1
vote
0answers
19 views

Algorithms to test vs. generate primes

What would be the value in having a true prime number generator algorithm instead of a prime number test algorithm? Also, if such a thing existed, what would be the impact on not only cryptography?
0
votes
0answers
15 views

Random Bytes in TLS Hadshake

During the TLS handshake, there are random bytes sent from the server to the client and random bytes sent from the client to the server. Since these bytes are sent in clear text, what is the ...
-1
votes
0answers
9 views

What do you think of Wire.com crypto? [on hold]

I'm curious to know how the crypto community feels about Wire? And how it might compare to Signal crypto! https://wire.com/ https://github.com/wireapp
1
vote
2answers
24 views

Why k-lists generalized birthday problem when $k=2$ is classical birthday problem?

David Wagner in his article A Generalized Birthday Problem in CRYPTO 2002 says that in k-dimensional (also k-lists) generalization of birthday problem (GBP), when $k=2$ "this is just the extremely ...
0
votes
1answer
11 views

Store and share data on intranet website

I'm developing an intranet for a company where admins are sharing a huge excel file containing all the necessary password, on the common TSE. I've managed making them encrypt it with a common password ...
48
votes
6answers
36k views

How can I generate large prime numbers for RSA?

What is the currently industry-standard algorithm used to generate large prime numbers to be used in RSA encryption? I'm aware that I can find any number of articles on the Internet that explain how ...
2
votes
2answers
32 views

When, where, and how to use HMAC

This question may seem like a duplicate of some others, namely this one, but even though that question asked when and how to use HMAC, the answers only addressed what HMAC was and why/how it worked. ...
3
votes
0answers
10 views

Bitcoin multi-sign and the amount of storage it required

I read this paper (Threshold-optimal DSA/ECDSA signatures and an application to Bitcoin wallet security), the authors said that in the optimal threshold signature that they propose players requires ...
0
votes
1answer
17 views

ElGamal recovering messages

If you use the same ephemeral key in Elgamal, someone can read the future messages. I have two ciphertexts $y_1=62$ and $y_2=4$. The difference between two plaintexts is $x_1-x_2=138$ how do I get $...
0
votes
1answer
17 views

How to show that any 2-round key-exchange protocol satisfying a given definition can be converted into a public-key encryption scheme?

How to show that any 2-round key-exchange protocol satisfying a given definition can be converted into a public-key encryption scheme that is CPA-secure? The given definition is as followed: ...
2
votes
1answer
27 views

Security model scalar multiplication in NaCl

I'm having trouble understanding what the “security model” for “scalar multiplication” in NaCl is. Security model crypto_scalarmult is designed to be ...
3
votes
1answer
141 views

RSA: special parameters construction

I have to show that the following construction of $q$ allows to factorize $N$ : $p \in \mathbb{P}$, the set of primes $q \gets p \cdot \left((p - 1)^{-1} \bmod e\right) \bmod e$ $k=1$ while $q \not \...
0
votes
1answer
16 views

Message Expansion / Encryption Blowup Factor / Ciphertext Expansion of ECC

In order to complete the following table with asymptotic times and message expansions, $\quad \quad \quad \quad \quad \quad \quad \quad \quad$ RSA $\quad$ McEliece $\quad$ ECC Encryption Speed $\...
0
votes
0answers
5 views

what is multi authority based weighted attribute based encryption ?? is this the current technique deployed in cloud?

As i'm interested in cloud computing domain, i have just got to see that MA-WABE is used as a cryptographic technique in cloud. can anyone brief about this technique?.if any algorithms present which ...
0
votes
0answers
9 views

Weakly Sublinear Compact FE from Succinct FE and XiO

I'm confused about a problem these days and I decided to seek an answer here. The question is about the section 4.1 of the paper LPST16. Let me recall the weakly sublinear compact FE scheme $\textrm{...
0
votes
2answers
29 views

The length of the shortest vector in Lattice

In Micciancio and Regev's paper "Lattice-based Cryptography",the length of the shortest vector is at least $\min\{q, 2^{2\cdot\sqrt{(n\cdot \log{q}\cdot\log{\delta}})}\}$ . I want to ask why the paper ...
1
vote
0answers
25 views

