0
votes
0answers
17 views

Device intercommunication with commands

I want to create a smart house project, and in that i bought some simple RF modules. Those modules don't support crypto out of the box but i want to connect them to a device that i would program to ...
0
votes
0answers
36 views

RSA, proof of correct work, if p is not a prime number [duplicate]

Is there any proof of correct work of RSA algorithm, if p is not a prime number? For example: n = p*q, p = p1*p2, where p1 and p2 are primes. Edit: I found that it's called Multiprime RSA, but i ...
0
votes
0answers
52 views

Prove that if we redefine the key space, we can assume Gen chooses a key uniformly

I am working on problem 2.1 in Introduction to Modern Cryptography 2nd edition by Katz and Lindell. 2.1) Prove that by redefining the key space, we may assume that the key generation algorithm ...
0
votes
1answer
33 views

Assemble RSA keys from components

I'm studying openpgp cryptography and struggling to understand some things. I can't use pgp tool for generating keys and ecryption, but have to write a simple app to generate keys, encrypt and decrypt ...
0
votes
0answers
9 views

Keystore and configuration file

It appears that Java Keystore is often used by web server using a configuration file, with the password opening the JKS written in it and also the password protecting the specific entry. How could ...
0
votes
0answers
24 views

Attack probability of an algorithm? [on hold]

I am currently working on improvising the blow fish algorithm. Is there any method to find the attack probability of the algorithm? I am in learning stage right now so please don't mind if the ...
0
votes
0answers
25 views

Zero knowledge of two factor

Here I overconfident in myself state that I can show, that n has two factors. This is not completely true, can possibly show $n$ is composite - prover generates RSA key with modulo $n$, and gives $e$ ...
0
votes
0answers
53 views

Collision attacks on digital signatures

After reading this document about MD5 collision attacks, I still don't understand how collisions can make digital signatures insecure. In the paper, the researchers created two files with the same ...
0
votes
0answers
39 views

RSA: If I know n, e, p, and q, how do I calculate d using the extended euclidean algorithm? [duplicate]

After doing a good amount of research, it's become fairly obvious that I ought to be using the extended Euclidean algorithm to calculate d from the data that I already have. However, this isn't an ...
0
votes
0answers
42 views

common ways / methods to try to break a SP network

I have a very little cryptography background (but a relatively solid maths background) so my below question is very general. Basically I have been given a SP network with an output to reverse. I ...
0
votes
2answers
61 views

Using the Vigenere Cipher to find key

Given a ciphertext message that was generated using the XOR cipher and a bit string found in the plaintext, how can you find the key that can be used to map the plaintext to the ciphertext?
0
votes
1answer
51 views

Encode-decode with different block sizes? [on hold]

I am implementing AES-ctr encryption. While encrypting I call dofinal on every 16 bytes of data. When I try to decrypt this data in different chunk size say 32 bytes I get different output (original ...
0
votes
0answers
8 views

How to import key BLOB generated from Microsoft CryptExportKey from Linux [migrated]

I have a private/public key pair saved as key BLOBs which were in fact exported with the Microsoft "CryptExportKey" API. Now I need to use the same key pair (specially the public key) under Linux ...
0
votes
0answers
41 views

Twofish encryption in Python [on hold]

I have a test tool which uses Twofish as the encryption algorithm to encrypt data before sending it to the server. The code is written in C++ and uses Bruce Schneier's optimized C implementation ...
0
votes
0answers
10 views

Paillier algorithm encryption [migrated]

Can any one tell me how to implement paillier algorithm for an file that i am uploading this is my code.. ...
0
votes
0answers
23 views

Key Confirmation Attack [Key Distribution Center (KDC)]

Okay this is how I understood it according to this: Alice $A$ establishes a connection to $KDC$ and prepares for session key Exchange $k_{ses}$ $A$ encrypts the request with her key $k_A(A, B)$ ...
0
votes
0answers
31 views

security of pairing based cryptography

while going through some papers on cryptographic accumulators i find the following statement "several pairing-based accumulators have been proposed in the past. However, due to continuous and recent ...
0
votes
0answers
8 views

Using ssh agent to sign a string [migrated]

