Jaiden Zhao

What I’m aiming at

Security is the plan

Nothing online is as sealed as it looks. The part that grabs me is the gap — where a system’s rules stop matching what it actually does, and what somebody could walk through. I want to work on the side that closes those gaps: network and internet security, defending real systems for a living.

SHA-256 · running in your browser

 

Edit one letter and almost every digit flips. That’s the point — you can’t nudge a hash toward a value you want, so you either have the original or you don’t. It’s how a site can check your password without ever storing it.

How two people agree on a secret

Nobody ever sends the key

Here is the part that surprised me when I first understood it. Two people who have never met can end up holding the same secret number, while someone reading every single message between them cannot work out what it is. That is a key exchange, and it is what happens before your browser sends a password anywhere.

Me

Jaiden

Pick a number and don’t tell anyone. Not even them.

private a—
sends g^a mod p—
shared key—

The open channel

p = 23, g = 5
→ A
B ←
→ …
Them

A friend

Same here. We’ll still end up with the same key.

private b—
sends g^b mod p—
shared key—

Eve is reading everything

Everything above the dashed line: p, g, A, B, and the scrambled message. The two private numbers never crossed the channel, so the key was never there to steal.

These numbers are tiny so you can check the arithmetic by hand — with p = 23 anyone could just try all 22 possibilities. Real ones are hundreds of digits long, which is the only thing standing between the two columns and the person reading the wire.