indicated that AES outperformed all other algorithms in encryption and decryption speed, especially as file size
scaled upward. Blowfish, although with flexible key lengths, exhibited slower throughput and higher latency
under large file sizes, making it less suitable for bulk data operations typical in cloud storage. The authors
concluded that AES’s consistent high performance across increasing file sizes, along with its strong security
properties, renders it the preferred choice when throughput and scalability are critical. In contrast, Blowfish
might only be recommended for legacy or low-resource contexts where high throughput is not essential. Koukou,
Othman, and Herve (2016) compared AES, Blowfish, CAST-128, and DES under different data loads,
examining encryption speed, block size, key size, avalanche effect, and data integrity using both ECB and CBC
modes. Their findings showed that AES consistently demonstrated the strongest avalanche effect and best
integrity characteristics, key security indicators across all tested conditions. Blowfish and the other algorithms
exhibited weaker diffusion and higher susceptibility to integrity issues under certain modes and data patterns.
The study thus supports AES as offering superior cryptographic robustness. While Blowfish remained
competitive in performance metrics for smaller data chunks, its weaker diffusion and block-size limitations
rendered it less desirable for high-security or large-scale encryption tasks.
Devi, et. al. (2015) studied encryption and decryption speed of DES, AES, and Blowfish specifically for image
files. They measured performance across several image sizes and concluded that Blowfish gave the lowest
encryption/decryption time among the tested algorithms for the majority of image workloads. Given that images
often constitute a large portion of user data in cloud storage (photos, scanned documents, etc.), this finding
implies that Blowfish might provide efficiency benefits for image-heavy storage scenarios. Nevertheless, the
authors cautioned that security, block size limitations, and the cipher’s relative age may pose long-term risks
thus recommending Blowfish only where speed matters more than maximal security, and AES when
confidentiality and resilience are paramount. Dhamala and Acharya (2024) explored a less common context,
DNA cryptography comparing DES, AES, and Blowfish for encoding data represented as DNA sequences. Their
work measured encryption and decryption times in this specialized environment and found that the
Blowfish-based implementation offered faster decryption times compared to AES, though encryption was slower
than with DES. While not directly related to conventional cloud storage, their results highlight Blowfish’s
potential in non-traditional data encoding contexts where decryption efficiency outweighs other factors. The
study suggests that for systems prioritizing fast retrieval or decoding (e.g., specialized storage formats), Blowfish
might be a viable candidate albeit with consideration of block size, security, and algorithmic age. Timur,
Royansyah, and Kusumaningsih (2025) conducted a contemporary comparison among AES, Blowfish, and a
modern cipher (ChaCha20) on image and document files, assessing encryption/decryption time, CPU and
memory usage, and security metrics including key strength and brute-force resistance. They reported that while
Blowfish remained faster for some smaller files, its performance degraded as file size increased — and its 64-
bit block size and older design posed limitations. AES maintained consistently high security and reliable
performance across large file sizes and mixed workloads, making it better suited for modern cloud storage
demands. The authors conclude Blowfish may be acceptable in scenarios involving small files or low resource
constraints, but AES remains the preferred cipher for large-scale, security-critical storage applications.
METHODOLOGY
A collection of chest X-ray pictures was used to test and deploy the AES and Blowfish encryption model for
COVID-19 detection. Each of the encryption methods AES and Blowfishuse a total of 20 pictures, evaluating
each method's performance in protecting medical photos, while preserving their quality after decryption was the
key goal. Basic preprocessing procedures, like resizing and format standardization, were applied to every image
to guarantee that it would work with the encryption interface. A regulated and uniform testing procedure for the
two procedures was made possible by the tests being carried out in MATLAB.The encryption and decryption
processes for the two algorithms were integrated into a MATLAB-based Graphical User Interface (GUI),
allowing users to load an image, select the desired encryption method, set the key size (128-bit or 256-bit), and
view both encrypted and decrypted outputs alongside performance metrics. The GUI also displayed critical
parameters such as encryption time, execution time, throughput, and mean squared error (MSE) for each
processed image. Figures 1 and 2 respectively illustrate the workflow and output for AES and Blowfish
respectively. These figures show the original image in the sender section, the encrypted version in the center
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