0
votes
1answer
9 views

Homomorphic multiplication by a scalar

Few homomorphic encryption schemes like Paillier , Ring-LWE support homomorphic multiplication operation by a scalar apart from additive homomorphic property. Loosely they could be defined as below ...
0
votes
0answers
9 views

Deoxys: disadvantages vs. AES?

The CAESAR candidate Deoxys is based on a tweakable block cipher that seems to be a strict improvement over AES, in that it is a tweakable cipher resistant to related-key attack. The mode proposed ...
0
votes
1answer
32 views

Where is the mistake in my RSA by-hand calculation?

Like several previous askers, I seem to have made a mistake in my RSA calculation, but despite going back over it three times, I cannot spot it. I picked 1000003 and 6000011 as my primes, ...
1
vote
1answer
28 views

Why is DSA falling out of favor?

Windows abandoned DSA rather than extend it to support > 1024 bits; but otherwise I cannot find a reason why DSA would be less desirable. I see in SSH the disabling it by default with a completely ...
0
votes
0answers
8 views

Cryptographic key with editing safeguard [on hold]

I need to encrypt a number in a file, say 142345. It encrypts to EfsFjs or something else. I need a method that safeguards ...
0
votes
0answers
14 views

Is AES-256 bit encryption secure against this kind of attack? [duplicate]

Recently I came across this article. http://www.cs.tau.ac.il/~tromer/acoustic/ Could this put all computers at risk for decryption?
1
vote
1answer
20 views

Can I get successful signature verification with just altering message and signature?

Assuming I can modify a message and also modify the verification signature, and I also have the public-key but not the private-key. Can I create a message that can be verified with a signature that I ...
0
votes
0answers
15 views

Determining an encryption key when ciphertext and algorithm are known

I would like to know how I can tell that I have successfully performed an exhaustive search attack on an encrypted message. Here are the conditions: key is 40 bit I am aware of the cipher text and ...
0
votes
0answers
10 views

What are the advatages or disadvatages of using seperate chaining over linear or quadratic probing?

I was looking through different hash methods the other day and was curious as to what the advantages or disadvantages of using separate chaining over linear or quadratic probing. I know that with ...
4
votes
2answers
587 views

Is this simple PRNG secure?

$G$ is a PRNG used in a stream cipher and defined in the following way: G receives $s_0$ as an input, which is a random string drawn from a uniform distribution. The output of step $i$ is $s_i = ...
0
votes
0answers
13 views

Dynamic Password Making [on hold]

I want to make a dynamic password for my server, the password should changeable with different algorithms, for example: password can be attached with the minutes of the clock. Then password may be ...
0
votes
1answer
24 views

CPA on theoretical OTP with CBC mode

Body of question Note: this is THEORETICAL exercise. I understand OTP and CBC does not get along. I have to find a CPA on CBC enc-mode using OTP as the encryption algorithm, s.t a new key is ...
5
votes
0answers
66 views

Algorithm for Boneh and Durfee attack on RSA

I am trying to understand various attacks on RSA and I believe that they only way to fully understand the algorithm is to implement it. I am trying to implement the code in this paper (Private Key $d$ ...
1
vote
0answers
54 views

Is it possible to combine two hash functions in such a way that cracking the constructed hash would require cracking the constituent hashes?

Suppose A is some arbitrary hash function, for example BCrypt or MD5. And B be some other arbitrary hash function, maybe SHA256 or SCrypt. Let ...
3
votes
0answers
70 views

Elgamal with secret key equal to zero possible?

From various sources (e.g. this paper, page 3), the key generation algorithm of Elgamal samples the secret key $x$ from $\mathbb{Z}_q$, which is identifiable to $\{0, 1, 2, \dots, q-1\}$. My ...
0
votes
0answers
25 views

What happens if someone implements tree-base signature scheme incorrectly?

