# All Questions

3k views

### Attacking 2DES efficiently

Meet in the middle on 2DES uses $2^{56}$ memory. Given the fact that the attacker has only $2^{45}$ memory. How can the attacker adjust the attack so even with this memory limit, it will still be more ...
796 views

### Openssl & RSA : how many public exponents are possible?

I would like to know if it is possible to set the public exponent we want with "OpenSSL RSA" or if it is really limited to 2 possible exponents: 3 65537 If yes, why ?
998 views

### How to hash a list of multiple items?

In some protocols, a key is derived from a hash of many parameters (K=H(param1,param2,param3)) Is there a hash function that takes many parameters as input ? Or we can simply use a function like ...
390 views

### Zero-knowledge proof using quadratic residue: why two options?

In the zero knowledge proof using QR, why do we even bother with the server sending us $b = 0$ back? As I understand it, the server selects $b = 0$ or $b = 1$. If $b = 0$, then the client (Alice) ...
331 views

### How does an oblivious test of plaintext equality work?

Assume an ElGamal Cryptosystem. Assume a set of three players, $P_1$, $P_2$ and $P_3$. The private key $x$ is shared among the players. The player $P_1$ has a piece of the private key $x_1$, $P_2$ has ...
761 views

131 views

### Checking the integrity of RSA public key

Let's say I need to verify a digital signature and the public key is stored in untrusted storage which I need to fetch before I verify the digital signature. However, I can store the cryptographic ...
175 views

### How can I factorize a 350 bit (106 decimal digits) number in two prime factors?

I have this large number: 1728098743723095094470726818328193358068864405124007684733613106475812450278961107574624070107782941006379 which is the multiplication of two unknown large prime numbers. I ...
313 views

### ECC keys vulnerable to brute force attack?

I have started learning about Elliptic curve cryptography. Since the key size required in ECC is relatively lesser than the key size in RSA to provide the same amount of strong encryptions, I wonder ...
127 views

### Is it true that 7zip doesn't use any salt with its KDF?

This issue claims that 7zip does not use any salt with its key derivation function: https://github.com/magnumripper/JohnTheRipper/issues/1679 If that's true, wouldn't that mean you can crack multiple ...
113 views

### Why is “semantically secure” important for cryptosystems?

The first question: what is the exact definition of semantically secure? Basically, a cryptosystem is semantically secure if given the public key and the ciphertext, an adversary cannot learn any ...