# Just Facts

DANG Fan‘s Blog

## How to compute $$R^2\mod N$$?

### Using Montgomery modular multiplication

In order to use Montgomery modular multiplication, we need to know (R^2\mod N). If we already have Montgomery multiplication in hand, can we avoid brute-force calculation?

## Ed25519 & X25519

### Algorithms with 25519

Ed25519 is often used in SSH, then what does this number mean? Is there any other algorithms related to 25519?

## Debug MIPI DSI of RK3399

RK3399 is the most recent hign-end SoC of Rockchip. Its previous generation RK3288 is widely used in various places. For example, ASUS C100PA Chromebook Flip uses the RK3288. As an upgraded model, RK3399 has a six-core CPU consisting of two A72 cores and four A53 cores, and the GPU has been upgraded to the Mali-T860.

## The New Domain is Online

The new .fan TLD is launched on December 12, 2018. Then I got this domain: dang.fan.

## Recommend Two Services

### FastMail & LastPass

Some time ago, I migrated all my email services to FastMail. At the same time, the password management is also switched to LastPass. This article will introduce the motivation.