-1
votes
0answers
51 views

can you attack to this protocol? [on hold]

can you attack to this protocol? ‎$ ‎A‎\rightarrow{B}‎‎\quad:\ P{_B(r_1,A)}‎\\A‎\leftarrow‎{B}\quad:\ P{_A(r_1,r_2)}\\A‎\rightarrow‎{B}\quad:\ r_2‎$ ‎$P_A,P_B\ are\ public\ keys\ and\ r_1,r_2\ are\ ...
-1
votes
0answers
31 views

nonce is a number that use once.so why in many protocol use nonce several times?

the Nonce is "a number that use once".so why in many protocol use nonce several times? how use nonce in protocols? if problem is save of nonce in database,how saved time stamp and signature in ...
-1
votes
1answer
32 views

What does L_n is the bit length of the group order n states need for my calculation in ECDSA algorithm?

I am doing the program of implementing ECDSA for which I am trying to solve the equation scenario. In ECDSA that signature generation algorithm which states as hash value from the SHA-1 and where $l$ ...
-1
votes
0answers
61 views

What are the difference between cryptographic primitives and encryption primitives?

For example, from reading I found that the cryptographic primitives of both AES and DES are Confusion and Diffusion. However the encryption primitive for DES was Substitution and Permutation while ...
-1
votes
0answers
63 views

How does this Cryptowall v3 working to encrypt the file?

In Wikipedia, I've found an explanation about this Cryptolocker, the predecessor of a new variant this Cryptowall v3. I think there's an interesting value to know more about this kind of Trojan. ...
-1
votes
0answers
58 views

In modern definition, what is Enigma, and what caused its downfall?

This question is sparked from the movie The Imitation Game. This single question will have lots of subquestions. The Germans must put the Enigma at the same settings before encrypting and decrypting ...
-1
votes
0answers
34 views

Can anyone explain how IV(Initial vector ) are chosen in GCM and in CBC MAC in detail?

I actually want to know in detail regarding the IV selection in CBC MAC and in GCM MAC. There is difference in IV between CBC encryption and CBC MAC. Please explain about MAC.
-1
votes
0answers
49 views

feistel structure? why decryption is so easy with reverse order of subkey

I am doing an assignment on writing own encryption and decryption algorithm..so i come across feistel structure...can someone explain to me why we only use reverse order of key in decrpytion and we ...
-1
votes
0answers
21 views

Choosing a cipher in SSH

When and how do the client/server agree on what cipher and MAC will be used during an SSH connection?
-1
votes
0answers
17 views

Substitution cipher with hexidecimal key and encrypted plaintext? [duplicate]

This is a challenge for a past CTF that I was unable to find a writeup for. The challenge gives two ciphers (http://pastebin.com/raw.php?i=Fq98trFw). The "key" has a length of 32, and the flag has a ...
-1
votes
1answer
85 views

Vigenere ciphers : Need help for math analysis

I've been learning about Vigenere ciphers and then thought of another method to Encrypt and decrypt that. This's my method to encrypt : ...
-1
votes
1answer
48 views

Generating cyclic group for Ciphertext-Policy Attribute-Based Encryption [closed]

I am doing Project under the topic CP-ABE.I need to generate a symmetric bilinear group Go of prime order p and with generator g...Then how to choose random elements from Zp....kindly anyone help ...
-1
votes
1answer
66 views

Montgomery and Galois fields

I'm a little bit confused about the design of a RSA module in VHDL. My question isn't directly related to hardware design. I've read a lot of publications and I bought also a book. In one publications ...
-1
votes
2answers
77 views

Is there a client-side program to cryptography a HTML page and decode if correct password is writen? [closed]

I want to know if there is an easy way to do this: create a complete HTML page cryptography the text content (image is not important) ask user some password check the password with a cryptographed ...
-1
votes
1answer
81 views

Problem with implementing DES in python

i'm implementing DES in python and i've stumbled upon a problem i can't really find the problem, after debugging it i narrowed it down to this function, can anyone tell me if i'm implementing the DES ...
-1
votes
1answer
86 views

