All Questions

83 views

What type of encryption scheme can prevent cheating in this coin flip protocol? [duplicate]

Consider the following protocol for two parties to flip a fair coin: Trusted party $T$ publishes her public key $p_k$ A chooses a random bit $b_A$, encrypts it under $p_k$, and announces the ...
209 views

How to verify a signature with openssl methods from the ECDSA class?

I'm trying to verify my signature like I explained in my question before. But I have some problems to program my own verification without the verify methods of openssl. Therefore I'm going on to use ...
375 views

How to crack SHA256 only letters

I recently created a program that hashes a password using SHA256 and potentially using salt. How can I crack that if I know that the password only contains lowercase letters?
1k views

Is the AES encryption scheme CPA secure?

Give a 256 bit key space and 128 message space would AES block cipher as the encryption scheme be CPA secure?
46 views

50 views

Can a Cramer-Shoup public key have two different private keys?

Since I am new to the Cramer-Shoup algorithm, I would like to know: Is it possible to have two different private keys for a public key due the key pair generation algorithm that Cramer-Shoup uses? I ...
20 views

Secure algorithm for calculating token and comparison

I am trying to define algorithm that would create a irreversible token from IDs, which are 10 digit information, and then would be compared on two different end points. Between end points, only ...
82 views

Can we use merely permutation to hide a message?

This question is related to this: When all shares of a secret are given to adversary as a permuted matrix I think the below question is a simplified version of that. Assume we have a 40-bit ...
59 views

Should we use modulus switching when dealing with ciphertexts encrypted in different rings?

Having a homomorphic encryption scheme like BGV or LTV-FHE at some point it is possible in the homomorphic evaluation to deal with ciphertexts that are encrypted with respect to different moduli. ...
213 views

Reversing a Psuedo Crytographic Hash [closed]

I'm trying to get a better understanding of cryptographic hashing. Take the example transformation function below, is it possible to reverse this formula to solve/isolate for message[i]? ...
667 views

With HMAC, can an attacker recover the key, given many known plaintext/tag pairs?

Given many pairs of $(m, t)$, can the attacker compute the key $k$ satisfying $\text{HMAC}(k,m) = t$? (Assume that $k$ was chosen at random.)
49 views

What's the best way to pad a message?

Currently my padding is adding a string of random characters $l(N)/3 - (l(M) + 1)$ Long and just adding it to the messages, is this sufficient? $l(x)$ = length of a variable
349 views

Cryptography based upon neural networks [closed]

I would like learn about use neural networks in cryptography. Is there any research literature on this subject? What should I do to learn about the subject? I am taking short course in neural ...
125 views

Why are there so many stream ciphers out there and even ongoing research?

What make them better than OTP using a CSPRNG initialized with a secret key?
2k views

Is it possible to generate an RSA SHA1 signature only from a public key?

Is it possible to generate signature only from Public key. See example below where i have valid signature but what if I change hash ? Is then any way to do this? Public key(160 bytes): ...