Refactor WebCrypto code

content/child/webcrypto/openssl/hmac_openssl.cc

+// 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 <openssl/hmac.h>
+
+#include "base/logging.h"
+#include "content/child/webcrypto/crypto_data.h"
+#include "content/child/webcrypto/jwk.h"
+#include "content/child/webcrypto/openssl/key_openssl.h"
+#include "content/child/webcrypto/openssl/sym_key_openssl.h"
+#include "content/child/webcrypto/openssl/util_openssl.h"
+#include "content/child/webcrypto/status.h"
+#include "content/child/webcrypto/webcrypto_util.h"
+#include "crypto/openssl_util.h"
+#include "crypto/secure_util.h"
+#include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
+#include "third_party/WebKit/public/platform/WebCryptoKeyAlgorithm.h"
+
+namespace content {
+
+namespace webcrypto {
+
+namespace {
+
+const blink::WebCryptoKeyUsageMask kAllKeyUsages =
+    blink::WebCryptoKeyUsageSign | blink::WebCryptoKeyUsageVerify;
+
+Status SignHmac(const std::vector<uint8>& raw_key,
+                const blink::WebCryptoAlgorithm& hash,
+                const CryptoData& data,
+                std::vector<uint8>* buffer) {
+  crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
+
+  const EVP_MD* digest_algorithm = GetDigest(hash.id());
+  if (!digest_algorithm)
+    return Status::ErrorUnsupported();
+  unsigned int hmac_expected_length = EVP_MD_size(digest_algorithm);
+
+  // OpenSSL wierdness here.
+  // First, HMAC() needs a void* for the key data, so make one up front as a
+  // cosmetic to avoid a cast. Second, OpenSSL does not like a NULL key,
+  // which will result if the raw_key vector is empty; an entirely valid
+  // case. Handle this specific case by pointing to an empty array.
+  const unsigned char null_key[] = {};
+  const void* const raw_key_voidp = raw_key.size() ? &raw_key[0] : null_key;
+
+  buffer->resize(hmac_expected_length);
+  crypto::ScopedOpenSSLSafeSizeBuffer<EVP_MAX_MD_SIZE> hmac_result(
+      Uint8VectorStart(buffer), hmac_expected_length);
+
+  unsigned int hmac_actual_length;
+  unsigned char* const success = HMAC(digest_algorithm,
+                                      raw_key_voidp,
+                                      raw_key.size(),
+                                      data.bytes(),
+                                      data.byte_length(),
+                                      hmac_result.safe_buffer(),
+                                      &hmac_actual_length);
+  if (!success || hmac_actual_length != hmac_expected_length)
+    return Status::OperationError();
+
+  return Status::Success();
+}
+
+class HmacImplementation : public AlgorithmImplementation {
+ public:
+  HmacImplementation() {}
+
+  virtual Status GenerateSecretKey(const blink::WebCryptoAlgorithm& algorithm,
+                                   bool extractable,
+                                   blink::WebCryptoKeyUsageMask usage_mask,
+                                   blink::WebCryptoKey* key) const OVERRIDE {
+    const blink::WebCryptoHmacKeyGenParams* params =
+        algorithm.hmacKeyGenParams();
+
+    unsigned int keylen_bits = 0;
+    Status status = GetHmacKeyGenLengthInBits(params, &keylen_bits);
+    if (status.IsError())
+      return status;
+
+    return GenerateSecretKeyOpenSsl(blink::WebCryptoKeyAlgorithm::createHmac(
+                                        params->hash().id(), keylen_bits),
+                                    extractable,
+                                    usage_mask,
+                                    keylen_bits / 8,
+                                    key);
+  }
+
+  virtual Status VerifyKeyUsagesBeforeImportKey(
+      blink::WebCryptoKeyFormat format,
+      blink::WebCryptoKeyUsageMask usage_mask) const OVERRIDE {
+    switch (format) {
+      case blink::WebCryptoKeyFormatRaw:
+      case blink::WebCryptoKeyFormatJwk:
+        return CheckKeyCreationUsages(kAllKeyUsages, usage_mask);
+      default:
+        return Status::ErrorUnsupportedImportKeyFormat();
+    }
+  }
+
+  virtual Status VerifyKeyUsagesBeforeGenerateKey(
+      blink::WebCryptoKeyUsageMask usage_mask) const OVERRIDE {
+    return CheckKeyCreationUsages(kAllKeyUsages, usage_mask);
+  }
+
+  virtual Status ImportKeyRaw(const CryptoData& key_data,
+                              const blink::WebCryptoAlgorithm& algorithm,
+                              bool extractable,
+                              blink::WebCryptoKeyUsageMask usage_mask,
+                              blink::WebCryptoKey* key) const OVERRIDE {
+    const blink::WebCryptoAlgorithm& hash =
+        algorithm.hmacImportParams()->hash();
+
+    // TODO(eroman): check for overflow.