How are calculated numbers in AES S-box? [duplicate]

My question is how to calculate the 0x02 value of AES S-Box? I followed this explanation, but my answer is not correct. 0x02 is ...
-1
votes
1answer
56 views

Modular Reduction of polynomials in GF(2^m)

Hello I am having trouble understanding the algorithm implementation in hardware of the reduction process over galois fields of F(2^163) In the following process it ...
-1
votes
1answer
77 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
-1
votes
1answer
106 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 ...
-1
votes
1answer
285 views

Collision resistant hash functions

Let (Gen1,H1) and (Gen2,H2) be two hash functions. Define (Gen,H) so that Gen runs Gen1 and Gen2 to obtain keys s1 and s2, respectively. Then define Hs1,s2(x)=Hs1(x)||Hs2(x). a) Prove that if at ...
-1
votes
1answer
90 views

Isn't Groth-Sahai proof system applicable beyond Bilinear groups?

Classical paper by Groth-Sahai on NIZK proof system is titled as "Efficient Non-interactive Proof Systems for Bilinear Groups". To my understanding, only (Pairing Product Equation) PPE are defined ...
-1
votes
1answer
112 views

What are the advantages of Certificate Authority and Key Distribution Center over each other?

I want know difference among them. What are advantages/disadvantage of one on other?
-1
votes
1answer
100 views

Bouncy Castle and Salsa 20

I want to use Salsa 20 in Java, so I downloaded Bouncy Castle, and... it makes no sense to me. I've got it working, but most of my choices were essentially random. But I can't see there anything ...
-1
votes
0answers
86 views

Calculating periodicity of a pseudo random number generator (Middle-square method) [closed]

Below is a Python code that calculates the periodicity of the middle-square method for a given 4 digit-numbers: ...
-1
votes
1answer
152 views

What does it mean that a protocol realizes “strong mutual authentication”?

What does it mean that a protocol realizes "strong mutual authentication"? And What does it mean that a protocol realizes "weak mutual authentication"? Can you define them formally ? I have found a ...
-1
votes
1answer
118 views

How is a Yubikey static password derived from the AES key?

When I configure a Yubikey slot as static, it's not documented or obvious how the static password yielded by a press relates to the AES key I set. For example: ...
-1
votes
1answer
114 views

How to benchmark custom crypto with OpenSSL benchmark suite? [closed]

OpenSSL benchmark suite currently tests the speed of algorithms supported by the library like md5 sha1 sha256 sha512. What if we have a custom crypto algorithm "abc" . How do we benchmark its ...
-1
votes
1answer
122 views

Attacking both authenticity and secrecy in authenticated encryption modes

looks like NIST only approved GCM mode for authenticated encryption and other modes don't have any approval or a good implementation available. Is that possible a weakness in $GHASH$ compromise ...
-1
votes
1answer
330 views

Guessing encryption algorithm based on key and ciphertext

Is it possible to tell which encryption algorithm was used, assuming I have a key and a encrypted text? To not complicate the situation let assume we are speaking about symmetric algorithms only. ...
-1
votes
0answers
166 views

Approaches to decoding data of an unknown type [closed]

This is a high level question. One area of computer science that I'm working on getting better at is encoding and decoding data. My background is that of a self-taught web engineer who is trying to ...
-1
votes
1answer
82 views

HMAC-Ripemd-160 in TrueCrypt

I'm wondering if it is still secure. I know TrueCrypt closed its doors but I continue using it because the cryptoaudit didn't find any huge bugs or security issues in TrueCrypt. But I have a bad ...
-1
votes
2answers
154 views

Encryption algorithm designed to be easy to decrypt by machine but impractical to decrypt by hand

I am looking for - or considering the design of a new - encryption algorithm that does not use variable keys, such that it is easy for a computer to encrypt and decrypt any message regardless of its ...
-1
votes
1answer
111 views

Can Diffie-Hellman generate values in a specified range?

