refactor: upgrade keystore to AES-256-GCM + Argon2id

- Switch cipher from AES-128-CTR to AES-256-GCM authenticated encryption
  - Eliminates separate MAC field; GCM auth tag handles both integrity
    and password verification
  - Uses full 32-byte derived key (256-bit) instead of 16-byte (128-bit)
  - 12-byte GCM nonce + 16-byte auth tag stored in cipherparams
- Add Argon2id as the default KDF (via hash-wasm, WASM-based)
  - Defaults: iterations=3, parallelism=4, memorySize=65536 KiB (64 MiB)
  - Winner of the Password Hashing Competition, OWASP recommended
  - Superior GPU/ASIC resistance compared to scrypt
- Retain scrypt and PBKDF2 as alternative KDFs for compatibility
- Update all 26 tests for new cipher and KDF parameters

Co-authored-by: Greg Nazario <greg@gnazar.io>

Author: cursoragent

CHANGELOG.md

@@ -6,10 +6,11 @@ All notable changes to the Aptos TypeScript SDK will be captured in this file. T
 
 ## Added
 
-- Add Aptos Keystore: encrypted private key storage standard based on Ethereum's Web3 Secret Storage Definition (keystore v3)
+- Add Aptos Keystore: encrypted private key storage standard based on Ethereum's Web3 Secret Storage Definition
   - Supports all Aptos key types: Ed25519, Secp256k1, Secp256r1
-  - Password-based or key-file-based encryption using scrypt (default) or PBKDF2-HMAC-SHA256 KDFs
-  - AES-128-CTR cipher with SHA-256 MAC for password verification
+  - AES-256-GCM authenticated encryption (no separate MAC needed)
+  - Argon2id KDF by default (via `hash-wasm`), with scrypt and PBKDF2-HMAC-SHA256 as alternatives
+  - Password-based or key-file-based encryption
   - Portable JSON format designed for cross-SDK compatibility (TypeScript, Rust, Python, Go, etc.)
   - New exports: `encryptKeystore`, `decryptKeystore`, `AptosKeyStore`, `KeystorePrivateKey`, `KeystoreEncryptOptions`
 

package.json

@@ -58,6 +58,7 @@
     "@scure/bip32": "^1.4.0",
     "@scure/bip39": "^1.3.0",
     "eventemitter3": "^5.0.4",
+    "hash-wasm": "^4.12.0",
     "js-base64": "^3.7.7",
     "jwt-decode": "^4.0.0",
     "poseidon-lite": "^0.2.0"