0
votes
0answers
35 views

How to find an impossible differential?

Given an arbitrary SPN-based cipher with X rounds. How to find an impossible differential for this cipher? What are strategies to find one?
0
votes
0answers
45 views

zero knowledge framework for c programs - how to prove correct C program execution with private inputs

I am looking for a zk framework that could be used for proving correct execution of programs written in C (or any other high level language) such as: I know x s.t. SHA-256(x) = y (y is public, x is ...
0
votes
0answers
45 views

Vigenère cipher frequency analysis not working

I'm writing a C++ program to use the Kasiski method to crack the Vigenère cipher. I'm testing it with a bit of Shakespeare encrypted with the key ABCDEFGHIJKL. It ...
0
votes
0answers
54 views

Is there any real practical group signature scheme deployed?

Groups signatures are a crypto primitive introduced in order to guarantee anonymity on signatures constructed by a group of people. Since there introduction and there exhaustive security requirements ...
0
votes
0answers
23 views

Creating a LCG with m = 32767 [migrated]

I hope this question is not too simple for you: I want to create a PRNG for an integer only (with a max of 32767) system and tried to use an LCG. So I've chosen as m = 32767 and c = 3 and I tried to ...
0
votes
0answers
48 views

Unicity Distance - AES

I am quite confused calculating the unicity distance and I was hoping that someone can clarify some things for me. My main issue comes from somewhat a difference of the calculation given by our ...
0
votes
1answer
43 views

computational complexity class of decryption of AES

I haven't really seen what computational complexity class of decryption of AES is. Can anyone provide reference papers or answers here?
0
votes
0answers
42 views

AM protocol for 2 distinct objects

Prover is going to convince verifier that 2 objects are distinct, do you know any Arthur-Merlin protocol for this problem?
0
votes
1answer
46 views

Key exchange using ECDH vs ECIES

I'm a beginner to ECC crypto programming. Does any one explain to me the difference with using ECDH for shared key exchange and use of ECIES by encrypting shared key with the public key of the ...
0
votes
1answer
56 views

Why is a Feistel network bijective?

EDIT: Fixed for clarity of intention I was reading "The FFX Mode of Operation for Format-Preserving Encryption" when I came across Figure 1 (see below). It's obvious why it's reversible (top-down ...
0
votes
0answers
38 views

Solving discrete logarithm when p is not a safe prime

If you have the cyclic group of integers modulo $p$, where $p$ is not a safe prime, as well as a generator $g$ with which for all factors $q$ of $(p-1)$, $g^{(p-1)/q} \ne 1$, This answer says that ...
0
votes
0answers
20 views

Generating whitening keys through encryption

Question, if I generated whitening keys by encrypting the plaintexts of 0000... and 0A0A... would this reduce vulnerability to meet in the middle and related key attacks? If so, any rough idea of how ...
0
votes
0answers
35 views

Anyone familiar with domain of hash functions in bilinear pairing based system?

I need a clarification regarding domain of hash functions. I have defined a bilinear pairing based system as follows: Let G1 and G2 be cyclic multiplicative groups of prime order p generated by g1 ...
0
votes
0answers
43 views

Property of Multiplicative group of integers mod n

While practising on paper I've realized of a property of multiplicative group of integers mod $n$. First, let's define $G$ being $p$ a prime and $g$ a primitive root mod n or a generator of a ...
0
votes
0answers
53 views

Is it possible to make an encrypted text look like a sentence consists of random words?

Without having any knowledge of common encryption methods, I wonder if an encrypted text can look like random valid words as if it is a sentence. Is it possible? If so, what methods should I use?
0
votes
1answer
55 views

Euler's Totient function for semiprime numbers

I have noticed, during the period I spent studying RSA, that Euler's Totient function can be calculated in another way than $ϕ(N) =(p-1).(q-1)$ Let me explain myself by pointing to a brief example: ...
0
votes
0answers
30 views

verify fails on 3rd party after signing with BouncyCastle

I am using BouncyCastle to perform ECDH and then encrypt the data between the mobile (Android) and my hardware with ECIES. It all works fine. When I try to sign a byte array and send it to the ...
0
votes
0answers
50 views

ElGamal Generator g problem

Having an ElGamal encryption scheme with p=19 which value can not be assigned to g? The answers were : 1,7,11,2 I think you can't assign value 1 to g.
0
votes
0answers
42 views

Elliptic curve point addition

I have this curve in E(F131) : $$Y^2 = X^3 + X + 2 $$ I want calculate the sum P + Q considering that $$P= (5,1)$$ and $$ Q = (60, 49)$$ For calculate the result i use these formulas: $$ xr = ...
0
votes
0answers
121 views

My attempt of combining socialist millionaire and Diffie-Hellman. Is it any good?

