// Copyright 2018 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
///////////////////////////////////////////////////////////////////////////////

#include "tink/subtle/rsa_ssa_pss_verify_boringssl.h"

#include <memory>
#include <string>
#include <utility>

#include "gtest/gtest.h"
#include "absl/status/status.h"
#include "absl/strings/escaping.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/str_split.h"
#include "absl/strings/string_view.h"
#include "openssl/bn.h"
#include "include/rapidjson/document.h"
#include "tink/config/tink_fips.h"
#include "tink/internal/err_util.h"
#include "tink/internal/rsa_util.h"
#include "tink/internal/ssl_unique_ptr.h"
#include "tink/public_key_sign.h"
#include "tink/public_key_verify.h"
#include "tink/subtle/common_enums.h"
#include "tink/subtle/wycheproof_util.h"
#include "tink/util/status.h"
#include "tink/util/statusor.h"
#include "tink/util/test_matchers.h"

// TODO(quannguyen):
//  + Add tests for parameters validation.
namespace crypto {
namespace tink {
namespace subtle {
namespace {

using ::crypto::tink::test::IsOk;
using ::crypto::tink::test::StatusIs;
using ::testing::TestParamInfo;
using ::testing::ValuesIn;

// Test vector from
// https://csrc.nist.gov/Projects/Cryptographic-Algorithm-Validation-Program/Digital-Signatures
struct NistTestVector {
  std::string n;
  std::string e;
  std::string message;
  std::string signature;
  HashType sig_hash;
  HashType mgf1_hash;
  int salt_length;
};

const NistTestVector GetNistTestVector() {
  NistTestVector test_vector = {
      absl::HexStringToBytes(
          "a47d04e7cacdba4ea26eca8a4c6e14563c2ce03b623b768c0d49868a57121301dbf7"
          "83d82f4c055e73960e70550187d0af62ac3496f0a3d9103c2eb7919a72752fa7ce8c"
          "688d81e3aee99468887a15288afbb7acb845b7c522b5c64e678fcd3d22feb84b4427"
          "2700be527d2b2025a3f83c2383bf6a39cf5b4e48b3cf2f56eef0dfff18555e31037b"
          "915248694876f3047814415164f2c660881e694b58c28038a032ad25634aad7b3917"
          "1dee368e3d59bfb7299e4601d4587e68caaf8db457b75af42fc0cf1ae7caced286d7"
          "7fac6cedb03ad94f1433d2c94d08e60bc1fdef0543cd2951e765b38230fdd18de5d2"
          "ca627ddc032fe05bbd2ff21e2db1c2f94d8b"),
      absl::HexStringToBytes("10e43f"),
      absl::HexStringToBytes(
          "e002377affb04f0fe4598de9d92d31d6c786040d5776976556a2cfc55e54a1dcb3cb"
          "1b126bd6a4bed2a184990ccea773fcc79d246553e6c64f686d21ad4152673cafec22"
          "aeb40f6a084e8a5b4991f4c64cf8a927effd0fd775e71e8329e41fdd4457b3911173"
          "187b4f09a817d79ea2397fc12dfe3d9c9a0290c8ead31b6690a6"),
      absl::HexStringToBytes(
          "4f9b425c2058460e4ab2f5c96384da2327fd29150f01955a76b4efe956af06dc0877"
          "9a374ee4607eab61a93adc5608f4ec36e47f2a0f754e8ff839a8a19b1db1e884ea4c"
          "f348cd455069eb87afd53645b44e28a0a56808f5031da5ba9112768dfbfca44ebe63"
          "a0c0572b731d66122fb71609be1480faa4e4f75e43955159d70f081e2a32fbb19a48"
          "b9f162cf6b2fb445d2d6994bc58910a26b5943477803cdaaa1bd74b0da0a5d053d8b"
          "1dc593091db5388383c26079f344e2aea600d0e324164b450f7b9b465111b7265f3b"
          "1b063089ae7e2623fc0fda8052cf4bf3379102fbf71d7c98e8258664ceed637d20f9"
          "5ff0111881e650ce61f251d9c3a629ef222d"),
      HashType::SHA256,
      HashType::SHA256,
      32,
  };
  return test_vector;
}

