When Julius Caesar sent letters to his generals, he moved every letter three places right so that his message looked like gibberish to an untrained eye.

That’s encryption - the act of turning a message into a secret.

Ciphertext is the intermediate gibberish, and decryption turns that gibberish back into a message.

Today’s cryptography is way more advanced than Caesar’s. We use tons of fancy math every day to encrypt our passwords, medical records, bank account info, etc. That’s what the “s” in https:// stands for...

🔒 Secure.

If you go one level deeper, you’ll find that there are a few types of math for keeping secrets:

1. Symmetric 🔑

2. Asymmetric 🔑🔑

3. Hashes ❌

🔑 Symmetric secret-keeping uses a single key to encrypt and decrypt. It’s fast and simple and the clear choice if you know exactly who you want to share your secret with.

🔑🔑 Asymmetric secret-keeping uses two keys. You need both to encrypt and decrypt, so it’s great if you don’t know who you want to share your secret with ahead of time.

❌ Hashes are wild because they don’t use a key. The math takes your message and spits out some ciphertext that nobody can decrypt, which is exactly what you want if you’re storing your secret somewhere.

For a while, the only people who really cared about cryptography were a handful of mathematicians and computer programmers. That changed in 2008 when a cryptographer named Satoshi used 🔑🔑 and ❌ to create a computer program that gave rise to an entire economy we now call “crypto.”

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🦉 who: @SpruceID (Founder & CEO: Wayne Chang)

✌️ why: protect individual privacy

🛠 how: let people control their data across the web, giving them power over where it is stored and who can access it

🎁 what: tools that make it easy for websites to create, integrate, and verify data governed by transparent code on blockchains

⏳ since: 2020

🤝 with: @ycombinator

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✌️ why: protect the world’s freedom

🛠 how: get more people using Ethereum, the world’s second most valuable blockchain (as of writing)

🎁 what: zkSync - math that securely consolidates, compresses, and records data to Ethereum, bringing down the cost of using the network

⏳ since: 2018

🤝 with: @a16z

jobs

✌️ why: improve the internet,

⚙️ how: a marketplace for storing computer files that exists outside the control of governments and big tech companies,

🛠 what: a file storage system (called IPFS) that makes computer files publicly accessible and a cryptocurrency (called Filecoin) that people pay to store their files on another person’s computer,

⏳ since: 2014,

🤝 with: @ycombinator,

🧑‍💻 jobs: click here

who: @ElectricCoinCo (Co-Founder & CEO: @zooko),

why: grow economic freedom,

how: allow people to exchange money privately, free from corporate bank surveillance and risk of government censorship,

what: a privacy-preserving payments network for 21 million digital coins (called zCash) accessible to anyone on Earth,

since: 2015,

with: @inflectionxyz,

jobs: click here

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who: @DuneAnalytics (Co-Founder & CEO: @hagaetc),

why: make blockchains easier to understand,

how: transform the raw public data that blockchains generate into structured, human-readable tables,

what: tools that data analysts can use to visualize blockchain activity, and tools for sharing these charts/graphs on the internet,

since: 2018,

with: @multicoincap,

jobs: click here

}

who: @MosDotCom (Founder & CEO: @Mira404),

why: help Gen Z pay for college,

how: connecting students with banking services, money-making opportunities, and personal financial advice,

what: a mobile app with checking accounts, micro-loans, scholarships, part-time jobs, cash-back deals, and online financial advisors,

since: 2017,

with: @sequoia,

jobs: click here

}

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who: @Dyno_Tx (Co-Founder & CEO: @ekelsic),

why: stop genetic diseases,

how: an artificial intelligence that guides scientific experimentation by predicting the therapeutic success of gene therapies,

what: gene vectors - sequences of DNA that doctors attach to a virus to infect your cells and fix a malfunctioning gene,

since: 2018,

with: @a16z,

jobs: click here

}

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who: @Replit (Founder: @Amasad)

why: bring the next 1 billion software developers online

how: make it easy to write, run, and share code written in any programming language

what: a collaborative workstation for software developers built directly into web browsers

since: 2016

with: @a16z

jobs: click here

}

who: @BayesianHealth (Founder: @SuchiSaria)

why: save lives and reduce cost in healthcare

how: provide better signals about patient health, helping medical professionals catch life-threatening complications sooner

what: artificial intelligence that monitors patient vitals, predicts worsening conditions, and alerts the right people at the right time

since: 2016

with: @a16z

jobs: click here

}

handle: @MakerDAO

why: offer economic freedom and opportunity to anyone, anywhere

creating: a decentralized, collateral-backed cryptocurrency, algorithmically-pegged to the US dollar

how: the Maker Protocol, autonomous code on Ethereum that issues $1 tokens in exchange for assets that are held as collateral

what: $DAI, the token soft-pegged to the US dollar, $MKR, the token that governs upgrades to the Maker Protocol, and Dai.js, the software library built to simplify adoption

who: @RuneKek + $MKR token holders

since: 2014

with: @a16z

}