I've come up with an algorithm to solve the socialist millionaire problem, but I'm not sure if the algorithm is secure. I wasn't able to find any flaw in it, but it seems too simple to be secure, so ...
0
votes
2answers
75 views

How to decrypt a PGP message with only the two primes and the public exponent?

I'm trying to decrypt a PGP Message that is encrypted with an RSA key, but I only have this information: Public exponent: 65537 Prime 1: ...
0
votes
0answers
46 views

Does the encryption algorithm DES perform random permutations? If so how is information not lost?

"Before round 1 begins, all 64 bits of an incoming message and all 56 bits of the secret key are seperately permuted (shuffled)" My question is this : Is the shuffling of the bits performed randomly? ...
0
votes
0answers
19 views

Type 1 pairings and encoding function from $\mathbb G_T$ to $\mathbb G$

Let $e : \mathbb G \times \mathbb G \to \mathbb G_T$ be a Type 1 bilinear pairing. Is it possible to define an encoding function $E : \mathbb G_T \to \mathbb G$? If so, how could this encoding ...
0
votes
0answers
42 views

Bilinear pairing arithmetic - cryptographic accumulators

For calculating accumulated values for set of elements chosen randomly from say $ { e_1 ,e_2,...e_n}\varepsilon X $ we use the formula $acc= g^{f(e,s)}$ where $ f(e,s)= (e_1+s)(e_2+s).....(e_n+s)$ ...
0
votes
1answer
66 views

PGP public RSA key format

I have been trying to use Go (I could post the code, but I think I posted enough already...) to generate a PGP RSA key. However every time I try to encrypt something with it, something fails. However, ...
0
votes
0answers
47 views

How many bits of entropy can I expect from /dev/urandom in iOS?

Apple's latest security documentation indicates that it now uses CTR_DRBG for generating pseudo-random numbers (previously Yarrow instead of CTR_DRBG), using "timing variations during boot" and ...
0
votes
0answers
37 views

Discrete log in Galois Extension Field

I was reading 'Pinocchio Coin' paper by Danezis et al. where they have said, "If we use the efficient pairing groups of Pinocchio, computing discrete logarithms in the exponent field $\mathbb{F}_p$ ...
0
votes
0answers
62 views

Name of this attack?

I am studying Merkle tree signature. Let $\sigma=(s,Y_s,\sigma_{\text{OTS}},As)$ be a signature of certain document. Here $s$ is the index of leaf, $Y_s$ is the respectively OTS public key and $A_s$ ...
0
votes
1answer
60 views

Are pseudorandom permutation really permutation in mathematical sense?

In security, and specifically Block Cipher (AES, DES, etc), when we talk about pseudo random permutations, is the term "permutation" refer to the same meaning as in discrete mathematics. That is, the ...
0
votes
0answers
27 views

Can you find the search space? [duplicate]

Let A is a random number and has 512 bits.we make B from A and B has 1024 bits.Process of B is following: C=f(A) that f is hash and C has 160 bits.Then C pass in a parallel manner 7 different hash ...
0
votes
0answers
42 views

Factorization of a number obtained by a modular multiplication operation can reveal factors of the used operands?

Consider a number $r$ obtained by: $r=a \cdot b \mod n$ Can knowing the factorization of $r$ reveal some information (bits) of $a$ and $b$ ?
0
votes
0answers
62 views

Finding Patterns in Encrypted Data

I am looking for an application (Windows) or code example that might help me find patterns in an encrypted file. I have a ciphertext for which I want to see when a key is repeated. I am not trying ...
0
votes
0answers
38 views

prepaid meters that rely on a disconnected system

i have some experience with cryptography in the banking sectors, mostly in block ciphers like DES 3DES etc. im interested in prepaid electricity meters as it is a number that is generated from a ...
0
votes
2answers
88 views

Is it possible to have identical public keys for different ciphers?

