Questions tagged [terminology]

Questions about the meaning and proper use of specific technical terms or notation within cryptography.

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Is Order-preserving encryption part of the functional encryption family?

I believe I know quite well OPE and ORE, but I'm unsure about what family to put them in. Can we consider them as a sub family of Functional Encryption, like Attribute Based Encryption or Inner ...
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Differences between algorithms, ciphers, primitives and functionalities

Working in security, I often hear terms such as algorithms, ciphers, primitives and functionalities. but as cryptography is not my field, they seem to be used interchangeably. What are the differences ...
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Probability conventions in cryptography

I am working on Victor Shoup's tutorial on game-based security proof and want to figure out some notions from the perspective of probability theory. Consider the following PRF advantage defined on ...
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About the definition of distinguishing advantage and computational indistinguishability

Given a polynomial-time adversary $A$ with binary output, the distinguishing advantage of $A$ with respect two games $G, H$ is defined as $$ \newcommand{\adv}{\mathbf{Adv}} \newcommand{\pr}{\mathbf{Pr}...
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What is the name of this kind of logic diagram?

I want to read this kind of diagram, but I haven't found the name of this, or somewhere I can find a legend of symbols used, or a tutorial to learn reading this... I've googled this for over an hour, ...
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How is ECB secure? [duplicate]

Setting aside legitimate concerns such as lack of CPA security (not to speak of malleability issues) and thus near-universal insuitability of AES-ECB for general purposes, I thought I recalled reading ...
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Meaning of the term "irreversible" for hashing

I was in an interesting discussion with Jon Skeet on StackOverflow. He indicated that hashes are irreversible, but he extended this to non-cryptographic hashes. A hash function has a specific output ...
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What are “weak” and “strong” output-input bit dependencies?

Section 3.3.5 of the paper “Schwaemm and Esch: Lightweight Authenticated Encryption and Hashing using the Sparkle Permutation Family” (the link to PDF can be found in this page) contains the following ...
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What is a ciphering key?

In Hebrew language there is the term tzophen (צופן) which means cipher. There is also a term "maphtech hatzpana" (מפתח הצפנה) which means "ciphering key". What is a ciphering key? ...
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Is there a hash function that is semi-two-way?

I am looking for a hash function that uses a timestamp as salt, and produces an output that when run through another function only returns the timestamp used. What would this be called? It's not a one-...
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What is an output symbol?

I'm reading Understanding Cryptography by Christof Paar and Jan Pelzl. In chapter 2 (Stream Ciphers). There is a section talking about "Bulding Key Streams from PRNGs". They assume a PRNG ...
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is Client Puzzle a challenge-response variant of Proof-of-work?

is Client Puzzle a challenge-response variant of Proof-of-work? I am kind of new to crypto, sorry if the question is kind of dumb. If it's not can you give examples of algorithms that implement the ...
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What is the difference between Solution-Verification and Challenge-Response variants of Proof of Work;

Sorry if question is really dumb, I am new to crypto :( If the client provides the solution for the PoW Challenge-Response, in my understanding, the solution of that challenge should be verified. So I ...
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What is "entropic security"?

I've come across a form of cryptographic security that I've never heard of: entropic security. I've read the Russel et al abstract and that doesn't seem to bear much relation to the wiki article. ...
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"randomized" indistinguishability vs "deterministic" indistinguishability

Let $X$ be a measurable space. For each $n\in\mathbb N$, let $P_n$ and $Q_n$ be probabilities on $X$. We say that $(P_n)_{n\in\mathbb N}$ and $(Q_n)_{n\in\mathbb N}$ are statistically ...
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What's the meaning of without loss of generality in cryptography? [closed]

What's the meaning of without loss of generality in the cryptography (Zero Knowledge Proof)? Without loss of generality, suppose we want to check if a 1 = a 2 . In the following description, j ∈ { 1, ...
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"Electronic signature" legal definition

A proposed California law contains the following definition: (i) “Electronic signature” means an electronic sound, symbol, or process attached to or logically associated with an electronic record and ...
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What's the difference between permutation and transposition?

I am trying to understand the difference between permutation and transposition. I have seen a similar question in the forum but I would like to ask you for proper definitions and examples of each. I'm ...
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What is the definition of function index

I'm reading through Indistinguishability Obfuscation from Well-Founded Assumptions and in Definition 3.1 describing sPRG, it mentions "samples a function index I." Can someone explain what a ...
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What is reaction attack?

In the paper of "Reaction Attacks against Several Public-Key Cryptosystems" CiteSeerX link, reaction attack is defined informally as "Obtaining information about the private key or ...
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What is aes in "operational mode"

I'm currently reading this report on the security of the IOT protocol "LoRaWAN". On page 3, it says the following: ...
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GL-SPHF and witness encryption

I recently came across this fascinating paper, and was wondering about whether the GL-SPHF that the paper constructs can be used to create a witness encryption scheme for algebraic branching programs. ...
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Is Keystore a file, a database, a specification?

What exactly are keystores? I understand they are used to store things like private keys, certificates etc. But how exactly is that done? Is it just an encrypted databases where you put all these ...
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What is the term to describe the combination of ciphertext, IV and authentication tag?

Authenticated encryption with associated data, such as AES-GCM, will take as input: IV, optional associated data, plaintext and key. A ciphertext and an authentication tag will be produced. Is there a ...
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What does it mean: Hardware vs software implementation of a cryptosystem

While reading some cryptography papers, I passed by some new terms like the hardware and software implementation of encryption systems. The question: what are the hardware and the software ...
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How do we say that one cryptographic primitive is stronger than another?

