Digital signatures allow us to verify that a piece of data has been unmodified and was produced by a certain entity. They are especially useful in the context of zero-knowledge proofs, where they enable a party with access to the signature and its underlying data to prove properties about the data without revealing the data itself.
To aid the development of zero-knowledge applications and the adoption of digital signatures as a whole, here is a list of types of data in the world that come with digital signatures, along with projects that generate zero-knowledge proofs about them.
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- Email (DKIM signatures)
- Passports (150+ countries have biometric/e-passports)
- [PROJECT] Proof of Passport
- EU Residence Cards for foreign nationals
- eIDAS (future electronic id cards for EU citizens)
- Credit Card Transactions (EMV cryptograms)
- [PROJECT] GOAT RAMP
- HTTPS/TLS (signatures are only used during the key-exchange handshake, to prove authenticity of sessions a workaround is needed)
- [PROJECT] TLS Notary (Performs an MPC with a 3rd party notary)
- [PROJECT] Reclaim Protocol (A 3rd party provides an attesting signature)
- Git commits
- Ethereum Attestation Service (EAS), including Coinbase onchain verification and Gitcoin Passport
- Proof of Humanity
- PDFs (some PDFs e.g. Docusign are digitally signed by certificate authorities)
- [PROJECT] zkCert
- India's Aadhaar
- [PROJECT] Anon aadhaar
- Japan's My Number Cards
- [PROJECT] Myna Wallet
- Taiwan DID
- [PROJECT] tw-did
- Ethereum transactions and state
- [PROJECT] Axiom
- Poaps
- Semaphore identities