All Questions

Is there a way to decrypt an encoded string without its key? Basically, I have a string that has been passed through three separate encryptions in the following order: Original -> Base64 -> AES-256 ->...

I'm trying to find hidden 8-length long key from following XOR and Rotation based cipher. ...

Which bit is retained in the Von Neumann debiasing algorithm? 00 and 11 are discarded and 10, 01 are retained but is the first or the second bit retained or does it matter? In other words: first: ...

Is there a cost model for each curve model and their conversions? For example: Take the curve models: Projective, Completed, Extended, Affine. Is there a table which shows how many multiplications, ...

(This question is a follow-up from another question I asked about MD5, which is why I'm insisting on using MD5 in this question as well) My imaginary Linux distribution, Sushi Linux has had a big ...

More generally, is it possible to construct a $(k,n)$ threshold secret sharing scheme (i.e. let than k shares leaks no statistical information about the secret) such that possession of the secret ...

E.g.: $k = N^a \mod P$ The attacker knows the prime $P$ and $N$, which is also a prime and (1.) prime root of $P$ or (2.) has a cycle size of $s$, so $1 = N^s \mod P$, (and for $\forall s'<s$, $...

OpenSSH 8 supports a post quantum KEX, namely sntrup4591761x25519-sha512@tinyssh.org It says in its description that it is basically NTRU + ECC X25519. However, I have tried but cannot understand how ...

I found an interesting concept in this paper, page 13, (Link to the paper) called "Decentralized private key generation", as follows: "Decentralized private key generation – Multiple Enigma nodes ...

Let $$ \begin{aligned} F_{i} \colon \{\, 0,1 \,\}^* \times \{\, 0,1 \,\}^* &\to \{\, 0,1 \,\}^* \\ (k, x) &\mapsto y \\ \end{aligned} $$ for $i \in \{\, 1,2 \,\}$. As we known, for every ...

Signal Protocol uses a counter (discussed in DoubleRatchet documentation) to define how many times KDF has derived a new key (aka a KDF step) which is then sent along with every message for the end ...

I read an article about password schemes that makes two seemingly conflicting claims: MD5 is broken; it’s too slow to use as a general purpose hash; etc The problem is that MD5 is fast I know ...

When I am reading some secure computing papers, the authors always assumed that there exist some adversaries, such as non-uniform adversary and the probabilistic polynomial-time adversary. So my ...

For example according to protocol I need calculate this: $b=F^{(1/h)} \bmod pq.$ Where $p$ and $q$ are prime numbers. I have $F$ and $h$. But how can I calculate $b$? I tried to do this: $\text{...

Can we hide a text first in a picture and then hide that image again in one more image? using a steganographic algorithm like Least significant bit (LSB)?

In ECDH, when two persons want to share private keys, they first select a point $G$ on the elliptic curve and after that, each of them picks a random integer $a$ and $b$, respectively, and multiply ...

To encrypt a message, one uses the algorithm for doing a CBC decryption. To decrypt a message, one uses the algorithm for doing a CBC encryption. Does this work?

It is about DEX, how users are in control of their funds, while they should deposit in smart contract?

How would we go about building a scheme for Shamir secret sharing for vectors? I have already tried to use a vector of secrets and random distribution of the secrets to $n$ parties and then use $t$ of ...

Suppose a node in a proof-of-stake blockchain network wants to forge a blockchain. I'm wondering what should this node do to forge it? Assume this node has a certain amount/fraction of money (but no ...

I have read that one of the PUF's application is software licensing, but do not know how. I have been reading different articles and forums (such as here), but still not clear for me. One vague point ...

Wikipedia claims key length can be very big in this cipher, so I assume it can offer a million bits of security provided entropy of key is the same? Of course I can SHA-256 hash the key to allow any ...

Was giving some thought to simple MMO constructions for fast single block hash functions for things like PQ crypto. There's Haraka, but that's not standard and readily available while simple AES is in ...

I am quite confused, I have been following a course on crypto provided by Dan Boneh, this is the lecture I am confused with - https://www.youtube.com/watch?v=EjWap3szsPk time stamp 8:58 - 11:00 I don'...

