Owning coins on a blockchain means controlling a key. This guide explains the handful of terms behind that — private key, public key, address and wallet — and what QRL does differently.
The chain of derivation
These four things form a one-way chain, each derived from the one before:
private key → public key → address
(secret) (shareable) (shareable, short)
- Private key — the secret. Whoever has it can sign transactions and move the funds. Guard it like cash.
- Public key — mathematically derived from the private key. It can be shared, and it's what the network uses to verify your signatures.
- Address — a short, hashed form of the public key that you give to others to receive funds. On QRL, addresses start with
Q. - Wallet — the software that stores your keys and assembles signed transactions. The wallet is not the money; the keys are.
The derivation only runs one way: you can compute the address from the key, never the key from the address. (At least, not without breaking the underlying cryptography — which for ECDSA is exactly what a quantum computer could do, and what QRL is built to prevent.)
What QRL does differently
On most chains, the public key → address step uses ECDSA. QRL replaces the signature scheme with a quantum-resistant one:
- QRL Legacy uses XMSS, and its addresses are 79 characters.
- QRL 2.0 uses ML-DSA-87, and its addresses are 41 characters.
Both start with Q, so you tell them apart by length — see QRL address formats.
The one-time-key rule (QRL Legacy)
There's one extra wrinkle unique to QRL Legacy. Because XMSS is built from one-time signatures, the wallet must track which signing keys it has already used — the OTS index — and never reuse one. Good QRL Legacy wallets handle this for you, but it's why restoring an old backup needs care.
QRL 2.0's ML-DSA-87 is stateless: there's no index to track, and you can sign as often as you like with the same key.
Keeping keys safe
The golden rule never changes: whoever holds the private key holds the funds. There is no support line that can reverse a theft or recover a lost key. Back up your wallet's recovery material, store it offline, and treat it as the single most important thing to protect.
Where to go next
- QRL address formats — the 79- vs 41-character split.
- One-time signatures and OTS keys — the XMSS index rule.
- Reading an address page — what the explorer shows for an address.