All Questions

I have read the papers Wide Trail Strategy and Wide Trail Design Strategy for Binary MixColumns. These papers describe the need for a good linear transformation in a cipher, a provable mechanism to ...

I apologize if this is in the wrong section. I am completely new to Cryptography. I was presented with the following problem and I am trying to find something that will explain to me how to proceed. ...

Consider the following ElGamal encryption (using a generator of $\mathbb Z^*_p$): Key gen: find a big prime $p$ and $g$ a generator of $\mathbb Z^*_p$. choose $a\in \mathbb Z_{p-1}$ randomly and ...

Stream ciphers are usually used for streaming data encryption, such as voice, and also for low layers data encryption. For example, MACSec uses AES-GCM encryption. In L3 ad L4 security protocols (...

Let F be a secure pseudorandom function with 128-bit key and 256-bit block length. Which are the following functions G are secure pseudorandom generators? (Select all that apply.) A. $G(x)=F_x(0...0)$...

I am wondering why CMS (PKCS#7) Signed Data contains always a different signature of the original data when the SHA256withRSA signature algorithm is used. (using ...

I want to implement AES-CBC mode with PKCS#7 padding, along with a way to validate a correct padding given the ciphertext. My initial understanding was that for an input of size ...

Supposing a secure hash function $f(\cdot): \{0,1\}^* \rightarrow \{0,1\}^n$ satisfies pre-image resistance. That is, given a hash value $y$ it should be difficult to find any message $x$ such that $y ...

I want to use AES CTR with a random IV, as this would be the easiest way for me. I have a cryptographic module, that supports true random number generation. Due to compatibility, I must use AES CTR. ...

Reading through the NodeJS API docs I came across IV for the first time. From what I can tell it has the same role as a salt in password hashing? Are they equivalent?

I need to create a RSA-SHA1 signature in nodeJS, I am using the following code ...

The SIGMA protocol proposed in 2003 and used in TLS 1.3 and IKE stands for "SIGn-and-MAc" and can optionally protect identity using encryption. The SIGMA-I variant illustrated below ...

In NIST's Submission Requirements and Evaluation Criteria for the Lightweight Cryptography Standardization Process document it is stated that: 3.1 AEAD (Authenticated Encryption with Associated Data) ...

I was looking at the proof of a change of base formula for the discrete logarithm in this paper (page 6, 4th bullet indent). In the intruduction, the paper states: Let $F_q$ be a finite field of order ...

I am trying to understand the security level of TinyJAMBU-128. As shown in Table 4.1 page 12 of this document, TinyJAMBU-128 claims 112-bit security. However, it has a 128-bit key. How have we lost 16 ...

For odd prime $p$, I have been given a group $\mathbb{Z}_p^*$ of all invertible elements from $\mathbb{Z}_p$. Basically, $\mathbb{Z}_p^* = \{1,2,\ldots , p-1 \}$. I also have $a$ and $b$, which are ...

I have problem with multiplying bytes by 3 in MixColumns (as in Cryptography And Network Security) $$\begin{bmatrix}02&03&01&01\\01&02&03&01\\01&01&02&03\\03&01&...

For example, let’s say I pick a random secret and hash it. Now, in the hypothetical hash-based scheme, my hash effectively replaces my public-key hash, and my random secret effectively replaces my ...

I've been looking into implementing cPace, and I saw that two cipher suites defined for it refered to draft-irtf-cfrg-hash-to-curve for its protocol definition. Part of cPace requires mapping a string ...

Let e be a bilinear pairing function and $g_1$ and $g_2$ be the generators of $G_1$ and $G_2$ Given $e(a,g_2^x), e(b,g_2^y), g_2^x,g_2^y$ is there a way to find out if $a = b$?

If one have files $x_1, x_2, .., x_n$. What are the benefits of using hashing trees $-$ also known as Merkle trees $-$ (for example in git) instead of computing one hash value $h(x_1,x_2,..,x_n)$ ?

In cryptography, a block cipher mode of operation is an algorithm that uses a block cipher to provide information security such as confidentiality or authenticity. A block cipher by itself is only ...

I have a python project and for this project, I need to use Weierstrass-based ECDSA. On the web, I've found two libraries; Library 1 is called fastecdsa: Library 2 is called ECPy: I couldn't see any ...

RSA as defined by PKCS#1v2.2 allows public exponent $e=n-2$. And textbook RSA was born with $e=n$ (see second bullet here). Are these variants essentially as secure as (textbook) RSA with fixed $e$? ...