I'm learning about signature schemes and read about Merkele's tree-base signature scheme. There are paragraphs about how the key and signings are generated. Using so-called tree structure and pseudo ...
-1
votes
0answers
25 views

Unknown Hash or Cipher [on hold]

I'm trying to identify what method was used to hash or encrypt a string of text, I have the plain text and the output, however, I have been unable to identify the method used to produce the output. ...
0
votes
1answer
31 views

How to find the time complexity of modular multiplication? [duplicate]

There are two number of length m bits. How do I prove that the complexity of modular multiplication of these two numbers is $O(m^2)$.
3
votes
1answer
73 views

What is the private key in RSA?

I'm new to cryptography and I have a doubt: I read some pages a bit different definition for the RSA private key: In 1 - (n, d) In 2 - ...
-3
votes
0answers
32 views

improve of cryptography algorithm [on hold]

This is my algorithm.. ...
0
votes
1answer
48 views

How do attacks on WEP work?

There is an abundance of tools and tutorials on how to break WEP encryption. However, I fail to find a nice resource that gives a clear break-down of why the attacks are possible. For example, I know ...
3
votes
1answer
60 views

How are boolean functions used in cryptography?

I recently started becoming interested in Boolean functions. Because they are defined as $f: \{0, 1\}^n \rightarrow \{0, 1\}$, or in other words only over $\{0, 1\}$, I guessed they can somehow be ...
0
votes
1answer
32 views

Symmetric cipher speed (AES vs Camellia vs Twofish)

If I have understand correct, Twofish is more secure (harder to break) than AES and Camellia, but Twofish is slower than AES and Camellia. But how can I mesure the speed difference between AES vs ...
11
votes
2answers
1k views

RSA encryption using multiplication

Generally in RSA we encrypt as $m^e \pmod n$. Will RSA work if we replace the power by normal multiplication? $E = (m \times e) \mod n$ and decryption as $c \times d \mod n$. What will be $d$ ...
-1
votes
0answers
22 views

Currently Best Integer not bit FHE [on hold]

HElib encrypts and evaluates on bits. Are there any FHE that evaluates on encrypted integers? If there are more than one, which one to choose?
1
vote
1answer
39 views

Can we do modulus switching for number theoretic encryption?

Can we do modulus switching for number theoretic encryption such as Paillier or ElGamal?
1
vote
0answers
58 views

Why are hash functions like SpookyHash and MurmurHash so highly collision resistant?

Why are hash functions like SpookyHash and MurmurHash so highly collision resistant? I tried to test these hash functions using a few billion input messages and I found that there is no hash value ...
3
votes
4answers
156 views

To what extent is WhatsApp's statement on secure messaging realistic?

As those of you who use WhatsApp Messenger probably know, with their recent update chats and calls are now encrypted. Here's what WhatsApp claims: Messages you send to this chat and calls are now ...
1
vote
1answer
65 views

What would happen to AES if we replaced MixColumns with ShiftColumns?

I have this as a question in an assignment and I guess I don't fully understand the steps. I understand that if we omit MixColumns, then every byte of the ...
-1
votes
1answer
31 views

Modelling crypto protocols using Formal methods

How to start working with SPIN/Promela for modelling cryptographic protocols using formal method such as LTL?
1
vote
1answer
40 views

How is decryption done in AES CTR mode?

Since AES CTR mode uses a unique IV and counter to produce the key to XOR with the plain text to get the ciphertext, the question is so as to how decryption is done. Since AES CTR produces a ...
3
votes
1answer
59 views

Is the use of a 4-round Blake2b permutation in OPP justified?

The MEM-AEAD construction uses a 4-round Blake2b permutation in masked Even-Mansour mode as a (tweakable) block cipher. 4 rounds of the Blake2b permutation are already broken to my knowledge. Why ...
0
votes
1answer
83 views

Is this cascading encryption, and is my security weakened as a result?

I'm trying to understand what is, and what is not, considered cascading encryption. All of the posts and conversations I've read over the past few days discourage the practice, including this article. ...
0
votes
0answers
11 views

Are there any free to use video and audio chat programs that offer end-to-end encryption that do not let the service know of the content? [migrated]

Skype is compromised, FaceTime is compromised, and I believe Ovoo is compromised. Does anyone know of any genuinely free (not free-to-try or in-app purchase-type applications) that offer end-to-end ...
1
vote
1answer
51 views

How secure is the OTR protocol?

