# All Questions

3k views

### Why hash or salt when signing? [duplicate]

I've seen an example of how to sign using RSA. Besides the signing itself (s = m^d mod n) it also hashes and adds an IV. Why is that needed?
444 views

### Making my steganography code more hard to detect and crack

I'm doing a college project about digital image steganography on MATLAB. So far i've been able to get the help i needed from cool guys on stackoverflow but i now need to make my algorithm more hard to ...
9k views

### “SHA-256” vs “any 256 bits of SHA-512”, which is more secure?

In terms of security strength, Is there any difference in using the SHA-256 algorithm vs using any random 256 bits of the output of the SHA-512 algorithm? Similarly, what is the security difference ...
225 views

### Do deterministic secret sharing schemes exist?

Are there algorithms for secure secret sharing such that the algorithm depends solely on the value being secured, relying on no randomness in its calculations. If there aren't, is such an algorithm ...
97 views

### Does a cofactor of an elliptic curve have to be an integer?

What are the implications of a curve having a non-integer co-factor for its generator point? Is that even possible?
510 views

### GCM encryption for 256-bit and 512-bit block ciphers

The Galois/Counter Mode of Operation (GCM) This paper describe using GCM mode with 128-bit and 64-bit block cipher. Can we use this mode for 256-bit and 512-bit block cipher?
175 views

### Known vulnerabilities in (EC-)KCDSA

Does anybody know if there's known vulnerabilities in KCDSA/EC-KCDSA? I have been researching for the past few hours and I haven't found anything. Wikipedia has very limited amount of information and ...
3k views

### The difference between these 4 breaking Cipher techniques?

I'm trying to understand the difference between the following and what they actually mean : Known plaintext attack Known ciphertext attack Chosen ciphertext attack Chosen plaintext attack Any ...
1k views

### Can a shift cipher attain perfect secrecy?

On a practice question for my intro cryptography exam, it asks the following: Assuming that keys are chosen with equal likelihood, the shift cipher provides:    A) computational security ...
109 views

### How unsafe is to share parts of a password

The best way to ask this question and have a concrete answer is to set a very specific example. This is the example I would be interested in reading an answer to: Consider that my friend Alice has ...
294 views

### Proof of work for standard computers

I'm interested in a proof-of-work system that works well on standard computers without using the GPU. Properties the system should have: Seed based proof-of-work. There is no distinguished ...
560 views

### Encrypting firmware with AES and no IV [closed]

I have an embedded device with a AES CBC engine on it that is used to ensure the integrity of the firmware. I know that CBC mode requires unique IVs to be any good, but I'm unsure if it makes a large ...
200 views

### Can a properly implemented ed25519 private key with public underlying data be cracked?

If the underlying data is public albeit hashed with SHA-512, does that make a difference on the strength of ed25519? Please quantify the extent. Can ed25519 be cracked after a certain amount of ...
2k views

### Why is a 2048-bit public RSA key represented by 540 hexadecimal characters in X.509 Certificates?

In the public certificate, an RSA public key specified as 2048 bits long is represented by 540 hexadecimal characters. Converted to base-2, this yields 2160 bits, 112 more than the stated 2048.
53 views

### gnupg: display digest of key [closed]

How can I display what digest algorithm has a key? If I import a public key which has MD5 as digest, I get a warning about this weak algorith. But how can I check, what digest algorithms all my keys ...