feat: Add deriveAddress

src/deriveAddress.spec.ts

+import { deriveAddress } from './deriveAddress';
+
+describe('generateKeypair', () => {
+  it('should work', () => {
+    const address = deriveAddress(
+      '0x96074594cccf1cd185fa8a72ceaeefd86648f8d45514f3ce33c31bdd07e4655d'
+    );
+
+    expect(address).toBe('Fy2rsYCoowQBtuFXqLE65ehAY9T6KWcGiNCQAyPDCkfpm4s');
+  });
+});

src/deriveAddress.ts

+import { encodeAddress } from '@polkadot/keyring';
+
+const KUSAMA_SS58_FORMAT = 2;
+
+/**
+ * Derive an address from a cryptographic public key offline
+ *
+ * @param publicKey - The public key to derive from
+ * @param ss58Format - The SS58 format to use
+ */
+export function deriveAddress(
+  publicKey: string | Uint8Array,
+  ss58Format: number = KUSAMA_SS58_FORMAT
+): string {
+  return encodeAddress(publicKey, ss58Format);
+}