TEST(RsaSsaPssVerifyBoringSslTest, BasicVerify) {
  if (IsFipsModeEnabled()) {
    GTEST_SKIP() << "Test not run in FIPS-only mode";
  }
  const NistTestVector kNistTestVector = GetNistTestVector();
  internal::RsaPublicKey pub_key{kNistTestVector.n, kNistTestVector.e};
  internal::RsaSsaPssParams params = {
      kNistTestVector.sig_hash,
      kNistTestVector.mgf1_hash,
      kNistTestVector.salt_length,
  };

  util::StatusOr<std::unique_ptr<RsaSsaPssVerifyBoringSsl>> verifier =
      RsaSsaPssVerifyBoringSsl::New(pub_key, params);
  ASSERT_THAT(verifier, IsOk());
  util::Status status =
      (*verifier)->Verify(kNistTestVector.signature, kNistTestVector.message);
  EXPECT_TRUE(status.ok()) << status << internal::GetSslErrors();
}

TEST(RsaSsaPssVerifyBoringSslTest, NewErrors) {
  if (IsFipsModeEnabled()) {
    GTEST_SKIP() << "Test not run in FIPS-only mode";
  }
  const NistTestVector kNistTestVector = GetNistTestVector();
  internal::RsaPublicKey nist_pub_key{kNistTestVector.n, kNistTestVector.e};
  internal::RsaSsaPssParams nist_params = {
      kNistTestVector.sig_hash,
      kNistTestVector.mgf1_hash,
      kNistTestVector.salt_length,
  };
  internal::RsaPublicKey small_pub_key{std::string("\x23"), std::string("\x3")};
  internal::RsaSsaPssParams sha1_hash_params = {
      HashType::SHA1, kNistTestVector.mgf1_hash, kNistTestVector.salt_length};

  {  // Small modulus.
    auto result = RsaSsaPssVerifyBoringSsl::New(small_pub_key, nist_params);
    EXPECT_FALSE(result.ok());
    EXPECT_EQ(absl::StatusCode::kInvalidArgument, result.status().code());
    EXPECT_PRED_FORMAT2(testing::IsSubstring,
                        "only modulus size >= 2048-bit is supported",
                        std::string(result.status().message()));
  }

  {  // Use SHA1 for digital signature.
    auto result = RsaSsaPssVerifyBoringSsl::New(nist_pub_key, sha1_hash_params);
    EXPECT_FALSE(result.ok());
    EXPECT_EQ(absl::StatusCode::kInvalidArgument, result.status().code());
    EXPECT_PRED_FORMAT2(testing::IsSubstring,
                        "SHA1 is not safe for digital signature",
                        std::string(result.status().message()));
  }
}

TEST(RsaSsaPssVerifyBoringSslTest, Modification) {
  if (IsFipsModeEnabled()) {
    GTEST_SKIP() << "Test not run in FIPS-only mode";
  }
  const NistTestVector kNistTestVector = GetNistTestVector();
  internal::RsaPublicKey pub_key{kNistTestVector.n, kNistTestVector.e};
  internal::RsaSsaPssParams params = {
      kNistTestVector.sig_hash,
      kNistTestVector.mgf1_hash,
      kNistTestVector.salt_length,
  };

  util::StatusOr<std::unique_ptr<RsaSsaPssVerifyBoringSsl>> verifier =
      RsaSsaPssVerifyBoringSsl::New(pub_key, params);
  ASSERT_THAT(verifier, IsOk());
  // Modify the message.
  for (std::size_t i = 0; i < kNistTestVector.message.length(); i++) {
    std::string modified_message = kNistTestVector.message;
    modified_message[i / 8] ^= 1 << (i % 8);
    util::Status status =
        (*verifier)->Verify(kNistTestVector.signature, modified_message);
    EXPECT_FALSE(status.ok()) << status << internal::GetSslErrors();
  }
  // Modify the signature.
  for (std::size_t i = 0; i < kNistTestVector.signature.length(); i++) {
    std::string modified_signature = kNistTestVector.signature;
    modified_signature[i / 8] ^= 1 << (i % 8);
    util::Status status =
        (*verifier)->Verify(modified_signature, kNistTestVector.message);
    EXPECT_FALSE(status.ok()) << status << internal::GetSslErrors();
  }
  // Truncate the signature.
  for (std::size_t i = 0; i < kNistTestVector.signature.length(); i++) {
    std::string truncated_signature(kNistTestVector.signature, 0, i);
    util::Status status =
        (*verifier)->Verify(truncated_signature, kNistTestVector.message);
    EXPECT_FALSE(status.ok()) << status << internal::GetSslErrors();
  }
}

