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- // Copyright 2014 The Chromium Authors. All rights reserved.
- // Use of this source code is governed by a BSD-style license that can be
- // found in the LICENSE file.
- #include <stddef.h>
- #include <stdint.h>
- #include <memory>
- #include "base/containers/span.h"
- #include "components/webcrypto/algorithm_implementation.h"
- #include "components/webcrypto/algorithms/ec.h"
- #include "components/webcrypto/algorithms/util.h"
- #include "components/webcrypto/blink_key_handle.h"
- #include "components/webcrypto/generate_key_result.h"
- #include "components/webcrypto/status.h"
- #include "crypto/openssl_util.h"
- #include "crypto/secure_util.h"
- #include "third_party/blink/public/platform/web_crypto_algorithm_params.h"
- #include "third_party/blink/public/platform/web_crypto_key.h"
- #include "third_party/blink/public/platform/web_crypto_key_algorithm.h"
- #include "third_party/boringssl/src/include/openssl/bn.h"
- #include "third_party/boringssl/src/include/openssl/digest.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/mem.h"
- namespace webcrypto {
- namespace {
- // Extracts the OpenSSL key and digest from a WebCrypto key + algorithm. The
- // returned pkey pointer will remain valid as long as |key| is alive.
- Status GetPKeyAndDigest(const blink::WebCryptoAlgorithm& algorithm,
- const blink::WebCryptoKey& key,
- EVP_PKEY** pkey,
- const EVP_MD** digest) {
- *pkey = GetEVP_PKEY(key);
- *digest = GetDigest(algorithm.EcdsaParams()->GetHash());
- if (!*digest)
- return Status::ErrorUnsupported();
- return Status::Success();
- }
- // Gets the EC key's order size in bytes.
- Status GetEcGroupOrderSize(EVP_PKEY* pkey, size_t* order_size_bytes) {
- crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
- EC_KEY* ec = EVP_PKEY_get0_EC_KEY(pkey);
- if (!ec)
- return Status::ErrorUnexpected();
- const EC_GROUP* group = EC_KEY_get0_group(ec);
- bssl::UniquePtr<BIGNUM> order(BN_new());
- if (!EC_GROUP_get_order(group, order.get(), nullptr))
- return Status::OperationError();
- *order_size_bytes = BN_num_bytes(order.get());
- return Status::Success();
- }
- // Formats a DER-encoded signature (ECDSA-Sig-Value as specified in RFC 3279) to
- // the signature format expected by WebCrypto (raw concatenated "r" and "s").
- //
- // TODO(eroman): Where is the specification for WebCrypto's signature format?
- Status ConvertDerSignatureToWebCryptoSignature(
- EVP_PKEY* key,
- std::vector<uint8_t>* signature) {
- crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
- bssl::UniquePtr<ECDSA_SIG> ecdsa_sig(
- ECDSA_SIG_from_bytes(signature->data(), signature->size()));
- if (!ecdsa_sig.get())
- return Status::ErrorUnexpected();
- // Determine the maximum length of r and s.
- size_t order_size_bytes;
- Status status = GetEcGroupOrderSize(key, &order_size_bytes);
- if (status.IsError())
- return status;
- signature->resize(order_size_bytes * 2);
- if (!BN_bn2bin_padded(signature->data(), order_size_bytes,
- ecdsa_sig.get()->r)) {
- return Status::ErrorUnexpected();
- }
- if (!BN_bn2bin_padded(&(*signature)[order_size_bytes], order_size_bytes,
- ecdsa_sig.get()->s)) {
- return Status::ErrorUnexpected();
- }
- return Status::Success();
- }
- // Formats a WebCrypto ECDSA signature to a DER-encoded signature
- // (ECDSA-Sig-Value as specified in RFC 3279).
- //
- // TODO(eroman): What is the specification for WebCrypto's signature format?
- //
- // If the signature length is incorrect (not 2 * order_size), then
- // Status::Success() is returned and |*incorrect_length| is set to true;
- //
- // Otherwise on success, der_signature is filled with a ASN.1 encoded
- // ECDSA-Sig-Value.
- Status ConvertWebCryptoSignatureToDerSignature(
- EVP_PKEY* key,
- base::span<const uint8_t> signature,
- std::vector<uint8_t>* der_signature,
- bool* incorrect_length) {
- crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
- // Determine the length of r and s.
- size_t order_size_bytes;
- Status status = GetEcGroupOrderSize(key, &order_size_bytes);
- if (status.IsError())
- return status;
- // If the size of the signature is incorrect, verification must fail. Success
- // is returned here rather than an error, so that the caller can fail
- // verification with a boolean, rather than reject the promise with an
- // exception.
- if (signature.size() != 2 * order_size_bytes) {
- *incorrect_length = true;
- return Status::Success();
- }
- base::span<const uint8_t> r_bytes = signature.first(order_size_bytes);
- base::span<const uint8_t> s_bytes = signature.subspan(order_size_bytes);
- *incorrect_length = false;
- // Construct an ECDSA_SIG from |signature|.
