I want to encode my secretKey to Uint8Array.

I use TextEncoder().

const secret = new TextEncoder().encode(secretKey);

I get secretKey from my phantom wallet.

it returns Uint8Array which is length 88. I need to Uint8Array which is length 64.

I want to convert it to Uint8Array which has 64 length.

  • I figure out ! I use bs58 library.
    – Jerry
    Jul 28, 2022 at 8:50

2 Answers 2


Here's the script I use for this:

import pkg from 'bs58';
const { decode } = pkg;

const args = process.argv.slice(2);
if (!args.length) {
  throw new Error('No key provided')

const key = args[0];
const decoded = decode(key)


You can call it with eg. node decode.js 5Ab... > key.json where 5aB... is your base-58 encoded private key from eg. Phantom

And then it'll save in key.json the 64-length Uint8array in the format the Solana CLI expects, ie a JSON array.

let bs58 = require("bs58");
  const connection = new Connection(clusterApiUrl("devnet"), "confirmed");
  const bs = bs58.decode(secretKey);

  const wallet = Keypair.fromSecretKey(bs);

I can call it with base58 library !

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