Glossary
The words of crypto payments,
explained plainly.
61 terms fintech teams run into when they add digital assets: what each one means, why it matters when you're moving money, and how Valtu handles it.
9 terms
Wallets and custody
Blockchain addressA public identifier that can receive coins on a network, derived from a key pair; anyone can send to it, only the key holder can spend from it.
Cold storageKeeping keys on devices that are never connected to a network, so signing needs deliberate, physical steps; very hard to attack remotely, and slow to use.
Custodial walletA wallet whose keys are held by a provider on the user's behalf; the user moves funds through the provider's software and rules instead of holding keys themselves.
Hot walletA wallet whose keys can sign automatically while connected, so payouts go out without manual steps; fast, but its protection depends entirely on how signing is isolated and controlled.
Private keyThe secret number that authorises spending from an address; whoever holds it controls the funds, so where it lives and who can use it is the core question of custody.
Seed phraseA master secret, often written as 12 or 24 words, from which a wallet derives all its private keys; whoever has it can recreate every address and spend from them.
Self-custodyHolding your own private keys, so no third party can move or freeze your funds, and no third party can recover them for you either.
Treasury walletThe wallet where a business collects its own funds, typically filled by sweeps from customer addresses and protected by the strictest sending rules.
Wallet-as-a-serviceAn API and dashboard that give a business wallets, deposits, payouts and key management for many customers, without running its own nodes and key storage.
6 terms
Deposits and payouts
Batch payoutSubmitting many payouts in one request, as payroll, marketplace and affiliate platforms do, where each payment still has to succeed or fail cleanly on its own.
Deposit addressAn address assigned to one customer so that anything sent to it can be credited to that customer, with no memo or reference to get wrong.
Payment linkA hosted page that asks for one specific amount: the payer picks a coin and network, pays to a fresh address, and the merchant is told whether it was paid, underpaid or expired.
PayoutSending coins from a business's wallet to someone else's address, such as a customer withdrawal, a seller payment or a contractor's pay.
ReconciliationRegularly comparing your own ledger with the provider's and the chain's records, so a missed webhook or a failed job never leaves a balance wrong.
SweepMoving confirmed deposits from many customer addresses into one wallet the business controls, an internal move that doesn't change what the customer is owed.
18 terms
Networks and tokens
BEP-20The name for ERC-20-style tokens on BNB Chain; same interface and address format as Ethereum, with fees paid in BNB.
Block explorerA website that shows a network's blocks, transactions, addresses and token contracts, the usual way to look up a transaction by its hash.
Chain reorganizationWhen a network replaces its most recent blocks with a competing version, removing the transactions that were only in the replaced blocks.
ConfirmationsThe number of blocks added on top of the block containing a transaction; the deeper it is, the less likely it can be undone.
Contract addressThe address of a token's smart contract, its true identity; the name and symbol can be copied by anyone, the contract address can't.
ERC-20The standard interface for fungible tokens on Ethereum and other EVM networks; USDT, USDC, DAI and LINK on Ethereum are ERC-20 tokens.
EVMThe execution environment of Ethereum, also used by BNB Chain, Polygon, Base, Lisk and many others, so they share address formats, token standards and tooling.
FinalityThe point at which a transaction can no longer be reversed or replaced, the moment it's safe to credit a deposit or treat a payout as done.
Layer 2A network that processes transactions separately and posts their data to Ethereum, giving much lower fees while relying on Ethereum for security.
MempoolThe waiting area of broadcast transactions not yet included in a block; when it's crowded, transactions with low fees wait longest.
Smart contractA program stored on a blockchain that runs exactly as written when called; tokens such as USDT and USDC are smart contracts that keep a ledger of balances.
StablecoinA token designed to hold a steady value, usually one US dollar, which makes it practical for payments, payouts and holding balances.
TestnetA copy of a network where coins have no value, used to build and test integrations; mainnet is the real network where coins have value.
Token decimalsHow many decimal places a token uses; on-chain amounts are whole numbers of the smallest unit, so 1 USDT with 6 decimals is 1,000,000 units.
TRC-20The token standard on Tron, modelled on ERC-20; USDT on Tron is a TRC-20 token and one of the most used stablecoins for everyday payments.