I am trying to learn more about asymmetric keys. I am writing a program that uses ssh-agent server to sign a message. This works well, but it generates a RSA-SHA1 signature of the message, which I am ...
0
votes
0answers
32 views

AES product function

Small description: consider a polynomial in GF($2^8$) , which has the form $$f(x) = b_7x^7 + b6x^6 + b_{5}x^5 + b_4x^4 + b_3x^3 + b_2x^2 + b_1x + b_0 $$ If we multiply by x , we have $$x * f(x) = ...
0
votes
0answers
32 views

About the Security of PCBC Encryption Mode

We are designing an encrypted file system. We plan to use the PCBC (Plaintext Cipher Block Chaining) encryption mode for encryption. This is because we desire the feature ("small changes in the ...
0
votes
0answers
20 views

Security of simple Skein PBKDF mentioned in the paper

From the Skein 1.3 paper section 4.8, Skein as a Password-Based Key Derivation Function (PBKDF), it mentions the following as a simple PBKDF (S = seed and P = password): An even simpler PBKDF is ...
0
votes
0answers
91 views

Moral dilemma on releasing a new E2EE Method [closed]

Please forgive me if this is not an appropriate question but I wanted the opinion of those working in this field as I kind of stumbled into this problem. Im not a cryptographer but I think it's fair ...
0
votes
0answers
58 views

How dangerous is it to encrypt with AES 256 if the end user knows the unencrypted value?

I am implementing a bit of security in a system that was originally built without encryption on a specific piece of data. The plan was to encrypt this piece of data and include it as part of the ...
0
votes
0answers
17 views

Behaviour of LDPC code as density of check matrix increases [closed]

My assignment is to implement a Loopy Belief Propagation algorithm for Low-density Parity-check Code. This code uses a parity-check matrix H which is rather sparse (say 750-by-1000 binary matrix with ...
0
votes
0answers
22 views

Construct rainbow table to cracking DES

I'm facing to a project that is build a rainbow table to cracking DES. I've already collected information about Hellman, DP, rainbow table method. Finally, i choose rainbow table. I've read topic ...
0
votes
0answers
32 views

how to calculate nonlinearity?

I am struggling to understand how to calculate non-linearty of an s-box, could someone show me a detailed example? I found this question which helped a little, but I still didn't get it, if someone ...
0
votes
0answers
95 views

Naive implementation of Rainbow Table and/or Hellman's trade-off

Is there any naive implementation of Hellman's cryptanalytic time memory tradeoff in C and/or a naive implementation of Oechslin's rainbow table algorithm in C as well? I have seen some ...
0
votes
0answers
44 views

Composition of non-perfect encryption keys

Definition 1: A key $k$ is called perfect if it is uniformly distributed from the adversary's point of view; a key $k$ is called $ε$-perfect, if its distribution has an $ε$ trace (statistical) ...
0
votes
0answers
47 views

Making PRFs out of PRGs

Is it possible that we take a $PRG$ $G(k)$ of stretch $n\cdot2^n$, and read its output as the table of a $PRF$ $F(K)$ with input and output size of $n$? Intuitively it sounds possible however I read ...
0
votes
0answers
30 views

Weaknesses of truncated hash value [duplicate]

I want to apply one of SHA-2 functions to a plain text and then truncate the hash value into parts and store them into different areas so are there any security implications for truncating the hash ...
0
votes
0answers
35 views

I was wondering if RSA is an homomorphic crypto system? [duplicate]

I was wondering if RSA is homomorphic and how secure is it. I have read there is a variable of this but i don't fully understand the mathematics.
0
votes
0answers
31 views

Practical strength of non-2^n RSA key lengths [duplicate]

It has for many years been popular to use RSA keys that have lengths that are powers of two. E.g. 1024-bit, 2048-bit and 4096-bit key lengths are all popular for use with OpenPGP implementations such ...
0
votes
1answer
83 views

Why not send the identity in the encrypted message?

