0
votes
0answers
2 views

Difference between single-pass and two-pass MACs

I am having trouble understanding where the count of "passes" come in. What constitutes a pass in the context of message authentication codes? How are single-pass MACs achieved?
0
votes
0answers
8 views

Is Shamir's Secret Sharing Scheme insecure for larger field?

According to wikipedia, if you are using shamir's secret sharing scheme with a field of order $p$, "High values of $p$ are risky because Eve knows that the chance for $f(x)\pmod{p}=f(x)$ increases ...
0
votes
1answer
6 views

Create big random number from 2 smaller numbers?

If i have 2 true random numbers from atmospheric noise or a different source. x= 299 and y= 499. Is it possible to create a bigger number with x to the power of y?. Can i use different sources ...
0
votes
0answers
8 views

Are there known fully homomorphic algorithms that are not secure?

I have a use of fully homomorphic encryption that isn't security based. Are there any known algorithms for fully homomorphic encryption which were discovered and found not to be secure? The simpler ...
0
votes
1answer
10 views

Metrics of PRNGs

I am a bit confused on the metrics that can be applied to the output of (deterministic) pseudo-random number generators. I've run output from many RNGs through ENT. The only metrics that really differ ...
0
votes
2answers
25 views

typical block size in RSA

if the input text is divided into a fixed block size for encrypting and decryption , what could be the typical block size for RSA algorithm for different size of input like 8 MB,16MB, 126 MB and 256 ...
7
votes
2answers
538 views

How does hash speed vary based on string length?

Surprisingly I have not been able to find an answer to this question on google. If I have a function that is based on any of the popular hashing algorithms used for password generation, by what ...
0
votes
0answers
37 views

Encrypt/Decrypt cloud passwords with master password

I know it's generally bad to store password in the clouds, and that I should be using salted-hashed password only. I'm making an application that will authenticate a user (with salted-hash), and then ...
0
votes
1answer
21 views

Pass a cookie down into an iframe (with 3rd party cookies disabled) through an untrusted domain

Here's an scenario we're running into. Let's say we have: Some untrusted domain, untrusted.com Our trusted domain, ...
0
votes
0answers
9 views

How often does /dev/urandom sample seeding from /dev/random? [migrated]

Unless I am totally confused and it doesn't do that. I want to know whether or not /dev/urandom will gain increased entropy if I take a hardware RNG and plug its entropy into /dev/random. So to ...
-1
votes
0answers
16 views

Differential Side-Channel Analysis on ECDSA

Joyce said assume we have some side channel information like power consumption traces. If we know k = (kl-1,...,k0). And we know biggest bit from k, such as (kl-1,...,kj+1). After that we quess next ...
0
votes
1answer
34 views

What is base of $log$ in Subexponential Algo for DLP?

I am currently going through this paper - "A Subexponential Algorithm for the Discrete Logarithm Problem" by Leonard Adleman. On page 56, author mentions that Dixon's algorithm - Asymptotically Fast ...
0
votes
0answers
13 views

Questions about Scyther tool [on hold]

everyone, I want to use Scyther tool to do a project about security protocol analysis but met some problems when I wanted to get familiar with the tool. I used the codes in the Scyther website but ...
0
votes
1answer
32 views

Breaking the Rabin Signature system with chosen message attack

I heard that we can break the Rabin Signature system using chosen-message attack. I can't find a message to ask for its signature in order to spoof my message M. Any suggestions?
-5
votes
0answers
20 views

Progrmaing Language [on hold]

I want to write encryption & decryption programs using ceaser,playfair,vigener,rail fence & monoalphabetic ciphers with c++ language. help me with sites or ideas
0
votes
0answers
30 views

Ways to identify mystery ciphers with no information but the code itself? [duplicate]

I recently offered to solve a cipher that was sent to my friend because he couldn't. I'm really having issues with the identification, I've tried a simple Caesar shift, and it came back with nothing. ...
1
vote
1answer
62 views

Diffie-Hellman key size to symmetric formula?