FIPS 186-4 seems to have an excessively complex q generation

So in DSA you have two primes - p and q. q is N bits long (let's assume 160 bits) and p is L bits long (let's assume 1024 bits). Here's what FIPS 186-4 says about generating the q parameter for DSA: ...
2
votes
1answer
334 views

Finding Elliptical curve points and encoding text using them

I recently got into learning Elliptical curve cryptography and are currently building a project in C#. Everything is working well so far, I can encode and decode points, and thanks to this forum I ...
0
votes
1answer
29 views

Questions regarding parallel AES CTR with merkle trees

I'm planning to implement a parallelizable variant of AES to end-to-end-encrypt files in a web application. As a mode of operation I'm most likely gonna use CTR mode with a 64 bit IV and 64 bit ...
3
votes
1answer
89 views
+100

Is security against semi honest adversary inheritable?

I have a two party protocol, let's call it $M$. At some point, there are $k$ steps, each one involving an oblivious transfer protocol, which is known to be secure against semi honest adversaries. ...
5
votes
1answer
164 views
+50

Applying machine learning algorithms to homomorphic encrypted data

I have a basic understanding of encryption and I got back to the topic because of an interesting site that encrypts financial data using homomorphic encryption (HE) and I would be happy for any input ...
5
votes
1answer
863 views

What characters are valid in PGP encrypted and signed messages?

What characters may be present in a PGP encrypted message or a PGP signature? For example, do encrypted messages only use the Roman alphabet + some numbers and symbols? Can the character set be ...
1
vote
1answer
16 views

Finding Linear Redundancy by counting the number of distinct frequency distributions of absolute walsh transform

I am writing a program to find linear redundancy in 4x4 s boxes. Is the number of distinct frequency distributions of absolute walsh transform a direct measure of linear redundancy in s boxes? byte[] ...
0
votes
1answer
40 views

Can a low density subset sum problem be intractable?

Hardness of a subset sum problem depends on it's density. Is it possible for a subset sum problem to be intractable even if it's density is less than 0.9408?
7
votes
2answers
378 views

Is calculating HMAC from hashed input a good idea?

The original HMAC algorithm is as follows: H(K XOR opad || H(K XOR ipad || text)) What if text would replaced with H(text)?...
2
votes
1answer
25 views

Proof that LFSR (with XOR feedback and nonzero seed) will never hit state of all 0s

Does anyone know a good proof that a LFSR (with XOR feedback and seeded with non-zero starting state) will never enter zero state? It is obvious that a zero state will always get stuck in a zero ...
0
votes
0answers
17 views

XOF/derivation as OTP

Probably a stupid question but I haven't seen it asked before... What would be wrong with expanding a key to the length of a given plaintext (using Shake or scrypt) and using that as a OTP on the ...
5
votes
0answers
237 views

Zero-knowledge proof for subset sum problem?

What is the currently most efficient (interactive) zero knowledge proof/argument for the subset sum problem? The most recent relevant paper I have found is Efficient Modular NIZK Arguments from Shift ...
2
votes
1answer
34 views

What are I2OSP & OS2IP in RSA-PSS verification?

I started working with RSA two weeks ago. But I coudn't really understand how exactly I2OSP & OS2IP are working. I am using some open source for signature verification through RSA PSS algo. I am ...
8
votes
2answers
210 views

Security of a self-decrypting block-cipher?

If I have a block-cipher like for example AES, a plaintext $x$, we use different function to encrypt and decrypt : $\text{encrypt}(x) = y$ , $\text{decrypt}(y)=x$. Now, if we build a function with a ...
2
votes
1answer
125 views

Authentication protocol which detects client impersonation from another machine

Consider following authentication protocol. Client ClientA knows some initial secret KeyA shared with server. Client also knows IP of legitimate server. Now when client wants to establish connection ...
1
vote
2answers
129 views

Detecting encryption in real-time?

Is there anyway to detect encryption in real-time through a common signature or pattern recognition. Say, a file is being encrypted using an AES-256 cipher, if I have access to the file stream - can ...
8
votes
1answer
771 views

What exactly is a “garbled circuit”?

