Add in ability to encrypt/decrypt msg with keyring (#1070)

* feat: able to encrypt & decrypt message in keyring - ed25519 & sr25519 types

* chore: make eslint happy

* test: add in one more test on cross-usage of ed25519 & sr25519

* make lint happy without eslint-disable

* assert away secp256k1 for encrypt/decrypt

* Update packages/keyring/src/pair/index.ts

* Update packages/keyring/src/pair/index.ts

Co-authored-by: Jaco <jacogr@gmail.com>

packages/util-crypto/src/nacl/convertKey.ts

@@ -0,0 +1,12 @@
+// Copyright 2017-2021 @polkadot/util-crypto authors & contributors
+// SPDX-License-Identifier: Apache-2.0
+
+import ed2curve from 'ed2curve';
+
+export function convertSecretKeyToCurve25519 (secretKey: Uint8Array): Uint8Array {
+  return ed2curve.convertSecretKey(secretKey);
+}
+
+export function convertPublicKeyToCurve25519 (publicKey: Uint8Array): Uint8Array {
+  return ed2curve.convertPublicKey(publicKey) as Uint8Array;
+}

packages/util-crypto/src/nacl/index.ts

@@ -15,3 +15,4 @@ export { naclVerify } from './verify';
 export { naclBoxKeypairFromSecret } from './box/fromSecret';
 export { naclOpen } from './open';
 export { naclSeal } from './seal';
+export { convertSecretKeyToCurve25519, convertPublicKeyToCurve25519 } from './convertKey';