Access ephemeral key in cipher instance

oasisprotocol · Jan 17, 2025 · 744fc57 · 744fc57
1 parent 58341fb
commit 744fc57
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Showing 2 changed files with 5 additions and 3 deletions.
diff --git a/clients/js/src/cipher.ts b/clients/js/src/cipher.ts
@@ -80,6 +80,7 @@ function formatFailure(fail: CallFailure): string {
 export abstract class Cipher {
   public abstract kind: CipherKind;
   public abstract publicKey: Uint8Array;
+  public abstract ephemeralKey: Uint8Array;
   public abstract epoch?: number;
 
   public abstract encrypt(
@@ -213,6 +214,7 @@ export abstract class Cipher {
 export class X25519DeoxysII extends Cipher {
   public override readonly kind = CipherKind.X25519DeoxysII;
   public override readonly publicKey: Uint8Array;
+  public override readonly ephemeralKey: Uint8Array;
   public override readonly epoch: number | undefined;
 
   private cipher: deoxysii.AEAD;
@@ -243,6 +245,7 @@ export class X25519DeoxysII extends Cipher {
     super();
 
     this.publicKey = keypair.publicKey;
+    this.ephemeralKey = keypair.secretKey;
     this.epoch = epoch;
 
     // Derive a shared secret using X25519 (followed by hashing to remove ECDH bias).

diff --git a/clients/js/src/provider.ts b/clients/js/src/provider.ts
@@ -164,8 +164,7 @@ export async function notifySapphireSnap(
   options: SapphireWrapOptions,
   provider: EIP2696_EthereumProvider,
 ) {
-  const secretKey = (cipher as any).secretKey as Uint8Array | undefined;
-  if (secretKey) {
+  if (cipher.ephemeralKey) {
     const peerPublicKey = await options.fetcher.fetch(provider);
     await provider.request({
       method: 'wallet_invokeSnap',
@@ -175,7 +174,7 @@ export async function notifySapphireSnap(
           method: 'setTransactionDecryptKeys',
           params: {
             id: transactionData,
-            ephemeralSecretKey: hexlify(secretKey),
+            ephemeralSecretKey: hexlify(cipher.ephemeralKey),
             peerPublicKey: hexlify(peerPublicKey.key),
             peerPublicKeyEpoch: peerPublicKey.epoch,
           },