How the value of prime integer taken in Shamir's Secret sharing scheme. I have taken p which is greater than my secret and the no of shares. When i do calculation without modp then secret reconstruct ...

I understand why $e$ must be co-prime to the totient of $N$, but I see in many explanations of RSA that $e$ should be less than $\varphi(N)$. Is there a reason for this? Is it for ease of a small ...

I am pretty sure there's a good reason for this, but it just occurred to me I've been just taking for granted that all PGP signed messages look something like this: ...

I have an exercise that says the following: Let $p$ be an odd prime, and let $a$ and $b$ be generators $\mathbb{Z}​_p^*$. Suppose that we have an efficient algorithm $A$ for computing discrete ...

In this article https://www.mdpi.com/2073-8994/12/10/1687/htm, specifically in the section 4.1 of the initialization phase,the following cryptographic hash functions have been chosen: \begin{align} ...

EDIT: My original problem was that if I have to encrypt large amounts of data, AES would expand the data even more, but this is not the case. This question states that AES does not expand data at all. ...

i'm studying RFC 5652 in order to know exactly how to encode/decode PKCS#7 ASN.1 data. I don't understand how one can create a signature when the field "signedAttrs" is present: The result ...

I need to sign some data using RSA. I have the digest that I can sign but the signature turns out different from the signing source data. There is data in data.bin and its sha256 digest in digest.bin <...

According to Wikipedia block cipher modes of operation, simplified CFB supports random read access. but what about the real CFB where we have a shift register? below are pictures extracted from the ...

I have a playfair cipher I’d like to decrypt however I need to find the key word first. Is it possible to use the Friedman test here to find the length of the key word? My cipher has no J’s in it ...

One could use Falcon-512 for establishing a private and public key for an asymmetric context. Whereas in a symmetric context, we could use firesaber/saber/variants in order to obtain a shared secret ...

(E,D) is a CPA-secure cipher defined over (K,M,C).H: C → T is collision resistant hash functions. E(k,m):=E(k,m), H(c)), D=(k,c1,c2):=D(k,c1) if H(c1)==C2 otherwise Reject. ps:the question is from the ...

In various messengers, we have end-to-end encryption, making it hard to know what the message said. But do these messengers have to pad the message to some maximum length every time, in order to hide ...

To avoid the dummy padding block, CMAC uses 2 separate keys K1 & K2. If padding is required, the final block is padded & then XORed with K1. If no padding is required, then it's XORed with K2. ...

I am trying to do a known plaintext attack on DES-OFB through crack.sh. I have been having trouble lately. I keep getting blank text file back with no keys returned. Does anybody know if DES-OFB is ...

I've been looking all over the internet for an answer, and I must not know how to search because I've been really surprised that I haven't been able to find one. I'd also love to know what makes a ...

In key management, one of the topics is key storage, I want to know where and how these keys(long-term and short-term) are stored? For example I read that android password apps use KeyStore api to ...

By hand, I computed $f(x,y) = x \oplus xy = (0, 0, 1, 0)$ since, in ascending (lexicographical) order, $f(0,0) = 0 \\ f(0,1) = 0 \\f(1,0) = 1 \\ f(1,1) = 0$ However, using the following code on ...

So I'm trying to design/make my own encryption algorithm and I believe it to be ok. I'm not saying it's extra secure but I know it's not useless so, what I was wondering is if there are any specific ...

I have a rough idea of what is symmetric and asymmetric encryption, but I can't apply the idea to the SET protocol (Secure Electronic Transaction Specification), so how the symmetric and asymmetric ...

This post on geeksforgeeks.org about block cipher modes of operation, says that one of the advantages of the CBC is that it works well for input greater than b bits. I also saw that in the book "...

Securing and authenticating messages is easy thanks to computers. Lately I've been thinking about something like Vigenère cipher with a OTP, how secure it is, and how easy it is to implement without ...

I have been given a task to explain if - given a public key and a portion of a private key (over 300bits) with a remain unknown of 80 bits - the private key can be broken with an algorithm faster than ...

I have been doing some research on security, and I am confused on the bits of security vs collision resistance, and I was wondering if someone could clarify my understanding. For instance, if you have ...

I know the needs of a basic cryptographic hash function (one way, collision unlikely, and minor changes in input are likely to produce major changes in output) and I can read the code for Sha-2 (it is ...

I am using the method presented in this paper to find the nonlinearity of the function $$ f: \mathbb{F}^1_2 \to \mathbb{F}^1_2 \\ f(x) = x$$ The truth table is $f = [0 \space \space 1]$. Now, I read ...