# All Questions

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What is the disadvantage of AES-GCM mode for authenticated encryption? Why does the CAESAR competition say that it’s one of the goals to find an AE scheme that offers an advantage over AES-GCM? What ...
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### Why is CBC with predictable IV considered insecure against CPA

I just learned that using CBC encryption with an IV which is predictable is not secure. From what I understand, using certain plain texts, and then guessing the IV that is uses, the attacker can ...
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### Key Derivation from random salted seed, HMAC and HMAC based KDF

I would like to generate a key which would be good enough to be used for encryption with AES in a mobile environment. My idea is to use as a seed ''random attributes'' from a mobile device. Is hashing ...
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### CSPRNG that cannot be used as random extractor

Are there any specific CSPRNG's that cannot be used as randomness extractor within a TRNG? In other words, can you simply provide enough entropy gathered from a good entropy source as seed in any ...
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### Implementing CD serial key system

I am trying to create a system where to unlock the application one needs to enter a serial code. I have read many articles on the theme but there are two problems bugging me. One is, If I have a ...
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### Why not the one-time pad with pseudo-number generator

I am very new to cryptography (so be kind), but I have a question that may seem silly. If the one-time pad is the perfect cipher and impossible to crack, why would the following algorithm not be one ...
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### The REACT transform and Replayable CCA

Before stating my questions, let us recall the REACT transform [OP01], which enables to construct a CCA-secure hybrid PKE scheme, $\varepsilon'_{pk}$, from an OW-CPA PKE scheme ...
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### TLS WG Charter and Security Goals [migrated]

I was looking at the TLS Working Group Charter. I noticed that confidentiality and integrity of messages for those who desire it are not goals for the group. Naively, I believe confidentiality and ...
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### Vigenère cipher: Security when key length and plaintext length are the same

I have read the Vigenère cipher is secure as long as the key length is the same as the length of the data to be ciphered. Is this true in cases where the same key is used multiple times. In that case ...
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### Known plaintext attack on ElGamal encryption

Assume that Alice uses Bob’s ElGamal public key (  = 2, Yb = 8) to send two messages M = 17 and M’ = 37 using the same random integer k = 9. Eve intercepts the ciphertext and somehow she finds the ...
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### Whitening and randomness extraction

The Von Neumann randomness extractor is explicitly mentioned in the randomness extractor page of Wikipedia, but strangely enough that page does not contain any reference to whitening the results of an ...
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### Understanding Lattice based cryptosystem [on hold]

I have heard that there is one paradigm of Public key cryptosystem, called Lattice based crytography. Further, its security claims are such that it will not be affected even if the quantum computers ...
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