All Questions

I will explain better my question here. Suppose to have a chipertext that you can't decrypt, but you know that the plaintext can be A,B or C. Then arrives to you the key which is used to encrypt the ...

I'm wondering the state-of-art result about how many bits are needed to commit a single-bit non-interactively? I noticed in the paper of Naor's bit commitment: http://www.wisdom.weizmann.ac.il/~naor/...

What if we encrypt sha-1 hash of the plain text, along with the plain text using AES-256 in CTR mode? How much future proof the above method would be in comparison to AES-GCM or any other method ...

Let $m \in \{0, 1\}^{2n} = m_1 || m_2$. Let's also assume that $F_k$ is a PRF and $G$ is a PRG defined as $G: \{0, 1\}^n \rightarrow \{0, 1\}^n$. Now, Let's define the $MAC$ scheme as follows: $$MAC(...

What if we use a counter within the plain text and then encrypt the plain text with aes 256 to encrypt & authenticate? For example: encryptAES(32bit_counter+plain_text_of_96bit); or encryptAES(...

In the encryption of MixColumn you use the constants 01, 02 and 03. I don't understand why the inverse of 01 becomes both 0D and 09. I also don't understand how you get 01, 02 and 03 in the first ...

$p$ is a 2048 bit prime number $q$ is a 224 bit prime number I know that $q$ is a prime divisor of $p-1$, thus $p=1 \bmod q$ but I couldn't write efficient code to calculate this. I can calculate ...

I'm applying the Arduino Crypto Library for the code fragments. In the above library, example of encryption and decryption using GCM given as follows: For encryption: ...

Assume $F$ is a PRP then the tweakable block-cipher based on the Merkle-Damgard construction (take this as the way I understand, here is the equation): $F_k[t](m) := F_{F_k(t)}(m)$ is a secure TBC. ...

I was considering algorithm 2.40 (arbitrary reduction polynomials) in the Guide to Elliptic Curve Cryptography and... it doesn't appear to work when the order of the polynomial you're trying to ...

What risks are involved when specific curves are chosen for an ECC implementation? How should I audit a system that uses ECC with regards to a specific curve? Bonus: How can I (or a cryptographer) ...

Please, I got the question "what is the computational complexity of SHA-3 (SHAKE128)"? What does that mean and how can I calculate that?? *I am using SHA-3 (SHAKE128) in my mechanism to hash fix ...

I understand all of the previous steps, but I don't understand what is happening to "S2" in that the number "775" showed up. Where does the 775 come from? I can't seem to get it, and I've tried ...

Why is the Rabin mapping: $f_i(x_i)=x_i^2 \bmod N_i$ not a Permutation over $\mathbb{Z}_N^*$?

I will venture myself into studying chaotic cryptography. However, I find it hard to explain what chaotic cryptography entails to those that have some knowledge of cryptography. Neither can I explain ...

Is it possible to prove that a given signature is a part of an aggregated BLS signature? Specifically, given: $m_1...m_n$ are $n$ distinct messages $p_1...p_n$ are private keys with $P_1...P_n$ being ...

This is a homework assignment, so I'm not expecting full solutions, just general guidance. Let a PRG $G:\left\{ 0,1\right\} ^{n}\to\left\{ 0,1\right\} ^{l\left(n\right)}$ (where $l\left(n\right)$ ...

I'm implementing WOTS+ in a new language and I can't seem to wrap my head around the fact that WOTS+ XOR's their input with its mask right before hashing it. I tried to look for any reasoning but so ...

Can cryptsetup suggestion of wiping a disk before encryption with zeros written to an encryted device as described in question 2.19 as the recommended method on the CryptsetupFAQ (the part that starts ...

Both SHA-384 and SHA-512 are limited to an input size of less than $2^{128}$ bits. Considering SHA-512 has a higher output size, couldn't it include more input data?

I'm reading the book "Serious Cryptography A Practical Introduction to Modern Encryption" from Jean-Philippe Aumasson, and in the first chapter, it is written this : We can try to abstract out the ...

Please, i need the answers of below questions.

I've had an idea about storing parts of SHA256 hashes and I'd like to find out how secure it is, or how much less secure it is than storing the entire hash. For example, users can share this list of ...

algorithm in python to decrypt ENIGMA plugboard (5 couples) i already created an algorithm who break rotors positions and rings , but plugboard i couldn't do something interesting, any propositions ?

i'm trying to decrypt a log file that containt some chat messages ( in french ) it is encrypted with AES-256-GCM then encapsulated into a TLS session: Take a look at the file here https://ufile.io/...

