Access to Seed number

[TourajOstovari]

Hello, I want to have access to the Seed value that is generated by the algorithm, and in which order does the Shuffle algorithm work? Because I want to use this in cryptography, and in decryption I need to repeat the same pattern from the end to the beginning, and there should be something like a Seed so that I can reverse the order and combination from the end to the beginning. Thank you.

[Shiroechi]

Hi @TourajOstovari ,
Thank you for reaching out. I understand you're looking for a deterministic and reversible shuffling mechanism for cryptographic purposes. I'd like to address your questions and offer some guidance.

1. Regarding the Seed
   By design, the algorithm does not expose the internally generated seed. However, you can provide your own seed to the generator if you need reproducibility. Keep in mind that even with a fixed seed, this alone will not solve your decryption/reversal requirement.

2. Shuffle Order & Reversibility
   The shuffle algorithm uses Fisher-Yates (Knuth Shuffle), which works as follows:

for i from n-1 down to 1:
    j = random integer in range [0, i]
    swap(a[i], a[j])

This algorithm is forward-only and destructive. Each swap operation overwrites positions, and the original ordering information is lost. It is not designed to be reversible, even if you know the seed.
To "reverse" it, you would need to record every single (i, j) swap pair and then replay them in reverse order — which is fundamentally different from having a seed-based decryption.

3. For Cryptography: From your description, I can see that what you actually need is reversible encryption, not shuffling. AES is a much better fit for your use case. Unlike shuffle, AES is designed for encryption and decryption — you can encrypt data with a key and later decrypt it back to the original.