[Custom]: Decryption Logic Issues – Shuffling Desync, Re-mapping Errors, and Performance Bottlenecks

[Cyberpunk-San]

Issue Summary

Brute-force decryption logic in the image encryption module suffers from inconsistencies in shuffling, incorrect pixel mapping, and serious performance issues in pixel_decoder.py

Issue Description

Double Shuffle Desync:

During decryption, both new_y and new_x are shuffled independently, while encryption likely used a consistent or sequential coordinate system. This inconsistency leads to improper image reconstruction.

Shuffling Order Mismatch:

Without knowing whether the image was encrypted using row-first, column-first, or flattened order, assuming both axes were shuffled randomly may result in mismatched decryption.

Incorrect Re-mapping Logic:

In the current brute-force approach:

reconstructed[y][x] = img[i][j] This is logically reversed. It should instead follow:

reconstructed[i][j] = img[y][x] This restores each pixel to its original position instead of assigning it incorrectly.

Image.show() in Loop:

Opening the image in a loop for each seed leads to hundreds of preview windows, overwhelming the system and hindering usability.

Performance Inefficiency:

Saving and displaying the image on every iteration consumes significant I/O and memory, especially during brute-force decryption across a wide seed range.

Proposed Solution (Optional)

1.)Use a consistent shuffling logic during encryption and store the shuffle map (indices).

2.)Implement a proper reverse mapping using index tracking.

3.)Replace image.show() in loops with seed logging or hash checking.

4.)Optionally preview only when a certain condition (e.g., perceptual hash similarity or user-defined threshold) is met.

5.)Optimize performance by avoiding I/O-heavy operations unless the result is likely to be correct.

Priority

High - Requires urgent attention

Category

• [ ] Enhancement
• [x] Refactor
• [ ] Security
• [ ] Design
• [x] Other

Additional Context (Optional)

Hi Maintainers,

I'm a GSSoC'25 contributor with 2+ years of experience in Python and have worked extensively on image processing and cryptographic utilities. While analyzing the decryption logic in pixel_decoder.py, I noticed the current implementation could significantly benefit from restructuring and bug resolution.

The brute-force decryption strategy lacks consistency with the encryption shuffle logic, which breaks accurate reconstruction. Furthermore, the current loop-based rendering and image preview logic (image.show()) makes the process both memory-heavy and impractical for real-world testing. A few lines of code, such as the remapping logic, are also reversed or non-functional under the current coordinate assumptions.

I would love to contribute a robust solution that:

Aligns encryption and decryption processes through reproducible shuffling.

Implements a clean reverse mapping mechanism.

Replaces expensive GUI operations with intelligent seed validation (e.g., perceptual hash comparisons or checksum-based checks).

Ensures readability, modularity, and PEP8 compliance throughout the affected files.

Looking forward to your response and hoping to submit a PR after your feedback.

Best regards, Sansriti Mishra GSSoC'25 Contributor

[github-actions[bot]]

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