Can anyone help me understand this: How do we say that one cryptographic primitive is stronger than another?
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One way function existence

Let $x = (x_1, x_2,...,x_n)\in\{0,1\}^n$ for $n\in\mathbb{N}$. Prove that if one-way functions (OWFs) exist, then there exists a one-way function $f$ such that for every bit $i\in[1,n]$ there exists ...
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What exactly is asymmetric about 'asymmetric cryptography'?

What exactly is asymmetric about 'asymmetric cryptography'? https://www.sysadmins.lv/blog-en/digital-signatures.aspx says: "In other words, anything that is encrypted by a public key can be ...
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What is a clearsigned message?

PGP Digital Timestamping Service webpage mentions The service operates in a number of different "modes" depending upon the required results. The current modes are:- ...
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What does this Big-O notation mean based on appendix?

I am reading the following book: Introduction to Modern Cryptography Second Edition by Jonathan Katz and Yehuda Lindell. I am going through page 533 where they list what some of the notation means, ...
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Measuring entropy of a uniform distribution source

What is entropy? I do not understand it at all. One article states: When there is an equal chance for all items to appear, we have a uniform distribution. In uniform distribution the entropy is high....
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Question about hiding commitment scheme for integers

Given a generic group $\mathbb{G}$ of an unknown order (such as a $3000$-bit RSA group) and a randomly generated element $g \in \mathbb{G}$, is the commitment scheme $\mathrm{Com}(x)= g^x$ not ...
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Does a hash function necessarily need to allow arbitrary length input?

I always assumed that a hash function allows input of arbitrary length, since that's what all the hash functions I was aware of did. Wikipedia's definition of a hash function is as follows: A hash ...
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What is the more accurate way of stating the correctness of a PK encryption scheme?

Is it more accurate to state that a public key encryption scheme is correct if for all $m \in M$ and $(pk, sk) \in \operatorname{Gen}(1^k)$ a. $\operatorname{Dec}_{sk}(\operatorname{Enc}_{pk}(m))=m\;$ ...
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There is Alice and there is Bob. But what is the name of the malicious user?

I know it is a kinda funny and maybe even naive question but its still security related, so I decided to ask. Bob and Alice are widely used names indicating the two end-users/parties for web protocols....
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What does it mean to be "sound"?

I've been reading this in many places and I still don't properly understand what it means to be "sound". As an example of what I am asking for: The Fiat-Shamir transfrom is sound in the ...
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What does perfect mean within perfect forward secrecy and why do some cryptographers disagree with the term?

In this blog post, Matthew Green says Forward secrecy (usually misnamed “perfect forward secrecy”)... The Wikipedia article on forward secrecy (which the same sentence links to in the blog) says ...
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Is it fair to say that MACs use a signing algorithm?

The Wikipedia page on MAC calls the algorithm that is used to generate the MAC as a signing algorithm. Is that a fair use of that term? Can we then say that HMAC-SHA-1 uses SHA-1 as the signing ...
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What is the fundamental difference between multipartite and multilevel secret sharing?

According to this paper , Multipartite secret sharing scheme is a scheme in which the set of participants is divided into disjoint parts and all participants in the same part play an equivalent role ...
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What is the difference between security parameter and $b$-bit security?

In a previous question, I read ... for $b$-bit security meaning $O(2^b)$ work for an attacker to break the system... While in Katz's Introduction to modern Cryptography, I read: The key-generation ...
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Difference between computationally and perfectly hiding (binding) properties

I am new to Cryptography and has a trouble of understanding the difference between perfect and computationally hiding (binding) properties of a commitment scheme. I also would like to ask what does it ...
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What is the difference between an encryption protocol and an encryption standard?

What is the difference between an encryption protocol and an encryption standard? Am I missing something here? Or are they in fact two different concepts altogether?
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Short term for "Purposely-slowed hash"

When Argon2, Balloon, scrypt, bcrypt¹, PBKDF2… are used for a password, we can call them password hash (for password storage) or password-based key derivation function (for use in encryption). But ...
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What is the difference between data compression and compression in cryptographic algorithms?

What is the differences between data compression as used in e.g. the ZIP protocol and compression as performed in cryptographic hashes? Are there common properties as well, apart from creating a ...
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What does it mean exactly that an adversary can control a polynomial number of parties?

I have an intuitive idea of this, but I am not sure if I am formally interpreting it correctly. In the scenario I am considering, each party is identified by a sequence of $n$ bits and I have $2^{n}$ ...
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Meaning of the term "Key Material"

I am reading specifications from my client that focuses on the topic of security. In these specs, the term key material has appeared many times. I used Google to look for what the term means. ...
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Function secret sharing and sharing a truth table

I was reading a paper (Function Secret Sharing by Boyle, Gilboa and Ishai, PDF) on Function Secret Sharing and in that the author talked about a naive construction of a p party DPF wherein the truth ...
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What is the definition of dummy password?

Recently, I try to read some papers about Password Authenticated Key Exchange (PAKE). I can’t understand the meaning of “dummy password .” Can someone gives a concrete definition of it. And what is ...
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is it necessary to write C=E(K,P), Can we write C=E(P,K)?

I just want to know that can we write encryption and decryption formula like $C=E(P,K)$ instead of $C=E(K,P)$
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What is Post-Compromise security exactly?

After reading these papers on Post-Compromise Security: Post Compromise Security Asynchronous Ratcheting Trees My understanding is the following: it is possible for a key-agreement protocol to ...
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