src/base/unverified_aes256.h

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#ifndef MOZC_BASE_UNVERIFIED_AES256_H_
#define MOZC_BASE_UNVERIFIED_AES256_H_

#include "base/port.h"

namespace mozc {
namespace internal {

// Note that this implemenation is kept just for the backward compatibility
// so that we can read previously obfuscated data.
// !!! Not FIPS-certified.
// !!! Performance optimization is not well considered.
// !!! Side-channel attack is not well considered.
// TODO(team): Consider to remove this class and stop doing obfuscation.
class UnverifiedAES256 {
 public:
  static const size_t kKeyBytes = 32;    // 256 bit
  static const size_t kBlockBytes = 16;  // 128 bit
  static const size_t kKeyScheduleBytes = 240;

  // Does AES256 CBC transformation.
  // CAVEATS: See the above comment.
  static void TransformCBC(const uint8 (&key)[kKeyBytes],
                           const uint8 (&iv)[kBlockBytes],
                           uint8 *buffer,
                           size_t block_count);

  // Does AES256 CBC inverse transformation.
  // CAVEATS: See the above comment.
  static void InverseTransformCBC(const uint8 (&key)[kKeyBytes],
                                  const uint8 (&iv)[kBlockBytes],
                                  uint8 *buffer,
                                  size_t block_count);

 protected:
  // Does AES256 ECB transformation.
  // CAVEATS: See the above comment.
  static void TransformECB(const uint8 (&w)[kKeyScheduleBytes],
                           uint8 buffer[kBlockBytes]);

  // Does AES256 ECB inverse transformation.
  // CAVEATS: See the above comment.
  static void InverseTransformECB(const uint8 (&w)[kKeyScheduleBytes],
                                  uint8 buffer[kBlockBytes]);

  // Declared as protected for unit test.
  static void MakeKeySchedule(const uint8 (&key)[kKeyBytes],
                              uint8 w[kKeyScheduleBytes]);
  static void SubBytes(uint8 buf[kBlockBytes]);
  static void InvSubBytes(uint8 buf[kBlockBytes]);
  static void MixColumns(uint8 buf[kBlockBytes]);
  static void InvMixColumns(uint8 buf[kBlockBytes]);
  static void ShiftRows(uint8 buf[kBlockBytes]);
  static void InvShiftRows(uint8 buf[kBlockBytes]);

 private:
  DISALLOW_IMPLICIT_CONSTRUCTORS(UnverifiedAES256);
};

}  // namespace internal
}  // namespace mozc

#endif  // MOZC_BASE_UNVERIFIED_AES256_H_