0
votes
0answers
4 views

Can someone please explain to me what this means?

I'm taking a cryptography class and I was assigned this for a project: Implement automatic ElGamal text encryption/decryption I'm not sure what it means (but I'm familiar with discrete logs and ...
0
votes
0answers
18 views

Javascript Information Dispersal Algorithm [on hold]

I am trying to implement a webapp that is encrypting and distributing files on multiple clouds - similar to the DepSky system (http://www.gsd.inesc-id.pt/~mpc/pubs/eurosys219-bessani.pdf), but I am ...
0
votes
0answers
15 views

Maturity of searchable encryption schemes [on hold]

Is searchable encryption industry ready with product implementations?If yes kindly give me the name of products over which it is used.
-1
votes
1answer
17 views

CoAP authentication using DTLS

what is the meaning of this notation ?? AES{Yi, (Yi XOR Ki | nonce1)} https://tools.ietf.org/html/draft-bhattacharyya-core-coap-lite-auth-00
0
votes
1answer
51 views

Elliptical curve cryptography key generation time

I am currently trying to learn more about Elliptical curve crypthography and have finally started to get things working and undestanding the different pieces. I've written a small project in C# and ...
0
votes
0answers
36 views

Cracking RSA with Small exponent 5

I have read following questions - Cracking an RSA with no padding and very small e Small Encryption Exponent where in first it says to run out all the possible m options and second says factor ...
0
votes
2answers
37 views

Sharing an encrypted file between a group of people

Is there any way to share an encrypted file with a group? In the other words, can I encrypt a file with a public key so that each person in a group decrypt it with his/her private key? Is there any ...
0
votes
0answers
15 views

Wiring pattern for field multiplier

I am doing a project to implement point multiplication unit in elliptic curve cryptography. Going for a galois field multiplier in normal basis. The point multiplication unit is for higher field size ...
0
votes
1answer
22 views

simulating rc4-256 with rc4-128

OpenSSL supports rc4 with 128-bit keys and rc4 with 40-bit keys. It does not support rc4 with 256-bit keys. My question is... is it possible to modify the state of the pseudo-random generation ...
2
votes
1answer
47 views

what are multi-primes and how are they different from semiprimes?

I came to know of semiprimes recently. The simplest explanation of semiprimes is you take any two prime numbers and you multiply them, say 3*11 = 33 in which case 33 would be a semiprime. The numbers ...
-1
votes
1answer
55 views

Cracking plain RSA by factoring the modulus n

This is the setup: I have both public and private keys of one "instance" of RSA. And I have only the public key of another RSA cryptosystem, but this system has the same modulus as the first one. I ...
-2
votes
0answers
25 views

Real life RSA/El Gamal examples

Can someone direct me to examples of El Gamal and RSA that would be similar to real life (i.e. large primes). I wrote a code for encryption and decryption, but I wanted to test it against some larger ...
0
votes
1answer
50 views

Where to store the file extension to retrieve it correctly after decryption

I am using Java to write AES-256 to encrypt various files with different extension, the problem is, where am I suppose to store the file extension so the if the data is decrypted, the file extension ...
0
votes
0answers
43 views

Research Path For Searchable Encryption [on hold]

Can anyone give me a list of basic cryptographic primitives and concepts I should know to take up a doctoral research in Searchable Encryption?(If it is impossible to list out, can somebody give links ...
1
vote
0answers
71 views

Less known hash functions producing 128 bit hash

Good day. While reversing a malware I stumbled upon a function producing 16 byte hash. I tried to determine which one is that by checking every function from wiki. Nothing fits. So, there are two ...
0
votes
0answers
38 views

Efficient proof of knowledge using Wegman-Carter hash

A verifier wants to ensure, with only little exchange of data with other systems, that a large block of data $M$ that the verifier holds is also available to some other system(s). It is not an ...
0
votes
1answer
70 views

Inverse of a function $f_k(x) := f (x ⊕ k) ⊕ k$

$f : \{0, 1\}^4 → \{0, 1\}^4$ Given a function $f_k(x) := f (x ⊕ k) ⊕ k$, what is the inverse function $f_k^{-1}$? I could not figure out how this would be done. Thanks.
0
votes
0answers
28 views

