Cryptography Stack Exchange Community Digest

Top new questions this week:

Is there asymmetric encryption in SSH?

I've read in DigitalOcean article about SSH that in order for a server to authenticate a client: The server sends the client this encrypted message. If the client actually has the associated ...

encryption public-key signature ssh  
asked by Stanislav Bashkyrtsev 5 votes
answered by DannyNiu 11 votes

Is LPN not as important as LWE and SVP?

I've been learning about lattice cryptography and have noticed that most resources such as this survey by Chris Peikart, the Winter School on Lattice Cryptography etc don't include material on LPN, ...

post-quantum-cryptography lattice-crypto lwe sis  
asked by picotard 5 votes

Why RSA-KEM is more secure than Textbook-RSA?

I am studying RSA-KEM but I can not see why it should be as secure as padding RSA messages (e.g with RSA-OAEP) when exchanging a key between two parties (say A and B). It is easy to see that ...

rsa public-key key-exchange key-derivation padding  
asked by NightRain23 4 votes
answered by SEJPM 3 votes

Who verifies the trust of certificate authorities?

Background Hello everyone, I am a novice in the field of cryptography and cyber-security, and while studying asymmetric-key encryption, I learned about the potential of a man-in-the-middle attack. ...

rsa public-key certificates  
asked by AlanSTACK 3 votes
answered by Maarten Bodewes 2 votes

RSA Accumulators with auxiliary information or known trapdoor information

In "Universal Accumulators with Efficient Nonmembership Proofs" by Jiangtao Li1, Ninghui Li2, and Rui Xue3 section "How to compute witness with the auxiliary information" the authors write: "The ...

rsa accumulators  
asked by Pedro Paixao 3 votes
answered by István András Seres 0 votes

Linear cryptanalysis of FEAL-4

I am trying to find the sub keys of a FEAL-4 cipher. I am able to get a number of possibilities for $K_0$ after using Michael Stamps formula using a as a constant and going through $2^{32}$ keys. The ...

linear-cryptanalysis feal  
asked by liam waters 3 votes

Why are cyclic keys in Feistel Networks insecure?

So everyone seems to agree that recurring round keys in a Feistel network (eg. using the same key for every round) are a massive security leak. When researching this, the only thing I found is the ...

block-cipher known-plaintext-attack feistel-network  
asked by Lukor 3 votes

Greatest hits from previous weeks:

Difference between stream cipher and block cipher

I read that A typical stream cipher encrypts plaintext one byte at a time, although a stream cipher may be designed to operate on one bit at a time or on units larger than a byte at a time. ...

encryption block-cipher algorithm-design stream-cipher  
asked by Ravindra Bagale 48 votes
answered by Paŭlo Ebermann 38 votes

How to check a file was encrypted (really & correctly)

I would like to audit how an implementation of an encryption algorithm is really performed with the following given data of the problem: the encryption mechanism is reversible (this isn’t a ...

cryptanalysis file-encryption  
asked by dan 17 votes
answered by Gilles 'SO- stop being evil' 29 votes

Why hash the message before signing it with RSA?

The diagram below illustrates the process of digitally signing a message with RSA: As diagram shows, the message is first hashed, and the signature is then computed on the hash, rather than on the ...

hash rsa signature protocol-analysis forgery  
asked by evening 41 votes
answered by DrLecter 29 votes

Why can't we reverse hashes?

First off, I know hashes are 1 way. There are an infinite number of inputs that can result in the same hash output. Why can't we take a hash and convert it to an equivalent string that can be hashed ...

hash collision-resistance  
asked by Hello World 134 votes
answered by adelphus 223 votes

What's the fundamental difference between Diffie-Hellman and RSA?

What is the difference in the purpose of DH and RSA? Aren't they both public-key encryption?

encryption public-key rsa diffie-hellman  
asked by Mehrdad 32 votes
answered by Mehrdad 30 votes

What is the practical impact of using System.Random which is not cryptographically random?

I recently noticed a .NET software using PBKDF to derive an encryption key from a password string. This password string was dynamically generated using System.Random. Now, I know that System.Random is ...

keys random-number-generator key-derivation randomness pseudo-random-function  
asked by learnerX 31 votes
answered by ymbirtt 44 votes

Basic explanation of Elliptic Curve Cryptography?

I have been studying Elliptic Curve Cryptography as part of a course based on the book Cryptography and Network Security. The text for provides an excellent theoretical definition of the algorithm but ...

public-key number-theory elliptic-curves  
asked by user5507 39 votes

Can you answer these questions?

How can a public-key encryption scheme be used to construct a commitment scheme in the CRS model?

For a PKE scheme $(Gen, Enc, Dec)$, the most 'obvious' idea is to commit to an encryption of a bit and in the reveal phase maybe send $r_g$, $r_e$ where $r_g$ is the randomness of $Gen$ and $r_e$ is ...

public-key commitments information-theory  
asked by Andy Dienes 1 vote
answered by poncho 0 votes

aeskeygenassist with only one imm8

I'm analyzing a binary which for its AES encryption, its only calling aeskeygenassist once and for the last argument (imm8, the round) its sending static value of 0x46. Does this mean its using only ...

aes key-derivation  
asked by pobam62 1 vote

What's the difference between a hash chain, transaction chain and a blockchain?

Can anyone explain to me what the difference is between a hash chain, transaction chain and a blockchain?

hash hash-signature  
asked by user10198470 2 votes
answered by Paul Uszak 0 votes
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