# All Questions

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### What are the difference between cryptographic primitives and encryption primitives?

For example, from reading I found that the cryptographic primitives of both AES and DES are Confusion and Diffusion. However the encryption primitive for DES was Substitution and Permutation while ...
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### Why is plain ElGamal not secure?

Why is plain ElGamal not secure? What is the proof behind it?
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### How does the Blowfish algorithm key initialization work

I'm having some trouble understanding the Blowfish encryption algorithm. From the Wikipedia article... The secret key is then, byte by byte, cycling the key if necessary, XORed with all the ...
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### Standards/RFCs for non-Diffie-Hellman perfect forward secrecy?

Some time has passed since PFS introduction and we now have secure&proven asymmetric ciphers that can generate strong keys very efficiently (elliptic RSA variants and/or QD-Mceliece can generate ...
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### Secure ElGamal with OAEP

Is it possible to make ElGamal IND-CCA2 using OAEP or OAEP+? The reason I ask is that I recently answered this question and it came to my mind that OAEP or OAEP+ might be possible solutions. Note ...
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### AES-XTS: find key from ciphertext and plaintext [duplicate]

Let's say I have a plaintext, the corresponding ciphertext encrypted using AES-XTS, and the initialization vectors. Is there any way - not brute force, of course - to compute the key? Even if there's ...
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### Prove there is PRG that is not necessarily one-to-one

We assume that there is at least one PRG .Now prove there is a PRG like $G:\{0,1\}^{n} \rightarrow \{0,1\}^{l(n)}$ such that it is not necessarily one-to-one.
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### CTR_DRBG versus OFB_DRBG

As far as I know, in the development of ANSI X9.82, there was consideration of OFB_DRBG, a pseudorandom number generator based on block ciphers like CTR_DRBG, but it appears to have been rejected of ...
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### Looking for C++/Python Open Source code library for cryptanalysis of classical ciphers

I've done a significant amount of coding over the years working on classical ciphers (e.g., Chaocipher, D'Agapeyeff). My main programming languages today are C++ and Python, although there was a time ...
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### Is the key schedule of Serpent a circle?

The creation of the prekeys for Serpent works by XORing some previous values with a counter and a fixed value. Every word is 32 bits big and 4 words form a round key (after applying a S-Box, but this ...
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### Why is a Feistel network not a type of substitution-permutation network?

I understand what substitution-permutation networks look like. I understand what Feistel networks and Feistel-like networks look like. A Feistel network or a Feistel-like network features substitution ...
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### difference between soundness in ZKPoK and special soundness for sigma proofs

What is the difference between soundness in ZKPoK and special soundness for sigma proofs?