# Questions tagged [terminology]

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

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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 ...
73 views

### 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 ...
37 views

### 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: ...
46 views

### 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. ...
63 views

### 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 ...
54 views

### 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 ...
345 views

### 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 ...
52 views

### 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?
193 views

### 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 ...
90 views

### 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 ...
78 views

### 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:- ...
67 views

### 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, ...
182 views

### 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....
45 views

### 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 ...
2k views

### 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. $\operatorname{Dec}_{sk}(\operatorname{Enc}_{pk}(m))=m\;$ ...
255 views

### 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....
458 views

### 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 ...
257 views

### 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 ...
395 views

### 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 ...
57 views

### 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 ...
164 views

### 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 ...
454 views

### 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?
146 views

### 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 ...
1k views

### 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 ...
37 views

### 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 $2^{n}$ ...
1k views

### 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 ...
417 views

### 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 ...
365 views

### 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 $C=E(K,P)$
843 views

### 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 ...
132 views