Refactor WebCrypto code

content/child/webcrypto/openssl/aes_gcm_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 <vector>
+#include <openssl/evp.h>
+
+#include "base/logging.h"
+#include "content/child/webcrypto/crypto_data.h"
+#include "content/child/webcrypto/openssl/aes_key_openssl.h"
+#include "content/child/webcrypto/openssl/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/scoped_openssl_types.h"
+#include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
+
+namespace content {
+
+namespace webcrypto {
+
+namespace {
+
+const EVP_AEAD* GetAesGcmAlgorithmFromKeySize(unsigned int key_size_bytes) {
+  switch (key_size_bytes) {
+    case 16:
+      return EVP_aead_aes_128_gcm();
+    // TODO(eroman): Hook up 256-bit support when it is available.
+    default:
+      return NULL;
+  }
+}
+
+Status AesGcmEncryptDecrypt(EncryptOrDecrypt mode,
+                            const blink::WebCryptoAlgorithm& algorithm,
+                            const blink::WebCryptoKey& key,
+                            const CryptoData& data,
+                            std::vector<uint8>* buffer) {
+  const std::vector<uint8>& raw_key = SymKeyOpenSsl::Cast(key)->raw_key_data();
+  const blink::WebCryptoAesGcmParams* params = algorithm.aesGcmParams();
+
+  crypto::OpenSSLErrStackTracer err_tracer(FROM_HERE);
+
+  unsigned int tag_length_bits;
+  Status status = GetAesGcmTagLengthInBits(params, &tag_length_bits);
+  if (status.IsError())
+    return status;
+  unsigned int tag_length_bytes = tag_length_bits / 8;
+
+  CryptoData iv(params->iv());
+  CryptoData additional_data(params->optionalAdditionalData());
+
+  EVP_AEAD_CTX ctx;
+
+  const EVP_AEAD* const aead_alg =
+      GetAesGcmAlgorithmFromKeySize(raw_key.size());
+  if (!aead_alg)
+    return Status::ErrorUnexpected();
+
+  if (!EVP_AEAD_CTX_init(&ctx,
+                         aead_alg,
+                         Uint8VectorStart(raw_key),
+                         raw_key.size(),
+                         tag_length_bytes,
+                         NULL)) {
+    return Status::OperationError();
+  }
+
+  crypto::ScopedOpenSSL<EVP_AEAD_CTX, EVP_AEAD_CTX_cleanup>::Type ctx_cleanup(
+      &ctx);
+
+  ssize_t len;
+
+  if (mode == DECRYPT) {
+    if (data.byte_length() < tag_length_bytes)
+      return Status::ErrorDataTooSmall();
+
+    buffer->resize(data.byte_length() - tag_length_bytes);
+
+    len = EVP_AEAD_CTX_open(&ctx,
+                            Uint8VectorStart(buffer),
+                            buffer->size(),
+                            iv.bytes(),
+                            iv.byte_length(),
+                            data.bytes(),
+                            data.byte_length(),
+                            additional_data.bytes(),
+                            additional_data.byte_length());
+  } else {
+    // No need to check for unsigned integer overflow here (seal fails if
+    // the output buffer is too small).
+    buffer->resize(data.byte_length() + tag_length_bytes);
+
+    len = EVP_AEAD_CTX_seal(&ctx,
+                            Uint8VectorStart(buffer),
+                            buffer->size(),
+                            iv.bytes(),
+                            iv.byte_length(),
+                            data.bytes(),
+                            data.byte_length(),
+                            additional_data.bytes(),
+                            additional_data.byte_length());
+  }
+
+  if (len < 0)
+    return Status::OperationError();
+  buffer->resize(len);
+  return Status::Success();
+}
+
+class AesGcmImplementation : public AesAlgorithm {
+ public:
+  AesGcmImplementation() : AesAlgorithm("GCM") {}
+
+  virtual Status Encrypt(const blink::WebCryptoAlgorithm& algorithm,
+                         const blink::WebCryptoKey& key,
+                         const CryptoData& data,
+                         std::vector<uint8>* buffer) const OVERRIDE {
+    return AesGcmEncryptDecrypt(ENCRYPT, algorithm, key, data, buffer);
+  }
+
+  virtual Status Decrypt(const blink::WebCryptoAlgorithm& algorithm,
+                         const blink::WebCryptoKey& key,
+                         const CryptoData& data,
+                         std::vector<uint8>* buffer) const OVERRIDE {
+    return AesGcmEncryptDecrypt(DECRYPT, algorithm, key, data, buffer);
+  }
+};
+
+}  // namespace
+
+AlgorithmImplementation* CreatePlatformAesGcmImplementation() {
+  return new AesGcmImplementation;
+}
+
+}  // namespace webcrypto
+
+}  // namespace content