Most Popular
1500 questions
16
votes
5 answers
Is there an intuitive explanation as to why only the private key can decrypt a message encrypted with the public key?
I have just learned about using PGP/GPG for email encryption and one thing bugs me:
How is it possible that a message encrypted with somebody's public key can be decrypted only with that person's private key?
This concept of asymmetric encryption is…
king_julien
- 411
- 4
- 8
16
votes
3 answers
Why Quantum Key Distribution (QKD) is impractical
In NSA's FAQ on Quantum Computing and Post-Quantum Cryptography, it is mentioned as
Q: Should I use a QKD system to protect my NSS from a quantum computer?
A: No. The technology involved is of significant scientific interest, but it only addresses…
kelalaka
- 48,443
- 11
- 116
- 196
16
votes
2 answers
Difference between "one-way function" and "cryptographic hash function"
What's the difference between a one-way function and a cryptographic hash function?
juaninf
- 2,701
- 2
- 18
- 28
16
votes
7 answers
Which is the simplest cryptographic algorithm which is close to commercial-level security?
An algorithm is simpler than another if
It is easier to explain to a noob with basic high-school math knowledge.
It is easier to securely self-implement by an intermediate programmer (Yes I know one should never 'roll their own' but this is just a…
An Ant
- 271
- 2
- 7
16
votes
2 answers
Quality of randomness on a Linux system with haveged
Has anyone checked if using haveged, a Linux daemon which uses the HAVEGE algorithm, changes the non-deterministic properties of the random data from /dev/random in any negative ways?
Hal Bal
- 171
- 1
- 4
16
votes
3 answers
Has AES-128 been fully broken?
Has AES-128 been broken over the full 10 rounds? If so, by what means? By a commercial entity? By a supercomputer?
If not, why is AES-256 used to replace AES-128 so frequently?
Offir
- 283
- 1
- 3
- 5
16
votes
3 answers
Why is the core ChaCha primitive not good for use in a CRCF? Why create BLAKE?
Why is the core ChaCha primitive not good for use in a collision-resistant compression function (crypto hash)? Why go through the trouble to create BLAKE?
What's wrong with using the core ChaCha primitive unaltered in a Merkle–Damgård like…
Charlie
- 374
- 1
- 10
16
votes
1 answer
Why is double encryption that's equivalent to single encryption no better than single encryption?
In the "Introduction to Cryptography: With Coding Theory" by Trappe and Washington, in the chapter about DES algorithm the authors say that:
"if a cryptosystem is such that double encryption is equivalent to a single encryption, then there is no…
AleWolf
- 461
- 3
- 10
16
votes
6 answers
Is the decompression of compressed and encrypted data without decryption also theoretically impossible?
We have two communication points in an information system, call them A(lice) and B(ackup).
B has to store encrypted data received from A. The storage of B is encrypted, but not compressed1.
B should have no option to decrypt the data of A2.
However,…
peterh
- 390
- 4
- 17
16
votes
1 answer
How long does it take to crack RSA 1024 with a PC?
Using an Intel Core i5 CPU, how long does it take to crack RSA using a key size of 1024 bit (generated using a secure key pair generation function)?
Suppose for instance that we have thousands of zombies or a big network of computers. To calculate…
R1w
- 1,952
- 4
- 20
- 45
16
votes
1 answer
Is this paper's technique for factoring RSA 2048 with noisy qubits realistic?
A paper titled How to factor 2048 bit RSA integers in 8 hours using 20 million noisy qubits has just come out which proposes a technique to factor RSA keys with moduli up to 2048 bits with a design whose assumptions they stress are realistic. What…
forest
- 15,253
- 2
- 48
- 103
16
votes
1 answer
Commitment scheme using hash functions
Let's say Alice and Bob are playing a game where Bob is trying to guess a number Alice has chosen.
Alice chooses a key $K$ and a number $N$ at random and performs $C=Commit(K, N)$ where $Commit(K, N)=h(h(K) \| h(N))$.
$h()$ is a collision-resistant…
rath
- 2,548
- 3
- 25
- 40
16
votes
6 answers
Is AES easier to crack when the input is small?
Say you just want to encrypt a number. For example, say the number could be any double. A double in C# and Java is 8 bytes.
If you were to encrypt a double using AES (MS-Doc, defaults to CBC as the mode):
var cypherText = AES.Encrypt(123d); // 8…
user875234
- 263
- 2
- 6
16
votes
1 answer
Selection of rotation constants in ARX design
My question is about choosing the rotation values in ARX design such as SIMON-like or SPECK-like ciphers to provide optimal differential and linear immunity. According to this, the selection of $a$ and $b$ values (shown in SIMON-like figure below)…
hardyrama
- 2,126
- 1
- 16
- 40
16
votes
2 answers
What are zk-STARK's?
The zk-STARK is a proof zero-knowledge proof system that, in contrast to the zk-SNARK, no longer relies on a trusted setup where the "toxic waste" parameters are initialized.
What are, in layman's terms, the basic building blocks of the zk-STARK,…
CRYPTONEWBIE
- 468
- 3
- 12