// Wycheproof test vector for RSA-SSA PSS.
struct RsaSsaPssWycheproofTestVector {
  std::string file_name;
  internal::RsaPublicKey key;
  HashType hash_type;
  HashType mgf_hash_type;
  int salt_length;
  std::string expected;
  std::string msg;
  std::string sig;
  std::string id;
  std::string comment;
};

// Reads the RSA-SSA PSS wycheproof test vectors from a given `file_name` and
// returns a vector of RsaSsaPssWycheproofTestVector.
std::vector<RsaSsaPssWycheproofTestVector> ReadTestVectors(
    absl::string_view file_name) {
  std::vector<RsaSsaPssWycheproofTestVector> test_vectors;
  std::unique_ptr<rapidjson::Document> root =
      WycheproofUtil::ReadTestVectors(std::string(file_name));
  for (const rapidjson::Value& test_group : (*root)["testGroups"].GetArray()) {
    for (const rapidjson::Value& test : test_group["tests"].GetArray()) {
      test_vectors.push_back({
          /*file_name=*/std::string(file_name),
          /*key=*/
          {
              WycheproofUtil::GetInteger(test_group["n"]),
              WycheproofUtil::GetInteger(test_group["e"]),
          },
          /*hash_type=*/WycheproofUtil::GetHashType(test_group["sha"]),
          /*mgf_hash_type=*/WycheproofUtil::GetHashType(test_group["mgfSha"]),
          /*salt_length=*/test_group["sLen"].GetInt(),
          /*expected=*/test["result"].GetString(),
          /*msg=*/WycheproofUtil::GetBytes(test["msg"]),
          /*sig=*/WycheproofUtil::GetBytes(test["sig"]),
          /*id=*/absl::StrCat(test["tcId"].GetInt()),
          /*comment=*/test["comment"].GetString(),
      });
    }
  }
  return test_vectors;
}

// Creates a verifier using the parameters in `test_vector`.
util::StatusOr<std::unique_ptr<RsaSsaPssVerifyBoringSsl>> GetVerifier(
    const RsaSsaPssWycheproofTestVector& test_vector) {
  internal::RsaPublicKey key = test_vector.key;
  internal::RsaSsaPssParams params = {
      test_vector.hash_type,
      test_vector.mgf_hash_type,
      test_vector.salt_length,
  };
  return RsaSsaPssVerifyBoringSsl::New(key, params);
}

using RsaSsaPssWycheproofTest =
    testing::TestWithParam<RsaSsaPssWycheproofTestVector>;

// Tests signature verification using a test vector.
TEST_P(RsaSsaPssWycheproofTest, SignatureVerify) {
  if (IsFipsModeEnabled()) {
    GTEST_SKIP() << "Test not run in FIPS-only mode";
  }
  RsaSsaPssWycheproofTestVector params = GetParam();
  util::StatusOr<std::unique_ptr<RsaSsaPssVerifyBoringSsl>> verifier =
      GetVerifier(params);
  ASSERT_THAT(verifier, IsOk());
  util::Status result = (*verifier)->Verify(params.sig, params.msg);

  if (params.expected == "valid") {
    EXPECT_THAT(result, IsOk());
  } else if (params.expected == "acceptable") {
    // The validity of the signature is undefined. Hence we skip the test but we
    // log the result since we might still want to know if the library is strict
    // or forgiving.
    GTEST_SKIP() << "Verification of an acceptable signature " << params.id
                 << " resulted in: " << result;
  } else {
    EXPECT_THAT(result, testing::Not(IsOk()));
  }
}

std::vector<RsaSsaPssWycheproofTestVector> GetTestParameters() {
  std::vector<RsaSsaPssWycheproofTestVector> test_vectors = ReadTestVectors(
      /*file_name=*/"rsa_pss_2048_sha256_mgf1_0_test.json");
  std::vector<RsaSsaPssWycheproofTestVector> others = ReadTestVectors(
      /*file_name=*/"rsa_pss_2048_sha256_mgf1_32_test.json");
  test_vectors.insert(test_vectors.end(), others.begin(), others.end());
  others = ReadTestVectors(
      /*file_name=*/"rsa_pss_3072_sha256_mgf1_32_test.json");
  test_vectors.insert(test_vectors.end(), others.begin(), others.end());
  others = ReadTestVectors(
      /*file_name=*/"rsa_pss_4096_sha256_mgf1_32_test.json");
  test_vectors.insert(test_vectors.end(), others.begin(), others.end());
  others = ReadTestVectors(
      /*file_name=*/"rsa_pss_4096_sha512_mgf1_32_test.json");
  test_vectors.insert(test_vectors.end(), others.begin(), others.end());
  return test_vectors;
}

