How public-key cryptography works
The two keys are generated together. Deriving the public key from the private one is quick, and going the other way is not feasible with today's computers: the security of every scheme rests on that one-way step. The pair serves three purposes:
- Digital signatures: the private key signs, and anyone verifies with the public key
- Encryption: anyone encrypts with the public key, and only the private key decrypts
- Key agreement: two parties derive a shared secret over an open channel
Public-key cryptography in blockchains
Blockchains use the first purpose. A transaction is valid because it carries a signature that matches the public key behind the sending address, and nothing is encrypted: the ledger is public.
Tron's developer documentation states that Tron signs with ECDSA over the secp256k1 curve, the same elliptic curve as Bitcoin and Ethereum.
Where a fintech product meets public-key cryptography
Well beyond crypto wallets: TLS on every API call, passkeys, chip cards, signed webhooks and app attestation all rest on key pairs.
For a product team the practical questions are where each private key is generated, where it lives (a secure element, a hardware security module or a set of MPC shares) and how it is rotated or recovered. A key pair proves control of a key, not the identity of a person, which is why identity checks sit alongside it.
Public-key or symmetric cryptography?
- Symmetric cryptography
- One shared key both encrypts and decrypts. It is faster and used for bulk data, but both sides must already hold the key.
- Hashing
- A one-way fingerprint of data, made with no key at all. A signature is usually made over a hash of the message.
Where Public-key cryptography shows up in a platform
Modules that do the work
- Custody & walletsWallets on every major chain, with MPC custody from leading providers or your own keys.
- AuthenticationSign-in, passkeys and second factors for customers and staff, on your identity provider or ours.
Platforms that need it
Where it is written
The laws and standards this page's facts come from.
General information, not legal advice: what applies to you depends on your services and your market.