Performance and Security Analysis of Aes-GCM, Chacha20-Poly1305, and Lightweight-PDAC Algorithms for Securing Exam Links at SMKN 1 Sukoharjo

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FORMOSA NEWS - Semarang - Lightweight-PDAC Algorithm Outperforms Standard Cryptography for Securing School Examination Links. In 2026, researchers Muhammad Rifqi Anshory and Eka Ardhianto from Universitas Stikubank conducted a comparative study to solve critical cyber vulnerabilities in digital education platforms. Published in the Formosa Journal of Computer and Information Science, their research evaluated three distinct encryption algorithms AES-GCM, ChaCha20-Poly1305, and Lightweight-PDAC to protect Google Forms examination links distributed to students at SMKN 1 Sukoharjo. The study revealed that Lightweight-PDAC delivers superior computational performance and low memory consumption while providing robust data security, making it the ideal cryptographic solution for heterogeneous student devices with limited hardware capacity.

Protecting Digital Assessments in Secondary Education
The digital transformation of education has replaced paper examinations with online assessment tools across primary and secondary schools. Educational institutions frequently distribute assessment access via Google Forms URLs. However, distributing these access links in unencrypted plaintext exposes the evaluation system to unauthorized access, link interception, and academic dishonesty. While standard encryption standards like Advanced Encryption Standard Galois/Counter Mode (AES-GCM) and ChaCha20-Poly1305 provide strong data protection, their heavy computational requirements frequently cause system latency on entry-level Android devices. This performance bottleneck highlighted the need for lightweight cryptographic methods capable of operating efficiently across diverse hardware environments without compromising data integrity.

Multi-Criteria Methodology and Experimental Design
To determine the most practical encryption model for educational deployment, the research team established an experimental quantitative framework. The evaluation analyzed 237 Google Forms URLs across 100 test iterations using uniform testing hardware and software. The benchmark framework measured five computational parameters:

• Encryption Time: The duration required to convert plaintext URLs into ciphertext.
  
• Decryption Time: The speed at which the encrypted string returns to a readable format.
  
• Memory Consumption: Peak RAM usage during cryptographic operations.
  
• Ciphertext Size: The data volume generated after encryption.
  
• Shannon Entropy: The mathematical measure of randomness indicating diffusion quality and security.
  

The technical benchmark data was subsequently integrated with the Open Web Application Security Project (OWASP) Risk Assessment framework, Cost-Benefit Analysis, and a Weighted Sum Model (WSM). To ensure real-world applicability, the researchers weighted these criteria using a comprehensive survey of 20 ICT experts, including computer science teachers, computer-based test administrators, and IT practitioners.

Key Research Findings

The comparative analysis demonstrated that Lightweight-PDAC outperformed conventional encryption algorithms across nearly all performance parameters:

• Rapid Encryption Speed: Lightweight-PDAC achieved an average encryption time of 0.0810 milliseconds (ms), significantly outperforming ChaCha20-Poly1305 (4.7893 ms) and AES-GCM (12.7000 ms).
  
• Ultra-Fast Decryption: The decryption process for Lightweight-PDAC averaged 0.0313 ms, compared to 0.3422 ms for ChaCha20-Poly1305 and 0.7199 ms for AES-GCM.
  
• Minimal RAM Requirement: Lightweight-PDAC consumed only 0.2950 KB of peak memory, whereas ChaCha20-Poly1305 used 2.3991 KB and AES-GCM required 12.1960 KB.
  
• Compact Ciphertext Payload: Lightweight-PDAC produced an average ciphertext size of 9,445 bytes, compared to 11,045 bytes generated by both AES-GCM and ChaCha20-Poly1305.
  
• Enhanced Data Randomness: Through an advanced cipher feedback mechanism, Lightweight-PDAC achieved a Shannon entropy value of 5.979 bits/byte, approaching the randomness levels of AES-GCM (6.225 bits/byte) and ChaCha20-Poly1305 (6.226 bits/byte) without incurring additional computational overhead.
  
• Highest Overall Decision Score: Applying the Weighted Sum Model yielded a final decision score of 0.9901 for Lightweight-PDAC, easily surpassing ChaCha20-Poly1305 (0.4924) and AES-GCM (0.4620).
  

Practical Implications for School Infrastructure and Cyber Security
The empirical evidence established by Muhammad Rifqi Anshory and Eka Ardhianto provides a scalable blueprint for securing digital examination infrastructure. The implementation of Lightweight-PDAC addresses the technological divide in educational environments where students rely on diverse Android devices.

Author Profiles
Muhammad Rifqi Anshory is a cybersecurity researcher at Universitas Stikubank specializing in applied cryptography, web security assessment, and mobile system optimization.
Eka Ardhianto is a senior researcher and faculty member at Universitas Stikubank with expertise in lightweight cryptographic algorithm design, information systems engineering, and multi-criteria decision-making models.

Source
Muhammad Rifqi Anshory, Eka Ardhianto. Performance and Security Analysis of Aes-GCM, Chacha20-Poly1305, and Lightweight-PDAC Algorithms for Securing Exam Links at SMKN 1 Sukoharjo. Formosa Journal of Computer and Information Science (FJCIS), Vol. 5, No. 2 (2026), halaman 259–278
DOI: https://doi.org/10.55927/fjcis.v5i2.16926
URL: https://journal.formosapublisher.org/index.php/fjcis