Questions tagged [security]

Questions about matters of computer, software and communication security, that is how to protect systems against attacks.

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Manually Performing ECB & CBC

I am learning about block ciphers and while I understand the concept of Electronic Codeblock mode and cipher block chaining, I could not find any relevant practical examples online. Can someone ...
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What is the benefit of using seeded hashes with blockckain?

I'm a student and my supervisor asked me to use seeded hashes with blockchain.I want to know what is the benefit of using seeded hashes with blockchains.. and how it affects the security of the ...
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2answers
20 views

encrypt with permutation ciphers

I came across this question: You are given a permutation cipher defined by the bijection t: N -> N where, ...
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1answer
30 views

Problem with understanding Multi-party security circuit for secure stable matching

I am reading the following paper: MPCircuits: Optimized Circuit Generation for Secure Multi-Party Computation Paper Link I have following question: We have two groups shown in the circuit. Why we ...
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Accessible CS Math Job [closed]

I am a CS undergrad and a huge enthusiast of pure math. I have been doing competitive programming and proofs for a while. My ambition is to become an academic in theoretical computer science. The ...
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2answers
57 views

Decryption of RSA

How can we decrypt an RSA message if we only have the public key? For example, Message: 21556870,12228498 Public Key: ...
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29 views

Protecting a specific sized message with some limitations

So I make a research on my own. I have a device it allows a 64bit message. I wanted to secure it but I 64bits arent just enough to hash it and encrypt it. Is there really any good Hash function out ...
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1answer
24 views

Why is a threshold determined for Byzantine Fault Tolerance of an “Asynchronous” network? (where it cannot tolerate even one faulty node)

In following answer (LINK: https://bitcoin.stackexchange.com/a/58908/41513), it has been shown that for Asynchronous Byzantine Agreement: "we cannot tolerate 1/3 or more of the nodes being ...
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24 views

Database that contains timespans of cyber attacks in the web

for a project I need to evaluate a model, that tries to predict wether a certain cyber-attack (i.e. connection to a low level honeypot) is just a random access, a new attack-wave or an already known ...
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2answers
49 views

Two way communication using asymmetric encryption

According to image 1, for two way communication, each person needs to generate a pair of keys. However, according to image 2, only one pair of keys is required for two way communication. Thanks to ...
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24 views

Is there any kind of secure computer system on the horizon?

I'm going to attempt to be as concise as possible, given this highly complicated subject. However, some basic things need to be said here to properly "paint the picture", so kindly don't see it as a "...
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41 views

Historical examples of bad security policies/mechanisms that we got stuck with through switching costs?

The following process seems to be a recurring one: Initial design. Commercial organisations invent and implement a design that seems at the time to work. Problem discovered, new design suggested. Due ...
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1answer
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Is “capability-based security” vs “hierarchical-protection-domain based security” a false dichotomy?

The wikipedia page on capability-based security states: Capability-based security is to be contrasted with an approach that uses hierarchical protection domains. However, in order to implement ...
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Why do we need full-fledged workstations running massive OSes with massive software?

I've grown up with computers. While watching old computer TV programmes and documentaries and reading the news about constant issues with these modern systems -- everything from the sheer amount of ...
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In Baggy Bounds Checking, why is an error raised when accessing more than half the slot size of the end boundary of an allocated memory?

In the second notes of MIT's Computer Systems Security class (6.858), there is this particular (slightly modified) snippet. ...
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6 views

Miner violation in Securify Tool: Transaction Ordering Vulnerability Detection

For the following paper, I can’t understand the text written below: Securify Research Paper Our violation pattern checks that the amount of the call instruction is determined by a value read from the ...
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1answer
7 views

Problem with understanding the Mathematical Equations related to Testing Tool

I have downloaded the slides from the site: [Compliance and Violation Patterns It says No writes after calls. I can understand this concept. It’s a remedy for reentrancy problem. But it shows ...
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1answer
50 views

What are Surnames' dataset usages?

I have found a dataset which involves surnames dispersion around the world that sorted by population which I use it for a name recommender system. Its readme page caught my attention because it has ...
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49 views

L1 Cache Missing Timing Attack

I'm trying to understand Section 3: L1 Cache Missing in the paper Cache Missing for Fun and Profit. I'm stuck on trying to figure out how the covert channel is ...
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1answer
26 views

Weaknesses arising from using same key in both channel directions

I came across the following question: Which of the following risk may arise, when same key is used to encrypt both directions of a communication channel, that are not present if using different keys ...
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1answer
31 views

When compiled into binary, what signifies the end of a string? How can this be differentiated from user input which compiles to the same binary?

Apologies for the strange title, this is one of those questions I can't find through a Google search just because I don't even know what I'm supposed to be searching for. As I understand it, programs ...
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18 views

Are Physical 2-Person Lock Systems Informed by The Byzantine Generals Problem

The Byzantine Generals Problem says a set of generals who are greater than 2/3rds loyal is required to guarantee that securely issuing an order is possible the loyal generals. Because of this, I am ...
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2answers
68 views

Why don't most websites I visit seem to use TLS with Ephemeral Diffie-Hellman?

When I click "view certificate," under Public Key Algorithm it usually says "RSA Encryption" or "Elliptic Curve Public Key." I assume this is the algorithm used to agree on a premaster secret (...
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825 views

Can you prevent a man in the middle from reading the message?

