# All Questions

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### Generate an insecure public / private key pair

I am looking for a way to generate an "insecure" public key pair. and by insecure I actually mean a pair that is breakable using brute-force (or other encryption) methods. As far as I know PGP ...
416 views

### Questions about proof of correct encryption in the Paillier cryptosystem

In the Paillier cryptosystem [1] the encryption of $m \in \mathbb{Z}_N$ with randomness $r \in \mathbb{Z}_n^*$ is $c = g^m r^n \bmod{n^2}$. A proof of correct encryption could look like presented in ...
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### What is bounded-retrieval model?

What is bounded-retrieval model in cryptography? How is it related (or apply) to leakage-resilient cryptography?
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### Are analog quantum computers a threat to RSA and DLP?

We already know that D-WAVE's "quantum computers" can't really run the Shor's algorithm, because the way they're built doesn't qualify them as universal quantum computers. Now researchers actually ...
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### Is the ring learning with errors problem still hard if the errors are drawn from some subspace?

Let $R=\mathbb{Z}_p[x]/x^n+1$ be the ring used in normal RLWE, which is linear space over $\mathbb{Z}_p$ with dimension of $n$, let $S$ be a linear subspace of $R$ which described by linear ...
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### Why SSH does not use a certificate authority in the same way as SSL [closed]

SSL requires the use of a trusted third party -- the certificate authority to verify a public key presented by a server to a client. SSH on the other hand relies on the client having the server's ...
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### Boneh/Franklin Identity based encryption with Tate pairing

Boneh/Franklin developed an identity based encryption scheme based on the Weil Pairing. This algorithm has also been standardised in IEEE P1363.3 . I know that this algorithm can also be implemented ...
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### Cryptographic Algorithm [closed]

I'd like to find out the cryptographic algorithm which uses only lowercase letters and numbers to encrypt a message, and it has 256 bits (always). For example: fff51ebcad2c44c75d7d5d4c5184b3e4
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### How to decrypt SSL data on a considered-to-be-compromised host? [closed]

I have a package which I want to encrypt on my machine and send it to another remote machine. If I use asymmetric encryption, I must have the private key on the remote side. However, I don't trust the ...
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### How to determine how good our generator of random numbers is [duplicate]

I am using SecureRandom class in java with default constructor and after i run it four times and each times i will take back 4 "supposed highly secured random numbers" . First run : -35 -43 -127 12 ...
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### Where and how to store private keys in web applications for private messaging with web browsers

I am working on a web application enabling users to communicate over private messages which is just one part of the whole system. The main focus during my development process is to protect the privacy ...
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### Designing a secure protocol to avoid MITM?

Imagine that you are designing an online game, the framework consists of a player A, a game host H and a trusted central server S. The player A has a symmetric key KAS and id A that is known to ...
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In one of the hot forums of today on how to convince friends cryptography is good one of the arguments stated is the knife paradox, I was unable to find the answer on Google and my question is what is ...
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### Security of randomized data dependant key schedules?

An example to demonstrate the point with two Feistel networks: Cipher A: \begin{align} roundkey = hash(key || counter)\\ roundkey = hash(key || roundkey)\\ left = left\oplus hash(roundkey || right)\\...
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### Can I serve data for user without the ability to access them? Which functions for the user remain?

My Problem I want to serve sesible data for users as a webservice that is accessed by the user via the browser. Restrictions: I may not be able to technically acces the data of the user Data is ...
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### Is this PRG secure?

$G$ is a safe PRG in range $\{0,1\}^n\rightarrow\{0,1\}^{n+1}$. Let us define $G'(S)=G(S\oplus G(S)_{1,...,n})$, s.t. $G(S)_{1,...,n}$ is the first n bits of $G(S)$. Is $G'(S)$ a secure PRG? ...
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### Proving CCA security for scheme constructed from secure PRP

We have a $PRP : \{0,1\}^{3n} \rightarrow \{0,1\}^{3n}$ and encryption scheme constructed from this $PRP$. $E_k(x\|r\|0^n)$, where $r$ is randomly chosen from $\{0,1\}^n$ and $0^n$ is a block of ...
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### Is there any symmetric key cipher (block or stream cipher) providing partial decryption?

symmetric key cipher (block or stream cipher) providing partial decryption of data at some points. Although the entire data has not been decrypted, the data decrypted to that specific point should be ...