I've noticed that on every site I checked I kept finding the relationship between D-H key size and symmetric encryption equivalent as a table, like: 384 - 56 768 - 80 1792 - 112 2304 - 128 10753 ...
1
vote
1answer
100 views

128 Bit AES Issue

I'm trying to use the 128bit TI_aes implementation on my 16bit microcontroller and I'm having the weirdest issue. Every input where two bytes within a word are identical two nibbles within a byte ...
2
votes
2answers
83 views

How to calculate key size of a security algorithm?

There are lots of security algorithms. One of the way to measure security of a cryptography algorithm is to find out its key size. There are many key size of a single algorithm. ECC (Elliptic ...
1
vote
1answer
28 views

How to construct Hash function of type H:{0,1} * X G -> Zp*?

In many cryptographic protocols design, I have seen the statement 'Choose a Hash function H1:{0,1}* X G -> Zp*' i.e a hash function which takes as input a binary string of finite length and a random ...
0
votes
1answer
46 views

Are these hash function compositions collision resistant?

If a hash function $H$ is collision resistant, are the following two hash functions collision resistant or not? ($||$ is concatenation) $H'(m) = H(H(m)) || H(m)$ $H''(m) = H(m) || H(m)$ My first ...
1
vote
1answer
25 views

Is it safer to use timestamp in REST authentication?

I am working on a personal project to build a REST authentication system which authenticate clients via three parameters: ...
2
votes
1answer
31 views

Why is AES-128 considered secure while RSA needs a 1024-bit size to be considered secure [duplicate]

I got asked this question today and I didn't know the answer, AES-128 is considered secure, the key size is 2^128, so you would need in average 2^127 tries to break the key. Why does RSA need at least ...
0
votes
0answers
18 views

Do most TLS 1.2 implementations express curves in a canonical form when performing EC arithmetic?

Sorry if this is a silly question, but does anyone know if the cryptographic libraries which implement TLS 1.2 for Firefox, Chrome, etc. express a given curve in a canonical form (i.e. one of ...
2
votes
1answer
64 views

Questions about a SHA3 cipher stream encryption scheme

I've written an encryption implementation using a hash as a cipherstream FOR DEMONSTRATION PURPOSES. I know it is slower than more sensible options such as AES but I'm interested in several things, ...
-4
votes
0answers
25 views

I have a challenge for anyone willing [on hold]

I am incredibly new to the world of cryptography, and perhaps this isn't quite the best site to post on, but I was hoping I could gain insight from some smart minds on my method. I encrypted an ...
1
vote
3answers
33 views

Possible to generate a one time secret which all nodes on the distributed network can know but cannot pre compute

I have a distributed P2P network. Everyday, I want each node to have a secret which is only valid for that day, while each of the other remaining nodes on the network will be able to calculate the ...
0
votes
0answers
31 views

Extracting key bits from linear cryptanalysis equation for SDES

From the linear cryptanalysis of SDES, we get a linear equation consisting the K[1, 3] of the round key 1 and 2. From this how will I retrieve the key bit? How do we solve the linear equation we get ...
0
votes
1answer
18 views

Vulnerabilities in specifying the hash algorithm used for signature verification on a per-message basis

Let's say that I have a 4096-bit RSA key and when I sign data, I typically use SHA-512. As far as I understand it, the hash algorithm used to sign/verify a message is specified in the message. If a ...
0
votes
0answers
12 views

How are the attributes of a user authenticated in attribute-based encryption?

It seems that the papers I am reading do not talk much about this point. That is how the attributes of a user are authenticated in ABE system. To my understanding, there is an attribute authority ...
0
votes
1answer
23 views

How is the root certificate transmitted to pc?

i understand that the purpose of root certificates and CA's is to ensure that the communication parties are who they say they are. But how is the root certificate acquired? Is it not possible that ...
3
votes
1answer
72 views

Convert ciphertexts of one encryption scheme to another without decryption

I want to convert ciphertexts of one encryption scheme to another without decrypting them under the first scheme and then encrypting with the second scheme. For example convert OPE encryption to ...
3
votes
2answers
49 views

How can we define division operation by using Fully homomorphic encryption

Last fews months, I'm working with homomorphic encryption. Now I am dealing with some computational problems with integers or real-numbers (like arithmetic mean, standard deviation) where division is ...
0
votes
1answer
45 views

