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1 answer

A balls and urns model for a hashing problem

Fix $N \in \mathbb{N}$. Suppose we throw $N$ numbered balls into $N$ numbered urns, so that for each $b \in \{1,\ldots,N\}$, ball $b$ lands in urn $j$ with equal probability $1/N$. Choose a number $c ...

1 answer

One-one correspondance complete function

I am reading the paper by John B. Kam and Georges I. Davida (1979) titled Structured Design of Substitution-Permutation Encryption Networks. On page 749 it reads the following: Definition: Given a ...

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How is $P = P_{ext}$ derived, for reversible processes?

I know that for a reversible process the inexact differential of $Q$ must be equal to $TdS$ because the total entropy of the universe must remain constant. Is there a way to formally derive that the ...

2 answers

Is Chaocipher a secure cipher under ciphertext-only attack?

Chaocipher was invented by John F. Byrne in 1919. The algorithm was recently revealed – see Moshe Rubin's Chaocipher Revealed, the Algorithm (PDF). While a known plaintext attack successfully finds ...

1 answer

Recombination thresholds in degree reduction of multiplied Shamir shares

Shamir's secret sharing can be considered multiplicatively homomorphic, if one is aware of the fact that multiplying two shares of a (n,t)-threshold shared secret yields a share of the same secret, ...

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What is the advantage of using the social millionaire protocol to authenticate vs HMACing some random number?

Say Alice and Bob have a shared secret $s$. Alice and Bob establish an encrypted channel and verify that it hasn't been MitM'ed by exchanging $r_1$ and $r_2$ where $r_1$ and $r_2$ are randomly ...

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Blowfish encryption and decryption across c sockets

I'm using the following implementation of blowfish (with some stuff cut out of the middle) to encrypt and decrypt messages. I am attempting to encrypt a message on a big endian machine (SunOS 5.10), ...

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PumpMessages in crypto++, reading a key file?

I'm writing an AES key and iv to the file with crypto++ by using following code: // write the key: SecByteBlock key(AES::DEFAULT_KEYLENGTH); SecByteBlock iv(AES::BLOCKSIZE); string file = ...

1 answers | 1 hour ago by codekiddy on Stack Overflow stackoverflow.com
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Does PKCS #7 (CMS) add assurance to an email if a CRL/OCSP response is included, then revoked?

Suppose I issue a signing certificate in January, and have a daily CRL issued (expires in 1 day) to verify the validity of that signature. Then sometime in July I need to revoke that certificate. My ...

2 answers

Power analysis and exponentiation by squaring

I am trying to understand how one can retrieve the secret exponent via a simple power analysis. Lets suppose that the exponentiation by squaring algorithm is implemented in its simplest form : ...

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Multinomial proxy variables: Bound on probability of their sums

Suppose $(X_1,X_2,..X_i,..,X_b)$ as multinomial vector of random variables with $N=\sum_{i=1}^b X_i$ and probabilities $p_i$ to parametrize the $X_i$. Let us take the following imagination to ...

3 answers

Difference between Future and Promise

What's the difference between future and promise? They both act like a placeholder for future results, but where is the main difference?

3 answers

128 bit 3DES Key and AES Key: what's the difference?

Apologies if this is really basic but I couldn't find the answer to this. I have heard some Info Sec colleagues talking about creating an AES key in preference to a DES or 3DES key but I don't know ...

3 answers | 2 hours ago by DST on Cryptography crypto.stackexchange.com
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How do I use MS-XCEP and MS-WSTEP in .NET or javascript to get a certificate from AD CS?

Active Directory Certificate Services offers a web service that implements MS-XCEP and MS-WSTEP for non-domain connected computers to submit a certificate request. This certificate can be used for ...

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CCM instead of key wrap

Is there any instance of NIST or other encryption standards using AES-CCM to encrypt/authenticate key data? I would like to use CCM over a keywrap function, but cannot find any precedent for this in ...

1 answer

Is it possible to encrypt an SQLite database when using offline data sync in Azure Mobile Services?

I have a WinRT app that saves an SQLite database using Azure Mobile Services. I followed the tutorial here: Using offline data in MobileServices I got the database working, but I was wondering if it ...

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Spring-MVC : Encryption/Decryption with user password

I am working on a Spring-MVC application which uses Hibernate as the ORM and PostgreSQL as the database, in which I am looking for on-the-fly encryption decryption solution, but only for 2 columns in ...

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creating digital signature in with rsa using public and private key c#

I'm currently working on implementing a Asymmetric encryption using RSA with a private key and public key. I trying to recreate the following commands below in order to save the digital signature to ...

2 answers

Post with many lines of display math takes up most of the Questions page

Loading the Questions page, my computer displayed this: Notice that a single question with many lines of display math is taking up most of the window. I actually thought I had accidentally clicked ...

2 answers | 4 hours ago by Strants on Mathematics Meta meta.math.stackexchange.com
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Entropy of loops in the PV plane

The change in entropy of the Carnot and reversible cycles is said to be 0. Several other loops are supposed to have a non-negative change in entropy. This presents 2 problems which I cannot ...

2 answers

Signing Files vs. Signing File Hashes

What are the security pitfalls that may occur by signing a list of file hashes, versus signing individual files? In short, the security trade-offs between: for file in $FILES; do gpg --clearsign ...

2 answers | 4 hours ago by Zach Riggle on Cryptography crypto.stackexchange.com
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Using C++11 futures: Nested calls of std::async crash: Compiler/Standard library bug?

After experiencing crashes when introducing nested calls of std::async in my real program, I was able to reproduce the problem in the following minimum example. It crashes often, but not always. Do ...

1 answer

Does a magnetic field decrease or increase entropy?

My question is just the title: Does a magnetic field decrease or increase the entropy of a system? For example if we apply a magnetic filed to a substance, is the entropy decreased or increased?

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How to encrypt small blob for specific AD user to decrypt on any domain machine?

We have an Active Directory domain, and some services than need to access small sensitive pieces of information (e. g., remote service credentials). We also have a Certificate Services running in the ...

1 answer

Is format preserving encryption suitable for use with words or names?

Is it possible to use FPE to encrypt names and language words like 'Bob' 'the' 'tree', in order to preserve both length and format (like keeping characters within a certain range like A-Z a-z) The ...

1 answer

Creating serial key generator using ECDSA, how to get signature short enough?

I've written some questions in this stackoverflow and got great responses but now I'm trying to wrap it all together. I have for the last couple of weeks been building a serial key generator project ...

1 answers | 6 hours ago by Johan O on Cryptography crypto.stackexchange.com
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How to choose the integer m in the general number field sieve (GNFS)?

Given an integer you want to factor $N$, GNFS starts by selecting a monic irreducible polynomial $f \in \mathbb{Z}[X]$ and an integer $m$ such that $f(m) \equiv 0 \text{ mod } N$. In practice, if $m$ ...

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TCP protocol instead of SSL/TLS in Wireshark

I am trying to use .NET implementation of SslStream by this tutorial. I did everything like in this article, but I have some question. I downloaded RawCap and captured packets from the localhost, ...

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Justice and Fairness: Part 2

A friend of yours was part of a secret society and was put on trial on 15 December 2014 without a lawyer. Alice encrypted the trial's transcript and sent it to Bob, but double agent Carol was able to ...

1 answer

Compile JSP classes - A workflow of errors between java and tomcat

I was doing a JSP webpage/app within eclipse. Since I had some problems with it, I wanted to change, so I backup my files (*.java and *.jsp) to another folder and forgot about eclipse. Builds in ...

1 answers | 7 hours ago by Btc Sources on Stack Overflow stackoverflow.com
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