Add ChaCha20Poly1305Encrypter, based on

net/quic/crypto/aead_base_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_12_encrypter.h"
+#include "net/quic/crypto/aead_base_encrypter.h"
 
 #include <openssl/err.h>
 #include <openssl/evp.h>
 #include <string.h>
 
 #include "base/memory/scoped_ptr.h"
 
 using base::StringPiece;
 
 namespace net {
 
 namespace {
 
-const size_t kKeySize = 16;
-const size_t kNoncePrefixSize = 4;
-const size_t kAESNonceSize = 12;
-
+// Clear OpenSSL error stack.
 void ClearOpenSslErrors() {
 #ifdef NDEBUG
   while (ERR_get_error()) {}
 #else
-  while (long error = ERR_get_error()) {
+  while (unsigned long error = ERR_get_error()) {
     char buf[120];
     ERR_error_string_n(error, buf, arraysize(buf));
     DLOG(ERROR) << "OpenSSL error: " << buf;
   }
 #endif
 }
 
 }  // namespace
 
-Aes128Gcm12Encrypter::Aes128Gcm12Encrypter() {}
+AeadBaseEncrypter::AeadBaseEncrypter(const EVP_AEAD* aead_alg,
+                                     size_t key_size,
+                                     size_t auth_tag_size,
+                                     size_t nonce_prefix_size)
+    : aead_alg_(aead_alg),
+      key_size_(key_size),
+      auth_tag_size_(auth_tag_size),
+      nonce_prefix_size_(nonce_prefix_size) {
+  DCHECK_LE(key_size_, sizeof(key_));
+  DCHECK_LE(nonce_prefix_size_, sizeof(nonce_prefix_));
+}
 
-Aes128Gcm12Encrypter::~Aes128Gcm12Encrypter() {}
+AeadBaseEncrypter::~AeadBaseEncrypter() {}
 
-bool Aes128Gcm12Encrypter::SetKey(StringPiece key) {
-  DCHECK_EQ(key.size(), sizeof(key_));
-  if (key.size() != sizeof(key_)) {
+bool AeadBaseEncrypter::SetKey(StringPiece key) {
+  DCHECK_EQ(key.size(), key_size_);
+  if (key.size() != key_size_) {
     return false;
   }
   memcpy(key_, key.data(), key.size());
 
   EVP_AEAD_CTX_cleanup(ctx_.get());
 
-  if (!EVP_AEAD_CTX_init(ctx_.get(), EVP_aead_aes_128_gcm(), key_,
-                         sizeof(key_), kAuthTagSize, NULL)) {
+  if (!EVP_AEAD_CTX_init(ctx_.get(), aead_alg_, key_, key_size_,
+                         auth_tag_size_, NULL)) {
     ClearOpenSslErrors();
     return false;
   }
 
   return true;
 }
 
-bool Aes128Gcm12Encrypter::SetNoncePrefix(StringPiece nonce_prefix) {
-  DCHECK_EQ(nonce_prefix.size(), kNoncePrefixSize);
-  if (nonce_prefix.size() != kNoncePrefixSize) {
+bool AeadBaseEncrypter::SetNoncePrefix(StringPiece nonce_prefix) {
+  DCHECK_EQ(nonce_prefix.size(), nonce_prefix_size_);
+  if (nonce_prefix.size() != nonce_prefix_size_) {
     return false;
   }
-  COMPILE_ASSERT(sizeof(nonce_prefix_) == kNoncePrefixSize, bad_nonce_length);
   memcpy(nonce_prefix_, nonce_prefix.data(), nonce_prefix.size());
   return true;
 }
 
-bool Aes128Gcm12Encrypter::Encrypt(StringPiece nonce,
-                                   StringPiece associated_data,
-                                   StringPiece plaintext,
-                                   unsigned char* output) {
-  if (nonce.size() != kNoncePrefixSize + sizeof(QuicPacketSequenceNumber)) {
+bool AeadBaseEncrypter::Encrypt(StringPiece nonce,
+                                StringPiece associated_data,
+                                StringPiece plaintext,
+                                unsigned char* output) {
+  if (nonce.size() != nonce_prefix_size_ + sizeof(QuicPacketSequenceNumber)) {
     return false;
   }
 
