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// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifdef UNSAFE_BUFFERS_BUILD
// TODO(crbug.com/351564777): Remove this and convert code to safer constructs.
#pragma allow_unsafe_buffers
#endif
#include "base/check.h"
#include "build/build_config.h"
#include "crypto/hash.h"
#include "crypto/signature_verifier.h"
#include "crypto/unexportable_key.h"
#include "third_party/boringssl/src/include/openssl/bn.h"
#include "third_party/boringssl/src/include/openssl/bytestring.h"
#include "third_party/boringssl/src/include/openssl/ec.h"
#include "third_party/boringssl/src/include/openssl/ec_key.h"
#include "third_party/boringssl/src/include/openssl/ecdsa.h"
#include "third_party/boringssl/src/include/openssl/evp.h"
#include "third_party/boringssl/src/include/openssl/obj.h"
#include "third_party/boringssl/src/include/openssl/rsa.h"
#if BUILDFLAG(IS_MAC)
#include "base/notreached.h"
#endif // BUILDFLAG(IS_MAC)
namespace crypto {
namespace {
std::vector<uint8_t> CBBToVector(const CBB* cbb) {
return std::vector<uint8_t>(CBB_data(cbb), CBB_data(cbb) + CBB_len(cbb));
}
class SoftwareECDSA : public UnexportableSigningKey {
public:
explicit SoftwareECDSA(bssl::UniquePtr<EC_KEY> key) : key_(std::move(key)) {}
~SoftwareECDSA() override = default;
SignatureVerifier::SignatureAlgorithm Algorithm() const override {
return SignatureVerifier::SignatureAlgorithm::ECDSA_SHA256;
}
std::vector<uint8_t> GetSubjectPublicKeyInfo() const override {
bssl::UniquePtr<EVP_PKEY> pkey(EVP_PKEY_new());
CHECK(EVP_PKEY_set1_EC_KEY(pkey.get(), key_.get()));
bssl::ScopedCBB cbb;
CHECK(CBB_init(cbb.get(), /*initial_capacity=*/128) &&
EVP_marshal_public_key(cbb.get(), pkey.get()));
return CBBToVector(cbb.get());
}
std::vector<uint8_t> GetWrappedKey() const override {
bssl::ScopedCBB cbb;
CHECK(
CBB_init(cbb.get(), /*initial_capacity=*/128) &&
EC_KEY_marshal_private_key(cbb.get(), key_.get(),
EC_PKEY_NO_PARAMETERS | EC_PKEY_NO_PUBKEY));
return CBBToVector(cbb.get());
}
std::optional<std::vector<uint8_t>> SignSlowly(
base::span<const uint8_t> data) override {
std::vector<uint8_t> ret(ECDSA_size(key_.get()));
std::array<uint8_t, hash::kSha256Size> digest = hash::Sha256(data);
unsigned int ret_size;
CHECK(ECDSA_sign(0, digest.data(), digest.size(), ret.data(), &ret_size,
key_.get()));
ret.resize(ret_size);
return ret;
}
#if BUILDFLAG(IS_MAC)
SecKeyRef GetSecKeyRef() const override { NOTREACHED(); }
#endif // BUILDFLAG(IS_MAC)
private:
bssl::UniquePtr<EC_KEY> key_;
};
class SoftwareRSA : public UnexportableSigningKey {
public:
explicit SoftwareRSA(bssl::UniquePtr<RSA> key) : key_(std::move(key)) {}
~SoftwareRSA() override = default;
SignatureVerifier::SignatureAlgorithm Algorithm() const override {
return SignatureVerifier::SignatureAlgorithm::RSA_PKCS1_SHA256;
}
std::vector<uint8_t> GetSubjectPublicKeyInfo() const override {
bssl::UniquePtr<EVP_PKEY> pkey(EVP_PKEY_new());
CHECK(EVP_PKEY_set1_RSA(pkey.get(), key_.get()));
bssl::ScopedCBB cbb;
CHECK(CBB_init(cbb.get(), /*initial_capacity=*/384) &&
EVP_marshal_public_key(cbb.get(), pkey.get()));
return CBBToVector(cbb.get());
}
std::vector<uint8_t> GetWrappedKey() const override {
bssl::ScopedCBB cbb;
CHECK(CBB_init(cbb.get(), 384) &&