Feistel network output if round function is the identity function

I v been trying to solve this question from the book Introduction to cryptography but fail to find an answer, can someone please explain to me. Thanks What is the output of an r-round Feistel ...
0
votes
0answers
25 views

Secure(verifiable, delegated, outsourced) computation

Can we think "secure (verifiable, delegated, outsourced, 2-parties and multi-parties) computation" as a same single concept, or should we consider these secure protocols as different concepts? If ...
-1
votes
1answer
22 views

El gamal correctness

I tried to find online for the correctness of El-Gamal, but I couldn't find any good resource that will teach me how to show the correctness of El-Gamal, could any body show me how is it done?
0
votes
0answers
32 views

ElGamal signatures' secret key

Assume I recovered the ElGamal signatures (75,18) and (75,67) Alice produced on the messages 81 and 14, respectively. Alice's public key is (alpha,beta,p)=(2,35,101). How can I recover Alice secret ...
1
vote
1answer
48 views

What is the difference between IND-CCA2 and NM-CCA2? And how does one imply another?

Is there any proof that shows the equivalence of these two?
0
votes
0answers
23 views

ECDSA algorithm using PBC library [on hold]

I am doing a project on Identity Based Cryptography.I am doing coding using PBC library. I have a problem in verifying signature .i am using ECDSA algorithm.. can u tell me why signature does not ...
0
votes
0answers
30 views

Mifare Classic and crypto1 algorithm

Mifare's Crypto1 algorithm uses a 48-bit LFSR. What does the 48-bit LFSR do exactly ?
0
votes
0answers
23 views

A rudimentary challenge–response authentication based on dot products in $\mathrm{GF}(2)^k$

We are building a rudimentary challenge–response authentication protocol based on dot products in $\mathrm{GF}(2)^k$. Assume a user has a password $\mathbf{p} \in \mathrm{GF}(2)^k$. When logging in, ...
1
vote
1answer
55 views

Building a pad for OTP on-the-fly with Diffie-Hellman

Through repeated DH attempts, could Alice and Bob build a large random key for use as a one-time pad? My intuition is that this protocol would be as hard as breaking DH (discrete logarithm).
0
votes
0answers
64 views

Decrypt with only the cipher file and the key?

I got an encrypted file, and I got the key. The only thing I don't know is "how it has been encrypted". The cipher file is "data" type (not readable by a text editor), but the key is a "text". Do ...
0
votes
0answers
22 views

Recipient ID asked whie using Symmetric encryption with GnuPG [migrated]

I'm trying to encrypt a file using AES algo and sign it using my private key in GPG. The command I'm using is gpg --encrypt --symmetric --cipher-algo aes256 --armor --sign input-file It asks me for ...
1
vote
1answer
66 views

Private Information Retrieval--Is it still theoretical?

Are there any real world products in which private information retrieval techniques are used?(a data hosting server oblivious of which data item was fetched from it?)If not what are the major barriers ...
-3
votes
1answer
57 views

Is salt bring more security for digital signature! [on hold]

Is it good idea to use salt in digital signature? Is it bring more security? If so, I should use it for key or the message?
1
vote
0answers
38 views

Recover a secret message in a .wav file [on hold]

First, I apologize for my english, I'll do my best. On my computer, I got a .wav audio file that hides a secret message. I want to recover that message. But I'm stuck and I need your help :). My ...
0
votes
0answers
24 views

How does hash function in Elgamal signature scheme prevent existential forgery attack?

