Enable public key type guessing in encryption

packages/keyring/src/keyring.ts

@@ -4,8 +4,8 @@
 import type { EncryptedJsonEncoding, Keypair, KeypairType } from '@polkadot/util-crypto/types';
 import type { KeyringInstance, KeyringOptions, KeyringPair, KeyringPair$Json, KeyringPair$Meta } from './types';
 
-import { assert, hexToU8a, isHex, isUndefined, stringToU8a } from '@polkadot/util';
-import { base64Decode, decodeAddress, ed25519PairFromSeed as ed25519FromSeed, encodeAddress, encrypt as cryptoEncrypt, ethereumEncode, hdEthereum, keyExtractSuri, keyFromPath, mnemonicToLegacySeed, mnemonicToMiniSecret, secp256k1PairFromSeed as secp256k1FromSeed, sr25519PairFromSeed as sr25519FromSeed } from '@polkadot/util-crypto';
+import { assert, hexToU8a, isHex, isUndefined, stringToU8a, u8aConcat } from '@polkadot/util';
+import { base64Decode, decodeAddress, ed25519PairFromSeed as ed25519FromSeed, encodeAddress, encrypt as cryptoEncrypt, ethereumEncode, hdEthereum, keyExtractSuri, keyFromPath, mnemonicToLegacySeed, mnemonicToMiniSecret, secp256k1PairFromSeed as secp256k1FromSeed, sr25519PairFromSeed as sr25519FromSeed, convertPublicKeyToCurve25519, sr25519DerivePublic } from '@polkadot/util-crypto';
 
 import { DEV_PHRASE } from './defaults';
 import { createPair } from './pair';
@@ -304,6 +304,33 @@ export class Keyring implements KeyringInstance {
    * The encrypted message can be decrypted by the corresponding keypair using keypair.decrypt() method
    */
   public encrypt (message: string | Uint8Array, recipientPublicKey: string | Uint8Array, recipientKeyType?: KeypairType): Uint8Array {
-    return cryptoEncrypt(message, recipientPublicKey, recipientKeyType || this.type);
+    const publicKey = decodeAddress(recipientPublicKey);
+    let keyType = recipientKeyType ? recipientKeyType : this.guessKeyType(publicKey);
+    const encryptedMessage = cryptoEncrypt(message, recipientPublicKey, keyType);
+    return u8aConcat(publicKey, encryptedMessage);
+  }
+
+  private guessKeyType (publicKey: Uint8Array): KeypairType {
+    if(this.isEd25519PublicKey(publicKey)) {
+      return "ed25519";
+    } {
+      return "sr25519";
+    }
+  }
+
+  private isEd25519PublicKey (publicKey: Uint8Array): boolean {
+    try {
+      convertPublicKeyToCurve25519(publicKey);
+      return true;
+    } catch(e) {
+      return false;
+    }
+  }
+
+  public decrypt (message: Uint8Array): Uint8Array | null {
+    const publicKeyBytes = message.slice(0, 32);
+    const encryptedMessage = message.slice(32);
+    const keyPair = this.getPair(publicKeyBytes);
+    return keyPair.decrypt(encryptedMessage);
   }
 }

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

@@ -243,7 +243,7 @@ describe('pair', (): void => {
     expect(keyring.alice.decrypt(encryptedMessage)).toEqual(null);
   });
 
-  it('allows encrypt/decrypt with sr25519 keypair', (): void => {
+  it('allows encrypt/decrypt with sr25519 keypairs', (): void => {
     const aliceSR25519KeyPair = new Keyring().createFromUri(mnemonicGenerate(), { name: 'sr25519 pair' }, 'sr25519');
     const bobSR25519KeyPair = new Keyring().createFromUri(mnemonicGenerate(), { name: 'sr25519 pair' }, 'sr25519');
     const message = new Uint8Array([0x61, 0x62, 0x63, 0x64, 0x65]);
@@ -253,11 +253,40 @@ describe('pair', (): void => {
     expect((): Uint8Array | null => aliceSR25519KeyPair.decrypt(encryptedMessage)).toThrow("Mac values don't match");
   });
 
+  it('allows encrypt/decrypt with ed25519 keypair and type guessing', (): void => {
+    const keyring = new Keyring();
+    const bobED25519KeyPair = keyring.addFromUri(mnemonicGenerate(), { name: 'ed25519 pair' }, 'ed25519');
+    const message = new Uint8Array([0x61, 0x62, 0x63, 0x64, 0x65]);
+    const encryptedMessage = keyring.encrypt(message, bobED25519KeyPair.publicKey);
+
+    expect(keyring.decrypt(encryptedMessage)).toEqual(message);
+  });
+
+  it('allows encrypt/decrypt with sr25519 keypair and type guessing with non-convertible public key', (): void => {
+    const keyring = new Keyring();
+    const mnemonic = "easily dust bright surface scale walnut stick buddy spare quick trial crane";
+    const bobSR25519KeyPair = keyring.addFromUri(mnemonic, { name: 'sr25519 pair' }, 'sr25519');
+    const message = new Uint8Array([0x61, 0x62, 0x63, 0x64, 0x65]);
+    const encryptedMessage = keyring.encrypt(message, bobSR25519KeyPair.publicKey);
+
+    expect(keyring.decrypt(encryptedMessage)).toEqual(message);
+  });
+
+  it('allows encrypt/decrypt with sr25519 keypair and type guessing with convertible public key', (): void => {
+    const keyring = new Keyring();
+    const mnemonic = "excess control wrestle sustain gauge swear unveil trap tunnel coil nurse salt";
+    const bobSR25519KeyPair = keyring.addFromUri(mnemonic, { name: 'sr25519 pair' }, 'sr25519');
+    const message = new Uint8Array([0x61, 0x62, 0x63, 0x64, 0x65]);
+    const encryptedMessage = keyring.encrypt(message, bobSR25519KeyPair.publicKey);
+
+    expect(keyring.decrypt(encryptedMessage)).toEqual(message);
+  });
+
   it('allows encrypt for an ed25519 keypair', (): void => {
     const message = new Uint8Array([0x61, 0x62, 0x63, 0x64, 0x65]);
     const encryptedMessage = new Keyring().encrypt(message, keyring.alice.publicKey, keyring.alice.type);
 
-    expect(keyring.alice.decrypt(encryptedMessage)).toEqual(message);
+    expect(keyring.alice.decrypt(encryptedMessage.slice(32))).toEqual(message);
   });
 
   it('allows encrypt for an sr25519 keypair', (): void => {
@@ -266,7 +295,7 @@ describe('pair', (): void => {
     const message = new Uint8Array([0x61, 0x62, 0x63, 0x64, 0x65]);
     const encryptedMessage = keyring.encrypt(message, sr25519KeyPair.publicKey, sr25519KeyPair.type);
 
-    expect(sr25519KeyPair.decrypt(encryptedMessage)).toEqual(message);
+    expect(sr25519KeyPair.decrypt(encryptedMessage.slice(32))).toEqual(message);
   });
 
   it('fails to encrypt when locked', (): void => {