# Questions tagged [notation]

Questions on the meaning, history, and usage of symbols and notation in cryptography. Please remember to mention where (book, paper, webpage, etc.) you encountered any notation you are asking about.

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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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### Perp notation question

What does the symbol $\perp$ mean? I saw this on a paper where some entity outputs $\perp$.
1 vote
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### what is the notation of nth power of 1? [duplicate]

when reading theoretical materials, it is often seen that "a common input 1^n..." what does it mean? Are there any similar questions and answers previously in StackExchange?
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### Can you identify these cryptographic algorithmic symbols?

I am mostly self taught and have limited knowledge of the symbology in the image below. It is a diagram of a sub block the RIPEMD-160 algorithm: Are such symbols standardized? Is there a good ...
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### Notation question: Dividing 2 Elliptic Curve Points producing a third point

I'm working my way through some papers and ran across what seems to be division of two points that produce a third point. I'm new to ECC and am having a terrible time trying to figure out what this ...
1 vote
113 views

### Superscript vs subscript notation in cryptographic formulation

I'm currently reading this paper [PDF]. On page 4, I bumped into these notations : \text { Experiment } \operatorname{Exp}_{\mathcal{F} \mathcal{E}, A}^{\text {ind-mode }}(k) \text { :...
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### Understanding this notation for the probability distribution of order preserving encryption

I'm reading this PDF: https://link.springer.com/content/pdf/10.1007/978-3-642-01001-9_13.pdf about order preserving encryption functions and there's this on page 9 (or 232): It's describing the ...
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### For a given security parameter $\kappa$. what does $poly(\kappa)$ mean?

Let ($Gen,Enc,Dec$) be an LHE scheme with security parameter $\kappa$ and message space $M$. Assume that a multiplication operation exists in $M$, i.e., is a finite ring. Let $F : \{0, 1\}^s × L → M$ ...
1 vote
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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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### RIBE Scheme Implementation - How to encrypt message

This question is regarding "A Fully Secure Revocable ID-Based Encryption in the Standard Model" - Tung-Tso TSAI, Yuh-Min TSENG, Tsu-Yang WU The encryption method specifies part of the encryption ...
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### Why is the BSI not using powers of two?

In their Technical Guideline TR-02102-2 Cryptographic Mechanisms: Recommendations and Key Lengths the BSI is giving minimal key lengths for - e.g. the TLS handshake protocol. All of these are not ...
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### How did || come to be used in crypto texts to represent concatenation?

In RFC5647, NIST SP 800-38D, etc., || is used to denote concatenation. How did that come to be? In most programming languages || ...
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### Why do crypto tools display key components in such an unusual format?

openssl x509 (v1.0.1f) displays public key moduli as arrays of hex-encoded bytes, 15 columns wide, starting with a leading 00:: ...
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### Encoding vs. Compression vs. Encryption

In what ways does encryption differ from proprietary/secret compression schemes and codecs?
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### What is the difference between =, ←, and := in crypto? [closed]

I have seen all of the following notations used to denote the encryption of a message $m$ with the key $k$ to produce the ciphertext $c$: $c = E(k,m)$ $c \leftarrow E(k,m)$ $c := E(k,m)$ Is there ...
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I know that the message space is the set of all possible messages, but I'm not sure how to generally define it, rather than for a specific cipher. For example, I've seen $$\{\forall c \in A\}$$, where ...
I have been watching a crypto course and when they wanted to prove that the OTP is a secure cipher they refer to the probability and what I can't get so far is the understanding of this notation ? ...