From 43ac36180692a1bd7838389f135841a51404852e Mon Sep 17 00:00:00 2001
From: Arjun Porwal <65214523+ap211unitech@users.noreply.github.com>
Date: Fri, 13 Jun 2025 18:46:25 +0530
Subject: [PATCH] Add input length validation in `scryptFromU8a` function
 (#1990)

* fix: add input length validation in scryptFromU8a function

* fix: improve input validation in scryptFromU8a function

* fix: linting

* fix: update default Scrypt parameters for improved security

* revert: 9070615

* fix: remove dymanic calculation
---
 packages/util-crypto/src/scrypt/fromU8a.ts | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/packages/util-crypto/src/scrypt/fromU8a.ts b/packages/util-crypto/src/scrypt/fromU8a.ts
index 5178249d3..bbe1550af 100644
--- a/packages/util-crypto/src/scrypt/fromU8a.ts
+++ b/packages/util-crypto/src/scrypt/fromU8a.ts
@@ -14,10 +14,19 @@ interface Result {
 }
 
 export function scryptFromU8a (data: Uint8Array): Result {
+  if (!(data instanceof Uint8Array)) {
+    throw new Error('Expected input to be a Uint8Array');
+  }
+
+  // Ensure the input is exactly 44 bytes: 32 for salt + 3 * 4 for N, p, r
+  if (data.length < 32 + 12) {
+    throw new Error(`Invalid input length: expected 44 bytes, found ${data.length}`);
+  }
+
   const salt = data.subarray(0, 32);
-  const N = u8aToBn(data.subarray(32 + 0, 32 + 4), BN_LE_OPTS).toNumber();
-  const p = u8aToBn(data.subarray(32 + 4, 32 + 8), BN_LE_OPTS).toNumber();
-  const r = u8aToBn(data.subarray(32 + 8, 32 + 12), BN_LE_OPTS).toNumber();
+  const N = u8aToBn(data.subarray(32, 36), BN_LE_OPTS).toNumber();
+  const p = u8aToBn(data.subarray(36, 40), BN_LE_OPTS).toNumber();
+  const r = u8aToBn(data.subarray(40, 44), BN_LE_OPTS).toNumber();
 
   // FIXME At this moment we assume these to be fixed params, this is not a great idea
   // since we lose flexibility and updates for greater security. However we need some