Product security and crypto lead at Google. Việt kiều yêu nước mắm.
Sep 13, 2021 • 9 tweets • 3 min read
Just in case you never saw RSA and didn't understand @0xfatty's fun discovery, here's some background.
A thread.
RSA is a famous cryptosystem invented in the 1970s, and still widely deployed. Its inventors won the Turing Award, computer science's equivalent of the Nobel Prize.
When used properly*, RSA allows humans and machines to digitally sign document to prove authenticity. Given a document and its RSA signature, anyone can verify that the document has not been modified. This is one of the most wonderful inventions of the 20th century.
Aug 31, 2021 • 11 tweets • 3 min read
A friend asked why they haven't seen much international news about the COVID outbreak in Vietnam. Honestly I don't know exactly why, but here's what I know.
Please spread the word. The world needs to know this.
My family has lost 3 members. My aunt died 3 days ago, her husband and another aunt's husband 2-3 weeks ago.
My dad and my uncle are hospitalized. My uncle is in bad shape, thanks God my dad has started recovering.
So far I've lost 8 people whom I'd known my whole life.
Aug 8, 2020 • 5 tweets • 3 min read
I reversed the Vietnam's contact tracing app, and found that it can silently upload all contact history to a centralized server, despite claiming that it only stores data on the client.
Somebody then said I was wrong and challenged me to provide evidences.
Well, challenge accepted and achieved! github.com/thaidn/bluezone
I now know much more than I ever wanted to about React Native and how to merge split APKs =)
Oct 2, 2019 • 8 tweets • 2 min read
How this works (from memory)
Problem:
-Client has a single pair of (username, password) that it wants to check if it was leaked.
-Server has a huge database of leaked (username, password).
Security/privacy requirements:
- Server cannot learn the client's password
- Server cannot distinguish between the client's username and k-1 others, i.e., k-anonymity
Jul 30, 2019 • 13 tweets • 2 min read
Kepler: so, you see, orbit of a planet is elliptical. To find where the Earth is, we need a method to calculate the arc length of the ellipse
Fermat: I have discovered such a marvelous method which this tweet is too narrow to contain
Newton: This is a fluent problem, and, as usual, it can be solved with an infinite series expansion
Leibniz: Pardon monsieur, what's a fluent? Arc length is an integral problem, and to calculate ∫f(x)dx first you need to find a closed form function such that F'(x) = f(x)