Is there any way to generate values only between $0$ and $255$ with the Diffie-Hellman method? I need to create keys for communication algorithms with $32$ and $16$ numbers between that range. The ...
-1
votes
1answer
56 views

Diffie-Hellman on infinite groups

The most common groups to be used as examples for the DH protocol are modular multiplication and elliptic curves. But I've realised that the groups doesn't need to be finite, a suitable infinite group ...
-1
votes
1answer
203 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.
-2
votes
5answers
210 views

Is symmetric encryption no longer necessary?

Here is it: Symmetric encryption is no longer necessary, because all security services can be implemented with public-key cryptography. Moreover, in public key cryptography the operations for ...
-2
votes
3answers
2k views

How secure is the Vigenère cipher in file encryption if you encrypt the password first?

I created a basic file encryption method, that seems pretty secure to me (based on an answer below, it seems to be an implementation of the Vigenère cipher) , but one of my colleagues claims that it ...
-2
votes
3answers
1k views

How can I find the prime numbers used in RSA?

I got this question in a local hacking event, but I couldn't solve it. Problem Statement ---- Continuing their snooping habit, NSA kept bugging Alice's communication. Resorting to the age old ...
-2
votes
4answers
317 views

Do Brute-Force Attacks and Cryptanalysis refute Kerckhoffs's principle? [closed]

According to Kerckhoffs's principle "A cryptosystem should be secure even if everything about the system, except the key, is public knowledge." Now I want to throw in a provoking formula of mine which ...
-2
votes
2answers
212 views

Is (2^333)-1 a prime number? [closed]

How can I see if $2^{333}-1 $ is a prime number? Does this have to do with Mersenne prime numbers ($2^n-1$) ?? Thank you!
-2
votes
1answer
95 views

How many bits of entropy would I get from 300 coin tosses? [closed]

Bonus question, what is the formula to calculate this?
-2
votes
1answer
59 views

moduli in SSL certificates [closed]

this is normally seen in a typical SSL certificate. For the modulus, I know that it is represented in hexadecimal form, but why is there a semicolon (:) after every group of 2 digits? ...
-2
votes
2answers
305 views

How do I choose the best 3*3 s-boxes?

I've read about 20 papers about the criteria for choosing best $n \times n$ s-boxes. Now, I've got two problems: How to generate $2^{24}$ s-boxes, and how to test them considering the criteria. ...
-2
votes
1answer
56 views

How to write the encrypted message after using RSA

I have created a RSA encryption/decryption program but how do i write out the results after doing a encryption? Right now I have it so that it will just print out the decimal value of one character ...
-2
votes
2answers
271 views

How to decrypt 3DES in ECB mode (using a wordlist)? [closed]

I have some encrypted texts (encrypted with 3DES in ECB mode without salt). My question: How can I decrypt them using a wordlist? (or without one) Example: Encrypted text: ...
-2
votes
2answers
120 views

How to best mix two arbitrary/random n-bit words? [closed]

Given two arbitrary/random $n$-bit words, how could one best mix them to get one $n$-bit word for general crypto usages? I suppose that one should have an adequate measure of goodness of the mix ...
-2
votes
2answers
113 views

What is the difference between homomorphic encryption and homomorphic signature? [closed]

I want to apply homomorphic signature instead of homomorphic encryption in Provable data possession. So I want to know about homomorphic signature and homomorphic encryption.
-2
votes
1answer
392 views

Is my one time pad cipher secure?

This is a program that I made for encrypting text files. It uses a one time pad cipher to encrypt the files, but I do not know if there is any holes in my program that could be a vulnerability. Is my ...
-2
votes
2answers
373 views

How weak/strong is this hand cipher? (updated) [closed]

In simple steps here the system: first write text. hand cipher then divide into groups of three letters: han dci phe r then choose a key consisting of three letters, for example ...
-2
votes
1answer
156 views

Why is 2 the inverse of 10?

I have one question about the ECDSA signature scheme. When Bob wants to send a message to Alice that is to be signed she makes following things (with for example $A = (5,1)$, $d=7$, $q=19$). ...

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