Add Aes128GcmEncrypter and Aes128GcmDecrypter

net/quic/crypto/aes_128_gcm_encrypter_openssl.cc

+// Copyright (c) 2013 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 "net/quic/crypto/aes_128_gcm_encrypter.h"
+
+#include <openssl/evp.h>
+#include <string.h>
+
+#include "base/memory/scoped_ptr.h"
+#include "net/quic/crypto/scoped_evp_cipher_ctx.h"
+
+using base::StringPiece;
+
+namespace net {
+
+namespace {
+
+const size_t kKeySize = 16;
+const size_t kNoncePrefixSize = 4;
+const size_t kAuthTagSize = 16;
+
+}  // namespace
+
+bool Aes128GcmEncrypter::SetKey(StringPiece key) {
+  if (key.size() != sizeof(key_)) {
+    return false;
+  }
+  memcpy(key_, key.data(), key.size());
+  return true;
+}
+
+bool Aes128GcmEncrypter::SetNoncePrefix(StringPiece nonce_prefix) {
+  if (nonce_prefix.size() != kNoncePrefixSize) {
+    return false;
+  }
+  memcpy(nonce_, nonce_prefix.data(), nonce_prefix.size());
+  return true;
+}
+
+QuicData* Aes128GcmEncrypter::Encrypt(QuicPacketSequenceNumber sequence_number,
+                                      StringPiece associated_data,
+                                      StringPiece plaintext) {
+  COMPILE_ASSERT(sizeof(nonce_) == kNoncePrefixSize + sizeof(sequence_number),
+                 incorrect_nonce_size);
+  memcpy(nonce_ + kNoncePrefixSize, &sequence_number, sizeof(sequence_number));
+  return EncryptWithNonce(StringPiece(reinterpret_cast<char*>(nonce_),
+                                      sizeof(nonce_)),
+                          associated_data, plaintext);
+}
+
+size_t Aes128GcmEncrypter::GetKeySize() const {
+  return kKeySize;
+}
+
+size_t Aes128GcmEncrypter::GetNoncePrefixSize() const {
+  return kNoncePrefixSize;
+}
+
+size_t Aes128GcmEncrypter::GetMaxPlaintextSize(size_t ciphertext_size) const {
+  return ciphertext_size - kAuthTagSize;
+}
+
+// An AEAD_AES_128_GCM ciphertext is exactly 16 bytes longer than its
+// corresponding plaintext.
+size_t Aes128GcmEncrypter::GetCiphertextSize(size_t plaintext_size) const {
+  return plaintext_size + kAuthTagSize;
+}
+
+QuicData* Aes128GcmEncrypter::EncryptWithNonce(StringPiece nonce,
+                                               StringPiece associated_data,
+                                               StringPiece plaintext) {
+  size_t ciphertext_size = GetCiphertextSize(plaintext.length());
+  scoped_ptr<char[]> ciphertext(new char[ciphertext_size]);
+
+  // |output| points to the position in the |ciphertext| buffer to receive
+  // the next output.
+  unsigned char* output = reinterpret_cast<unsigned char*>(ciphertext.get());
+  // |output_len| is passed to an OpenSSL function to receive the output
+  // length.
+  int output_len;
+
+  ScopedEVPCipherCtx ctx;
+
+  // Set the cipher type and the key. The IV (nonce) is set below.
+  if (EVP_EncryptInit_ex(ctx.get(), EVP_aes_128_gcm(), NULL, key_,
+                         NULL) == 0) {
+    return NULL;
+  }
+
+  // Set the IV (nonce) length.
+  if (EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_GCM_SET_IVLEN, nonce.size(),
+                          NULL) == 0) {
+    return NULL;
+  }
+  // Set the IV (nonce).
+  if (EVP_EncryptInit_ex(ctx.get(), NULL, NULL, NULL,
+                         reinterpret_cast<const unsigned char*>(
+                             nonce.data())) == 0) {
+    return NULL;
+  }
+
+  // Set the associated data. The second argument (output buffer) must be
+  // NULL.
+  if (EVP_EncryptUpdate(ctx.get(), NULL, &output_len,
+                        reinterpret_cast<const unsigned char*>(
+                            associated_data.data()),
+                        associated_data.size()) == 0) {
+    return NULL;
+  }
+
+  if (EVP_EncryptUpdate(ctx.get(), output, &output_len,
+                        reinterpret_cast<const unsigned char*>(
+                            plaintext.data()),
+                        plaintext.size()) == 0) {
+    return NULL;
+  }
+  output += output_len;
+
+  if (EVP_EncryptFinal_ex(ctx.get(), output, &output_len) == 0) {
+    return NULL;
+  }
+  output += output_len;
+
+  if (EVP_CIPHER_CTX_ctrl(ctx.get(), EVP_CTRL_GCM_GET_TAG, kAuthTagSize,
+                          output) == 0) {
+    return NULL;
+  }
+
+  return new QuicData(ciphertext.release(), ciphertext_size, true);
+}
+
+}  // namespace net