Use AlignmentBuffer<> for MDx_HashFunction

randombit · Sep 12, 2023 · 53a1765 · 53a1765
1 parent 78c09ba
commit 53a1765
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Showing 2 changed files with 26 additions and 34 deletions.
diff --git a/src/lib/hash/mdx_hash/mdx_hash.cpp b/src/lib/hash/mdx_hash/mdx_hash.cpp
@@ -23,8 +23,7 @@ MDx_HashFunction::MDx_HashFunction(size_t block_len, bool byte_big_endian, bool
       m_block_bits(ceil_log2(block_len)),
       m_count_big_endian(byte_big_endian),
       m_count(0),
-      m_buffer(block_len),
-      m_position(0) {
+      m_buffer(block_len) {
    if(!is_power_of_2(block_len)) {
       throw Invalid_Argument("MDx_HashFunction block length must be a power of 2");
    }
@@ -40,8 +39,8 @@ MDx_HashFunction::MDx_HashFunction(size_t block_len, bool byte_big_endian, bool
 * Clear memory of sensitive data
 */
 void MDx_HashFunction::clear() {
-   zeroise(m_buffer);
-   m_count = m_position = 0;
+   m_buffer.clear();
+   m_count = 0;
 }
 
 /*
@@ -50,57 +49,49 @@ void MDx_HashFunction::clear() {
 void MDx_HashFunction::add_data(std::span<const uint8_t> input) {
    const size_t block_len = static_cast<size_t>(1) << m_block_bits;
 
-   m_count += input.size();
-
-   if(m_position) {
-      buffer_insert(m_buffer, m_position, input.data(), input.size());
+   BufferSlicer in(input);
 
-      if(m_position + input.size() >= block_len) {
-         compress_n(m_buffer.data(), 1);
-         input = input.last(input.size() - block_len + m_position);
-         m_position = 0;
+   while(!in.empty()) {
+      if(m_buffer.store_unaligned_data(in); m_buffer.ready_to_consume()) {
+         compress_n(m_buffer.take().data(), 1);
       }
-   }
-
-   // Just in case the compiler can't figure out block_len is a power of 2
-   const size_t full_blocks = input.size() >> m_block_bits;
 
-   BufferSlicer in(input);
-   if(full_blocks > 0) {
-      compress_n(in.take(full_blocks * block_len).data(), full_blocks);
+      if(m_buffer.in_alignment()) {
+         // Just in case the compiler can't figure out block_len is a power of 2
+         const size_t full_blocks = in.remaining() >> m_block_bits;
+         if(full_blocks > 0) {
+            compress_n(in.take(full_blocks * block_len).data(), full_blocks);
+         }
+      }
    }
 
-   const auto remaining = in.take(in.remaining());
-   buffer_insert(m_buffer, m_position, remaining.data(), remaining.size());
-   m_position += remaining.size();
+   m_count += input.size();
 }
 
 /*
 * Finalize a hash
 */
 void MDx_HashFunction::final_result(std::span<uint8_t> output) {
-   const size_t block_len = static_cast<size_t>(1) << m_block_bits;
-
-   clear_mem(&m_buffer[m_position], block_len - m_position);
-   m_buffer[m_position] = m_pad_char;
+   m_buffer.append({&m_pad_char, 1});
 
-   if(m_position >= block_len - m_counter_size) {
-      compress_n(m_buffer.data(), 1);
-      zeroise(m_buffer);
+   if(m_buffer.elements_until_alignment() < m_counter_size) {
+      m_buffer.fill_up_with_zeros();
+      compress_n(m_buffer.take().data(), 1);
    }
 
    BOTAN_ASSERT_NOMSG(m_counter_size <= output_length());
    BOTAN_ASSERT_NOMSG(m_counter_size >= 8);
 
    const uint64_t bit_count = m_count * 8;
 
+   m_buffer.fill_up_with_zeros();
    if(m_count_big_endian) {
-      store_be(bit_count, &m_buffer[block_len - 8]);
+      store_be(bit_count, m_buffer.directly_modify_last(8).data());
    } else {
-      store_le(bit_count, &m_buffer[block_len - 8]);
+      store_le(bit_count, m_buffer.directly_modify_last(8).data());
    }
 
-   compress_n(m_buffer.data(), 1);
+   compress_n(m_buffer.take().data(), 1);
    copy_out(output.data());
    clear();
 }

diff --git a/src/lib/hash/mdx_hash/mdx_hash.h b/src/lib/hash/mdx_hash/mdx_hash.h
@@ -10,6 +10,8 @@
 
 #include <botan/hash.h>
 
+#include <botan/internal/alignment_buffer.h>
+
 namespace Botan {
 
 /**
@@ -54,8 +56,7 @@ class MDx_HashFunction : public HashFunction {
       const bool m_count_big_endian;
 
       uint64_t m_count;
-      secure_vector<uint8_t> m_buffer;
-      size_t m_position;
+      AlignmentBuffer<secure_vector<uint8_t>> m_buffer;
 };
 
 }  // namespace Botan