All Questions

From a crypto challenge i have the following PMAC variant where the task is to forge a signature to fulfil a specific condition: Preparation: in the finite Field GF(2^128) with the polynomial x^128 + ...

3qqIPPNX0fxjJv/krWhw7L8P83cTm2Dm2aOHHiAfNZQG1Q/1t1zPaY7CEwZBrHIC I am guessing it is base64 encoded, however base64 decoding won't work on it. I can't figure out how to solve it.

I am using HKDF with an IKM and salt, the OKM is used as the key for an HMAC operation. The HMAC algorithm is authenticating messages in a communications system The salt is the concatenation of 2 ...

In a book called: "Intelligent,Secure and Dependable Systems in Distributed and Cloud Systems" where we can find some of its pages on the following URL: https://books.google.com.lb/books?id=...

I have just learned about the CBC mode of operation and that it gives the cipher by xoring the plaintext m0 with random IV and then encrypt it with random key and I found out that the CBC is not CPA-...

so, the question is: will it be less secure if I use a random key and static zero nonce? key = random; nonce = 0;

I have a question regarding the LPN problem. The search LPN problem is to find $s$ given $(A,As+e)$ I am thinking about another problem that given $(A,As+e,As'+e',s+s')$ to find $s$, where $A$ is a ...

My question seems specific for Java since I am looking for KMAC generation in JVM. Java runtime currently supports HMAC code generation. why is there no support for KMAC out of the box? Any standard ...

I have a 128bit PreSharedKey. I don't want to use it directly. I'd much rather generated a session key with HKDF + PSK + SALT = SESSIONKEY. But... I'm under strict size limits for packet size. So I'm ...

Alice and Bob have agreed to use the Three Pass Protocol. p=1009 Alice chooses the encryption exponent e_A = 101 Bob chooses the encryption exponent e_B = 209 Now Alice and Bob send three ...

I have a PSK. I don't want to use it directly. I want to pass a "salt"/password into a KDF and get a new key. I need to give the other side the nonce used. I don't have enough space to fit all of ...

I am pretty much a newbie in this field, but I have been searching for an answer last 4 hours, without break. So I wanted to type it on here. My main goal is to build Raspberry Pi cloud storage and I ...

I have two endpoints that go through a middleman. Both have a pre-shared and secure key, 16bytes to be used with ChaCha20-Poly1305. Extremely constrained device. No packet larger than 100 bytes total. ...

When using the BB84 algorithm for QKD, you arbitrarily choose which of two filters (bases) to use when detecting a photon: rectilinear or diagonal. If you choose rectilinear, you can detect ...

I don't understand the popularity of the idea of QKD (often coupled with OTP). From what I can tell, a quantum-safe key exchange algorithm like McEliece has just as much security while being able to ...

I am trying to understand https, as I understand https uses the Diffie–Hellman method for keys exchange and then AES for encryption. But Diffie–Hellman needs two prime numbers, where do these come ...

In this link: Has GMAC mode a future outside GCM?, the last comment given by the user Demi, indicates that the larger the size of the text to be encrypted, the lower the security of the gmac. Why is ...

The BIP39/44 off-line tool does not contain XTZ coin. Therefore, I cannot derive (from my 24 words) my ledger nano s private key associated with my Public key for my Tezos account. Is there another ...

It happens that on the internet I often find that AES encryption should use a 128-bit key only if it is used in conjunction with the GCM mode of operation. Why only with 128-bit keys? What happens ...

We have a POS(Ingenico) that uses DES3_CBC encryption using a derived key. It sends encrypted data, and 10 bytes size KSN. I tried to use CKM_DES3_CBC_ENCRYPT_DATA to derive the key, and decrypted the ...

It is related to my earlier question: Can zkSNARK or other zero-knowledge proofs be used to proof message authenticity without revealing private key? Are there any algorithms for which generating ...

Is there a good way to do repeatable (with the same result) encryption for pseudonymisation where the pseudonym can be decrypted? I want to set up a system to allow multiple services to communicate ...

What's the security of Elliptic Curve Cryptography over finite fields of word-sized characteristic $p\approx2^{50\pm10}$? We are talking about $\Bbb F_q$ where $q=p^k$ for some suitable $k$. ...

I actually do want to know how to generate the multiplication inverse (M.I) table, I mean the calculation how the M.I been generated.. such as the M.I of 22 is 5A regarding to the table.. Do you know ...

Can anyone give the mathematical definition of deterministic and non-deterministic random bit generator? Providing a reference will also be very helpful.

