| // Copyright 2017 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/ecies_hkdf_sender_kem_boringssl.h" |
| |
| #include <string> |
| #include <utility> |
| |
| #include "absl/memory/memory.h" |
| #include "absl/status/status.h" |
| #include "absl/strings/string_view.h" |
| #include "openssl/bn.h" |
| #include "openssl/evp.h" |
| #include "tink/internal/ec_util.h" |
| #include "tink/internal/ssl_unique_ptr.h" |
| #include "tink/subtle/common_enums.h" |
| #include "tink/subtle/hkdf.h" |
| #include "tink/util/secret_data.h" |
| |
| namespace crypto { |
| namespace tink { |
| namespace subtle { |
| |
| // static |
| util::StatusOr<std::unique_ptr<const EciesHkdfSenderKemBoringSsl>> |
| EciesHkdfSenderKemBoringSsl::New(subtle::EllipticCurveType curve, |
| const std::string& pubx, |
| const std::string& puby) { |
| switch (curve) { |
| case EllipticCurveType::NIST_P256: |
| case EllipticCurveType::NIST_P384: |
| case EllipticCurveType::NIST_P521: |
| return EciesHkdfNistPCurveSendKemBoringSsl::New(curve, pubx, puby); |
| case EllipticCurveType::CURVE25519: |
| return EciesHkdfX25519SendKemBoringSsl::New(curve, pubx, puby); |
| default: |
| return util::Status(absl::StatusCode::kUnimplemented, |
| "Unsupported elliptic curve"); |
| } |
| } |
| |
| EciesHkdfNistPCurveSendKemBoringSsl::EciesHkdfNistPCurveSendKemBoringSsl( |
| subtle::EllipticCurveType curve, const std::string& pubx, |
| const std::string& puby, internal::SslUniquePtr<EC_POINT> peer_pub_key) |
| : curve_(curve), |
| pubx_(pubx), |
| puby_(puby), |
| peer_pub_key_(std::move(peer_pub_key)) {} |
| |
| // static |
| util::StatusOr<std::unique_ptr<const EciesHkdfSenderKemBoringSsl>> |
| EciesHkdfNistPCurveSendKemBoringSsl::New(subtle::EllipticCurveType curve, |
| const std::string& pubx, |
| const std::string& puby) { |
| auto status = |
| internal::CheckFipsCompatibility<EciesHkdfNistPCurveSendKemBoringSsl>(); |
| if (!status.ok()) return status; |
| |
| auto status_or_ec_point = internal::GetEcPoint(curve, pubx, puby); |
| if (!status_or_ec_point.ok()) return status_or_ec_point.status(); |
| std::unique_ptr<const EciesHkdfSenderKemBoringSsl> sender_kem( |
| new EciesHkdfNistPCurveSendKemBoringSsl( |
| curve, pubx, puby, std::move(status_or_ec_point.value()))); |
| return std::move(sender_kem); |
| } |
| |
| util::StatusOr<std::unique_ptr<const EciesHkdfSenderKemBoringSsl::KemKey>> |
| EciesHkdfNistPCurveSendKemBoringSsl::GenerateKey( |
| subtle::HashType hash, absl::string_view hkdf_salt, |
| absl::string_view hkdf_info, uint32_t key_size_in_bytes, |
| subtle::EcPointFormat point_format) const { |
| if (peer_pub_key_.get() == nullptr) { |
| return util::Status(absl::StatusCode::kInternal, |
| "peer_pub_key_ wasn't initialized"); |
| } |
| |
| auto status_or_ec_group = internal::EcGroupFromCurveType(curve_); |
| if (!status_or_ec_group.ok()) { |
| return status_or_ec_group.status(); |
| } |
| internal::SslUniquePtr<EC_GROUP> group = |
| std::move(status_or_ec_group.value()); |
| internal::SslUniquePtr<EC_KEY> ephemeral_key(EC_KEY_new()); |
| if (1 != EC_KEY_set_group(ephemeral_key.get(), group.get())) { |
| return util::Status(absl::StatusCode::kInternal, "EC_KEY_set_group failed"); |
| } |
| if (1 != EC_KEY_generate_key(ephemeral_key.get())) { |
| return util::Status(absl::StatusCode::kInternal, |
| "EC_KEY_generate_key failed"); |
| } |
| const BIGNUM* ephemeral_priv = EC_KEY_get0_private_key(ephemeral_key.get()); |
| const EC_POINT* ephemeral_pub = EC_KEY_get0_public_key(ephemeral_key.get()); |
| auto status_or_string_kem = |
| internal::EcPointEncode(curve_, point_format, ephemeral_pub); |
| if (!status_or_string_kem.ok()) { |
| return status_or_string_kem.status(); |
| } |
| std::string kem_bytes = status_or_string_kem.value(); |
| auto status_or_string_shared_secret = internal::ComputeEcdhSharedSecret( |
| curve_, ephemeral_priv, peer_pub_key_.get()); |
