Refactor WebCrypto code

content/child/webcrypto/openssl/aes_cbc_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/aes.h>
+#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/status.h"
+#include "content/child/webcrypto/webcrypto_util.h"
+#include "crypto/scoped_openssl_types.h"
+#include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
+
+namespace content {
+
+namespace webcrypto {
+
+namespace {
+
+const EVP_CIPHER* GetAESCipherByKeyLength(unsigned int key_length_bytes) {
+  switch (key_length_bytes) {
+    case 16:
+      return EVP_aes_128_cbc();
+    case 24:
+      return EVP_aes_192_cbc();
+    case 32:
+      return EVP_aes_256_cbc();
+    default:
+      return NULL;
+  }
+}
+
+// OpenSSL constants for EVP_CipherInit_ex(), do not change
+enum CipherOperation { kDoDecrypt = 0, kDoEncrypt = 1 };
+
+Status AesCbcEncryptDecrypt(CipherOperation cipher_operation,
+                            const blink::WebCryptoAlgorithm& algorithm,
+                            const blink::WebCryptoKey& key,
+                            const CryptoData& data,
+                            std::vector<uint8>* buffer) {
+  const blink::WebCryptoAesCbcParams* params = algorithm.aesCbcParams();
+  const std::vector<uint8>& raw_key = SymKeyOpenSsl::Cast(key)->raw_key_data();
+
+  if (params->iv().size() != 16)
+    return Status::ErrorIncorrectSizeAesCbcIv();
+
+  if (data.byte_length() >= INT_MAX - AES_BLOCK_SIZE) {
+    // TODO(padolph): Handle this by chunking the input fed into OpenSSL. Right
+    // now it doesn't make much difference since the one-shot API would end up
+    // blowing out the memory and crashing anyway.
+    return Status::ErrorDataTooLarge();
+  }
+
+  // Note: PKCS padding is enabled by default
+  crypto::ScopedOpenSSL<EVP_CIPHER_CTX, EVP_CIPHER_CTX_free>::Type context(
+      EVP_CIPHER_CTX_new());
+
+  if (!context.get())
+    return Status::OperationError();
+
+  const EVP_CIPHER* const cipher = GetAESCipherByKeyLength(raw_key.size());
+  DCHECK(cipher);
+
+  if (!EVP_CipherInit_ex(context.get(),
+                         cipher,
+                         NULL,
+                         &raw_key[0],
+                         params->iv().data(),
+                         cipher_operation)) {
+    return Status::OperationError();
+  }
+
+  // According to the openssl docs, the amount of data written may be as large
+  // as (data_size + cipher_block_size - 1), constrained to a multiple of
+  // cipher_block_size.
+  unsigned int output_max_len = data.byte_length() + AES_BLOCK_SIZE - 1;
+  const unsigned remainder = output_max_len % AES_BLOCK_SIZE;
+  if (remainder != 0)
+    output_max_len += AES_BLOCK_SIZE - remainder;
+  DCHECK_GT(output_max_len, data.byte_length());
+
+  buffer->resize(output_max_len);
+
+  unsigned char* const buffer_data = Uint8VectorStart(buffer);
+
+  int output_len = 0;
+  if (!EVP_CipherUpdate(context.get(),
+                        buffer_data,
+                        &output_len,
+                        data.bytes(),
+                        data.byte_length()))
+    return Status::OperationError();
+  int final_output_chunk_len = 0;
+  if (!EVP_CipherFinal_ex(
+          context.get(), buffer_data + output_len, &final_output_chunk_len)) {
+    return Status::OperationError();
+  }
+
+  const unsigned int final_output_len =
+      static_cast<unsigned int>(output_len) +
+      static_cast<unsigned int>(final_output_chunk_len);
+  DCHECK_LE(final_output_len, output_max_len);
+
+  buffer->resize(final_output_len);
+
+  return Status::Success();
+}
+
+class AesCbcImplementation : public AesAlgorithm {
+ public:
+  AesCbcImplementation() : AesAlgorithm("CBC") {}
+
+  virtual Status Encrypt(const blink::WebCryptoAlgorithm& algorithm,
+                         const blink::WebCryptoKey& key,
+                         const CryptoData& data,
+                         std::vector<uint8>* buffer) const OVERRIDE {
+    return AesCbcEncryptDecrypt(kDoEncrypt, 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 AesCbcEncryptDecrypt(kDoDecrypt, algorithm, key, data, buffer);
+  }
+};
+
+}  // namespace
+
+AlgorithmImplementation* CreatePlatformAesCbcImplementation() {
+  return new AesCbcImplementation;
+}
+
+}  // namespace webcrypto
+
+}  // namespace content