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Questions tagged [coding-theory]

Coding theory studies the properties of codes and their fitness for specific applications, and typically involves the removal of redundancy and the detection and/or correction of errors in transmitted data.

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Why doesn't “Classic McEliece” need scrambling?

The original McEliece scheme uses two random matrices S and P to scramble the generator matrix and uses $\mathsf S·\mathsf G·\mathsf P$ as the public key. The Niederreiter variant also does about the ...
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0answers
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Ciphertext indistinguishability under a noisy channel w/ error correction

The objective is to broadcast information over a noisy digital channel (corruption rate of say, 10-20 %, where bits flip). Assume the broadcasting software is public and there is no possibility of ...
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construct parity check matrix from hamming code (3,4) [migrated]

So I have this question. let $${F_4} = \{0, 1 , x, x^2 | x^2 = x + 1 \}$$ Use Ham(3,4), with a parity-checkmatrix having columns in lexicographical order, to decode (a) 1111111 1111111 1111111; (...
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1answer
72 views

Reed Solomon secret sharing and as a one-time symmetric key?

Shamir's Secret Sharing is just a special case of Reed-Solomon where only one coefficient is used to store the secret instead of the entire polynomial. McEliece however, suggests that the latter can ...
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2answers
77 views

Hardness of LPN problem with small secret

The Learning Parity with Noise (LPN) assumption states that, for a fixed secret $s$ chosen uniformly from $\{0,1\}^n$, then the distribution that outputs $(a,a\cdot s+e)$, where $a$ is uniform in $\{0,...
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22 views

What are dual codes and the codewords denoted by these dual codes in terms of trace?

I am currently reading a research paper (linked below) that mentions "Consider only maps that vanish at 0, their short codes $C_f$ and their duals $C_f^\perp$. The duals can be written as $C_f^\perp = ...
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1answer
37 views

What is the link between the parity check matrix, double-error-correcting codes and APN permutations?

I am currently reading a research paper (linked below) which mentions that a map $f:V:=GF(2^{m}) \rightarrow V$ which vanishes at 0 is APN if it satisfies the condition that it is a binary code $C_{f}$...
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1answer
48 views

What does 2-flat mean when discussing APN permutations?

I am currently reading a research paper that uses the term 2-flat. However, I don't understand what this term means. For example, the paper mentions in its definition of APN that for all distinct $a$,...
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1answer
70 views

Unique decoding Radius in Reed Solomon Codes

In one of the coding theory books I read the unique decoding radius for Reed Solomon codes is $\frac{1-\rho}{2}$. Precisely, if the relative distance be less than these amount so the receiver is able ...
3
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2answers
92 views

Finding Nonlinear boolean functions

Let $\mathbb{F}_2=\{0,1\}$ be the field with two elements. I wonder if there is any known algorithm/construction that, given any $n\geq 1$, returns a boolean function $f:\mathbb{F}^n_2\rightarrow \...
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0answers
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Suggestion for proof of retrievability (via coding theory)

I want to build a fully open-source open-everything protocol/service for massively-distributed shared storage (P2P). I came up with a suggestion for a proof-of-retrievability scheme, but I would like ...
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Breaking soft McEliece with soft Stern

I am nearly new in Code-based cryptography and I am trying to understand the soft Stern attack in [GJMS17] which the authors used to break the soft McEliece cryptosystem [BSC16]. The description of ...
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2answers
92 views

Difference between $F_2^n$ and $\Bbb F_2^n$ for a field

I am confused between the notation $F_2^n$ and $\Bbb F_2^n$ for a field in regards to codes. I thought that $F_2^n$ and $\Bbb F_2^n$ were both fields composed by codes of length n and entries in mod ...
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0answers
74 views

Entropy of the union of two sources

I am given that $S_1=(S_1,P_1)$ and $S_2=(S_2,P_2)$ are sources, where $S_1=\{s_1,...,s_n\}$, $P_1(x_i)=p_i$ and $S_2=\{y_1,...,s_m\}$, $P_2(y_j)=q_j$. I have to find the entropy of $S_{\lambda}=(S_i ...
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1answer
157 views