I have heard that hashing the message M prevents an existential forgery attack. I was wondering how.
3
votes
2answers
116 views

Real life systems that use concepts of crypto computing [on hold]

Are there any working cloud/internet solutions/products that operates on encrypted data such as systems using homomorphic encryption, secure multiparty computation, electronic voting, private ...
0
votes
1answer
78 views

Addition / Multiplication modulo 13

I am currently studying Diffie-Helman protocol. In my lecture notes I have a generator g=2 and I'm in group $Z_{13}^*$ . There I calculate a remainder cycle from 1 to 12 with $r =g^i \mod 13 \forall ...
0
votes
1answer
68 views

PHP secure random number generator [on hold]

I was trying to find a better way to generate random numbers in PHP and thought that using /dev/urandom would be the way to go (based on a few lectures). So I thought I would implement the following, ...
0
votes
0answers
14 views

Change of axis positions in Vigenere Square

Is there any history of codes in which there have been changes in the normal axis positions of the Vigenere Square? Have been working on a code which has two non-normal positions -- one with the ...
0
votes
1answer
72 views

Python. RSA common modulus attack problem

I have: N = /*500 decimal numbers*/ E1 = 3740453 E2 = 4226171 M^E1 = /*500 decimal numbers*/ M^E2 = /*500 decimal numbers*/ I must use RSA common modulus ...
1
vote
0answers
57 views

Bilinear Map vs Inner Product [migrated]

What is the difference between a Bilinear Map and a Inner Product?
2
votes
1answer
47 views

Gap problem for Learning With Errors

Informally, a "Gap" problem is the one that arises when solving the computational (or search) version using an oracle for the decisional version. For example, the Gap Diffie-Hellman Problem (GDH) is ...
1
vote
0answers
40 views

Can a secret message be securely transmitted within a MAC tag?

A sender wants to transmit an ultra secret code $M$ which could be either 'go', 'stop' or 'wait'. This could be any selection of code words really and adopted for any use such as transmitting short ...
0
votes
0answers
26 views

java.util.Random and Dice Rolls

For this question, a dice roll will be considered two 6 six sided dice, to give a possible output of 2-12. Given a java.util.Random instance r, the output of one roll would be: ...
0
votes
1answer
35 views

What Java actually stores inside Keystore when generating Keys?

When we use Keytool to generate a Keystore to store Private/Public keys, what Java actually stores inside the Keystore file ? I ...
0
votes
0answers
19 views

Problem description “SAFE” [on hold]

So this is the problem, sorry for the bad img quality. The answer which i don't know is 10 chars long. And there are thease 3 safe knobs with numbers inside them. I have been trying to solve it,yet ...
0
votes
0answers
25 views

Designing hash function in space-efficient identity based encryption

Let $n$ be an RSA-prime and we know prime factorization of $n(=pq)$. The hash function is the current context maps from a given user identity(id) to a positive integer less than $n$, whose jacobi ...
-1
votes
0answers
24 views

CBC-MAC, possible attack that violates computational resistance

received this question in an assignment and figured the wizards of crypto.stackexchange could give me some useful and relevant input. Suppose an attacker knows three message/CBC-MAC pairs $(M_1 , ...
1
vote
1answer
87 views

Hash collision using the leading 40-bits of SHA-1

I am trying to implement Floyd's cycle finding algorithm for finding a leading 40-bit hash collision in the SHA-1 algorithm. However, my code will not find a repetition even with 800,000,000 hashes. ...
2
votes
0answers
36 views

Are all binary-additive stream ciphers reciprocal?

I'm writing a thesis focused on Maurer's provably-secure stream cipher. Long story short, this cipher works by expanding a short key into a long keystream and then XORring this keystream with the ...
2
votes
1answer
65 views

What is the difference between order of base point and curve order in EC?

When I was read about the elliptic curve cryptography I found some definition about domain parameter of elliptic curve like the follow. But I did not understand something $p$: prime number. $a, b$: ...
5
votes
0answers
108 views

Verbatim of early work on public-key cryptography?

In late 1997, the history of public-key cryptography was turned around with the announcement by the CESG (April 2000 archive) that public-key cryptography was theorized in a 1970 note [1] by James ...
1
vote
0answers
20 views

Is there a Javascript and Java implementation of a good CSPRNG [on hold]

I need to use a cryptographically secure pseudo random number generator in my client running Javascript and in my server running Java. Is there a well-known implementation of a good CSPRNG in both ...

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