Questions tagged [terminology]

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

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Definition of "verification"?

I am trying to better understand the concept of verification in cryptography. Verification algorithms are commonly used in message authentication codes (MACs) and digital signatures to confirm the ...
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Can media encoding formats on computers be considered a type of encryption?

To store information on a computer, you always have to encode the information as sequences of 1s and 0s. Can these encodings also be considered ciphertexts? Which definitions of encryption may ...
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Signature forgery in different adversarial settings

I'm currently studying the different adversarial settings for digital signatures. In Goldwasser, Micali and Rivests paper they propose three different chosen message attack settings, which are vastly ...
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Clarifying terms for cipher, algorithm, rsa, asymmetric, openssl

I am a self taught front-end developer and I am just trying to get my cryptography terminologies straight. I will make some statements. Can someone correct my mistakes? Question 1 I read that cipher ...
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234 views

Is Goldreich's proof with polynomial number of hybrid arguments wrong?

Oded Goldreich in his book [Foundations of Cryptography, 2004, Section 3.2.3] proves a theorem by polynomial number of hybrids. In rather recent years, Marc Fischlin and Arno Mittelbach published a ...
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1 vote
151 views

Name for number of output values a hash function can produce?

Any hash function has fixed output size but it does not mean that all values of output values are ever used. What's the term for the size of output set? As an aside: Can it be calculated? How do most ...
62 views

Cartesian Product Notation for Encryption and Decryption

I'm learning about encryption $(E)$ and decryption $(D)$ algorithms and am wondering what the following notation means, specifically the cartesian product for $E$ and $D$. $k$ represents key, $P$ ...
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92 views

Definition of Dual Lattice: $\vec{v}\in span_{\mathbb{R}}(\mathcal{L}(\mathbf{B}))$

Consider the definition of the dual lattice for a lattice $\mathcal{L}(\mathbf{B}_{m\times n})\in\mathbb{R}^{m}$ where $\mathbf{B}\in\mathbb{R}^{m\times n}$ and $n\leq m$ [sp2 Seminar, Luxembourg 2019,...
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1 vote
137 views

Decision LWE vs Search LWE: Which one is harder?

Sometimes if we have an attacker who's able to solve decision-LWE problem then we can use them (as a sub-routine) to solve (search) LWE problem, i.e., $\mathsf{sLWE} \leq \mathsf{dLWE}$. Conversely, ...
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107 views

Is it safe to derive a secret from a signature?

Many blockchain users have wallets that hold a private key, which can interact with a website. For example, the website can request the wallet to sign a specific message. 'Do only sign this message if ...
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1 vote
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Definition of Dual Lattice

1- Can someone explain why we have the definition of dual of a lattice like $\Lambda^*=\{\vec{v}\in span(\textbf{B}): \langle \vec{v},\vec{x} \rangle \in \mathbb{Z}, \forall \vec{x} \in \Lambda\}$. 2-...
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What's the name of the property of ideal cryptographic hash functions that effectively make it a random number generator?

Wikipedia says that, for an ideal cryptographic hash function, "the probability of a particular n-bit output result [...] for a random input string [...] is $2^{-n}$ (as for any good hash), so ...
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What is the difference between Post-Compromise Security and Backward Security?

Post-Compromise Security and Backward Security seem to mean that the attacker has obtained the communication key between two parties or groups in the current state, but cannot further obtain ...
224 views

Origin of "abort" in cryptography proofs

It's a very standard move in a game-based security proof to have a transition in which we "abort" on some event such as a hash collision; the two games are identical apart from the abort ...
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1 vote
121 views

Difference between PRF, Pseudorandom Function and Pseudorandom Function Family

According to Wikipedia, PRF is an abbreviation for Pseudorandom function family. But this answer says that PRF means Pseudorandom Function. Does that mean that a Pseudorandom Function is the same as a ...
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369 views

Is the secret key kept constant in IND-CPA game?

I read the Wikipedia Page on ciphertext indistinguishability. Here it gives the following outline of the IND-CPA game: The challenger generates a key pair PK, SK based on some security parameter k (e....
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Pseudo random generator notation

So I'm reading this article where they talk shortly about pseudo random generators where I'm not quite familiar with some of the notation. They call $\lambda$ the security parameter. "...
1 vote
459 views

Why does ECIES use "Key Encapsulation"? Does it?

In yet another twist that is the terminology around key establishment I found out that ECIES is often denoted as key encapsulation followed by data encapsulation. I'm wondering how the term "key ...
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104 views

What does the "static" assumption mean?

We can prove the security of a cryptographic scheme in standard model and non-standard model. Standard models like using some computational assumptions, on the other hand, non-standard models like ...
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Which one is more general, attribute based encryption or inner product predicate encryption?

If we have a scheme for inner product predicate encryption (IPPE), then can we claim that we already have designed an attribute based encryption (ABE) scheme; So we do not need to design an ABE again. ...
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1 vote
86 views

name/acronym/abbreviation explanation for hashes

(Cryptographically and hash/checksum wise consider me a rookie, as I'm rather just using algorithms.) While there are many names, not all of them are explained - I tried searching for the meaning of a ...
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Can blockchain be considered a cryptographic primitive?

