From c68481052a88ab1749aed9c4f6a801936d04a276 Mon Sep 17 00:00:00 2001
From: levlam <levlam@telegram.org>
Date: Sat, 13 Jun 2020 04:45:40 +0300
Subject: [PATCH] AES CTR improvements.

GitOrigin-RevId: c4ed8fdc883fdf7cc2ed10334d3bb9487d590d41
---
 benchmark/bench_crypto.cpp  |  2 +-
 tdutils/td/utils/crypto.cpp | 18 ++++++++++--------
 tdutils/td/utils/crypto.h   |  2 +-
 3 files changed, 12 insertions(+), 10 deletions(-)

diff --git a/benchmark/bench_crypto.cpp b/benchmark/bench_crypto.cpp
index 0b313b43a..e861914c5 100644
--- a/benchmark/bench_crypto.cpp
+++ b/benchmark/bench_crypto.cpp
@@ -73,7 +73,7 @@ class AesEcbBench : public td::Benchmark {
     for (int i = 0; i <= n; i++) {
       size_t step = 16;
       for (size_t offset = 0; offset + step <= data_slice.size(); offset += step) {
-        state.encrypt(data_slice.ubegin() + offset, data_slice.ubegin() + offset, (int)step);
+        state.encrypt(data_slice.ubegin() + offset, data_slice.ubegin() + offset, static_cast<int>(step));
       }
     }
   }
diff --git a/tdutils/td/utils/crypto.cpp b/tdutils/td/utils/crypto.cpp
index 175bb79f6..4908eecda 100644
--- a/tdutils/td/utils/crypto.cpp
+++ b/tdutils/td/utils/crypto.cpp
@@ -382,8 +382,8 @@ class AesCtrState::Impl {
     auto n = from.size();
     while (n != 0) {
       if (current.empty()) {
-        if (N != 1) {
-          counter.as_mutable_slice().copy_from(counter.as_slice().substr((N - 1) * AES_BLOCK_SIZE));
+        if (BLOCK_COUNT != 1) {
+          counter.as_mutable_slice().copy_from(counter.as_slice().substr((BLOCK_COUNT - 1) * AES_BLOCK_SIZE));
         }
         inc(counter.as_mutable_slice().ubegin());
         fill();
@@ -403,9 +403,9 @@ class AesCtrState::Impl {
  private:
   AesState aes_state;
 
-  static constexpr size_t N = 32;
-  SecureString counter{AES_BLOCK_SIZE * N};
-  SecureString encrypted_counter{AES_BLOCK_SIZE * N};
+  static constexpr size_t BLOCK_COUNT = 32;
+  SecureString counter{AES_BLOCK_SIZE * BLOCK_COUNT};
+  SecureString encrypted_counter{AES_BLOCK_SIZE * BLOCK_COUNT};
   Slice current;
 
   void inc(uint8 *ptr) {
@@ -415,17 +415,19 @@ class AesCtrState::Impl {
       }
     }
   }
+
   void fill() {
     auto *src = counter.as_slice().ubegin();
     auto *dst = counter.as_mutable_slice().ubegin() + AES_BLOCK_SIZE;
-    for (size_t i = 0; i + 1 < N; i++) {
-      memcpy(dst, src, AES_BLOCK_SIZE);
+    for (size_t i = 0; i + 1 < BLOCK_COUNT; i++) {
+      std::memcpy(dst, src, AES_BLOCK_SIZE);
       inc(dst);
       src += AES_BLOCK_SIZE;
       dst += AES_BLOCK_SIZE;
     }
 
-    aes_state.encrypt(counter.as_slice().ubegin(), encrypted_counter.as_mutable_slice().ubegin(), (int)counter.size());
+    aes_state.encrypt(counter.as_slice().ubegin(), encrypted_counter.as_mutable_slice().ubegin(),
+                      static_cast<int>(counter.size()));
     current = encrypted_counter.as_slice();
   }
 };
diff --git a/tdutils/td/utils/crypto.h b/tdutils/td/utils/crypto.h
index 2996e72d2..c97ad4c22 100644
--- a/tdutils/td/utils/crypto.h
+++ b/tdutils/td/utils/crypto.h
@@ -19,7 +19,7 @@ uint64 pq_factorize(uint64 pq);
 #if TD_HAVE_OPENSSL
 void init_crypto();
 
-struct AesState {
+class AesState {
  public:
   AesState();
   AesState(const AesState &from) = delete;