aes_util: Allow SetIV to be non-allocating

In a few places, the data to be set as the IV is already within an array.
We shouldn't require this data to be heap-allocated if it doesn't need
to be. This allows certain callers to reduce heap churn.

src/core/crypto/aes_util.cpp

@@ -2,6 +2,7 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <array>
 #include <mbedtls/cipher.h>
 #include "common/assert.h"
 #include "common/logging/log.h"
@@ -10,8 +11,10 @@
 
 namespace Core::Crypto {
 namespace {
-std::vector<u8> CalculateNintendoTweak(std::size_t sector_id) {
-    std::vector<u8> out(0x10);
+using NintendoTweak = std::array<u8, 16>;
+
+NintendoTweak CalculateNintendoTweak(std::size_t sector_id) {
+    NintendoTweak out{};
     for (std::size_t i = 0xF; i <= 0xF; --i) {
         out[i] = sector_id & 0xFF;
         sector_id >>= 8;
@@ -63,13 +66,6 @@ AESCipher<Key, KeySize>::~AESCipher() {
     mbedtls_cipher_free(&ctx->decryption_context);
 }
 
-template <typename Key, std::size_t KeySize>
-void AESCipher<Key, KeySize>::SetIV(std::vector<u8> iv) {
-    ASSERT_MSG((mbedtls_cipher_set_iv(&ctx->encryption_context, iv.data(), iv.size()) ||
-                mbedtls_cipher_set_iv(&ctx->decryption_context, iv.data(), iv.size())) == 0,
-               "Failed to set IV on mbedtls ciphers.");
-}
-
 template <typename Key, std::size_t KeySize>
 void AESCipher<Key, KeySize>::Transcode(const u8* src, std::size_t size, u8* dest, Op op) const {
     auto* const context = op == Op::Encrypt ? &ctx->encryption_context : &ctx->decryption_context;
@@ -124,6 +120,13 @@ void AESCipher<Key, KeySize>::XTSTranscode(const u8* src, std::size_t size, u8*
     }
 }
 
+template <typename Key, std::size_t KeySize>
+void AESCipher<Key, KeySize>::SetIVImpl(const u8* data, std::size_t size) {
+    ASSERT_MSG((mbedtls_cipher_set_iv(&ctx->encryption_context, data, size) ||
+                mbedtls_cipher_set_iv(&ctx->decryption_context, data, size)) == 0,
+               "Failed to set IV on mbedtls ciphers.");
+}
+
 template class AESCipher<Key128>;
 template class AESCipher<Key256>;
 } // namespace Core::Crypto

src/core/crypto/aes_util.h

@@ -6,7 +6,6 @@
 
 #include <memory>
 #include <type_traits>
-#include <vector>
 #include "common/common_types.h"
 #include "core/file_sys/vfs.h"
 
@@ -32,10 +31,12 @@ class AESCipher {
 
 public:
     AESCipher(Key key, Mode mode);
-
     ~AESCipher();
 
-    void SetIV(std::vector<u8> iv);
+    template <typename ContiguousContainer>
+    void SetIV(const ContiguousContainer& container) {
+        SetIVImpl(std::data(container), std::size(container));
+    }
 
     template <typename Source, typename Dest>
     void Transcode(const Source* src, std::size_t size, Dest* dest, Op op) const {
@@ -59,6 +60,8 @@ public:
                       std::size_t sector_size, Op op);
 
 private:
+    void SetIVImpl(const u8* data, std::size_t size);
+
     std::unique_ptr<CipherContext> ctx;
 };
 } // namespace Core::Crypto

src/core/crypto/ctr_encryption_layer.cpp

@@ -2,6 +2,7 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <algorithm>
 #include <cstring>
 #include "common/assert.h"
 #include "core/crypto/ctr_encryption_layer.h"
@@ -10,8 +11,7 @@ namespace Core::Crypto {
 
 CTREncryptionLayer::CTREncryptionLayer(FileSys::VirtualFile base_, Key128 key_,
                                        std::size_t base_offset)
-    : EncryptionLayer(std::move(base_)), base_offset(base_offset), cipher(key_, Mode::CTR),
-      iv(16, 0) {}
+    : EncryptionLayer(std::move(base_)), base_offset(base_offset), cipher(key_, Mode::CTR) {}
 
 std::size_t CTREncryptionLayer::Read(u8* data, std::size_t length, std::size_t offset) const {
     if (length == 0)
@@ -39,9 +39,8 @@ std::size_t CTREncryptionLayer::Read(u8* data, std::size_t length, std::size_t o
     return read + Read(data + read, length - read, offset + read);
 }
 
