# All Questions

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### What role plays Quantum Fourier Transformation in Shor's integer factorization algorithm?

I cannot seem to understand the role or goal of Quantum Fourier Transformation in Shor's integer factorization algorithm. Is it used to collapse all quantum states into one, in which it has a factor ...
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### Since it gives negative power, how is rcon(0) calculated in AES?

I'm trying to calculate Rijndael key schedule "Rcon" values manually. I know how to calculate each value with the equation ...
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### Two different approaches for Key Expansion using the AES-256 algorithm?

I am implementing AES 256-bit Algorithm from the Theory given in the book, "Cryptography and Network Security" by Behrouz A. Forouzan. The Algorithm described in the Book in relation to ...
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### Brute forcing CRC-32

I'm working on a cryptosystem which uses IDEA. The designer made the mistake of including a CRC-32B hash of the password unencrypted in the header, so that the system can quickly reject bad ...
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### Understanding CRC

There are zillions of articles describing CRC. What can I read to (more deeply) understand what's really going on? Both from an algebraic perspective and a bit-manipulation perspective, I'd like to ...
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### Necessity of Randomness of Salts?

Given the desire to have unique salts for each user of your system, is it actually necessary to create a cryptographically-random salt for each user? If your system already has some other unique user ...
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On page 11, definition 2 of "Simultaneous Hardcore Bits and Cryptography Against Memory Attacks", the paper outlines the following steps (PK,SK) public key and secret key are generated by defender ...
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### Cryptanalysis not based on method used to encrypt? [closed]

When doing cryptanalysis on RSA or something number theory based, there are various attacks that all seem to involve number theory (Wikipedia: RSA_(algorithm) ~ Attacks_against_plain_RSA). Similarly, ...
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### Initialization Vector Properties

This is a multi-layer problem, and I want to take you through the whole thing rather than just asking about IVs. Bear with me. Also, all code below is in Common Lisp because that's what I'm using, but ...
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### Is SHA-256 a one way permutation when restricting the domain to {0,1}^256? [duplicate]

Suppose we consider the space of $\lbrace 0,1 \rbrace^{256}$ as the domain and SHA-256 as our hash function. Does SHA-256 become a one way permutation? Has anyone tried to prove this? Or can it be ...
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### Will our app be FIPS 140-2 compliant if we use our own AES algorithm implementation?

We are in the processing to understand if our software applications is FIPS 140-2 compliant or not. Currently in our application, we are using our own implementation of AES algorithm. AES is a FIPS ...
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### Key-size of encryption method

Is there a definied keysize to be used with the "AES_256-CBC" method in PHP, and what is the size? Some background: I want to store encrypted text into a PostgreSQL database. The user who posts the ...