I am using Adium and wondering how secure it is. I believe it uses AES-256 (I do not understand what that means) by default. It also requests that users exchange fingerprints with each other before ...
0
votes
1answer
32 views

How robust is my coded output?

I create codes and ciphers and as a hobby and I was wondering if there was any outfit that would 'test' your output to see how resilient it is. Is there a group anywhere that will accept code, try to ...
4
votes
1answer
86 views

Backdoor in NIST elliptic curves

Let $E$ be an elliptic curve defined over a finite field $F_q$ with prime order $n$ and $P,Q \in E$ and $k$ be private key such that $kP=Q$. Since $n$ is prime, $E$ is isomorphic to $Z_n$. Suppose ...
0
votes
0answers
4 views

EmailAddress in x500name for CSR? [migrated]

I would like to add EmailAddress to my PKCS10 CSR: .addRDN( BCStrictStyle.EmailAddress, emailAddr ) Why does the Bouncy/Spongey spec say the following?: ...
-5
votes
0answers
58 views

Shamir secret sharing and homomorphism [on hold]

Problem: Implement Shamir’s (k, n) Secret Sharing (SSS) scheme, with $k = 3, n = 5$, to (a) Find shares of a given set of numbers. (b) Compute average from shares (c) Choose any ...
-3
votes
0answers
46 views

How solid is this method of encryption? [on hold]

Let's say your message is "This is a message." Now translate it into numbers. a=1 b=2 c=3 so on and so forth. Now take those numbers and turn them into three digits based on a randomly generated ...
-3
votes
0answers
13 views

Can someone please decrypt “NUZGIEJX” using Vigenére [on hold]

The key is "FUN". I just want to make sure I am doing it correctly.
0
votes
0answers
8 views

Deciphering and encrypting using Vigenére square for kids?

Is Vigenére cipher the most basic form of enrypting or is there another simpler way? I'd like to expose my niece to it.
0
votes
1answer
46 views

Best known attack

I always have listened the term best known attack but I have doubts respect to this term, becase there are several kinds of attacks for example structural attacks, inversion attacks. It is possible to ...
1
vote
1answer
55 views

Understanding the Hidden Subgroup Problem specific to Integer Factorization

I've been reading about the Hidden Subgroup Problem (HSP), specifically trying to understand how it is related to the integer factorization problem. I've read What exactly is the impact of the hidden ...
1
vote
1answer
15 views

Question about Cipher Block Chaining(CBC)

I'm studying at the moment the CBC Encryption method,and I was asked in an excercise how many bits would be wrong after decryption if during the transmission 2 bits are interchanged. My guess is that ...
0
votes
2answers
331 views

mode of operation in cryptography

We need to choose a mode of operation for a Telnet like application where the average message size is between 7 and 1024 bytes. What is the best mode of operation in this case? a. CBC b. CFB c. ...
-4
votes
0answers
12 views

Breaking El Gamal defined over Sn

How can we break EL-GAMAL Encryption defined over Sn the permutation group ? Kindly give the efficient algorithm for it.
1
vote
1answer
11 views

One time Key Encapsulation Mechanism?

For KEM's, do you only exchange a private key once via the public key encryption and then do all further encryption with this private key, or is a fresh private key sent out with each message? The ...
0
votes
2answers
43 views

Length of encryption password aes-256-cbc

I'm encrypting a file with sensitive information with cat secret | openssl aes-256-cbc -a -salt > secret.enc I am choosing a random encryption password with ...
0
votes
0answers
12 views

Two nodes in p2p network exchange data and read data in same time [on hold]

I want to finde paper about exchange data between two nodes in p2p network. They must read each other's data in same time. In example two player a,b play rock scissors paper. A must read b's data ...

15 30 50 per page