Derive operation on keypair (#487)

* Derive operation on keypair

* nobody -> derive

* Derivation tests

packages/keyring/src/pair/index.spec.ts

@@ -2,14 +2,19 @@
 // This software may be modified and distributed under the terms
 // of the Apache-2.0 license. See the LICENSE file for details.
 
-import { setSS58Format } from '@polkadot/util-crypto';
+import { cryptoWaitReady, setSS58Format } from '@polkadot/util-crypto';
 
+import { PAIRS } from '../testing';
 import testingPairs from '../testingPairs';
 import createPair from '.';
 
 const keyring = testingPairs({ type: 'ed25519' }, false);
 
 describe('pair', (): void => {
+  beforeEach(async (): Promise<void> => {
+    await cryptoWaitReady();
+  });
+
   const SIGNATURE = new Uint8Array([80, 191, 198, 147, 225, 207, 75, 88, 126, 39, 129, 109, 191, 38, 72, 181, 75, 254, 81, 143, 244, 79, 237, 38, 236, 141, 28, 252, 134, 26, 169, 234, 79, 33, 153, 158, 151, 34, 175, 188, 235, 20, 35, 135, 83, 120, 139, 211, 233, 130, 1, 208, 201, 215, 73, 80, 56, 98, 185, 196, 11, 8, 193, 14]);
 
   it('has a publicKey', (): void => {
@@ -66,6 +71,8 @@ describe('pair', (): void => {
     expect(keyring.alice.address).toEqual(
       '7sGUeMak588SPY2YMmmuKUuLz7u2WQpf74F9dCFtSLB2td9d'
     );
+
+    setSS58Format(42);
   });
 
   it('allows getting public key after decoding', (): void => {
@@ -77,4 +84,13 @@ describe('pair', (): void => {
 
     expect(pair.isLocked).toEqual(false);
   });
+
+  it('allows derivation on the pair', (): void => {
+    const alice = createPair('sr25519', { publicKey: PAIRS[0].publicKey, secretKey: PAIRS[0].secretKey }, {});
+    const stash = alice.derive('//stash');
+    const soft = alice.derive('//funding/0');
+
+    expect(stash.publicKey).toEqual(PAIRS[1].publicKey);
+    expect(soft.address).toEqual('5ECQNn7UueWHPFda5qUi4fTmTtyCnPvGnuoyVVSj5CboJh9J');
+  });
 });

packages/keyring/src/pair/index.ts

@@ -6,8 +6,8 @@ import { Keypair, KeypairType } from '@polkadot/util-crypto/types';
 import { KeyringPair, KeyringPair$Json, KeyringPair$Meta, SignOptions } from '../types';
 import { PairInfo } from './types';
 
-import { u8aConcat } from '@polkadot/util';
-import { encodeAddress, naclKeypairFromSeed as naclFromSeed, naclSign, naclVerify, schnorrkelKeypairFromSeed as schnorrkelFromSeed, schnorrkelSign, schnorrkelVerify } from '@polkadot/util-crypto';
+import { u8aConcat, assert } from '@polkadot/util';
+import { encodeAddress, keyExtractPath, keyFromPath, naclKeypairFromSeed as naclFromSeed, naclSign, naclVerify, schnorrkelKeypairFromSeed as schnorrkelFromSeed, schnorrkelSign, schnorrkelVerify } from '@polkadot/util-crypto';
 
 import decode from './decode';
 import encode from './encode';
@@ -87,10 +87,21 @@ const verify = (type: KeypairType, message: Uint8Array, signature: Uint8Array, p
  */
 export default function createPair (type: KeypairType, { publicKey, secretKey }: PairInfo, meta: KeyringPair$Meta = {}, encoded: Uint8Array | null = null): KeyringPair {
   return {
-    type,
     get address (): string {
       return encodeAddress(publicKey);
     },
+    get meta (): KeyringPair$Meta {
+      return meta;
+    },
+    get isLocked (): boolean {
+      return !secretKey || secretKey.length === 0 || isEmpty(secretKey);
+    },
+    get publicKey (): Uint8Array {
+      return publicKey;
+    },
+    get type (): KeypairType {
+      return type;
+    },
     decodePkcs8: (passphrase?: string, _encoded?: Uint8Array | null): void => {
       const decoded = decode(passphrase, _encoded || encoded);
 