| if (!status_or_string_shared_secret.ok()) { |
| return status_or_string_shared_secret.status(); |
| } |
| util::SecretData shared_secret = status_or_string_shared_secret.value(); |
| auto symmetric_key_or = Hkdf::ComputeEciesHkdfSymmetricKey( |
| hash, kem_bytes, shared_secret, hkdf_salt, hkdf_info, key_size_in_bytes); |
| if (!symmetric_key_or.ok()) { |
| return symmetric_key_or.status(); |
| } |
| util::SecretData symmetric_key = symmetric_key_or.value(); |
| return absl::make_unique<const KemKey>(std::move(kem_bytes), |
| std::move(symmetric_key)); |
| } |
| |
| EciesHkdfX25519SendKemBoringSsl::EciesHkdfX25519SendKemBoringSsl( |
| internal::SslUniquePtr<EVP_PKEY> peer_public_key) |
| : peer_public_key_(std::move(peer_public_key)) {} |
| |
| // static |
| util::StatusOr<std::unique_ptr<const EciesHkdfSenderKemBoringSsl>> |
| EciesHkdfX25519SendKemBoringSsl::New(subtle::EllipticCurveType curve, |
| const std::string& pubx, |
| const std::string& puby) { |
| auto status = |
| internal::CheckFipsCompatibility<EciesHkdfX25519SendKemBoringSsl>(); |
| if (!status.ok()) return status; |
| |
| if (curve != CURVE25519) { |
| return util::Status(absl::StatusCode::kInvalidArgument, |
| "curve is not CURVE25519"); |
| } |
| if (pubx.size() != internal::X25519KeyPubKeySize()) { |
| return util::Status(absl::StatusCode::kInvalidArgument, |
| "pubx has unexpected length"); |
| } |
| if (!puby.empty()) { |
| return util::Status(absl::StatusCode::kInvalidArgument, |
| "puby is not empty"); |
| } |
| |
| internal::SslUniquePtr<EVP_PKEY> peer_public_key(EVP_PKEY_new_raw_public_key( |
| /*type=*/EVP_PKEY_X25519, /*unused=*/nullptr, |
| /*in=*/reinterpret_cast<const uint8_t*>(pubx.data()), |
| /*len=*/internal::Ed25519KeyPubKeySize())); |
| if (peer_public_key == nullptr) { |
| return util::Status(absl::StatusCode::kInternal, |
| "EVP_PKEY_new_raw_public_key failed"); |
| } |
| std::unique_ptr<const EciesHkdfSenderKemBoringSsl> sender_kem( |
| new EciesHkdfX25519SendKemBoringSsl(std::move(peer_public_key))); |
| return std::move(sender_kem); |
| } |
| |
| util::StatusOr<std::unique_ptr<const EciesHkdfSenderKemBoringSsl::KemKey>> |
| EciesHkdfX25519SendKemBoringSsl::GenerateKey( |
| subtle::HashType hash, absl::string_view hkdf_salt, |
| absl::string_view hkdf_info, uint32_t key_size_in_bytes, |
| subtle::EcPointFormat point_format) const { |
| if (point_format != EcPointFormat::COMPRESSED) { |
| return util::Status( |
| absl::StatusCode::kInvalidArgument, |
| "X25519 only supports compressed elliptic curve points"); |
| } |
| |
| // Generate an ephemeral key pair; the public key is the KEM key to use. |
| util::StatusOr<std::unique_ptr<internal::X25519Key>> ephemeral_key = |
| internal::NewX25519Key(); |
| |
| internal::SslUniquePtr<EVP_PKEY> ssl_priv_key(EVP_PKEY_new_raw_private_key( |
| /*type=*/EVP_PKEY_X25519, /*unused=*/nullptr, |
| /*in=*/(*ephemeral_key)->private_key, |
| /*len=*/internal::Ed25519KeyPrivKeySize())); |
| if (ssl_priv_key == nullptr) { |
| return util::Status(absl::StatusCode::kInternal, |
| "EVP_PKEY_new_raw_private_key failed"); |
| } |
| |
| util::StatusOr<util::SecretData> shared_secret = |
| internal::ComputeX25519SharedSecret(ssl_priv_key.get(), |
| peer_public_key_.get()); |
| |
| auto public_key = absl::string_view( |
| reinterpret_cast<const char*>((*ephemeral_key)->public_value), |
| internal::X25519KeyPubKeySize()); |
| |
| util::StatusOr<util::SecretData> symmetric_key_or = |
| Hkdf::ComputeEciesHkdfSymmetricKey(hash, public_key, *shared_secret, |
| hkdf_salt, hkdf_info, |
| key_size_in_bytes); |
| if (!symmetric_key_or.ok()) { |
| return symmetric_key_or.status(); |
| } |
| util::SecretData symmetric_key = *symmetric_key_or; |
| return absl::make_unique<const KemKey>(std::string(public_key), |
| symmetric_key); |
| } |
| |
| } // namespace subtle |
| } // namespace tink |
| } // namespace crypto |