USDCCircle's US-dollar stablecoin, issued natively on Ethereum, Base and other networks, and widely used by regulated businesses.
USDTTether's US-dollar stablecoin, issued separately on Tron, Ethereum, BNB Chain and other networks; the most widely used stablecoin.
Wrapped tokenA token on one network that represents a coin from somewhere else, such as WBTC for bitcoin on Ethereum; it's only as good as whoever holds the original.
10 terms
Network fees
DustAn amount so small that moving it would cost more in network fees than it's worth; dust is also sometimes sent deliberately to track or trick recipients.
GasThe unit of work on Ethereum and other EVM networks; a transaction's fee is the gas it uses times the price per unit, paid in the network's native coin.
Gas walletA wallet holding each network's native coin that tops up other wallets with exactly the fee they need, so wallets holding only tokens can still send.
Native coinA network's own coin, such as ETH, BNB, POL, TRX or BTC, the one its fees are paid in; tokens can't pay their own transfer fees.
Native SegWitThe Bitcoin address type starting with bc1q, which stores signature data more efficiently and so pays lower fees than older address types.
NonceOn EVM networks, a counter on each account that numbers its transactions in order; a transaction can't confirm until every lower number has.
Replace-by-feeResending an unconfirmed Bitcoin transaction with a higher fee, spending the same coins, so only one version can ever confirm and nobody is paid twice.
TRON bandwidthThe Tron resource that pays for a transaction's size in bytes; every account gets a small free daily allowance, and beyond it TRX is burned.
TRON energyThe resource Tron uses to pay for running smart contracts, so every TRC-20 transfer needs it; without energy, the network burns TRX instead.
UTXOBitcoin's model of money: a wallet holds separate unspent coins of different sizes, and each payment spends whole coins and sends the remainder back as change.
11 terms
Key security
Approval policyRules that decide, before anything is signed, whether a transfer goes straight out, waits for people to approve it, or is refused.
Enclave measurementA cryptographic hash of the code loaded into an enclave, reported in its attestation, so a single changed byte gives a different value.
Hardware enclaveAn isolated compute environment, enforced by hardware, that even the machine's own operators can't read or log in to, and that can prove which code it runs.
HSMA tamper-resistant device that stores keys and performs signing inside itself, so keys can be used without ever being exposed to the host computer.
Key ceremonyA scripted, witnessed procedure for creating master keys on offline hardware, so no single person or connected machine ever has the full secret.
MPC walletA wallet whose key exists only as separate shares on different machines, which cooperate to produce a signature without the full key ever being assembled.
MultisigA wallet that needs signatures from several separate keys, such as 2 of 3, before the network accepts a transaction.
PasskeyA sign-in and approval credential held on a person's own device, a key pair instead of a password, that can't be phished or reused on another site.
Remote attestationA document, signed by the hardware vendor, in which an enclave proves to anyone which exact code it's running and which public keys it holds.
Reproducible buildA build process that turns the same source into byte-for-byte identical output every time, so anyone can confirm a binary came from the published code.
Shamir secret sharingA way to split a secret into several shares so that a set number of them together rebuild it, while any fewer reveal nothing at all.
2 terms
Compliance and risk
Address poisoningA scam that plants look-alike addresses or fake tokens in a wallet's history, hoping someone copies the wrong address or mistakes a worthless token for a real one.
KYTScreening the addresses that money comes from and goes to against risk data, such as sanctions, mixers and stolen funds, before acting on a transaction.
5 terms
Building on the API
API request signingProving each API request comes from the key holder by signing its details with a timestamp and a one-time nonce, so a captured request can't be changed or replayed.
Ed25519A fast, modern public-key signature scheme; the signer holds a private key, and anyone with the public key can check a signature without being able to forge one.
HMACA message signature made with a shared secret; both sides compute it the same way, and a match proves the message came from someone who knows the secret.
IdempotencyDesigning a request so that sending it twice has the same effect as sending it once, which is what makes it safe to retry a payout after a timeout.
WebhookAn HTTP request a service sends to your server when something happens, such as a deposit confirming, so you don't have to keep asking.
A–Z
Every term.
Put it into practice.
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