## Composition of privacy mechanisms

This is the third post of my data privacy series. Please refer to the first post for the definition of differential privacy and the second post for privacy mechanism. Robustness of differential privacy versus processing If a mechanism is -differential private to begin with, then further operation on is still -differential private. Proof: Let’s assume…

## Privacy Mechanisms

This is the second post of my data privacy series. You may want to also check out this post for an introduction to data privacy and differential privacy. 🙂 For convenient, let’s repeat the definition of differential privacy from the previous post. Definition: -Differential Privacy The query is -differentially private if and only if for…

## Differential privacy

I need to work on a data privacy project and so am spending some time to review some notes I wrote couple years ago. I guess it would be a great exercise to reorganize them into a post series.  And this will be my first post of this series. 🙂 Introduction to data privacy From…

## Public key cryptography and RSA encryption algorithm

Let say if Alice would like to send a secret message to Bob, she may want to first encrypt the message before sending it. Modern cryptographic techniques all use some secret keys to encrypt and decrypt a message. For example, we may generate a random sequence with a predefined seed (the key) and take the…

## Lagrange’s theorem, Euler’s theorem, Fermat’s little theorem, and a short introduction to groups

A group in the context of math is a simple algebraic structure with a product operation . Naturally, the operator won’t be of much use if the structure is not closed under the operation. Namely, we would like to have also in if both elements and   are in . Moreover, we would like to…

## Change resolution with terminal (Ubuntu 16.04 and Thinkpad x230)

Getting nostalgia and suddenly would like to play a round of old StarCraft. I have upgraded to 16.04 since last year and couldn’t set resolution to 640×480 from Displays setting. But simply using xrandr -s actually works: xrandr -s 640×480 I can then recalibrate the stylus with the usual Wacom Tablet setting.  🙂

## SageMath

Trained as an electrical engineer, I am most comfortable with Matlab in terms of serving my math need. However, for symbolic math problems, Matlab is not as intuitive as Mathematica (of course, we can still do it though. Check out “syms”). But I never get used to the syntax of Mathematica. And I found the…

## Install Ubuntu to Nvidia laptop

I tried to install Ubuntu 18.04 to MSI  GS43VR 7RE laptop. It is a laptop with GTX 1060 gpu. I kind of expected hiccups with installation. Actually, I couldn’t even get Ubuntu to start with plain installation. The culprit is NVidia driver as expected. Adding “nomodeset” to boot option fixed the problem.  One may also…

## Install Gogs on 16.04

My goal is trying to setup a git server along side with one of my existing sites. Say my site has a domain name example.com. I want to setup a git server at https://git.example.com.  I chose Gogs as it is quite light-weight and it appears to be sufficient for me. For security purpose, I tried…

## Reinstalling ubuntu packages

I lost my mariadb root password and the recovery process does not work after many tries. Since I was not actually using any databases on that machine. I decided to simply reinstall MySQL server. But just running sudo apt purge mysql* didn’t clean up everything. I still got configuration errors when I try to reinstall…