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Nombre de programmes trouvés : 15057
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le (4m55s)

2.8. Reducing the Key Size - MDPC codes

This is the last session where we will talk about reducing the key size. Here we will introduce the MDPC codes.In 2012, the MDPC codes were proposed for the McEliece schemes. An MDPC code is a code that admits a binary moderate density-parity check matrix. Typically, the Hamming weight of each row is of the order the square of the length. In this sequence, I will describe this scheme of quasi-cyclic MDPC McEliece for a binary code of rate one half. So, we use circulant matrices of blocks of size p ...
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le (3m59s)

2.9. Implementation

This is the last session of the second week. The cryptography community has different options for using public key cryptosystems, among others, they have RSA or DSA. But … McEliece has the same level of performance of the current protocol? eBATS is a competition to identify the most efficient public key cryptosystem. They mesure among other criteria: the key size, the time of the key generation algorithm, the encryption algorithm, and the decryption algorithm. The eBATS benchmarking includes seven public key encryption schemes. A McEliece implementation, from Biswas and Sendrier, ...
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le (3m58s)

3.1. From Generic Decoding to Syndrome Decoding

Welcome to the third week of the MOOC on code-based cryptography. This week, we will learn about message attacks. Among the ten sessions of this week, the first six will present the most essential part of generic decoding and the last four will be devoted to more advanced matters. The first session is about generic decoding; a   presentation of what a message attack and what generic decoding is about. A cryptogram in the McEliece encryption scheme has the following form. A cryptogram is composed by multiplying a message by a public ...
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le (4m13s)

[Live] Finding Methods with Finder

J’aimerais vous montrer comment on utilise le Finder pour trouver de l'information. Donc le Finder c'est un outil que vous allez trouver dans le menu Tools, donc Finder. Imaginons que je veuille chercher maintenant une méthode qui s'appelle match. Je tape son nom, match.  Et là, je choisis Selectors.  Donc maintenant là, je vois toutes les méthodes qui contiennent le mot match avec le code ici. Donc comme j'avais mis les fontes en très gros, on va essayer de retailler un petit peu. Donc maintenant vous voyez que quand il y a un petit triangle devant, ça veut dire que ...
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le (5m17s)

3.2. Combinatorial Solutions: Exhaustive Search and Birthday Decoding

In this session, I will detail two combinatorial solutions to the decoding problem. The first one is the Exhaustive Search. To find our w columns, we will simply enumerate all the tuples j1 to jw and check whether the corresponding column plus the syndrome is equal to zero modulo 2. In detail here is how we will do. We have w loops enumerating the indices from j1 to jw, and in the innermost loop, we add the w columns plus the syndrome and either we test the value of the syndrome or ...
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le (3m12s)

3.3. Information Set Decoding: the Power of Linear Algebra

In this third session, we will present the most important concept of the week: Information Set Decoding. The problem of decoding is not only a combinatorial problem. Because we are dealing with linear code, we may also use Linear Algebra. In particular, we are able to transform the Computational Syndrome Decoding problem by multiplying the matrix by a permutation P on the right and a nonsingular matrix U on the left. This will transform the problem of syndrome decoding into an equivalent one. It is very easy to prove that the ...
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le (9m57s)

[Live] GTInspector 1: Inspect and Interact with Objects

Dans cette vidéo, je voudrais vous montrer l'inspecteur et comme on l'utilise. Qu'est-ce que l'inspecteur ? C'est un outil qui va nous permettre d'interagir avec n'importe quel objet du système. Comme Pharo, tout est écrit à base d'objets, vous allez pouvoir inspecter tous les objets qui composent Pharo. La métaphore la plus proche de ce qu'est un inspecteur, je dirais que c'est un microscope, mais un microscope qui aurait des possibilités d'interagir avec les objets qu'il est en train d'observer. C'est comme si vous étiez un biologiste avec des cellules ou une culture de bactéries et que tout d'un ...
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le (5m30s)

3.4. Complexity Analysis

In this session, I will present the main technique to make the analysis of the various algorithms presented in this course. So, Information Set Decoding refers to a family of algorithms which is similar to the Prange algorithm that we have just seen. All variants of Information Set Decoding repeat a large number of independent iterations which all have a constant cost K and a success probability P. This means that this iteration has to be repeated an expected number of times N where N = 1/P. And the total workfactor ...
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le (3m8s)

3.5. Lee and Brickell Algorithm

In this fifth session, we will study a variant of information set decoding proposed by Lee and Brickell. So, the main idea consists in relaxing the Prange algorithm to amortize the cost of the Gaussian elimination. So, instead of error patterns with all positions on the left, we will allow error patterns of the form given in the slide. So, in the left part we have w-p coordinate to 1 and on the right hand side we allow a small number p of positions to have a value 1. So, at each ...
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le (6m37s)

3.6. Stern/Dumer Algorithm

In this session, we will present the Stern algorithm for decoding. In fact, the idea is to combine two algorithms that we have seen before, the Lee and Brickell algorithm and the Birthday Decoding.  So, instead of a full Gaussian elimination, we will simply have a partial Gaussian elimination as presented here. And if we look at the lower part, what is called step 1, in red here in this slide, it is, in fact, a smaller CSD problem with a smaller matrix H', with a smaller target syndrome s' and with ...
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