   ssize_t len = EVP_AEAD_CTX_seal(
-      ctx_.get(), output, plaintext.size() + kAuthTagSize,
+      ctx_.get(), output, plaintext.size() + auth_tag_size_,
       reinterpret_cast<const uint8_t*>(nonce.data()), nonce.size(),
       reinterpret_cast<const uint8_t*>(plaintext.data()), plaintext.size(),
       reinterpret_cast<const uint8_t*>(associated_data.data()),
       associated_data.size());
 
   if (len < 0) {
     ClearOpenSslErrors();
     return false;
   }
 
   return true;
 }
 
-QuicData* Aes128Gcm12Encrypter::EncryptPacket(
+QuicData* AeadBaseEncrypter::EncryptPacket(
     QuicPacketSequenceNumber sequence_number,
     StringPiece associated_data,
     StringPiece plaintext) {
   size_t ciphertext_size = GetCiphertextSize(plaintext.length());
   scoped_ptr<char[]> ciphertext(new char[ciphertext_size]);
 
   // TODO(ianswett): Introduce a check to ensure that we don't encrypt with the
   // same sequence number twice.
-  uint8 nonce[kNoncePrefixSize + sizeof(sequence_number)];
-  COMPILE_ASSERT(sizeof(nonce) == kAESNonceSize, bad_sequence_number_size);
-  memcpy(nonce, nonce_prefix_, kNoncePrefixSize);
-  memcpy(nonce + kNoncePrefixSize, &sequence_number, sizeof(sequence_number));
-  if (!Encrypt(StringPiece(reinterpret_cast<char*>(nonce), sizeof(nonce)),
+  uint8 nonce[sizeof(nonce_prefix_) + sizeof(sequence_number)];
+  const size_t nonce_size = nonce_prefix_size_ + sizeof(sequence_number);
+  DCHECK_LE(nonce_size, sizeof(nonce));
+  memcpy(nonce, nonce_prefix_, nonce_prefix_size_);
+  memcpy(nonce + nonce_prefix_size_, &sequence_number, sizeof(sequence_number));
+  if (!Encrypt(StringPiece(reinterpret_cast<char*>(nonce), nonce_size),
                associated_data, plaintext,
                reinterpret_cast<unsigned char*>(ciphertext.get()))) {
     return NULL;
   }
 
   return new QuicData(ciphertext.release(), ciphertext_size, true);
 }
 
-size_t Aes128Gcm12Encrypter::GetKeySize() const { return kKeySize; }
+size_t AeadBaseEncrypter::GetKeySize() const { return key_size_; }
 
-size_t Aes128Gcm12Encrypter::GetNoncePrefixSize() const {
-  return kNoncePrefixSize;
+size_t AeadBaseEncrypter::GetNoncePrefixSize() const {
+  return nonce_prefix_size_;
 }
 
-size_t Aes128Gcm12Encrypter::GetMaxPlaintextSize(size_t ciphertext_size) const {
-  return ciphertext_size - kAuthTagSize;
+size_t AeadBaseEncrypter::GetMaxPlaintextSize(size_t ciphertext_size) const {
+  return ciphertext_size - auth_tag_size_;
 }
 
-// An AEAD_AES_128_GCM_12 ciphertext is exactly 12 bytes longer than its
-// corresponding plaintext.
-size_t Aes128Gcm12Encrypter::GetCiphertextSize(size_t plaintext_size) const {
-  return plaintext_size + kAuthTagSize;
+size_t AeadBaseEncrypter::GetCiphertextSize(size_t plaintext_size) const {
+  return plaintext_size + auth_tag_size_;
 }
 
-StringPiece Aes128Gcm12Encrypter::GetKey() const {
-  return StringPiece(reinterpret_cast<const char*>(key_), sizeof(key_));
+StringPiece AeadBaseEncrypter::GetKey() const {
+  return StringPiece(reinterpret_cast<const char*>(key_), key_size_);
 }
 
-StringPiece Aes128Gcm12Encrypter::GetNoncePrefix() const {
+StringPiece AeadBaseEncrypter::GetNoncePrefix() const {
+  if (nonce_prefix_size_ == 0) {
+    return StringPiece();
+  }
   return StringPiece(reinterpret_cast<const char*>(nonce_prefix_),
-                     kNoncePrefixSize);
+                     nonce_prefix_size_);
 }
 
 }  // namespace net