Latest Crypto related questions

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Maarten Bodewes avatar
Meaning of the term "irreversible" for hashing
in flag

I was in an interesting discussion with Jon Skeet on StackOverflow. He indicated that hashes are irreversible, but he extended this to non-cryptographic hashes. A hash function has a specific output size while the function can handle any sized messages. So if you argue from that point of view, a hash is always irreversible as there are many messages that have the same hash.

However I wonder if th ...

Score: 1
rusty avatar
Signature delegation without secret keys
ky flag

Scenario: have an entity A that cannot hold any secret keys. A concrete example would be: an application that needs to be open sourced and cannot be modified. In order to send any signed messages, it uses a proxy signer P. P holds the secret key and signs on behalf of A.

The issue: how does the message recipient verify that A actually initiated the message via P, and P did not generate/send the m ...

Score: 3
user7778287 avatar
Are Memory-Hard Functions de-facto quantum resistant?
us flag

Searches have returned absolutely no results on this question. With that in mind, I assume the answer is either painfully obvious ('of course quantum computers get no advantage when it comes to storing data') or the question has just not been studied. Intuitively it makes sense the quantum algorithms would gain no advantage related to storage, but memory hard functions seem to be a rather budding new te ...

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kmart875 avatar
Paper that specifies how to define number ranges inside the ECC with varying equations
cz flag

I am looking for a textbook or published paper that provides specific information on how to configure an ECC. I came across it several years ago and now cannot find it. Does anyone know the source? Specifically, it talked about how to define number ranges inside the ECC with varying equations.

Score: 1
Eduardo Andrés Castillo Perera avatar
What’s the relationship between P-256 and Dual EC DRBG?

It is said that Dual EC DRBG has a backdoor given the values of the curve. Hence some people do not trust it.

With that in mind, some people also distrust NIST P-256 Curve. Why? Is it purely because it’s from NIST? Is it the same curve as Dual EC DRBG? Or is it merely by association? Does P-256 use Dual EC DRBG? Or can you use any Cryptographically Secure PRNG?

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muhammad haris avatar
Where there is special Modulus in Microsoft Seal?
es flag

As explained in their example here, Microsoft Seal uses a special modulus that is used for all key material like relinearization key. I wanted to ask why special modulus is used?

Score: 0
donaastor avatar
Does this encryption scheme have any major vulnerabilities?
br flag

Recently I asked a question of whether there is any cryptosystem that satisfies a number of properties (read the properties). Continuing to the promise I gave there, this is my attempt to construct it. I expect this attempt to satisfy all of the properties, although maybe not provably. The thing that I'm asking here is whether or not there are some easily noticeable vulnerabilities in it.

Modified RSA-OAE ...

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Maria Ejaz avatar
How many number of sequences (sample size) should be selected for randomness testing of bock cipher with 256 bits key and block length?
pt flag

I am working on randomness testing of block cipher. I have gone through the NIST two papers of randomness testing of AES candidate algorithm, links are given below

https://csrc.nist.gov/csrc/media/publications/nistir/6390/final/documents/ir6390.pdf https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=151216 enter image description here NIST used sample size for 128 bits block and key length which is attached in picture and for 2 ...

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donaastor avatar
Is there a public-key, "deal-less", all-or-nothing, "secret-length message" cryptosystem or some easy way to derive it?
br flag

I want to make an ecryption algorithm that is secure in, well, really many ways, which is hard I see, so I came up with some ideas of how to implement it using some primitives that I know and I actually discovered some online that resemble it, but I thought it's time to consult the forum about it.

Firstly I should define my goal. All participants have their private and public keys. Communication  ...

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alphazwest avatar
Decrypting Mono-Alphabetic Substitution Ciphertext
pr flag

I am reading Introduction to Modern Cryptography 3rd Edition (Google Books Preview of Relevant section, pages 10-11) and am struggling to understand the description of an attack method on a monoalphabetic substitution cipher.

It seems to be an improved version of a letter-frequency analysis approach, eliminating the need to "check what makes sense" manually. Some given information:

  1. All letters of the ...

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