Merge pull request #60 from zama-ai/fix/eaddress

fixture(eaddress): truncate hex string from decrypted bytes (leading 00)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "fhevmjs",
-  "version": "0.4.0-8",
+  "version": "0.4.0-9",
   "description": "fhEVM SDK for blockchain using TFHE",
   "main": "lib/node.cjs",
   "types": "lib/node.d.ts",

src/sdk/decrypt.test.ts

@@ -44,4 +44,32 @@ describe('decrypt', () => {
     const cleartext = decryptAddress(keypair, ciphertext);
     expect(cleartext).toBe(getAddress(value.toString(16)));
   });
+
+  it('decrypts an address Uint8Array value bigger than 160 bits', async () => {
+    const keypair = sodium.crypto_box_keypair();
+    const address = '0x9b8a8ba1f109551bd432803012645ac136ddd64dba72'
+    // Must truncate to 40-digit
+    const expected = '0x8ba1f109551bd432803012645ac136ddd64dba72'
+    const value = BigInt(address);
+    const ciphertext = sodium.crypto_box_seal(
+      bigIntToBytes(value),
+      keypair.publicKey,
+    );
+    const cleartext = decryptAddress(keypair, ciphertext);
+    expect(cleartext).toBe(getAddress(expected));
+  });
+
+  it('decrypts an address Uint8Array value lower than 160 bits', async () => {
+    const keypair = sodium.crypto_box_keypair();
+    const address = '0x8ba1f109551bd432803012645ac136ddd64d'
+    // Must add padding until to 40-digit
+    const expected = '0x00008ba1f109551bd432803012645ac136ddd64d'
+    const value = BigInt(address);
+    const ciphertext = sodium.crypto_box_seal(
+      bigIntToBytes(value),
+      keypair.publicKey,
+    );
+    const cleartext = decryptAddress(keypair, ciphertext);
+    expect(cleartext).toBe(getAddress(expected));
+  });
 });

src/sdk/decrypt.ts

@@ -28,5 +28,14 @@ export const decryptAddress = (
     keypair.publicKey,
     keypair.privateKey,
   );
-  return getAddress(bytesToHex(decrypted));
+
+let hexString = bytesToHex(decrypted);
+// Ensure hexString forms a valid 40-digit Ethereum address.
+// Truncate or pad with leading zeros as necessary to correct length issues.
+if (hexString.length > 40) {
+  hexString = hexString.substring(hexString.length - 40);
+} else {
+  hexString = hexString.slice(2).padStart(40, '0');
+}
+  return getAddress(hexString);
 };

src/utils.ts

@@ -18,25 +18,17 @@ export const bytesToHex = function (byteArray: Uint8Array): string {
   if (!byteArray || byteArray?.length === 0) {
     return '0x0';
   }
-
-  const length = byteArray.length;
-
   const buffer = Buffer.from(byteArray);
-  const result = buffer.toString('hex');
-
-  return result;
+  return `0x${buffer.toString('hex')}`;
 };
 
 export const bytesToBigInt = function (byteArray: Uint8Array): bigint {
   if (!byteArray || byteArray?.length === 0) {
     return BigInt(0);
   }
 
-  const length = byteArray.length;
-
   const buffer = Buffer.from(byteArray);
   const result = toBigIntBE(buffer);
-
   return result;
 };