Code families in McEliece cryptosytem

What are the families of codes frequently used in McEliece cryptosystem or its variants? I know that binary Goppa codes were used in the original system but many codes with efficient decoding ...
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1answer
62 views

Value of $t$ in Fuzzy Exractor

Is there a defined method to choose value of $t$ when using fuzzy extractor to reconcile two close secrets? I did try with multiple values ranging from 5 to close to half of the sequence. I ...
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1answer
121 views

Traitor tracing - codeword properties

Let $c ≥ 2$. A code $C ⊂ Q^n$ is a $c$-frameproof code if for any set $X ⊂ C$ with $|X| ≤ c$ we have desc$(X) ∩ C = X$. Thus the only codewords that a coalition of up to $c$ pirates is capable of ...
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1answer
74 views

Traitor tracing - determining a set of codewords

I am reading some notes and having trouble understanding the following example: Let $F$ be a finite set of size $q$, where $q ≥ 2$. Let $n$ be an integer, where $n ≥ 2$. For a subset $X ⊆ F^n$ of ...
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1answer
127 views

Need an example to write permutation in cycle notation [closed]

Actually, I don't quite understand the question. What does $a_{i,j}$ means? Is it the element in the matrix from row i and column j? Can anyone give me an example? Better use another matrix because I ...
5
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1answer
707 views

What does this notation stand for when describing a code?

This code has appeared in some online course material. I understand the $(5, 4, 3)$ refers to (length, num codewords, distance) but no explanation of the $Z_2^5$ notation is given: One $(5,4,3)$ ...
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2answers
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How to hash similar strings to the same hash value?

Suppose that $s_1$ and $s_2$ are two stings that have a small hamming distance. Is there a preimage resistant "hash" function ($H$) that can map them to the same value i.e., $H(s_1) = H(s_2)$?
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0answers
76 views

Words having weight near to minimum distance

I am studying the NP-Problem of the codes Syndrome Decoding. The formulation is show below. Input: a binary matrix $H$ of dimension $r \times n$ and a bit string $S$ of length $r$. Property: there ...
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238 views

Convolution and catastrophic codes

i'm reading the article of Massey and Sain (here) and i cannot unserstand - what is "foreforward inversion"? I mean There is a description of circles in convolutional codes and a little bit ...
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1answer
296 views

Implementing the Mceliece Encryption - making the Generator Matrix

I am working on an implementation of the Mceliece Encryption system (MCE) and the Niederreiter encryption system. I have been through the basics of finite fields, polynomial arithmetic and some coding ...
3
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1answer
72 views

Question about block erasure codes

I have a question about linear block erasure codes that are described in this paper. I briefly describe the idea behind the linear erasure codes and then I ask my question. Given a set $d=\langle x_i ...
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3answers
231 views

About using mistakes as part of a code

Could a code be developed where one uses intentional errors say in english, as a text to encode? For example someone might have a message 'Agent X must report to station 5'. This could be distorted ...
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2answers
1k views

Does there exist a proof-of-retrievability scheme that is publicly-verifiable, limited-use, and does not use homomorphic encryption?

I find myself wanting to test out a practical implementation of a proof-of-retrievability scheme, simply out of curiosity. These schemes seem to be divided into two variations, publicly-verified and ...
7
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3answers
3k views

RS Erasure Coding and Shamir's Secret Sharing

So I was trying to understand the basic difference between erasure coding and secret sharing, and I found this paper (that you can find here or here). For what I understand, it states that Shamir's ...
3
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3answers
392 views

Where can I find useful data for cryptography/coding theory?

When implementing cryptographic/coding theory algorithms one need to use data like big prime numbers, numbers in $Z_n$ and their inverses, irreducible polynomials in $Z_n[x]$ and so on... While ...
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1answer
342 views

Hermitian curves introductory references

Could you give me some reference to start on Hermitian Curves. Some papers or textbooks would be perfect, and please mention if it's math inclined or comp.sci. inclined. I've only seen hermitian ...
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7answers
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Current mathematics theory used in cryptography/coding theory

What are the mainstream techniques borrowed from algebraic geometry (or some other branch of mathematics) which are currently used in cryptography/coding theory? I've only heard about a small subset ...