Is it possible (and is there any research I can read) to have 2 key pairs for different ciphers, for example RSA 1024 and some yet to be released EC (or other asymmetric cipher) than uses 1024 bit ...
0
votes
1answer
42 views

Why exactly Blowfish max key length is 448

Could anyone, please, tell me history of birth of Blowfish algorithm? Specifically, what is substantiation of Blowfish key length to be in range from 32 till 448 bits? Why, for example, it wasn't ...
0
votes
1answer
40 views

How to perform homomorphic multiplication in ElGamal?

How can I compute homomorphic multiplication in ElGamal? That is: Given two ciphertexts $(R_1,c_1)$ and $(R_2,c_2)$ corresponding to plaintexts $m_1$ and $m_2$ under some public key; how can I compute ...
0
votes
1answer
50 views

RSA Signature : Process of Sign the message and Verify

I have read that the RSA numeric signature works as the following: Generation of keys : $p,q,N,e,d$ Process of signing the message $m$ (which is BigInteger) : it uses the secret key $sk=(p,q,d)$ so ...
0
votes
0answers
21 views

Is sending encrypted message and signed message a secure way of transmitting data? [duplicate]

I know that the industrial standard is normally sending data in the following format: Send Encr(msg, Sign(msg)) Is the following way a secure as well? ...
0
votes
1answer
50 views

Exist this chat protocol?

I want to implement a secure chat on mobile. I like to know if the following protocol for key agreement that use any asymmetric encryption exists: Suppose Alice and Bob are two clients of the app. ...
0
votes
0answers
28 views

RSA_DH vs ECDH implementation

In ECDH protocol is possible, naturally, to use the same algorithm for calculate a secret key for both communication parties (Alice and Bob for example). It is possible to design also a same algorithm ...
0
votes
0answers
43 views

What are some hashes that do not exhibit the avalanche effect?

I do not know much about cryptography. But, I'm in a situation where I need a hashing method that does not exhibit the avalanche effect. I tried Googling but couldn't find anything.
0
votes
1answer
54 views

Is there an asymmetric One-Time-Pad? [duplicate]

Is there something like a perfect asymmetric crypto-algo? Is there proof that there must be one or not. From a logical point of view it seems to be possible to design such algorithm if your keysize is ...
0
votes
1answer
42 views

Which of the following hash functions is collision resistant?

Let $H: M \to T\ $ be a collision resistant hash function. Which of the following is collision resistant: $ 1.H'(m) = H(m \big\| m)$ $2.H'(m) = H(m) \big\| H(0)$ $3.H'(m) = H(m) \oplus H(m)$ ...
0
votes
0answers
79 views

Which of these is a secure MAC?

Let (S,V) be a secure MAC defined over $(K,M,T)$ where $M = \{0,1\}^n$ and $T =\{0,1\}^{128}$. Which of the following is a secure MAC: $S'(k,m) = S(k,m)[0,\ldots,126]\quad and \quad V'(k,m,t) = ...
0
votes
0answers
53 views

Enigma algorithm Question about the Ringstellung

This might be a stupid question but I need to implement the Enigma algorithm and I don't fully understand how it works. I've googled the subject and I am confused about what the Ringstellung is and ...
0
votes
1answer
36 views

Ephemeral Diffie-Hellman in a symmetric crypto context

I'd like forward secrecy in a case where the two sides have a shared long-term symmetric key. I intend to use AES in GCM. It looks like ephemeral Diffie-Hellman is the best way to generate the session ...
0
votes
0answers
31 views

Outsourced Multiparty computation proof in Ideal world

I need to know in an outsourced two party computation where honst $A$ and $B$ outsource their private and secure data to a malicious server, why we need to design a simulator that interacts with an ...
0
votes
0answers
46 views

Role of trusted party in the Ideal model in Malicious case

Imagine there is a protocol supporting outosurced multi party computation. There are three parties involved in the protocol: client $A$, client $B$ and a server. Client $A$ and $B$ send their private ...
0
votes
0answers
54 views

Security of a custom non linear hill cipher

Initially let me state that this is an atypical type of cryptographic encoding. First I break up my key into three parts $k = {W,\overrightarrow{b},\alpha}$. the $W$ is simply a $n \times n$ matrix, ...
0
votes
1answer
45 views

How are messages from server secured when using SSL certificate

In case of using SSL the certificate server has a primary key and a public key that is published to all clients - as far as I understood. So in this case when message is encrypted by public key (on ...

15 30 50 per page