+    unsigned int keylen_bits = key_data.byte_length() * 8;
+
+    return ImportKeyRawOpenSsl(
+        key_data,
+        blink::WebCryptoKeyAlgorithm::createHmac(hash.id(), keylen_bits),
+        extractable,
+        usage_mask,
+        key);
+  }
+
+  virtual Status ImportKeyJwk(const CryptoData& key_data,
+                              const blink::WebCryptoAlgorithm& algorithm,
+                              bool extractable,
+                              blink::WebCryptoKeyUsageMask usage_mask,
+                              blink::WebCryptoKey* key) const OVERRIDE {
+    const char* algorithm_name =
+        GetJwkHmacAlgorithmName(algorithm.hmacImportParams()->hash().id());
+    if (!algorithm_name)
+      return Status::ErrorUnexpected();
+
+    std::vector<uint8> raw_data;
+    Status status = ReadSecretKeyJwk(
+        key_data, algorithm_name, extractable, usage_mask, &raw_data);
+    if (status.IsError())
+      return status;
+
+    return ImportKeyRaw(
+        CryptoData(raw_data), algorithm, extractable, usage_mask, key);
+  }
+
+  virtual Status ExportKeyRaw(const blink::WebCryptoKey& key,
+                              std::vector<uint8>* buffer) const OVERRIDE {
+    *buffer = SymKeyOpenSsl::Cast(key)->raw_key_data();
+    return Status::Success();
+  }
+
+  virtual Status ExportKeyJwk(const blink::WebCryptoKey& key,
+                              std::vector<uint8>* buffer) const OVERRIDE {
+    SymKeyOpenSsl* sym_key = SymKeyOpenSsl::Cast(key);
+    const std::vector<uint8>& raw_data = sym_key->raw_key_data();
+
+    const char* algorithm_name =
+        GetJwkHmacAlgorithmName(key.algorithm().hmacParams()->hash().id());
+    if (!algorithm_name)
+      return Status::ErrorUnexpected();
+
+    WriteSecretKeyJwk(CryptoData(raw_data),
+                      algorithm_name,
+                      key.extractable(),
+                      key.usages(),
+                      buffer);
+
+    return Status::Success();
+  }
+
+  virtual Status Sign(const blink::WebCryptoAlgorithm& algorithm,
+                      const blink::WebCryptoKey& key,
+                      const CryptoData& data,
+                      std::vector<uint8>* buffer) const OVERRIDE {
+    const blink::WebCryptoAlgorithm& hash =
+        key.algorithm().hmacParams()->hash();
+
+    return SignHmac(
+        SymKeyOpenSsl::Cast(key)->raw_key_data(), hash, data, buffer);
+  }
+
+  virtual Status Verify(const blink::WebCryptoAlgorithm& algorithm,
+                        const blink::WebCryptoKey& key,
+                        const CryptoData& signature,
+                        const CryptoData& data,
+                        bool* signature_match) const OVERRIDE {
+    std::vector<uint8> result;
+    Status status = Sign(algorithm, key, data, &result);
+
+    if (status.IsError())
+      return status;
+
+    // Do not allow verification of truncated MACs.
+    *signature_match = result.size() == signature.byte_length() &&
+                       crypto::SecureMemEqual(Uint8VectorStart(result),
+                                              signature.bytes(),
+                                              signature.byte_length());
+
+    return Status::Success();
+  }
+};
+
+}  // namespace
+
+AlgorithmImplementation* CreatePlatformHmacImplementation() {
+  return new HmacImplementation;
+}
+
+}  // namespace webcrypto
+
+}  // namespace content