RSA_marshal_private_key(cbb.get(), key_.get()));
return CBBToVector(cbb.get());
}
std::optional<std::vector<uint8_t>> SignSlowly(
base::span<const uint8_t> data) override {
std::vector<uint8_t> ret(RSA_size(key_.get()));
std::array<uint8_t, hash::kSha256Size> digest = hash::Sha256(data);
unsigned int ret_size;
CHECK(RSA_sign(NID_sha256, digest.data(), digest.size(), ret.data(),
&ret_size, key_.get()));
ret.resize(ret_size);
return ret;
}
#if BUILDFLAG(IS_MAC)
SecKeyRef GetSecKeyRef() const override { NOTREACHED(); }
#endif // BUILDFLAG(IS_MAC)
private:
bssl::UniquePtr<RSA> key_;
};
class SoftwareProvider : public UnexportableKeyProvider {
public:
~SoftwareProvider() override = default;
std::optional<SignatureVerifier::SignatureAlgorithm> SelectAlgorithm(
base::span<const SignatureVerifier::SignatureAlgorithm>
acceptable_algorithms) override {
for (auto algo : acceptable_algorithms) {
switch (algo) {
case SignatureVerifier::SignatureAlgorithm::ECDSA_SHA256:
case SignatureVerifier::SignatureAlgorithm::RSA_PKCS1_SHA256:
return algo;
case SignatureVerifier::SignatureAlgorithm::RSA_PKCS1_SHA1:
case SignatureVerifier::SignatureAlgorithm::RSA_PSS_SHA256:
continue; // Not supported
}
}
return std::nullopt;
}
std::unique_ptr<UnexportableSigningKey> GenerateSigningKeySlowly(
base::span<const SignatureVerifier::SignatureAlgorithm>
acceptable_algorithms) override {
if (!SelectAlgorithm(acceptable_algorithms)) {
return nullptr;
}
for (auto algo : acceptable_algorithms) {
switch (algo) {
case SignatureVerifier::SignatureAlgorithm::ECDSA_SHA256: {
bssl::UniquePtr<EC_KEY> key(
EC_KEY_new_by_curve_name(NID_X9_62_prime256v1));
CHECK(EC_KEY_generate_key(key.get()));
return std::make_unique<SoftwareECDSA>(std::move(key));
}
case SignatureVerifier::SignatureAlgorithm::RSA_PKCS1_SHA256: {
bssl::UniquePtr<RSA> key(RSA_new());
bssl::UniquePtr<BIGNUM> e(BN_new());
BN_set_word(e.get(), RSA_F4);
RSA_generate_key_ex(key.get(), 2048, e.get(), nullptr);
return std::make_unique<SoftwareRSA>(std::move(key));
}
case SignatureVerifier::SignatureAlgorithm::RSA_PKCS1_SHA1:
case SignatureVerifier::SignatureAlgorithm::RSA_PSS_SHA256:
continue; // Not supported
}
}
return nullptr;
}
std::unique_ptr<UnexportableSigningKey> FromWrappedSigningKeySlowly(
base::span<const uint8_t> wrapped_key) override {
{ // Try to parse ECDSA
CBS cbs;
CBS_init(&cbs, wrapped_key.data(), wrapped_key.size());
bssl::UniquePtr<EC_GROUP> p256(
EC_GROUP_new_by_curve_name(NID_X9_62_prime256v1));
bssl::UniquePtr<EC_KEY> key(EC_KEY_parse_private_key(&cbs, p256.get()));
if (key && CBS_len(&cbs) == 0) {
return std::make_unique<SoftwareECDSA>(std::move(key));
}
}
{ // Try RSA
CBS cbs;
CBS_init(&cbs, wrapped_key.data(), wrapped_key.size());
bssl::UniquePtr<RSA> key(RSA_parse_private_key(&cbs));
if (key && CBS_len(&cbs) == 0) {
return std::make_unique<SoftwareRSA>(std::move(key));
}
}
return nullptr;
}
bool DeleteSigningKeySlowly(base::span<const uint8_t> wrapped_key) override {
// Unexportable software keys are stateless.
return true;
}
};
} // namespace
std::unique_ptr<UnexportableKeyProvider>
GetSoftwareUnsecureUnexportableKeyProvider() {
return std::make_unique<SoftwareProvider>();
}
} // namespace crypto
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