-void CTREncryptionLayer::SetIV(const std::vector<u8>& iv_) {
-    const auto length = std::min(iv_.size(), iv.size());
-    iv.assign(iv_.cbegin(), iv_.cbegin() + length);
+void CTREncryptionLayer::SetIV(const IVData& iv_) {
+    iv = iv_;
 }
 
 void CTREncryptionLayer::UpdateIV(std::size_t offset) const {

src/core/crypto/ctr_encryption_layer.h

@@ -4,7 +4,8 @@
 
 #pragma once
 
-#include <vector>
+#include <array>
+
 #include "core/crypto/aes_util.h"
 #include "core/crypto/encryption_layer.h"
 #include "core/crypto/key_manager.h"
@@ -14,18 +15,20 @@ namespace Core::Crypto {
 // Sits on top of a VirtualFile and provides CTR-mode AES decription.
 class CTREncryptionLayer : public EncryptionLayer {
 public:
+    using IVData = std::array<u8, 16>;
+
     CTREncryptionLayer(FileSys::VirtualFile base, Key128 key, std::size_t base_offset);
 
     std::size_t Read(u8* data, std::size_t length, std::size_t offset) const override;
 
-    void SetIV(const std::vector<u8>& iv);
+    void SetIV(const IVData& iv);
 
 private:
     std::size_t base_offset;
 
     // Must be mutable as operations modify cipher contexts.
     mutable AESCipher<Key128> cipher;
-    mutable std::vector<u8> iv;
+    mutable IVData iv{};
 
     void UpdateIV(std::size_t offset) const;
 };

src/core/crypto/partition_data_manager.cpp

@@ -346,10 +346,9 @@ FileSys::VirtualFile PartitionDataManager::GetPackage2Raw(Package2Type type) con
 }
 
 static bool AttemptDecrypt(const std::array<u8, 16>& key, Package2Header& header) {
-    const std::vector<u8> iv(header.header_ctr.begin(), header.header_ctr.end());
     Package2Header temp = header;
     AESCipher<Key128> cipher(key, Mode::CTR);
-    cipher.SetIV(iv);
+    cipher.SetIV(header.header_ctr);
     cipher.Transcode(&temp.header_ctr, sizeof(Package2Header) - 0x100, &temp.header_ctr,
                      Op::Decrypt);
     if (temp.magic == Common::MakeMagic('P', 'K', '2', '1')) {
@@ -388,7 +387,7 @@ void PartitionDataManager::DecryptPackage2(const std::array<Key128, 0x20>& packa
     auto c = a->ReadAllBytes();
 
     AESCipher<Key128> cipher(package2_keys[revision], Mode::CTR);
-    cipher.SetIV({header.section_ctr[1].begin(), header.section_ctr[1].end()});
+    cipher.SetIV(header.section_ctr[1]);
     cipher.Transcode(c.data(), c.size(), c.data(), Op::Decrypt);
 
     const auto ini_file = std::make_shared<FileSys::VectorVfsFile>(c);

src/core/file_sys/content_archive.cpp

@@ -495,9 +495,10 @@ VirtualFile NCA::Decrypt(const NCASectionHeader& s_header, VirtualFile in, u64 s
 
             auto out = std::make_shared<Core::Crypto::CTREncryptionLayer>(std::move(in), *key,
                                                                           starting_offset);
-            std::vector<u8> iv(16);
-            for (u8 i = 0; i < 8; ++i)
-                iv[i] = s_header.raw.section_ctr[0x8 - i - 1];
+            Core::Crypto::CTREncryptionLayer::IVData iv{};
+            for (std::size_t i = 0; i < 8; ++i) {
+                iv[i] = s_header.raw.section_ctr[8 - i - 1];
+            }
             out->SetIV(iv);
             return std::static_pointer_cast<VfsFile>(out);
         }

src/core/file_sys/nca_patch.cpp

@@ -3,6 +3,7 @@
 // Refer to the license.txt file included.
 
 #include <algorithm>
+#include <array>
 #include <cstddef>
 #include <cstring>
 
@@ -66,7 +67,7 @@ std::size_t BKTR::Read(u8* data, std::size_t length, std::size_t offset) const {
     Core::Crypto::AESCipher<Core::Crypto::Key128> cipher(key, Core::Crypto::Mode::CTR);
 
     // Calculate AES IV
-    std::vector<u8> iv(16);
+    std::array<u8, 16> iv{};
     auto subsection_ctr = subsection.ctr;
     auto offset_iv = section_offset + base_offset;
     for (std::size_t i = 0; i < section_ctr.size(); ++i)