# All Questions

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### Openssl using the cipher parameter result in handhsake failure

When i use Openssl to connect to facebook.com I see 'ECDHE-ECDSA-AES128-GCM-SHA256' ciphersuite used. openssl s_client -connect www.facebook.com:443 ...
17 views

### Why error propagation in CBC mode encryption affect two blocks?

I copy this from Wikipedia: Error propagation it was common to discuss the "error propagation" properties as a selection criterion for a mode of operation. It might be observed, for example, ...
28 views

### RSA-FDH Signature Scheme EUF-CMA

I am aware of attacks whereby an attacker is able to forge a message IF the hash of the original message is the same hash as their current message. The question is, is it still possible for RSA-FDH to ...
5 views

### Estimation of boot time for Veracrypt [migrated]

Hypothetically,can the boot time of a PC be calculated if the method of encryption,hash,password length,PIM(specific to veracrypt) and PC specs are known? Assume someone uses the AES-TwoFish-Serpent ...
41 views

### Discrete logarithm problem particularly hard for Schnorr groups?

The Wikipedia article on Discrete Logarithm just states without source: In some cases (e.g. large prime order subgroups of groups ($\mathbb{Z}_p)^×$) there is not only no efficient algorithm known ...
28 views

### The definition and origin of Schnorr groups?

Wanting to write something on Schnorr groups in a publication I realised how hard it is to find anything citable about them on the internet. Who can help me with the following questions? What (and ...
23 views

### can someone just tellme how to create or remmember s box matrix values for DES(Data Encryption Standar) [on hold]

how is substitution and permutation matrix created for s box. i have already got technique to remembering IP and reverse IP for DES, but just get any clue about s box
28 views

### CIPHER TEXT PROVIDED WHICH NEEDS TO BE DECIPHER- [on hold]

Police have been inspecting a crime scene that they were called into, during their investigation they found a USB stick that belongs to the suspect. Police believe the USB stick contains an important ...
15 views

### Known-plaintext attack against E0 with 2745 bits per frame instead of 24

In the paper The Conditional Correlation Attack: A Practical Attack on Bluetooth Encryption, an attack against the E0 cipher is described which can break it efficiently in a known-plaintext attack: ...
63 views

### Finding tetration in a multiplicative group modulo p

I have a variant on the discrete logarithm problem, involving finding tetration in a multiplicative cyclic group of integers modulo a large prime $p$: $$a = x^x \mod p$$ Where $a$ and $p$ are known, ...
44 views

### How to prove if a Hash Function is collision resistant

Say we have the following Hash Function, H(x) = 4x mod N where N is a number generated by multiplying two prime numbers and x={0,1,2,3,...,N-1}. So lets assume that ...
36 views

### Points on elliptic curve

I am making a program using the library cryptopp using curve secp521, in which at the end of that program I get n*Point Because I am writing that program I know that what is the value of 'n'. So, I ...
66 views

### Modification of vigenere cipher cryptographically secure?

After looking for ages online for a python implementation of the Vigenere cipher, and finding few, I decided to implement it myself. After ironing out all of the flaws, it's now a working (and secure) ...
69 views

### How to compute the inner product on encrypted vector by using a third party?

I want to compute the inner product of two vectors on a third party, i.e. $f(x) \cdot f(y) = x \cdot y$ where $x$ and $y$ are two vectors. However, I do not want the third party knows the real value ...
34 views

### How to compute ElGamal decryption by hand

Lets say that $u=3, x=5, v=2$, how do we work out $u^{-x}*v$, so $3^{-5} * 2$. I know how to work out the answer if it was $3^5 * 2$ but how do we do it with negative exponents?
58 views

### Birthday Attack Probability of Collision in Introduction to Modern Cryptography

I have some questions about the chapter of Birthday Attack in Introduction to Modern Cryptography. When $q=\Theta(2^{l/2})$ the probability of this collision is roughly $1/2$ What's the meaning of ...
49 views