This might be a silly question. But since more and more people simply use public blockchains as a secure ledger to store mutually agreed information to secure their high level applications, could we ...
132 views

Functional Encryption in Private-key setting vs. Public-key setting

$\bullet$ What does private-key functional encryption mean? Or functional encryption in private-key setting? Wasn't functional encryption a generalization of public key encryption? So now, why do we ...
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4k views

Would sending audio fragments over a phone call be considered a form of cryptology?

I have been wondering if sending audio fragments over a phone call would be considered a form of cryptology. Let's say that you own two mobile phones and say that one of your phones is on the Verizon ...
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RFCs & IANA specs about Ed25519 inaccurate?

While designing a crypto system based on existing standards and specifications i find myself questioning some of the accuracy in the current RFC-8037 and IANA specs around Edwards curves, 25519 and ...
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Average- and worst-case complexity

The terms "average-case", "worst-case" hardness are quite confusing. What do they mean when they say certain problems (like lattices) have an average-case to worst-case ...
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What is "auxiliary information" in context of cryptographic accumulators?

I have been reading a paper about accumulators (title of the paper: "Universal Accumulators with Efficient Nonmembership Proofs"). It mentions "auxiliary information" about a ...
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"Supported groups" in RFC 8446 (TLS 1.3)

What is meant by "supported groups" in the section 4.2.7. "Supported Groups" of RFC 8446: /* Finite Field Groups (DHE) */ ffdhe2048(0x0100), ffdhe3072(0x0101), etc: Is the digits - ...
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1 vote
49 views

Plain Text and Cipher Text terminology when double encrypting?

Say I have some message like "Hello World" that I want to encrypt, I get that Hello World is the Plain Text and the output from the encryption is called Cipher Text. But, let's say I want to ...
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108 views

What is the modern terminology for a digital signature scheme with a shadow?

In Guillou and Quisquater's 1988 paper "A 'Paradoxical' Indentity-Based Signature Scheme Resulting from Zero-Knowledge", they say that an RSA identity has a shadow and go on to state that ...
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1 vote
406 views

Correct terminology for ECC in PGP

These days I'm generating some PGP keypairs, and I'm struggling to understand the correct terminology behind ECC keys. Moslty in the differences between ed25519/<...
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171 views

What is the difference between Ring Signature and Multi User Designated Verifier Signature?

I was going through some text related to designated verifier signature (DVS). I came to know that DVS can be thought of as the two party ring signature. Can we extend this concept and say that ring ...
227 views

UOWHF vs CRHF / Relevance of UOWHF

What's the difference between UOWHF and CRHF and why are UOWHF useful? As far as I understand, Universal One-Way Hash Functions are an alternative to CRHF. While for CRHF it is hard, given randomly ...
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Does Quantum Key Distribution (aka: QKD) qualify as "Cryptography"?

This may be a polemic question, but since I did read the rules of the site and "terms and definitions" appear to be legitimate subjects, I want to raise this because I find this interesting, ...
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Significance of theoretical weaknesses?

What is the significance of theoretical weaknesses? Any real life incident where a theoretical weakness was ignored and later it compromised the system? Whats the dividing line between theoretical and ...
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How is the Unix / PostgreSQL crypt function a trapdoor function?

I am looking at this in the context of password hashing in PostgreSQL, specifically, the crypt function of the pgcrypto ...
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1 vote
155 views

What exactly is a "pass" when talking about hashing, ciphers and MAC algorithms?

I was very surprised when I said that hashing the same data twice was "double pass" and a comment came in that this wasn't the case if the hashing could be performed in parallel. This would ...
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1 vote
50 views

What qualifies as a key?

For my own project and the fun of it I have created an algorithm that turns plain text into cipher by interacting between entered text and a given password. My question is, in this instance, does the ...
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3k views

What does puncturing in cryptography mean

While I was reading the documentation for the cryptocode $\LaTeX$ package I stumbled across the "primitive" called puncturing in subsection 2.12. This was the first time I read about this &...
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Use of term "Commitment"

As an amateur, my first encounter with commitments has been in the form of an hash of the committed value, then I have learnt about seeding the hash as blinding technique. Going on I have discovered ...
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What do you call a random number that affects the calculation, but not the result?

This is about the same random ladder algorithm as my previous question. It computes f(g,n,r)=n*g or g^n (depending on the group notation), where g is a generator of a group. Suppose n=5882353. This ...
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145 views

Randomized encodings and Indistinguishability obfuscation

I want to understand the difference between randomized encodings and indistinguishability obfuscation (iO). Are randomized encodings a special type of iO?
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1k views

What does the modulo plus minus mean?

May someone please explain what the notations in the image means? In general, for a modulus $q$, what does the $+$ in here $\bmod^+ q$ indicate? What does the $\pm$ in here $\bmod^\pm q$ mean?
360 views

What does "key version" refer to when talking about AES 128 in NXP's datasheet?

I'm going through the datasheet for MifareDesfire ICs. Throughout the document, there are mentions of "key version". For example, section 9.3 of the document states: Hardware AES using 128-...
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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 ...
628 views

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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