From 41061cfde8067317d7b13363a5bcadfc9630db71 Mon Sep 17 00:00:00 2001
From: Jonathan White <support@dmapps.us>
Date: Fri, 1 Apr 2022 07:10:11 -0400
Subject: [PATCH] Improve speed of AES KDF transform

* Remove parallel left/right block calculations in favor of calculating both blocks simultaneously. This brings the calculation within parity of 2.6.6.
* Fix #7682
---
 src/crypto/kdf/AesKdf.cpp | 29 +++++++++--------------------
 1 file changed, 9 insertions(+), 20 deletions(-)

diff --git a/src/crypto/kdf/AesKdf.cpp b/src/crypto/kdf/AesKdf.cpp
index 481b7e461..119765785 100644
--- a/src/crypto/kdf/AesKdf.cpp
+++ b/src/crypto/kdf/AesKdf.cpp
@@ -62,30 +62,19 @@ QVariantMap AesKdf::writeParameters()
 
 bool AesKdf::transform(const QByteArray& raw, QByteArray& result) const
 {
-    QByteArray resultLeft;
-    QByteArray resultRight;
-
-    QFuture<bool> future = QtConcurrent::run(transformKeyRaw, raw.left(16), m_seed, m_rounds, &resultLeft);
-
-    bool rightResult = transformKeyRaw(raw.right(16), m_seed, m_rounds, &resultRight);
-    bool leftResult = future.result();
-
-    if (!rightResult || !leftResult) {
-        return false;
-    }
-
-    QByteArray transformed;
-    transformed.append(resultLeft);
-    transformed.append(resultRight);
-
-    result = CryptoHash::hash(transformed, CryptoHash::Sha256);
-    return true;
+    return transformKeyRaw(raw, m_seed, m_rounds, &result);
 }
 
 bool AesKdf::transformKeyRaw(const QByteArray& key, const QByteArray& seed, int rounds, QByteArray* result)
 {
-    *result = key;
-    return SymmetricCipher::aesKdf(seed, rounds, *result);
+    if (!result) {
+        return false;
+    }
+
+    auto out = key;
+    SymmetricCipher::aesKdf(seed, rounds, out);
+    *result = CryptoHash::hash(out, CryptoHash::Sha256);
+    return true;
 }
 
 QSharedPointer<Kdf> AesKdf::clone() const