So I'm trying to reverse engineer a lock system that consists of a chip reader and a control unit. There are only two devices on this network, the reader which reads a rfid like chip and the control ...

I'm currently trying to understand and apply edge differential privacy to social network data using Python. As an example, the original network has n = 3012 nodes ...

I read a book about one-way function. In this book, I saw 2 exercises that I can't understand and don't know how to solve. Can anyone help me to solve these? Is $f(x,y)=x+y$ a one way function? Is $f(...

I'm trying to understand how Diffie Helman is still secure when $A$ ends up being a power of $g$ less than $p$. I chose $p$, where p is prime, and $g$ is a primitive root modulo $p$. $g=2$ and $p=...

If you are carrying a standard 52 card pack of cards (no jokers) what is the largest key size, or the amount of data the cards can hold? Without the cards being marked or distinguishable from an ...

I'm looking for a data structure similar to a dynamic accumulator that has the following properties: Small size: ideally under 100 bytes for the accumulator, and also under 100 bytes for witnesses ...

Please help me help me. I would appreciate if someone help to solve this for me Please.

An answer explaining Dragonfly, a form of key exchange used in WPA3, has an interesting footnote: One final note: reviewing the Firefly RFC, I see that it would (as written) leak some information ...

I'm reading the paper "How to Leak a Secret" (Rivest, Shamir, Tauman; 2001). On page 8/14, in chapter 3.4, the authors present the following "combining function": $$C_{k,v}(y_1, y_2,\ldots,y_r) = ...

Here's a quote from Douglas Stinson: “[i]f a cryptosystem can be ‘broken’ in some specific way, then it would be possible to efficiently solve some well-studied problem that is thought to be ...

Here's a quote from Douglas Stinson: “[i]f a cryptosystem can be ‘broken’ in some specific way, then it would be possible to efficiently solve some well-studied problem that is thought to be ...

I'm trying to figure out how long the modulus $n$ has to be in the Rabin Signature scheme, to provide 128 bit security. We assume that the used hash function is "secure enough". Then the naive ...

Say there are 2 sides that wish to communicate: side A and side B. Let's say we are looking at side ...

I want to ask if I have a RSA private key can I use it to generate RSA key that is identical. If yes how can I do it?

Please give help! how can I calculate the probability of collision? I need a mathematical equation for my studying. Assume, I am using SHA256 to hash 100-bits. Thus: SHA256 {100} = 256-bits (hash ...

Some time ago, I proposed making the site more educational by teaching correct cryptographic programming. The proposal had had somewhat good reception, but was met with cold ice as there had been ...

Reading the Schnorr signature Wikipedia page, I stumbled upon the following statement: All users agree on a cryptographic hash function $H:\{0,1\}^*\to\mathbb{Z}_q$. What do these curly brackets ...

Let's say we have: client_id_ran: 256 bit random text (chosen only once for whole system) used to generate client_id by ...

In the AES encryption, suppose that the key is known. The ciphertext is also known except for a block of the same size as the key. In the worst case scenario for the attacker, how hard is it for ...

I have read this answer on Crypto.SE and I want to clarify a few details. Does this property of $\text{Keccak-}f[1600](x)$ imply that if we know a particular $1600$-bit output $Y$, it is feasible ...

I'm using multiple RSA keys to encrypt a piece of data. The data length is constant but the data itself is not. Each time I encrypt I prepend a 64 bit string to the newly encrypted ciphertext. This ...

I have around 1500 numbers. The numbers $x_i$ are calculated as $x_i$=($p*t_i$) mod m. $p$ constant and same for all the numbers while $t_i$ are chosen randomly everytime. For example the given ...

I have full bits of public key $(n,e=65537)$ but from the private key, I have the lower half bits of $d$. Can I restore the whole RSA private key from that data and use it for decryption?

In JWEs there's a unprotected data field as well as recipients are not integrity protected. Is there a case where integrity protecting this data would be a problem? If it doesn't make a difference, ...

I am trying to solve this exercise. Assume an oblivious transfer protocol that uses a trusted third party Trent. Alice's messages $M_0$ and $M_1$ are binary values of length $k$. Bob's message ...