1 // Copyright 2021 Google LLC
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 // http://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 //
15 ///////////////////////////////////////////////////////////////////////////////
16
17 #include "tink/hybrid/internal/hpke_decrypt_boringssl.h"
18
19 #include <memory>
20 #include <string>
21 #include <utility>
22
23 #include "absl/status/status.h"
24 #include "absl/strings/str_cat.h"
25 #include "openssl/base.h"
26 #include "openssl/err.h"
27 #include "openssl/hpke.h"
28 #include "tink/hybrid/internal/hpke_util_boringssl.h"
29 #include "tink/subtle/subtle_util.h"
30 #include "tink/util/status.h"
31 #include "tink/util/statusor.h"
32 #include "proto/hpke.pb.h"
33
34 namespace crypto {
35 namespace tink {
36 namespace internal {
37
New(const google::crypto::tink::HpkeParams & params,const HpkeKeyBoringSsl & hpke_key,absl::string_view encapsulated_key,absl::string_view context_info)38 util::StatusOr<std::unique_ptr<HpkeDecryptBoringSsl>> HpkeDecryptBoringSsl::New(
39 const google::crypto::tink::HpkeParams& params,
40 const HpkeKeyBoringSsl& hpke_key, absl::string_view encapsulated_key,
41 absl::string_view context_info) {
42 auto hpke_decrypt = absl::WrapUnique(new HpkeDecryptBoringSsl());
43 util::Status status =
44 hpke_decrypt->Init(params, hpke_key, encapsulated_key, context_info);
45 if (!status.ok()) {
46 return status;
47 }
48 return std::move(hpke_decrypt);
49 }
50
Init(const google::crypto::tink::HpkeParams & params,const HpkeKeyBoringSsl & hpke_key,absl::string_view encapsulated_key,absl::string_view context_info)51 util::Status HpkeDecryptBoringSsl::Init(
52 const google::crypto::tink::HpkeParams& params,
53 const HpkeKeyBoringSsl& hpke_key, absl::string_view encapsulated_key,
54 absl::string_view context_info) {
55 util::StatusOr<const EVP_HPKE_KEM *> kem = KemParam(params);
56 if (!kem.ok()) {
57 return kem.status();
58 }
59 if (params.kem() != hpke_key.kem()) {
60 return util::Status(
61 absl::StatusCode::kInvalidArgument,
62 absl::StrCat("Specified KEM parameter '", params.kem(),
63 "' does not match given HPKE key's KEM parameter '",
64 hpke_key.kem(), "'."));
65 }
66 util::StatusOr<const EVP_HPKE_KDF *> kdf = KdfParam(params);
67 if (!kdf.ok()) {
68 return kdf.status();
69 }
70 util::StatusOr<const EVP_HPKE_AEAD *> aead = AeadParam(params);
71 if (!aead.ok()) {
72 return aead.status();
73 }
74 if (!EVP_HPKE_CTX_setup_recipient(
75 recipient_ctx_.get(), hpke_key.recipient_private_key(), *kdf, *aead,
76 reinterpret_cast<const uint8_t *>(encapsulated_key.data()),
77 encapsulated_key.size(),
78 reinterpret_cast<const uint8_t *>(context_info.data()),
79 context_info.size())) {
80 return util::Status(absl::StatusCode::kUnknown,
81 "Unable to set up BoringSSL HPKE recipient context.");
82 }
83 return util::OkStatus();
84 }
85
Decrypt(absl::string_view ciphertext,absl::string_view associated_data)86 util::StatusOr<std::string> HpkeDecryptBoringSsl::Decrypt(
87 absl::string_view ciphertext, absl::string_view associated_data) {
88 std::string plaintext;
89 subtle::ResizeStringUninitialized(&plaintext, ciphertext.size());
90 size_t plaintext_size;
91 if (!EVP_HPKE_CTX_open(
92 recipient_ctx_.get(), reinterpret_cast<uint8_t *>(&plaintext[0]),
93 &plaintext_size, plaintext.size(),
94 reinterpret_cast<const uint8_t *>(ciphertext.data()),
95 ciphertext.size(),
96 reinterpret_cast<const uint8_t *>(associated_data.data()),
97 associated_data.size())) {
98 return util::Status(absl::StatusCode::kUnknown,
99 "BoringSSL HPKE decryption failed.");
100 }
101 subtle::ResizeStringUninitialized(&plaintext, plaintext_size);
102 return plaintext;
103 }
104
105 } // namespace internal
106 } // namespace tink
107 } // namespace crypto
108