### 1/(2^n)! is negligible function?

By definition $\frac {1} {n}$, $\frac{1}{2^n}$ and $\frac{1}{n!}$ are negligible functions. I have got the function $$f(n) = \frac{1}{(2^n)!}$$ where $n$ is security parameter. I don't understand, ...
82 views

### What is the difference between computational complexity and time complexity?

Computational complexity seems to be used quite a lot in cryptographic papers. The time complexity I am referring to is the one from Computational Complexity Theory. Are these two the same things?
16 views

### TPMS simple data encryption [on hold]

I have some TPMS sensors. Which run on 8bit microprocessor. There are no AES, 3DES or any other kind of encryption. Data packages are send over RF and the data is encrypted. There should be simple ...
50 views

### Hash key expansion

A hash H is given by H = SHA256(K + N), where K is an unknown 64 character hex key and N is a known nonce. The nonce N is then mapped to a final result R between 1 ...
20 views

### Designing a hash prediction model for a draw result, unmodifiable [duplicate]

I have to create a prediction model that forms a draw result of a prediction, essentially encoding the future draw result and the draw date. Then others will be able to check if the prediction is ...
40 views

### How re-encryption can be done through RSA

Both RSA and Elgamal have homomorphic properties. So both can re-encrypt the ciphertext. Re-encryption with Elgamal works as seen here. How does re-encryption work using RSA? What modification / ...
32 views

### Determining susceptibility to frequency analysis

I'm looking to create some tokens using a keyed hash mechanism to represent our individual customers. I was planning on using combinations of the customer's personal information (e.g. ...
14 views

### Can there be backdoors in a Windows 10 Veracript, AES(two fish(serpent) encrypted laptop? [on hold]

I managed to encrypt a laptop. It has 3 drives, one has encrypted Ubuntu, the second an encrypted Windows (Veracript, AES(two fish(serpent)). I use NordVPN to encrypt my internet connection. I do my ...
18 views

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65 views

### Using an AES-256-GCM key as a salt to SHA-256

Assume 256 bit keys are randomly generated and data is encrypted using AES-GCM-256 prior to being sent to a server. The goal is to enable the server to determine uniqueness of data it receives ...
39 views

### Backdoor Hash Streebog (?) [on hold]

There was a news that possibly has a backdoor hash Streebog. https://twitter.com/bascule/status/1094830326201835521 https://www.golem.de/news/kuznyechik-streebog-russische-...
26 views

### How can I guess that a combination of Atbasch and Caesar / Vigenère has been used?

If I'm given a ciphertext, what kind of patterns, index of coincidence, frequency analysis would lead me to guess that it had been encrypted by a combination of Atbasch plus Caesar / Vigenère?
17 views

### How do I calculate key rotation schedules?

tl;dr: How do I formulaically determine key rotation schedules for different kinds of keys and use cases? The organization I'm a part of for utilizes both symmetric and public/private key encryption ...
18 views

### What's the cipher algorithm used? [on hold]

Given a 8 digit text and a password I get the following outputs password: T912159 Samples: input: 00000000 output: 21955508 input: 00000001 output: 31406077 input: 00000002 output: 08254408 ...
51 views

### Applications of machine learning in classical ciphers?

Machine learning is definitely applicable in analyzing simple shift ciphers like Caesar and affine ciphers, as well as substitution ciphers like Vigenère, but is it possible for machine learning to ...
28 views

### Is SZK better than CZK?

Is it better to have statistical zero-knowledge or computational zero- knowledge in a system? If it depends, is there a slightly accurate generalisation that can be made? Maybe one can be somewhat ...
41 views

### Why is this OTP decryption wrong? [on hold]

i have a problem that goes: ...
24 views

### System of constraints in Sonic zk-SNARK protocol

I am reading up on Sonic: Zero Knowledge SNARKS from Linear - Sized Universal And Updateable Structured Reference Strings. There is an example of representing $\ x^2 + y^2 = z$ constraint (page 7 of ...
15 views