In order to avoid memory errors, I always write safe C++ wrappers with strong type-safety for any C encryption library I use. To test my wrapper of ...

This question is related to this one. Specifically, assume that we have $p$ = 2048, $m$ = 13 and $c$ = 357. In this case, $c\ =m^e\ \bmod \ p$. I know that many algorithms rely on the difficulty of ...

Not long ago I saw a discussion on the Bitcoin Talk forum: https://bitcointalk.org/index.php?topic=5060735.msg50736695#msg50736695 Please give advice and working methods? Is it possible to find at ...

I am searching for a way to make the noise X pattern fully forward secret. The X pattern is a way to encrypted and authenticated messages. As a building block to achieve this I started pondering if ...

How to check if two points are equivalent given their projective coordinates (XYTZ)? For example if I do unproject() of a point to pass from XYTZ to XY coordinates and then I come back to XYTZ ...

I have read many answers but I cannot get the basic explanation. There's no need for full details. I just need some basic information about who can create a mac and verify it.

What sort of fields is efficient over an arithmetic circuit? Efficient meaning that given a field $\mathbb{F}_p$, reduction (modulo) does not require many multiplications and preferably inversion was ...

After looking at the Wikipedia page for the Fiestel cipher, I thought about making a variation of it that is very general. I basically followed the diagram on Wikipedia in order to structure the ...

I have a encoded hex values of 3 cipher text(encoded) and corresponding length of plain text too. The plain text and cipher(encoded) text is different in length. I also have some bytes of known Plain ...

I need some example values for the message schedule stage of SHA256 to test this part of my implementation. If possible in binary, for the string 'abc'.

How do you figure out the multiplicative and additive identity with respects to R? I pick some R such that gcd(R, N) = 1 where N is the size of the group. Given some field element x in the group, I ...

Hey is there a way to Print the (binary) version of the IV and not the Hexadecimal? I'm required to show it for class. I'm doing an encryption/decryption of plaintext using CBC mode and I have to ...

How do I write Inverse Sub Bytes for AES Decryption in C++? I only found Sub Bytes for AES Encryption, which is shown below. ...

When I'm reading literature about proof-of-stake blockchain, I found that it seems there is no concept about confirmation blocks (which is used to confirm a posted transaction is indeed honestly ...

how to choose a good OmegaP(input difference) for the characteristic used in differential crypt-analysis on DES?

My friend gave me this puzzle or code and I need to crack it for a game. The only hint they have given me is that kdjVDyb8QL means Think on it more.

I was advised to use crypto_secretbox_xsalsa20poly1305 due to its simplicity and because it's safe against timing attacks. I'm reading the secretbox tutorial, and ...

Assume I want to make my RSA secure because I heard that textbook RSA, especially in conjunction with low exponents, is very risky. I decide to limit my message length to 100 and subsequently ...

It is well-known that keys (generator matrices) of code-based cryptography are very large for its practical usage. To reduce them scientists propose to use families of quasi-cyclic codes. I remind ...

I know that Shor's algorithm can factor semi-primes ($N = p \times q \space, \{p, \space q \in \Bbb{P} \space \vert \space p, \space q \gt 0 \} $). Assuming that all prime numbers are so large that ...

I am confused with round keys and round constant in AES. Are they the same? Can someone explain it to me?

Is there a technical difference between decryption and deciphering?

We consider a $(2, 6)$ Shamir secret sharing scheme over $Z_{11}$. Four players $A,B,C,D$ cooperate to find the secret, but one of them is cheating (so the share he claims to have might not be an ...

Say an attacker has access to a non-rate-limited API that takes (IV, data) and outputsAES-CBC(key, input, data), with the key ...

so I was just wondering if anyone can help me understand how Side-channel attacks like specifically a timing attack affects The Advanced Encryption Standard, or AES. I have read many article, but they ...

Suppose I have two messages $m_1$ and $m_2$ as well as $c_1$ and $n$. It's standard RSA so $c_1 = m_1^e \ mod \ n$, $c_2 = m_2^e \ mod \ n$. Further assume the only information we have about e is that ...