INSTANTIATE_TEST_SUITE_P(
    RsaSsaPssWycheproofTests, RsaSsaPssWycheproofTest,
    ValuesIn(GetTestParameters()),
    [](const TestParamInfo<RsaSsaPssWycheproofTest::ParamType>& info) {
      // Testcase name is partly using the test name.
      std::vector<std::string> parts =
          absl::StrSplit(info.param.file_name, ".");
      return absl::StrCat(parts[0], "_tid", info.param.id);
    });

// FIPS-only mode test
TEST(RsaSsaPssVerifyBoringSslTest, TestFipsFailWithoutBoringCrypto) {
  if (!IsFipsModeEnabled() || FIPS_mode()) {
    GTEST_SKIP()
        << "Test assumes kOnlyUseFips but BoringCrypto is unavailable.";
  }
  const NistTestVector kNistTestVector = GetNistTestVector();
  internal::RsaPublicKey pub_key{kNistTestVector.n, kNistTestVector.e};
  internal::RsaSsaPssParams params = {
      /*sig_hash=*/HashType::SHA256,
      /*mgf1_hash=*/HashType::SHA256,
      /*salt_length=*/32,
  };
  EXPECT_THAT(RsaSsaPssVerifyBoringSsl::New(pub_key, params).status(),
              StatusIs(absl::StatusCode::kInternal));
}

TEST(RsaSsaPssVerifyBoringSslTest, TestAllowedFipsModuli) {
  if (!IsFipsModeEnabled() || !FIPS_mode()) {
    GTEST_SKIP() << "Test assumes kOnlyUseFips and BoringCrypto.";
  }

  internal::SslUniquePtr<BIGNUM> rsa_f4(BN_new());
  internal::RsaPrivateKey private_key;
  internal::RsaPublicKey public_key;
  internal::RsaSsaPssParams params = {
      /*sig_hash=*/HashType::SHA256,
      /*mgf1_hash=*/HashType::SHA256,
      /*salt_length=*/32,
  };
  BN_set_word(rsa_f4.get(), RSA_F4);
  ASSERT_THAT(
      internal::NewRsaKeyPair(3072, rsa_f4.get(), &private_key, &public_key),
      IsOk());
  EXPECT_THAT(RsaSsaPssVerifyBoringSsl::New(public_key, params).status(),
              IsOk());
}

TEST(RsaSsaPssVerifyBoringSslTest, TestRestrictedFipsModuli) {
  if (!IsFipsModeEnabled() || !FIPS_mode()) {
    GTEST_SKIP() << "Test assumes kOnlyUseFips and BoringCrypto.";
  }

  internal::SslUniquePtr<BIGNUM> rsa_f4(BN_new());
  internal::RsaPrivateKey private_key;
  internal::RsaPublicKey public_key;
  internal::RsaSsaPssParams params = {
      /*sig_hash=*/HashType::SHA256,
      /*mgf1_hash=*/HashType::SHA256,
      /*salt_length=*/32,
  };
  BN_set_word(rsa_f4.get(), RSA_F4);
  ASSERT_THAT(
      internal::NewRsaKeyPair(2560, rsa_f4.get(), &private_key, &public_key),
      IsOk());
  EXPECT_THAT(RsaSsaPssVerifyBoringSsl::New(public_key, params).status(),
              StatusIs(absl::StatusCode::kInternal));

  ASSERT_THAT(
      internal::NewRsaKeyPair(4096, rsa_f4.get(), &private_key, &public_key),
      IsOk());
  EXPECT_THAT(RsaSsaPssVerifyBoringSsl::New(public_key, params).status(),
              StatusIs(absl::StatusCode::kInternal));
}

}  // namespace
}  // namespace subtle
}  // namespace tink
}  // namespace crypto