sw/device/tests/aes_entropy_test.c

// Copyright lowRISC contributors.
// Licensed under the Apache License, Version 2.0, see LICENSE for details.
// SPDX-License-Identifier: Apache-2.0

#include "hw/ip/aes/model/aes_modes.h"
#include "sw/device/lib/base/memory.h"
#include "sw/device/lib/base/mmio.h"
#include "sw/device/lib/dif/dif_aes.h"
#include "sw/device/lib/runtime/log.h"
#include "sw/device/lib/testing/aes_testutils.h"
#include "sw/device/lib/testing/entropy_testutils.h"
#include "sw/device/lib/testing/test_framework/check.h"
#include "sw/device/lib/testing/test_framework/ottf_main.h"

#include "hw/top_earlgrey/sw/autogen/top_earlgrey.h"

#define TIMEOUT (1000 * 1000)

// The mask share, used to mask kKey. Note that the masking should not be done
// manually. Software is expected to get the key in two shares right from the
// beginning.
static const uint8_t kKeyShare1[] = {
    0x0f, 0x1f, 0x2f, 0x3f, 0x4f, 0x5f, 0x6f, 0x7f, 0x8f, 0x9f, 0xaf,
    0xbf, 0xcf, 0xdf, 0xef, 0xff, 0x0a, 0x1a, 0x2a, 0x3a, 0x4a, 0x5a,
    0x6a, 0x7a, 0x8a, 0x9a, 0xaa, 0xba, 0xca, 0xda, 0xea, 0xfa,
};

OTTF_DEFINE_TEST_CONFIG();

bool test_main(void) {
  dif_aes_t aes;

  // Initialise AES.
  CHECK_DIF_OK(
      dif_aes_init(mmio_region_from_addr(TOP_EARLGREY_AES_BASE_ADDR), &aes));
  CHECK_DIF_OK(dif_aes_reset(&aes));

  // Mask the key. Note that this should not be done manually. Software is
  // expected to get the key in two shares right from the beginning.
  uint8_t key_share0[sizeof(kAesModesKey256)];
  for (int i = 0; i < sizeof(kAesModesKey256); ++i) {
    key_share0[i] = kAesModesKey256[i] ^ kKeyShare1[i];
  }

  // "Convert" key share byte arrays to `dif_aes_key_share_t`.
  dif_aes_key_share_t key;
  memcpy(key.share0, key_share0, sizeof(key.share0));
  memcpy(key.share1, kKeyShare1, sizeof(key.share1));

  // "Convert" iv byte arrays to `dif_aes_iv_t`.
  dif_aes_iv_t iv;
  memcpy(iv.iv, kAesModesIvCbc, sizeof(iv.iv));

  // Setup CBC encryption transaction.
  dif_aes_transaction_t transaction = {
      .operation = kDifAesOperationEncrypt,
      .mode = kDifAesModeCbc,
      .key_len = kDifAesKey256,
      .key_provider = kDifAesKeySoftwareProvided,
      .mask_reseeding = kDifAesReseedPerBlock,
      .manual_operation = kDifAesManualOperationManual,
      .reseed_on_key_change = false,
      .ctrl_aux_lock = false,
  };

  // Write the initial key share, IV and data in CSRs (known combinations).
  CHECK_DIF_OK(dif_aes_start(&aes, &transaction, &key, &iv));
  dif_aes_data_t in_data_plain;
  memcpy(in_data_plain.data, kAesModesPlainText, sizeof(in_data_plain.data));
  AES_TESTUTILS_WAIT_FOR_STATUS(&aes, kDifAesStatusInputReady, true, TIMEOUT);
  CHECK_DIF_OK(dif_aes_load_data(&aes, in_data_plain));

  // Write the PRNG_RESEED bit to reseed the internal state of the PRNG.
  CHECK_DIF_OK(dif_aes_trigger(&aes, kDifAesTriggerPrngReseed));

  // Trigger the AES operation to run and wait for it to complete.
  CHECK_DIF_OK(dif_aes_trigger(&aes, kDifAesTriggerStart));
  AES_TESTUTILS_WAIT_FOR_STATUS(&aes, kDifAesStatusOutputValid, true, TIMEOUT);

  // Check the ciphertext against the expected value.
  dif_aes_data_t out_data;
  CHECK_DIF_OK(dif_aes_read_output(&aes, &out_data));
  CHECK_ARRAYS_EQ((uint8_t *)out_data.data, kAesModesCipherTextCbc256,
                  sizeof(out_data.data));

  // Write the KEY_IV_DATA_IN_CLEAR and DATA_OUT_CLEAR trigger bits to 1 and
  // wait for it to complete by polling the status idle bit.
  CHECK_DIF_OK(dif_aes_trigger(&aes, kDifAesTriggerDataOutClear));
  CHECK_DIF_OK(dif_aes_trigger(&aes, kDifAesTriggerKeyIvDataInClear));
  AES_TESTUTILS_WAIT_FOR_STATUS(&aes, kDifAesStatusIdle, true, TIMEOUT);

  // Read back the data out CSRs - they should all read garbage values.
  CHECK(dif_aes_read_output(&aes, &out_data) == kDifError);
  CHECK(!aes_testutils_get_status(&aes, kDifAesStatusOutputValid));

  // Assertion check verifies that the internal states (data_in, key share and
  // IV are also garbage, i.e. different from the originally written values.
  CHECK_DIF_OK(dif_aes_read_iv(&aes, &iv));
  CHECK_ARRAYS_NE((uint8_t *)iv.iv, kAesModesIvCbc, sizeof(kAesModesIvCbc));

  CHECK_DIF_OK(dif_aes_end(&aes));
  return true;
}