How Diffie-Hellman authentication works? [duplicate]

There are a lot of good videos on a simple Diffie-Hellman in the internet but unfortunately that is susceptible to the MITM attack. I understand how with DH the two parties are able to calculate a ...
1
vote
0answers
37 views

Caculated time One Point Multiplication with double and method

I am using double and add method for point multiplication in affine coordinates. How we compute 1PM in double and method? Di Wang said one point multiplication consists of repeated addition and ...
0
votes
0answers
25 views

Gaussian distribution in lattices

In many lattice based cryptosystems, Gaussian distribution is used. Can you explain why only Gaussian distribution is preferred?
2
votes
1answer
17 views

What does the probability subscript mean in Shannon's secrecy definition?

Shannon's secrecy can be defined as: $$P_M (M=m) = P_{SK,M}(M=m|E(SK,m)=c)$$ What does $P_M$ means? (same question for $P_{SK,M}$) I know that is the probability space M, M being the messages; I do ...
3
votes
0answers
14 views

What happens to NORX if the same (key, nonce, header data) triple is reused

As I understand it, reusing a (key, nonce, header data) triple in NORX leaks the XOR of the initial common prefix (but this is zero, so only its length is leaked) the XOR of the first distinct ...
0
votes
0answers
32 views

Fast hash for 64-bit inputs

I am looking for a fast hash (~few machine instructions) to be used for hash tables with 64-bit keys. I can't use SipHash as the hash function will be inlined in too many places and so the code size ...
4
votes
1answer
47 views

How to design a deliberately weak PRNG for experimentation?

I'm looking for a PRNG that is deliberately weak, that is, follows a set of rules stochasticly. For example: Encounters a set of bits that is a multiple of X, starts exhibiting bias, or starts to ...
0
votes
0answers
35 views

How to convert the 128 bit output of AES_CTR to 32 bit number? [on hold]

I want to run Dieharder test suite on the output of AES_CTR. How should I form the text file consisting of the cipher text obtained from AES_CTR, to be run directly with Dieharder package for linux? ...
3
votes
1answer
136 views

RSA private key finding method

Bob uses RSA with $p=83$ and $q=103$. His public key is $e=445$. Alice claims that she can calculate Bob's private key without using the definition $d=e^{−1}\bmod φ(n)$? But how?
0
votes
0answers
20 views

why OCB over AES for authentication encryption? [on hold]

why should anyone use OCB-offset code book over AES algorithm?
0
votes
1answer
23 views

Determining collision resistance of a function?

I am having trouble trying to understand if the function is collision resistant. As I understand it, preimage resistance means that it is hard for an adversary to find two messages that produce the ...
1
vote
0answers
13 views

Attribute based access control and role based, online bookstore example

I am asked to answer a question that says: One online book-store wants to grand access to clients regarding their subscription. There are 3 types of subscriptions A , B and C. Customers get access ...
0
votes
1answer
15 views

Multi Authority Attribute Based Encryption Library

Anyone aware of a library that has MA-ABE implemented in any language preferably python? P/S - I hope this is the right place to ask this. Apologies if not, then a redirect will be appreciated
3
votes
1answer
50 views

The sign of the correlation in linear approximation

${\text{Let }}g:{\{ 0,1\} ^n} \to {\{ 0,1\} ^n}$ be a round function of an $n$-bit iterated block cipher and let $K \in {\{ 0,1\} ^n}$ be a fixed round-key, and denote ${g_K}(x) = g(x \oplus K).$ Show ...
0
votes
0answers
25 views

Have ciphertext and key but need to figure out encryption method

So I have a block cipher (I think) that I need to break. I have the ciphertext and the key, but not the method of encryption, and was wondering if anyone could help me figure that out? The key is a 9 ...
0
votes
0answers
30 views

AES Twofish Serpent [duplicate]

AES-Twofish-Serpent how to create this combo encryption? I am using Linux Mint and i want to encrypt few big folders in one folder, but to be hiden.
-1
votes
0answers
15 views

M3 Bitlocker Recovery

Has anyone used this software? Is this a legitiamate solution? I am working on rolling out bitlocker encryption on some devices and I want to have a data recovery plan in place. I am looking for ...

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