There are plenty of questions here about the details and how-to's of "garbled circuits", but I have not seen anything that defines what garbled circuits are. What exactly is a garbled circuit? What ...
6
votes
2answers
153 views

RSA: revealing the modulus factorization by choosing a bad message

I started reading the book Cryptanalysis of RSA and its variants by M. Jason Hinek and I stumbled upon a phrase that intrigued me: plaintext messages that are relatively prime to the modulus (i....
-1
votes
0answers
35 views

How can I find all points on an elliptic curve?

I have an elliptic curve $$y^2=x^3 + 8 \times x + 6 \mod 13$$ How do I find all the points on this EC? Also, could you give me more examples?
3
votes
2answers
124 views

Bit level permutation

Could anyone explain how secure is bit level permutation? What is the most serious threat against the security of this kind of cipher?
3
votes
1answer
243 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 ...
2
votes
1answer
533 views

Building a cryptography system by combining a block cipher and a stream cipher?

I have to come up with a design for a cryptography system by combining a block cipher and a stream cipher. I can't seem to come up with anything on my own. Can someone point me in the right direction ...
-1
votes
0answers
39 views

Garbled table for 3 inputs

I have a truth table of a full adder with 3 inputs (A,B,Cin) and 2 outputs (S, Cout). How can I create a garbled truth table? I mean, in the general form it is ...
4
votes
1answer
250 views

what are the NTRU keysize and application in industry?

I'm a student currently working on a research project on the NTRU cryptosystem, I've read some papers about this cryptosystem, and in those papers they are talking about keysize, is it the size of the ...
1
vote
1answer
107 views

pairing parameters in PBC library

I would like to know what are the pairing parameters of PBC library and what are they used for? Here an example where they are used. I noticed that we can give any file in the param subdirectory. Is ...
2
votes
0answers
69 views

Ciphertext size of any CPA-secure public-key encryption scheme

I know that, for any CPA-secure public-key encryption scheme, the size of the ciphertext after encrypting a single bit is superlogarithmic in the security parameter. That is, for $(pk,sk) \leftarrow ...
4
votes
2answers
120 views

Is pseudorandom function also a one-way function?

Can I assume this? Specifically, I want to know if the following two cases are valid. Suppose $prf_k(m)=c$ One-wayness: Only given $c$, we cannot reveal $m$. Without key $k$, even given $m$, cannot ...
-1
votes
0answers
44 views

Existence of a random function under constraints

Let $F_1$ and $F_2$ be two random functions taking as input $N$ bits and returning $N$ bits. Let $C_1$ and $C_2$ two constants of $N$ bits. Is there a random function $P$ taking as input $2N$ bits ...
2
votes
2answers
486 views

Triple-DES DUKPT CBC PIN variant vs Data variant

Does any know the difference between triple des dukpt decryption algorithm with PIN variant and Data variant? I have done Triple DES DUKPT PIN variant, which generate session key from KSN and BDK. ...
4
votes
2answers
94 views

One-way function definition

I cannot understand why a one-way function $f$ is defined in this way $\text{Pr}(f(A(f(x))) = f(x)) < \frac{1}{p(n)}$ and not $\text{Pr}(A(f(x)) = x) < \frac{1}{p(n)}$ where $A$ is a ...
1
vote
1answer
84 views

How to encrypt a vector $e\in Z^{m}$ using LWE

I have a vector $e \in Z^{m}$, now I want to encrypt it by using LWE (Learning With Errors). Because in LWE, we have to encrypt of a bit $\{0,1\}$. How can I encrypt a vector $e \in Z^{m}$?
2
votes
1answer
137 views

AES with different modulo operations?

I don't get the modulo 10001 operation in MixColumns so much. If I have to take the byte computations mod 100011011 anyway ...
2
votes
1answer
131 views

Size of a MAC for a quickly checked message?

Let suppose that we have to check a message that was written one second ago. The message is discarded immediately after having being checked. What "minimal" size for such a MAC is secure?
1
vote
1answer
288 views

Encryption schemes and pseudorandom permutations

Can an encryption scheme (deterministic or not) be viewed as a pseudorandom permutation taking as input a message and returning a value of the same bit-encoding length?

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