, M., 2024. Malware analysis methodology applied to the WannaCry ransomware.
• Bentley, P., 2023. A taxonomy of encryption and encoding algorithms used by advanced persistent threats with emphasis on bespoke encryption algorithms.
• Himel, S., 2022. CYBER DEFENSE EXERCISES IN XAMK VIRTUAL LABORATORY.
• Hoa, N.N. and Van On, D.P., 2025. ENHANCING WEBSHELL DETECTION WITH DEEP LEARNING-POWERED METHODS.
• Ispahany, J., Islam, M.R., Islam, M.Z. and Khan, M.A., 2024. Ransomware detection using machine learning: A review, research limitations and future directions. IEEE Access.
• Kim, K., Alfouzan, F.A. and Kim, H., 2021. Cyber-attack scoring model based on the offensive cybersecurity framework. Applied Sciences, 11(16), p.7738.
• Mohamed, N., 2022. State-of-the-Art in Chinese APT Attack and Using Threat Intelligence for Detection. A Survey. Journal of Positive School Psychology, pp.4419-4443.
• Poudyal, S., 2021. Multi-level analysis of Malware using Machine Learning. The University of Memphis.
• Schmidbauer, T., Keller, J. and Wendzel, S., 2022, August. Challenging channels: Encrypted covert channels within challenge-response authentication. In Proceedings of the 17th International Conference on Availability, Reliability and Security (pp. 1-10).
• Thakur, S., 2025. Conti Ransomware Practical Study of Static and Dynamic Methedologies.
• Tolboom, R., 2023. Computer Systems Security.
• Viet, H.L., Phung, O.V. and Nguyen, H.N., 2024. Enhancing Webshell Detection With Deep Learning-Powered Methods. arXiv preprint arXiv:2412.05532.