I have heard about all these Man-In-The-Middle Attack preventions and I am wondering, how this can possibly work if the man in the middle only listens to your stream and does not want to change the ...
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3answers
90 views

How long does it take to crack a password by brute force

My computer teacher says that hackers can know any password by simply writing a permutation combination program and it will take around 21 days. Is this true?
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1answer
83 views

Matrix to Multi-level security

How to convert access control matrix to Bell-LaPadula. Can teach me step by step What best way to control converting Bell-LaPadula Model lattice using Access Control Matrix Matrix GIVEN $\quad\quad\...
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1answer
344 views

How pictures and videos are usually loaded in Memory? [closed]

Lets assume I'm talking about Jpeg and Mp4 and a general video player(not sure if different ones load it differently, if they do please tell) So do video players (process) usually load the entire ...
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1answer
182 views

NX Bit in x86 vs x86_64

I've been reading about how the kernel manages memory in x86 from this popular blog post(https://manybutfinite.com/post/how-the-kernel-manages-your-memory/) and had a few questions. There is a part ...
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2answers
76 views

Password authentication over an insecure connection

I was thinking a way to send password to server secure way without using secure connection,I found one solution.I want to find flaw in this.(Note: I am begginer,dont judge me, I know little about ...
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0answers
44 views

Agreeing on a Time in a Trustless Network

Imagine a chord-like network $N$. each machine $m \in N$ is directly connected to $N_m \subset N$. Without relying on official timeservers, I want all machines to synchronize to some time with ...
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1answer
28 views

how to defend against DOS caused by SYN cookies? [closed]

i have read about SYN cookies and i understood that they help to avoid DOS .. BUt my prof wants an answer as how SYN cookies can be used to cause DOS and how can it be avoided ? any help woul dbe ...
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0answers
103 views

How does a vpn connection work?

I have been looking into vpn (virtual private network). And I wanted to know more about the theory, how does it work really: what does it do with the packages? why is it secure? (or why can it be ...
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1answer
169 views

How does a buffer overrun corrupt the return address?

I got stuck on the following note while reading a paper about computer security: The stack mixes program data and control data – by overrunning buffers on the stack we can corrupt the return ...
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1answer
35 views

Can SSL be hacked if we know some of plain data?

As I know, SSL/HTTPS is two stage, first stage is public key encryption/decryption which transfers key of the second stage which is symmetric. It is true we don't have key, but we can have some of ...
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1answer
25 views

Formally modelling and describing access rights

Is there a formal theory or framework described in text books that models access rights in a mathematical way. I would expect things similar to the following: We have data (objects). We have ...
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29 views

Secrecy rate of eavesdropper channel?

I want to find secrecy rate of a main channel in case of Gaussian broadcast channel. e.g. I have a single transmitter and a receiver where eavesdropper wants to eavesdrop the communication over ...
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2answers
39 views

Would limiting the number of operations in a transaction prevent SQL injection?

In my understanding all SQL injections need to add another operation to the one intended by the programmer. For example, a badly written query: ...
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1answer
80 views

How is tamper-proofing of software evaluated for effectiveness?

How is tamper-proofing of software evaluated for effectiveness? I've been implementing a few algorithms listed within Surreptitious Software: Obfuscation, Watermarking, and Tamperproofing for ...
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Importance of Needham–Schroeder Protocol

I'm working on a paper about model checking on cryptographic protocols and many of the papers I have read, base their approaches in the Needham-Schroeder protocol. I undestand this was one of the ...
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3answers
237 views

Can software itself be encrypted?

Imagine that I need to install my server in a remote location, so my algorithm can do something fancy (collocation of server at a financial exchange is how I thought of this question, but it applies ...
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4answers
188 views

Using two hash functions for increased password security?

Forgive me for my brief knowledge on hash functions as I am not from a computer science background, however I am researching password security for my thesis and have been looking into hashing ...
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1answer
501 views

Computer Security versions of the Halting Problem

I'm plenty familiar with the Halting Problem for Turing Machines. It occurred to me after reading several posts on this site that it would be interesting, educational and useful to start a list of ...
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1answer
70 views

Are there any examples of programming synthesis in vulnerability research?

Program Synthesis To borrow from Microsoft: Program synthesis is the task of automatically discovering an executable piece of code given user intent expressed using various forms of constraints ...
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79 views

Could an OS relinquish control back to the bootloader?

I'm wondering if it is feasible for an OS to return control back to the bootloader, and boot a second OS after itself. Reason being -- I've been musing on bootkits, and wondering if it would be ...
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113 views

What is an access control graph?

A question I came across describes a scenario of an information system in a clerical office and states- "Identify the sets of S={subjects}, O={objects} and P={privileges} for the above systems of the ...
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155 views

Zero-knowledge proof: Abstract example

So I was reading about ZKP on wikipedia, the abstract example in summary goes like this: Peggy wants to prove to Victor that she knows the secret to a door inside a cave that connect A and B ...
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494 views

How Can a Network Server Identify a Specific Computer, Is There a Computer Fingerprint?

Most of websites put some restrictions on how to use their services; the following paragraphs are taken from “Terms of Service” of such website: Only one account per computer is allowed to view ads. ...
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1answer
83 views

User recognition through keystroke pattern

Hello thank you for taking time looking at this question. Is it possible to determine the keystroke patterns for a certain user? My idea is that, when the user enters their username & password it ...
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1answer
533 views

Why do ACLs (access control lists) have better persistence than capabilities?

Although I understand the principles on which both ACLs and Capabilities operate, I do not see why on system restart it would be favourable to store privileges by using ACLs, instead of capabilities ...
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1answer
45 views

What exactly would stop me from registering a domain from my own nameserver? [closed]

Can I just make a nameserver and claim away? Are there implemented measures to stop this from happening?