Cryptography
Key pairs

Key pairs

The Sui TypeScript SDK provides Keypair classes that handle logic for signing and verification using the cryptographic key pairs associated with a Sui address.

The Sui TypeScript SDK supports three signing schemes:

Sign schemeClass nameImport folder
Ed25519Ed25519Keypair@mysten/sui.js/keypairs/ed25519
ECDSA Secp256k1Secp256k1Keypair@mysten/sui.js/keypairs/secp256k1
ECDSA Secp256r1Secp256r1Keypair@mysten/sui.js/keypairs/secp256r1

For information on these schemes, see the Sui Wallet Specifications (opens in a new tab) topic.

To use, import the key pair class your project uses from the @mysten/sui.js/keypairs folder. For example, to use the Ed25519 scheme, import the Ed25519Keypair class from @mysten/sui.js/keypairs/ed25519.

import { Ed25519Keypair } from '@mysten/sui.js/keypairs/ed25519';

To create a random key pair (which identifies a Sui address), instantiate a new Keypair class. To reference a key pair from an existing secret key, pass the secret to the fromSecretKey function.

// random Keypair
const keypair = new Ed25519Keypair();
// Keypair from an existing secret key (Uint8Array)
const keypair = Ed25519Keypair.fromSecretKey(secretKey);

With your key pair created, you can reference it when performing actions on the network. For example, you can use it to sign transactions, like the following code that creates and signs a personal message using the public key from the key pair created in the previous code:

const publicKey = keypair.getPublicKey();
const message = new TextEncoder().encode('hello world');
 
const { signature } = await keypair.signPersonalMessage(message);
const isValid = await publicKey.verifyPersonalMessage(message, signature);

Public keys

Each Keypair has an associated PublicKey class. You use the public key to verify signatures or to retrieve its associated Sui address. You can access a Keypair from its PublicKey or construct it from the bytes (as a Uint8Array) of the PublicKey, as in the following code:

import { Ed25519Keypair, Ed25519PublicKey } from '@mysten/sui.js/keypairs/ed25519';
 
const keypair = new Ed25519Keypair();
const bytes = keypair.getPublicKey().toBytes();
 
const publicKey = new Ed25519PublicKey(bytes);
 
const address = publicKey.toSuiAddress();

Verifying signatures without a key pair

When you have an existing public key, you can use it to verify a signature. Verification ensures the signature is valid for the provided message and is signed with the appropriate secret key.

The following code creates a key pair in the Ed25519 scheme, creates and signs a message with it, then verifies the message to retrieve the public key. The code then uses toSuiAddress() to check if the address associated with the public key matches the address that the key pair defines.

import { Ed25519Keypair } from '@mysten/sui.js/keypairs/ed25519';
import { verifyPersonalMessage } from '@mysten/sui.js/verify';
 
const keypair = new Ed25519Keypair();
const message = new TextEncoder().encode('hello world');
const { signature } = await keypair.signPersonalMessage(message);
 
const publicKey = await verifyPersonalMessage(message, signature);
 
if (publicKey.toSuiAddress() !== keypair.getPublicKey().toSuiAddress()) {
	throw new Error('Signature was valid, but was signed by a different key pair');
}

Verifying transaction blocks

Verifying transaction blocks is similar to signature verification, except you use verifyTransactionBlock:

import { Ed25519Keypair } from '@mysten/sui.js/keypairs/ed25519';
import { verifyTransactionBlock } from '@mysten/sui.js/verify';
// import SuiClient to create a network client and the getFullnodeUrl helper function
import { SuiClient, getFullnodeUrl } from '@mysten/sui.js/client';
 
// see Network Interactions with SuiClient for more info on creating clients
const client = new SuiClient({ url: getFullnodeUrl('testnet') });
const txb = new TransactionBlock();
// ... add some transactions...
const bytes = await txb.build({ client });
 
const keypair = new Ed25519Keypair();
const { signature } = await keypair.signTransactionBlock(bytes);
 
// if you have a public key, you can verify it
//   const isValid = await publicKey.verifyTransactionBlock(bytes, signature);
// or get the public key from the transaction block
const publicKey = await verifyTransactionBlock(bytes, signature);
 
if (publicKey.toSuiAddress() !== keypair.getPublicKey().toSuiAddress()) {
	throw new Error('Signature was valid, but was signed by a different keyPair');
}

Deriving a key pair from a mnemonic

The Sui TypeScript SDK supports deriving a key pair from a mnemonic phrase. This can be useful when building wallets or other tools that allow a user to import their private keys.

const exampleMnemonic = 'result crisp session latin ...';
 
const keyPair = Ed25519Keypair.deriveKeypair(exampleMnemonic);
Building OfflineMulti-Signature Transactions