# Questions tagged [mceliece]

McEliece cryptosystem is an asymmetric encryption algorithm and is a candidate for "post-quantum cryptography", as it is immune to attacks using Shor's algorithm and — more generally — measuring coset states using Fourier sampling.

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### What is $z$ in specification of Classic Mceliece?

I have a question about $z$ in Classic Mceliece Algorithm specification. I have no idea about this $z$! In parameter set kem/mceliece348864, Field polynomial $f(z) = z^{12} + z^3 + 1$. is this $z$ in ...
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### How can I change the McEliece main parameters?

I use the Bouncy Castle Crypto API to implement McEliece in Java. I have also managed to encrypt and decrypt a message and it works without any problems. When I use the debugger, I see that the ...
1 vote
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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 ...
1 vote
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### McEliece cryptosystem

There is something intriguing me about this cryptosystem. That is : Let $(S, G, P)$ be the secret key: $S$ : invertible matrix $G$ : generator matrix for some linear code $C$ $P$ : permutation ...
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### Why has the McEliece cryptosystem not gained much acceptance, but now is a candidate for post-quantum cryptography?

I understand that the McEliece cryptosystem is an asymmetric encryption algorithm developed in 1978 by Robert McEliece, almost around the same time RSA came about. Why has the McEliece cryptosystem ...
1 vote
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### Why in the Rao-Nam private key version of McEliece scheme, P matrix is multiplied after adding error vector?

The private key version of McEliece known as Rao-Nam scheme, the encryption is done as c = (mSG + e)P. What is the need for applying permutation matrix on the error vector?
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### How can we prove that the scrambled G matrix in McEliece cryptosystem preserves the minimum distance properties of G matrix?

In McEliece cryptosystem, G matrix is scrambled using S and P so that scrambled G matrix is G' = SGP. Here G is the generator matrix of a linear code and after scrambling it is converted into another ...
1 vote
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### Can the McEliece cryptosystem be used as an additively homomorphic encryption scheme?

Since the McEliece cryptosystem is linear, if matrix G is kept constant for different plaintexts, it can be used for linearly combining the corresponding ciphertexts. In that case, what are the ...
1 vote
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### 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 ...
1 vote
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### McEliece parameter tuple (n, k, t) through BouncyCastles (m, t, poly) [closed]

I am using BouncyCastles Java API and want to use McEliece encryption. After browsing through various paper for finding good parameters (e.g. How to choose McEliece's parameters?) I am now having the ...
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### What are the properties of error vector used in symmetric McEliece cryptosystem?

In the symmetric version of McEliece cryptosystem, we are adding intentional error vector during encryption. During decryption, first, we cancel the effect of error vector and then multiply the ...
1 vote
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### key size of public key in McEliece

The length of public-key matrix in McEliece cryptosystem is $n \times k$. Then the key size is $\frac{n \times k}{8}$ bytes. But I find that the key size is $\frac{(n-k) \times k}{8}$ bytes. why ?
1 vote
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### McEliece variants that support signatures

Besides the Niederreiter cryptosystem, are there any other variants that support digital signatures? Can any of them sign arbitrary signatures unlike the Niederreiter cryptosystem? What are the key ...
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### How is McEliece chosen plaintext secure?

Suppose a challenger creates a McEliece encryption system where there is a public key consisting of a matrix $G$ representing some linear code, and a number $t$ for the number of errors. Then the ...
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### Efficiency of McEliece cryptography (ciphertext expansion)

Most of the sources say McEliece has never gained acceptance because of its large size of private and public keys. However I have never heard about the size (or length) of its ciphertext. ("...
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### How to choose McEliece's parameters?

At the time of this writing, there are 3 sources for parameters for the McEliece public-key cryptosystem out there. The first paper is the original McEliece paper ("A Public-Key Cryptosystem based on ...
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### 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 ...
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### McEliece and cryptanalysis

What is the computational time to break McEliece on a quantum computer? I've seen that polynomial time algorithms exist, but for special conditions. What about the general case?
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### Basic attacks on McEliece; finding S and P

Take a McEliece cryptosystem with public generator matrix $G' = S G P$ where $G$ is a generator of a secret code with known fast decoding (not necessarily a Goppa code over $\mathbb{F}_2$), $S$ is ...
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### McEliece information set decoding attack vulnerability

Wikipedia states that McEliece is open to "information set decoding attack". What is an "information set decoding attack" and how serious is the vulnerability? (is it just a matter of choosing proper ...
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### McEliece key size

There's a lot of references about McEliece key size being the barrier for proper usage of the algorithm, exactly (or roughly) how large are the keys?
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### Is the Couvreur et al. polynomial time attack on McEliece practical?

There's a new e-print out on arXiv titled "A Polynomial Time Attack against Algebraic Geometry Code Based Public Key Cryptosystems" by Alain Couvreur, Irene Márquez-Corbella and Ruud Pellikaan: "We ...
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### What is the impact of the Goppa code distinguisher on the CFS and McEliece?

What is the impact of the distinguisher for the high-rate Goppa codes (as published in "A Distinguisher for High Rate McEliece Cryptosystems") on the CFS signature scheme and the McEliece/Niederreiter ...
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### McEliece Public Key Encryption

The definition of Public Key Encryption(PKE) say that: A PKE scheme is a triple of probabilistic polynomial time algorithm (PPT) (Gen,Enc,Dec). The definition of PPT say: In complexity theory, ...
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### Is there any restriction in using lossless compression algorithms for huge key sizes?

I'm studying McEliece and Multivariate Public Key cryptographic systems. The main problem here is the huge key size. Is there any restriction in using lossless compression algorithms to fix this ...
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### Sematically Secure McEliece

I am read the Lemma 2 (pp13) in the paper "Kazukuni Kobara and Hideki Imai: Semantically Secure McEliece Public-Key Cryptosystems –Conversions for McEliece PKC– (PKC 2001)". Related to the question "...
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### PKC McEliece + $S$ + $P$ [closed]

I am trying implement the McEliece crytosystem in SAGE. My question is How I will be able to choose the appropriate matrix $S$ and $P$?. I ask this because when I trying obtain the vector $\hat{m}=mS$ ...
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### Efficient decoding of irreducible binary Goppa codes and the role of matrix P in McEliece cryptosystem

If we assume that the support for an irreducible binary Goppa code $\gamma_1, ..., \gamma_n$ is publicly known, when is it possible to efficiently decode the code? I know it's possible if one knows ... 