I've recently started reading the book "Applied Cryptography" written by Bruce Schneier. Quite a few times I stumbled across protocols who send the identity outside of the encrypted message (see step ...
0
votes
0answers
30 views

Resynchronizing brute-force attack against stream ciphers

There is a stream cipher without any known cryptographic weaknesses. The attacker knows parts of the key so she can reduce the key-space to a size that can be practically brute-forced. However the ...
0
votes
0answers
28 views

Signature constructor using Self-signed certificate

I've the following scenario: One application signs JWT access/id tokens using the private key contained in a self-signed certificate, and then passes its public key to other parties to validate that ...
0
votes
0answers
24 views

Where I can find a list of certified software / hardware RNGs compliant to NIST SP 800-22?

I need to use NIST SP 800-22 approved software / hardware to generate RSA key pair. Where I can find a list of certified software / hardware RNGs compliant to NIST SP 800-22? And how is the SP ...
0
votes
2answers
111 views

Reusing a one-time pad?

I have an embedded device. It produces larges files (200 MB). I want the device to encrypt the file before writing to disk, so I gave them all a 16-byte random key. How can I transform the large ...
0
votes
0answers
17 views

Block size of 128 bit in (quantum) future [duplicate]

Is a block size of 128 bit enough to ward off expected attacks in the future (something like 30 years ahead) with the possible risk of quantum computers? Other formulation: If we were to create a ...
0
votes
0answers
33 views

Requested to encrypt data with AES256, digital certification, timestamped

at my job we have been tasked by gov to encrypt some data we send to them. The "law" says we have to do the title above, but they only need us to do the AES256 thing because the data is not really ...
0
votes
1answer
50 views

decrypt a saml 2.0 response having aes 128 and rsa [closed]

I need to decrypt a saml 2.0 response. But, the response object has reference to aes 128 and rsa algorithms, and I am having hard time in finding a way to decrypt. Below is the structure of the ...
0
votes
0answers
26 views

How to check if a sequence is generated by a linear congruential generator? [duplicate]

Assume a linear congruential generator is defined by $x_i=(x_{i-1}\cdot a+c)\bmod m$ and I am given the values $a$, $c$, $m$ and a sequence of numbers starting at the $n$th bit. Can I tell whether ...
0
votes
1answer
87 views

Rijndael S-boxes: Where do the $\mu$ and $\nu$ polynomial ring elements come from?

I've asked some other questions before about Rijndael's S-boxes, and step by step I'm coming to an understanding; but those steps often guide me to new questions. I did some lines of code to ...
0
votes
1answer
25 views

What is the benefit of applying the tweak a second time using XTS?

I tried to understand the inner working of XTS. What I understood is that it is applying the tweak two times: once on the plaintext and once on the output. What is the benefit of applying the tweak ...
0
votes
0answers
39 views

Is there any task better and less complex than oblivious transfer? [closed]

I wanna know whether there can be any algorithm less complex than oblivious transfer because OT consumes O(n) time complexity where n is the number of messages involved. So can you please help me out ...
0
votes
0answers
23 views

Weakness in double hashing? [duplicate]

I remember reading an account of how double hashing (i.e. sha256(sha256(x))) can make some form of communication protocol between Alice and Bob trivially insecure, ...
0
votes
0answers
54 views

Key exchange using hash function

Consider two types of attackers on a key exchange (KE) protocol and subsequent communication between the parties which used this KE instance to establish a secure communication key. Attacker Eve ...
0
votes
0answers
39 views

Attack on key exchange with authentication

Suppose the honest parties - Alice and Bob - exchange public key in person/via telephone so that attacker can only eavedrop on the line. Alice has hashed the public key using a collision resistance ...
0
votes
0answers
5 views

draw a function in Latex [migrated]

I'm a beginner to latex and tikz, I've learned some basics but I still don't have a clue to draw functions in latex or tikz. Could anyone provide me with the codes for the two functions shown in ...
0
votes
0answers
11 views

Best practices for Private Key management [migrated]

How should I go about handling my RSA Private Key for my high-security Rails web application? This may seem like a "soft" question, not related to cryptography per-se, but is nevertheless very ...
0
votes
1answer
56 views

How to compute accumulated values in bilinear map accumulators

How to compute $ g^{1/(e_1+s)}$, where $g$ is the generator of group $\mathbb G$, and $e_1$ and $s$ are keys? I know only $s$ and $g^{e_1}$, not $e_1$. $\mathbb G$ has prime order for some prime $p$ ...

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