I was solving a Crypto Challenge in a CTF, and I got a Nihilist Cipher Encoded String. Luckily the additive key was given as a hint, and for the polybius Square key, I kinda bruteforced or I just got ...

The wikipedia page for Length Extension Attacks says "Note that since HMAC doesn't use [Merkle–Damgård constructions], HMAC hashes are not prone to length extension attacks." However, HMACs can be ...

I am trying to understand the runtime complexity of the discrete log problem (in the most basic sense). So, if we have $\langle g \rangle = G$ and are trying to find $g^x = a, a \in G, 0 < x < ...

this code decrypts encrypted rom code from an arcade game pcb (it is from source code of Mame emulator) for each byte in rom... ...

I am a master student in computer security, I am preparing a dissertation thesis in the theme is: Algebraic cryptanalys by auxiliary channels, I need reference on this theme (book, thesis, ...), and ...

Some cryptographic schemes are based on the hardness of this problem. The answer to this question determines if those schemes are quantum resistant or not. There are a number similar questions but ...

This is not homework, but a random thought. Let $G(x)$ be a PRG. We define the following function: $$F_k(x) = G(k\oplus x)$$ My intuition is that it shouldn't be a PRF but I couldn't come with an ...

After reading this question, I understood that "game-based" and "simulation-based" have to do with the way that security properties are postulated. In particular, IND-CPA is a canonical example of ...

In https://www.win.tue.nl/~berry/papers/crypto99.pdf, Schoenmakers proposes a publicly verifiable secret sharing scheme, that uses a non-interactive DLEQ proof to allow any participant to verify the ...

ssh.com's Tectia offers a few algorithms seemingly unique to itself. Chief among them: crypticore128@ssh.com, crypticore-mac@ssh.com and seed-cbc@ssh.com Are these algorithms publicly defined ...

I read the Wikipedia page on a discrete log zkp, but I don't understand how $$C' = g^{r'} \cdot (g^x)^{-1} \bmod p$$ would be calculated. Would it be $$C' = g^{r} \cdot \frac{1}{y} \bmod p$$ ...

Is it possible to build a bilinear map where the underlying group is an RSA group? I.e. $e: \mathbb{Z}_N \times \mathbb{Z}_N \rightarrow \mathbb{Z}_N$ where N is an RSA modulo? Alternatively, a ...

Working on a boot process where the application image has to be verified before loading it into DRAM. We found 2 strategies; RSA-1024, where the private key is secure in premises and the only public ...

Let $X$ denote one distribution. Let $f,g, \text{ and } h$ denote three functions. If we have the results: $g(X)$ is within a negligible statistical distance of $h(X)$. Is it possible to prove $$(f(...

There are lots of attacks which are on reduced block ciphers. There are practical attack on five rounds of AES-128five rounds aes broken in six minutes. I was just wondering if there is any practical ...

If I had many, say a million random numbers (technically public keys.. ~600 bytes each) and I wanted to hash them all together using a fuzzy hash, how accurately could I test that a given hash was a ...

I read the statement of the Decision Learning with error problem is: distinguish between $(\vec a, \langle \vec a, \vec s \rangle + e)$ from uniformly random samples. Can anyone explain what does ...

I need to prove, that for a key with $n$ dimensions, they order of the key would be $n!$ and to prove that, I need to use mathematical induction: $$\text{Let n = 1} \Rightarrow {1} \text{ if there ...

This is basically a duplicate of this question which was not answered very clearly. From the documentation, these are the calculations that happen for Alice to compute the shared secret key: ...

I am currently working on a Koblitz curve. I have found the curve has two matching groups based on the base curve point and N-1 point. My question is as follows: Is there an algorithm to determine how ...

Using web crypto API and it won't let me store an AES key in the indexeddb (it requires a public/private key). Does anyone have suggestions on how to do this? Should I/could I create a public/private ...

The situation: Alice and Bob are exchanging messages encrypted by some known asymmetric encryption protocol. All their encrypted messages, as well as public keys are intercepted by Charlie. Can ...

Say, $X= a\cdot b$, where $(a, b) \in Z_q^*$ and $q$ is a large prime. If $X$ is given, then what is the complexity (or hardness) of finding $a$ and $b$? Note that, either $a$ or $b$ can be reused to ...

In RSA key exchange, the client picks a premaster secret and encrypts it with the RSA public key in the server certificate, and sends it to the server. This offers no forward secrecy. In ECDHE key ...

I just want to know if there's something obvious that renders this hard problem useless. Not a full cryptoanalisys. Any hint on whatever is welcomed. We will work with the Ring $\mathbb{Z}_{p}$, $p$ ...