@@ -104,20 +115,19 @@ export default function createPair (type: KeypairType, { publicKey, secretKey }:
         secretKey = pair.secretKey;
       }
     },
+    derive: (suri: string, meta?: KeyringPair$Meta): KeyringPair => {
+      assert(secretKey, 'Cannot derive on a locked keypair');
+
+      const { path } = keyExtractPath(suri);
+      const derived = keyFromPath({ publicKey, secretKey: secretKey as Uint8Array }, path, type);
+
+      return createPair(type, derived, meta, null);
+    },
     encodePkcs8: (passphrase?: string): Uint8Array =>
       encode({ publicKey, secretKey }, passphrase),
-    get meta (): KeyringPair$Meta {
-      return meta;
-    },
-    get isLocked (): boolean {
-      return !secretKey || secretKey.length === 0 || isEmpty(secretKey);
-    },
     lock: (): void => {
       secretKey = new Uint8Array(0);
     },
-    get publicKey (): Uint8Array {
-      return publicKey;
-    },
     setMeta: (additional: KeyringPair$Meta): void => {
       meta = { ...meta, ...additional };
     },

packages/keyring/src/pair/nobody.ts

@@ -24,13 +24,16 @@ const json: KeyringPair$Json = {
 };
 
 export default function everybody (): KeyringPair {
-  return {
+  const pair: KeyringPair = {
     type: 'ed25519',
     address,
     // eslint-disable-next-line @typescript-eslint/no-unused-vars
     decodePkcs8: (passphrase?: string, encoded?: Uint8Array): void =>
       undefined,
     // eslint-disable-next-line @typescript-eslint/no-unused-vars
+    derive: (suri: string, meta?: KeyringPair$Meta): KeyringPair =>
+      pair,
+    // eslint-disable-next-line @typescript-eslint/no-unused-vars
     encodePkcs8: (passphrase?: string): Uint8Array =>
       new Uint8Array(0),
     meta,
@@ -52,4 +55,6 @@ export default function everybody (): KeyringPair {
     verify: (message: Uint8Array, signature: Uint8Array): boolean =>
       false
   };
+
+  return pair;
 }

packages/keyring/src/testing.ts

@@ -21,7 +21,7 @@ interface PairDef {
 // keyring is for testing - what happens is that in most cases the keyring is initialises
 // before anything else. Since the sr25519 crypto is async, this creates problems with
 // adding the keys when only the keyring is used.
-const PAIRS: PairDef[] = [
+export const PAIRS: PairDef[] = [
   {
     seed: 'Alice',
     secretKey: hexToU8a('0x98319d4ff8a9508c4bb0cf0b5a78d760a0b2082c02775e6e82370816fedfff48925a225d97aa00682d6a59b95b18780c10d7032336e88f3442b42361f4a66011'),

packages/keyring/src/types.ts

@@ -38,15 +38,16 @@ export interface SignOptions {
 }
 
 export interface KeyringPair {
+  readonly address: string;
+  readonly meta: KeyringPair$Meta;
+  readonly isLocked: boolean;
+  readonly publicKey: Uint8Array;
   readonly type: KeypairType;
 
-  address: string;
   decodePkcs8: (passphrase?: string, encoded?: Uint8Array) => void;
+  derive: (suri: string, meta?: KeyringPair$Meta) => KeyringPair;
   encodePkcs8: (passphrase?: string) => Uint8Array;
-  meta: KeyringPair$Meta;
-  isLocked: boolean;
   lock: () => void;
-  publicKey: Uint8Array;
   setMeta: (meta: KeyringPair$Meta) => void;
   sign (message: Uint8Array, options?: SignOptions): Uint8Array;
   toJson (passphrase?: string): KeyringPair$Json;