argon2: reload wasm module after timeout when using memory heavy pa…

…rams (#199)

We manually reload the module if no memory-heavy (128MB+) argon2 computation has been requested
in a while, to deallocate the memory.
This is better than reloading the module every time (automatically done if the memory exceeds
`Argon2S2K.ARGON2_WASM_MEMORY_THRESHOLD_RELOAD`),
as doing so comes with a performance hit.

Co-authored-by: Daniel Huigens <d.huigens@protonmail.com>

lib/crypto/argon2.ts

@@ -12,8 +12,36 @@ export interface Argon2Options {
     params: Argon2Params
 }
 
+// We manually reload the module if no memory-heavy (128MB+) argon2 computation has been requested in a while,
+// to deallocate the memory.
+// This is better than reloading the module every time (automatically done if the memory exceeds `Argon2S2K.ARGON2_WASM_MEMORY_THRESHOLD_RELOAD`),
+// as doing so comes with a performance hit.
+const SECOND = 1000;
+const TimeoutHandler = {
+    id: undefined,
+    cancelReloadingTimeout: (memoryExponent: number) => (
+        memoryExponent > ARGON2_PARAMS.MINIMUM.memoryExponent && clearTimeout(TimeoutHandler.id)
+    ),
+    setupReloadingTimeout: (memoryExponent: number) => {
+        const shouldReloadAfterTimeout = memoryExponent > ARGON2_PARAMS.MINIMUM.memoryExponent &&
+            memoryExponent <= Argon2S2K.ARGON2_WASM_MEMORY_THRESHOLD_RELOAD;
+        // @ts-ignore NodeJS.Timeout typedef interfering
+        TimeoutHandler.id = shouldReloadAfterTimeout ?
+            setTimeout(
+                () => Argon2S2K.reloadWasmModule(),
+                10 * SECOND
+            ) as any as number
+            : undefined;
+    }
+};
+
 export async function argon2({ password, salt, params = ARGON2_PARAMS.RECOMMENDED }: Argon2Options) {
+    TimeoutHandler.cancelReloadingTimeout(params.memoryExponent);
+
     const s2k = new Argon2S2K({ ...defaultConfig, s2kArgon2Params: params });
     s2k.salt = salt;
-    return s2k.produceKey(password, params.tagLength);
+    const result = await s2k.produceKey(password, params.tagLength);
+
+    TimeoutHandler.setupReloadingTimeout(params.memoryExponent);
+    return result;
 }

package.json

@@ -34,7 +34,7 @@
         "@openpgp/tweetnacl": "^1.0.3",
         "@openpgp/web-stream-tools": "^0.0.13",
         "jsmimeparser": "npm:@protontech/jsmimeparser@^3.0.1",
-        "openpgp": "npm:@protontech/openpgp@~5.11.1-0"
+        "openpgp": "npm:@protontech/openpgp@~5.11.2-0"
     },
     "devDependencies": {
         "@types/bn.js": "^5.1.1",