- bssl::UniquePtr<ECDSA_SIG> ecdsa_sig(ECDSA_SIG_new());
- if (!ecdsa_sig)
- return Status::OperationError();
- if (!BN_bin2bn(r_bytes.data(), r_bytes.size(), ecdsa_sig->r) ||
- !BN_bin2bn(s_bytes.data(), s_bytes.size(), ecdsa_sig->s)) {
- return Status::ErrorUnexpected();
- }
- // Encode the signature.
- uint8_t* der;
- size_t der_len;
- if (!ECDSA_SIG_to_bytes(&der, &der_len, ecdsa_sig.get()))
- return Status::OperationError();
- der_signature->assign(der, der + der_len);
- OPENSSL_free(der);
- return Status::Success();
- }
- class EcdsaImplementation : public EcAlgorithm {
- public:
- EcdsaImplementation()
- : EcAlgorithm(blink::kWebCryptoKeyUsageVerify,
- blink::kWebCryptoKeyUsageSign) {}
- const char* GetJwkAlgorithm(
- const blink::WebCryptoNamedCurve curve) const override {
- switch (curve) {
- case blink::kWebCryptoNamedCurveP256:
- return "ES256";
- case blink::kWebCryptoNamedCurveP384:
- return "ES384";
- case blink::kWebCryptoNamedCurveP521:
- // This is not a typo! ES512 means P-521 with SHA-512.
- return "ES512";
- default:
- return nullptr;
- }
- }
- Status Sign(const blink::WebCryptoAlgorithm& algorithm,
- const blink::WebCryptoKey& key,
- base::span<const uint8_t> data,
- std::vector<uint8_t>* buffer) const override {
- if (key.GetType() != blink::kWebCryptoKeyTypePrivate)
- return Status::ErrorUnexpectedKeyType();
- crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
- EVP_PKEY* private_key = nullptr;
- const EVP_MD* digest = nullptr;
- Status status = GetPKeyAndDigest(algorithm, key, &private_key, &digest);
- if (status.IsError())
- return status;
- // NOTE: A call to EVP_DigestSignFinal() with a NULL second parameter
- // returns a maximum allocation size, while the call without a NULL returns
- // the real one, which may be smaller.
- bssl::ScopedEVP_MD_CTX ctx;
- size_t sig_len = 0;
- if (!EVP_DigestSignInit(ctx.get(), nullptr, digest, nullptr, private_key) ||
- !EVP_DigestSignUpdate(ctx.get(), data.data(), data.size()) ||
- !EVP_DigestSignFinal(ctx.get(), nullptr, &sig_len)) {
- return Status::OperationError();
- }
- buffer->resize(sig_len);
- if (!EVP_DigestSignFinal(ctx.get(), buffer->data(), &sig_len))
- return Status::OperationError();
- buffer->resize(sig_len);
- // ECDSA signing in BoringSSL outputs a DER-encoded (r,s). WebCrypto however
- // expects a padded bitstring that is r concatenated to s. Convert to the
- // expected format.
- return ConvertDerSignatureToWebCryptoSignature(private_key, buffer);
- }
- Status Verify(const blink::WebCryptoAlgorithm& algorithm,
- const blink::WebCryptoKey& key,
- base::span<const uint8_t> signature,
- base::span<const uint8_t> data,
- bool* signature_match) const override {
- if (key.GetType() != blink::kWebCryptoKeyTypePublic)
- return Status::ErrorUnexpectedKeyType();
- crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
- EVP_PKEY* public_key = nullptr;
- const EVP_MD* digest = nullptr;
- Status status = GetPKeyAndDigest(algorithm, key, &public_key, &digest);
- if (status.IsError())
- return status;
- std::vector<uint8_t> der_signature;
- bool incorrect_length_signature = false;
- status = ConvertWebCryptoSignatureToDerSignature(
- public_key, signature, &der_signature, &incorrect_length_signature);
- if (status.IsError())
- return status;
- if (incorrect_length_signature) {
- *signature_match = false;
- return Status::Success();
- }
- bssl::ScopedEVP_MD_CTX ctx;
- if (!EVP_DigestVerifyInit(ctx.get(), nullptr, digest, nullptr,
- public_key) ||
- !EVP_DigestVerifyUpdate(ctx.get(), data.data(), data.size())) {
- return Status::OperationError();
- }
- *signature_match =
- 1 == EVP_DigestVerifyFinal(ctx.get(), der_signature.data(),
- der_signature.size());
- return Status::Success();
- }
- };
- } // namespace
- std::unique_ptr<AlgorithmImplementation> CreateEcdsaImplementation() {
- return std::make_unique<EcdsaImplementation>();
- }
- } // namespace webcrypto
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