From 8600c5149b9fc9d090d846b5b6fc44eb214127b9 Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Mon, 21 Jul 2025 07:31:33 -0400
Subject: [PATCH] LibCrypto: Allow moving SignedBigInteger / UnsignedBigInteger

We defined copy operations but not move operations, so every existing
move() resulted in a copy.
---
 .../LibCrypto/BigInt/SignedBigInteger.cpp     | 23 +++++++++++++++++++
 Libraries/LibCrypto/BigInt/SignedBigInteger.h |  3 +++
 .../LibCrypto/BigInt/UnsignedBigInteger.cpp   | 23 +++++++++++++++++++
 .../LibCrypto/BigInt/UnsignedBigInteger.h     |  3 +++
 Tests/LibCrypto/TestBigInteger.cpp            | 17 ++++++++++++++
 5 files changed, 69 insertions(+)

diff --git a/Libraries/LibCrypto/BigInt/SignedBigInteger.cpp b/Libraries/LibCrypto/BigInt/SignedBigInteger.cpp
index 32e43317a10..c6998ca980e 100644
--- a/Libraries/LibCrypto/BigInt/SignedBigInteger.cpp
+++ b/Libraries/LibCrypto/BigInt/SignedBigInteger.cpp
@@ -52,6 +52,14 @@ SignedBigInteger::SignedBigInteger(SignedBigInteger const& other)
     MP_MUST(mp_init_copy(&m_mp, &other.m_mp));
 }
 
+SignedBigInteger::SignedBigInteger(SignedBigInteger&& other)
+    : m_mp(other.m_mp)
+    , m_hash(other.m_hash)
+{
+    other.m_mp = {};
+    other.m_hash.clear();
+}
+
 SignedBigInteger& SignedBigInteger::operator=(SignedBigInteger const& other)
 {
     if (this == &other)
@@ -64,6 +72,21 @@ SignedBigInteger& SignedBigInteger::operator=(SignedBigInteger const& other)
     return *this;
 }
 
+SignedBigInteger& SignedBigInteger::operator=(SignedBigInteger&& other)
+{
+    if (this == &other)
+        return *this;
+
+    mp_clear(&m_mp);
+    m_mp = other.m_mp;
+    m_hash = other.m_hash;
+
+    other.m_mp = {};
+    other.m_hash.clear();
+
+    return *this;
+}
+
 SignedBigInteger::SignedBigInteger()
 {
     MP_MUST(mp_init(&m_mp));
diff --git a/Libraries/LibCrypto/BigInt/SignedBigInteger.h b/Libraries/LibCrypto/BigInt/SignedBigInteger.h
index 6db09b3aa73..0cce9529531 100644
--- a/Libraries/LibCrypto/BigInt/SignedBigInteger.h
+++ b/Libraries/LibCrypto/BigInt/SignedBigInteger.h
@@ -29,7 +29,10 @@ public:
     explicit SignedBigInteger(i64 value);
 
     SignedBigInteger(SignedBigInteger const&);
+    SignedBigInteger(SignedBigInteger&&);
+
     SignedBigInteger& operator=(SignedBigInteger const&);
+    SignedBigInteger& operator=(SignedBigInteger&&);
 
     SignedBigInteger();
     ~SignedBigInteger();
diff --git a/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp b/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
index bd697fe1473..b2b8f279da6 100644
--- a/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
+++ b/Libraries/LibCrypto/BigInt/UnsignedBigInteger.cpp
@@ -55,6 +55,14 @@ UnsignedBigInteger::UnsignedBigInteger(UnsignedBigInteger const& other)
     MP_MUST(mp_init_copy(&m_mp, &other.m_mp));
 }
 
+UnsignedBigInteger::UnsignedBigInteger(UnsignedBigInteger&& other)
+    : m_mp(other.m_mp)
+    , m_hash(other.m_hash)
+{
+    other.m_mp = {};
+    other.m_hash.clear();
+}
+
 UnsignedBigInteger& UnsignedBigInteger::operator=(UnsignedBigInteger const& other)
 {
     if (this == &other)
@@ -67,6 +75,21 @@ UnsignedBigInteger& UnsignedBigInteger::operator=(UnsignedBigInteger const& othe
     return *this;
 }
 
+UnsignedBigInteger& UnsignedBigInteger::operator=(UnsignedBigInteger&& other)
+{
+    if (this == &other)
+        return *this;
+
+    mp_clear(&m_mp);
+    m_mp = other.m_mp;
+    m_hash = other.m_hash;
+
+    other.m_mp = {};
+    other.m_hash.clear();
+
+    return *this;
+}
+
 UnsignedBigInteger::UnsignedBigInteger()
 {
     MP_MUST(mp_init(&m_mp));
diff --git a/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h b/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h
index 85d28261ac7..a0511838658 100644
--- a/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h
+++ b/Libraries/LibCrypto/BigInt/UnsignedBigInteger.h
@@ -31,7 +31,10 @@ public:
     explicit UnsignedBigInteger(u64 value);
 
     UnsignedBigInteger(UnsignedBigInteger const&);
+    UnsignedBigInteger(UnsignedBigInteger&&);
+
     UnsignedBigInteger& operator=(UnsignedBigInteger const&);
+    UnsignedBigInteger& operator=(UnsignedBigInteger&&);
 
     UnsignedBigInteger();
     ~UnsignedBigInteger();
diff --git a/Tests/LibCrypto/TestBigInteger.cpp b/Tests/LibCrypto/TestBigInteger.cpp
index 169c79af207..aeab0d8c474 100644
--- a/Tests/LibCrypto/TestBigInteger.cpp
+++ b/Tests/LibCrypto/TestBigInteger.cpp
@@ -901,6 +901,23 @@ TEST_CASE(unsigned_bigint_double_comparisons)
 #undef EXPECT_EQUAL_TO
 }
 
+TEST_CASE(moving_bigints)
+{
+    Crypto::UnsignedBigInteger bigint1;
+    {
+        auto bigint2 = "123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789"_bigint;
+        bigint1 = move(bigint2);
+        EXPECT(bigint2.is_zero());
+    }
+
+    EXPECT_EQ(MUST(bigint1.to_base(10)), "123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789"sv);
+
+    Crypto::UnsignedBigInteger bigint3 { move(bigint1) };
+    EXPECT(bigint1.is_zero());
+
+    EXPECT_EQ(MUST(bigint3.to_base(10)), "123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789123456789"sv);
+}
+
 namespace AK {
 
 template<>