### Are there any advantages and disadvantages with what type of model of homomorphic computation is used?

I am curious about the advantage or disadvantage in using the different models of homomorphic computation (boolean circuits, modular arithmetic, approximate number arithmetic). Are there any specific ...
43 views

### Can zero-knowledge proof be used to determine if another person knows a certain movie with a twist ending?

Suppose I want to talk with a co-worker about a movie called "The Twist Movie". I know the movie contains an interesting twist, and bringing up the movie in a discussion about twists in movies might ...
38 views

### Which Exchanges have the crypto hardware wallets with super fast transaction speed? [on hold]

Many exchanges claimed to be faster than other exchanges and am new in crypto. Anyone who can help me getting started with a super fast exchnage? or anyone who can suggest me about a real decentralizd ...
26 views

### AES decryption L lookup table [on hold]

In L lookup table there is no value for 00 condition then what do we do when 00 occurs? Because of this 00 condition i am not getting the output if anyone know please help me to solve this
26 views

### what is the area of 8-input xor in Gate equivalent in 130 nm CMOS library to implement lightweight cryptographic algorithm in hardware? [on hold]

in most recent lightweight cryptographic algorithms hardware implementation are using 130 nm cmos library. 2 input XOR AREA (11 – 16 ) in GE (2.75 – 4) XOR 3 INPUT (22 – 26) IN GE (5.5 – 6.5) XOR 4 ...
91 views

### Are any block ciphers provably free of equivalent keys?

There are $2^n!$ possible permutations of an $n$-bit block cipher $E_k:\{0,1\}^n \rightarrow \{0,1\}^n$, and any given key $k$ selects one of these permutations at random. Define equivalent keys as a ...
48 views

### What is the possibility of collision of trailing 160 bits of Keccak_256, for any two differing public-keys as pre-images?

Earlier today I was answering a question on the ethereum SE site that analyzed the potential for more than one private key on curve secp256k1 (which maps to a distinct public key) to control the same ...
16 views

### Need help to decipher the following text [on hold]

Need help. The phrase, date, highlight and underlining is a clue of some what. Plus, also the snake head is a clue. I did this much: Instead of ------ ----- ------- these, ------ them. Let them guide ...
29 views

### what is the difference between self issued and an intermediate certificate

Hashicorp vault has an API they call Sign Self-Issued. The use case is for rotating root CAs. A user creates a new root self signed CA and then passes it to this API and what is returned is roughly ...
24 views

### What are the maximal possible locks [on hold]

Suppose, you and your friends have a few numbers of locks and you all want to share that numbers among yourselves securely using RSA based cryptosystem. You are using the private key as (5,27) and ...
30 views

### How to implement GSW13 using Helib or SEAL?

I want to implement the homomorphic encryption scheme proposed in GSW13, and make some changes to it, but seems that there is no library that has already been implemented it. Since this is a ...
79 views

### Zero Knowledge Proofs: to establish a public key cryptography encryption

I am very interested to know in the general sense how two parties who know each other are able to continue a conversation IF and ONLY IF they both earn the same salary. For example, we have a person X ...
64 views

### Why are some group representations much easier to compute discrete logarithm for? [duplicate]

The multiplicative group mod $p$ is isometric to the additive group mod $p-1$, yet computing discrete logarithms in the additive group is easy and completing discrete logarithms in the multiplicative ...
130 views

### Efficient way of generating a random number of N (less than 64) bits with exactly M bits equal to one [closed]

Would there be an efficient way to implement a function with the following signature: unsigned long long int random_word(size_t n, size_t m) that would generate ...
Let $k$ be uniformly sampled from $\{0,1\}^\lambda$, $F$ be a secure PRP with block length $\lambda$ and let $Enc(k, m)$ be such that it returns $c = (F(k,r), r \oplus F(k,m))$ with $r$ uniformly ...