| // Copyright 2021 Google LLC |
| // |
| // 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/aead/internal/zero_copy_aead_wrapper.h" |
| |
| #include <memory> |
| #include <string> |
| #include <utility> |
| #include <vector> |
| |
| #include "absl/strings/string_view.h" |
| #include "tink/crypto_format.h" |
| #include "tink/subtle/subtle_util.h" |
| |
| namespace crypto { |
| namespace tink { |
| namespace internal { |
| |
| namespace { |
| |
| typedef crypto::tink::PrimitiveSet<ZeroCopyAead>::Entry<ZeroCopyAead> |
| ZeroCopyAeadEntry; |
| |
| util::Status Validate(PrimitiveSet<ZeroCopyAead>* aead_set) { |
| if (aead_set == nullptr) { |
| return util::Status(absl::StatusCode::kInternal, |
| "aead_set must be non-NULL"); |
| } |
| if (aead_set->get_primary() == nullptr) { |
| return util::Status(absl::StatusCode::kInvalidArgument, |
| "aead_set has no primary"); |
| } |
| return util::OkStatus(); |
| } |
| |
| class ZeroCopyAeadSetWrapper : public Aead { |
| public: |
| explicit ZeroCopyAeadSetWrapper( |
| std::unique_ptr<PrimitiveSet<ZeroCopyAead>> aead_set) |
| : aead_set_(std::move(aead_set)) {} |
| |
| util::StatusOr<std::string> Encrypt( |
| absl::string_view plaintext, |
| absl::string_view associated_data) const override; |
| |
| util::StatusOr<std::string> Decrypt( |
| absl::string_view ciphertext, |
| absl::string_view associated_data) const override; |
| |
| ~ZeroCopyAeadSetWrapper() override {} |
| |
| private: |
| std::unique_ptr<PrimitiveSet<ZeroCopyAead>> aead_set_; |
| }; |
| |
| util::StatusOr<std::string> ZeroCopyAeadSetWrapper::Encrypt( |
| absl::string_view plaintext, absl::string_view associated_data) const { |
| std::string ciphertext = aead_set_->get_primary()->get_identifier(); |
| int64_t key_id_size = ciphertext.size(); |
| ZeroCopyAead& aead = aead_set_->get_primary()->get_primitive(); |
| subtle::ResizeStringUninitialized( |
| &ciphertext, key_id_size + aead.MaxEncryptionSize(plaintext.size())); |
| |
| // Write ciphertext at position ciphertext + CryptoFormat::kNonRawPrefixSize. |
| util::StatusOr<int64_t> ciphertext_size = |
| aead.Encrypt(plaintext, associated_data, |
| absl::MakeSpan(ciphertext).subspan(key_id_size)); |
| if (!ciphertext_size.ok()) return ciphertext_size.status(); |
| ciphertext.resize(key_id_size + *ciphertext_size); |
| |
| return ciphertext; |
| } |
| |
| util::StatusOr<std::string> ZeroCopyAeadSetWrapper::Decrypt( |
| absl::string_view ciphertext, absl::string_view associated_data) const { |
| if (ciphertext.size() > CryptoFormat::kNonRawPrefixSize) { |
| std::string key_id = |
| std::string(ciphertext.substr(0, CryptoFormat::kNonRawPrefixSize)); |
| util::StatusOr<const std::vector<std::unique_ptr<ZeroCopyAeadEntry>>*> |
| primitives = aead_set_->get_primitives(key_id); |
| |
| if (primitives.ok() && *primitives != nullptr) { |
| absl::string_view raw_ciphertext = |
| ciphertext.substr(key_id.size(), ciphertext.size()); |
| |
| for (const std::unique_ptr<ZeroCopyAeadEntry>& entry : **primitives) { |
| ZeroCopyAead& aead = entry->get_primitive(); |
| std::string plaintext; |
| subtle::ResizeStringUninitialized( |
| &plaintext, aead.MaxDecryptionSize(raw_ciphertext.size())); |
| util::StatusOr<int64_t> plaintext_size = entry->get_primitive().Decrypt( |
| raw_ciphertext, associated_data, absl::MakeSpan(plaintext)); |
| if (plaintext_size.ok()) { |
| plaintext.resize(*plaintext_size); |
| return plaintext; |
| } |
| } |
| } |
| } |
| |
| // Try raw keys because matching keys failed to decrypt. |
| util::StatusOr<const std::vector<std::unique_ptr<ZeroCopyAeadEntry>>*> |
| raw_primitives = aead_set_->get_raw_primitives(); |
| if (raw_primitives.ok() && *raw_primitives != nullptr) { |
| for (const std::unique_ptr<ZeroCopyAeadEntry>& entry : **raw_primitives) { |
| ZeroCopyAead& aead = entry->get_primitive(); |
| std::string plaintext; |
| subtle::ResizeStringUninitialized( |
| &plaintext, aead.MaxDecryptionSize(ciphertext.size())); |
| util::StatusOr<int64_t> plaintext_size = |
| aead.Decrypt(ciphertext, associated_data, absl::MakeSpan(plaintext)); |
| if (plaintext_size.ok()) { |
| plaintext.resize(*plaintext_size); |
| return plaintext; |
| } |
| } |
| } |
| |
| return util::Status(absl::StatusCode::kInvalidArgument, "Decryption failed"); |
| } |
| |
| } // anonymous namespace |
| |
| util::StatusOr<std::unique_ptr<Aead>> ZeroCopyAeadWrapper::Wrap( |
| std::unique_ptr<PrimitiveSet<ZeroCopyAead>> aead_set) const { |
| util::Status status = Validate(aead_set.get()); |
| if (!status.ok()) return status; |
| std::unique_ptr<Aead> aead = |
| absl::make_unique<ZeroCopyAeadSetWrapper>(std::move(aead_set)); |
| return std::move(aead); |
| } |
| |
| } // namespace internal |
| } // namespace tink |
| } // namespace crypto |