Key pairs

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

The IOTA TypeScript SDK supports three signing schemes:

Sign scheme	Class name	Import folder
Ed25519	Ed25519Keypair	@iota/iota-sdk/keypairs/ed25519
ECDSA Secp256k1	Secp256k1Keypair	@iota/iota-sdk/keypairs/secp256k1
ECDSA Secp256r1	Secp256r1Keypair	@iota/iota-sdk/keypairs/secp256r1

For information on these schemes, see the Signatures topic.

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

import { Ed25519Keypair } from '@iota/iota-sdk/keypairs/ed25519';

To create a random key pair (which identifies a IOTA 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 IOTA 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 '@iota/iota-sdk/keypairs/ed25519';

const keypair = new Ed25519Keypair();

// method 1
const bytes = keypair.getPublicKey().toRawBytes();
const publicKey = new Ed25519PublicKey(bytes);
const address = publicKey.toIotaAddress();

// method 2
const address = keypair.getPublicKey().toIotaAddress();

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 toIotaAddress() to check if the address associated with the public key matches the address that the key pair defines.

import { Ed25519Keypair } from '@iota/iota-sdk/keypairs/ed25519';
import { verifyPersonalMessageSignature } from '@iota/iota-sdk/verify';

const keypair = new Ed25519Keypair();
const message = new TextEncoder().encode('hello world');
const { signature } = await keypair.signPersonalMessage(message);

const publicKey = await verifyPersonalMessageSignature(message, signature);

if (publicKey.toIotaAddress() !== keypair.getPublicKey().toIotaAddress()) {
    throw new Error('Signature was valid, but was signed by a different key pair');
}

Verifying transaction signatures

Verifying transaction signatures is similar to personal message signature verification, except you use verifyTransactionSignature:

// import IotaClient to create a network client and the getFullnodeUrl helper function
import { getFullnodeUrl, IotaClient } from '@iota/iota-sdk/client';
import { Ed25519Keypair } from '@iota/iota-sdk/keypairs/ed25519';
import { verifyTransactionSignature } from '@iota/iota-sdk/verify';

// see Network Interactions with IotaClient for more info on creating clients
const client = new IotaClient({ url: getFullnodeUrl('testnet') });
const tx = new Transaction();
// ... add some transactions...
const bytes = await tx.build({ client });

const keypair = new Ed25519Keypair();
const { signature } = await keypair.signTransaction(bytes);

// if you have a public key, you can verify it
//   const isValid = await publicKey.verifyTransaction(bytes, signature);
// or get the public key from the transaction
const publicKey = await verifyTransactionSignature(bytes, signature);

if (publicKey.toIotaAddress() !== keypair.getPublicKey().toIotaAddress()) {
    throw new Error('Signature was valid, but was signed by a different keyPair');
}

Verifying zkLogin signatures

ZkLogin signatures can't be verified purely on the client. When verifying a zkLogin signature, the SDK uses the GraphQL API to verify the signature. This will work for mainnet signatures without any additional configuration.

For testnet signatures, you will need to provide a testnet GraphQL Client:

import { IotaGraphQLClient } from '@iota/iota-sdk/graphql';
import { verifyPersonalMessageSignature } from '@iota/iota-sdk/verify';

const publicKey = await verifyPersonalMessageSignature(message, zkSignature, {
    client: new IotaGraphQLClient({
        url: 'https://graphql.testnet.iota.cafe',
    }),
});

Deriving a key pair from a mnemonic

The IOTA 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);

Deriving a Keypair from a Bech32 encoded secret key

You can derive a Keypair by converting the 33-byte secret key encoded in Bech32 string to a Uint8Array and passing it to the fromSecretKey method of a Keypair class.

import { decodeIotaPrivateKey, encodeIotaPrivateKey } from '@iota/iota-sdk/cryptography';
import { Ed25519Keypair } from '@iota/iota-sdk/keypairs/ed25519';

const encoded = encodeIotaPrivateKey(
    [
        59, 148, 11, 85, 134, 130, 61, 253, 2, 174, 59, 70, 27, 180, 51, 107, 94, 203, 174, 253, 102,
        39, 170, 146, 46, 252, 4, 143, 236, 12, 136, 28,
    ],
    'ED25519',
);
const { schema, secretKey } = decodeIotaPrivateKey(encoded);
// use schema to choose the correct key pair
const keypair = Ed25519Keypair.fromSecretKey(secretKey);

If you know your keypair schema, you can use the fromSecretKey method of the appropriate keypair to directly derive the keypair from the secret key.

const secretKey = 'iotaprivkey1qzse89atw7d3zum8ujep76d2cxmgduyuast0y9fu23xcl0mpafgkktllhyc';

const keypair = Ed25519Keypair.fromSecretKey(secretKey);

You can also export a keypair to a Bech32 encoded secret key using the getSecretKey method.

const secretKey = keypair.getSecretKey();

Deriving a Keypair from a hex encoded secret key

If you have an existing secret key formatted as a hex encoded string, you can derive a Keypair by converting the secret key to a Uint8Array and passing it to the fromSecretKey method of a Keypair class.

import { Ed25519Keypair } from '@iota/iota-sdk/keypairs/ed25519';
import { fromHex } from '@iota/iota-sdk/utils';

const secret = '0x...';
const keypair = Ed25519Keypair.fromSecretKey(fromHex(secret));

Feedback Form

Title *

Describe your feedback here