net/quic/crypto/aead_base_encrypter_nss.cc

   1 // Copyright (c) 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/quic/crypto/aead_base_encrypter.h"
   6
   7 #include <pk11pub.h>
   8
   9 #include "base/memory/scoped_ptr.h"
  10 #include "crypto/scoped_nss_types.h"
  11
  12 using base::StringPiece;
  13
  14 namespace net {
  15
  16 AeadBaseEncrypter::AeadBaseEncrypter(CK_MECHANISM_TYPE aead_mechanism,
  17                                      PK11_EncryptFunction pk11_encrypt,
  18                                      size_t key_size,
  19                                      size_t auth_tag_size,
  20                                      size_t nonce_prefix_size)
  21     : aead_mechanism_(aead_mechanism),
  22       pk11_encrypt_(pk11_encrypt),
  23       key_size_(key_size),
  24       auth_tag_size_(auth_tag_size),
  25       nonce_prefix_size_(nonce_prefix_size) {
  26   DCHECK_LE(key_size_, sizeof(key_));
  27   DCHECK_LE(nonce_prefix_size_, sizeof(nonce_prefix_));
  28 }
  29
  30 AeadBaseEncrypter::~AeadBaseEncrypter() {}
  31
  32 bool AeadBaseEncrypter::SetKey(StringPiece key) {
  33   DCHECK_EQ(key.size(), key_size_);
  34   if (key.size() != key_size_) {
  35     return false;
  36   }
  37   memcpy(key_, key.data(), key.size());
  38   return true;
  39 }
  40
  41 bool AeadBaseEncrypter::SetNoncePrefix(StringPiece nonce_prefix) {
  42   DCHECK_EQ(nonce_prefix.size(), nonce_prefix_size_);
  43   if (nonce_prefix.size() != nonce_prefix_size_) {
  44     return false;
  45   }
  46   memcpy(nonce_prefix_, nonce_prefix.data(), nonce_prefix.size());
  47   return true;
  48 }
  49
  50 bool AeadBaseEncrypter::Encrypt(StringPiece nonce,
  51                                 StringPiece associated_data,
  52                                 StringPiece plaintext,
  53                                 unsigned char* output) {
  54   if (nonce.size() != nonce_prefix_size_ + sizeof(QuicPacketSequenceNumber)) {
  55     return false;
  56   }
  57
  58   size_t ciphertext_size = GetCiphertextSize(plaintext.length());
  59
  60   // Import key_ into NSS.
  61   SECItem key_item;
  62   key_item.type = siBuffer;
  63   key_item.data = key_;
  64   key_item.len = key_size_;
  65   PK11SlotInfo* slot = PK11_GetInternalSlot();
  66
  67   // TODO(wtc): For an AES-GCM key, the correct value for |key_mechanism| is
  68   // CKM_AES_GCM, but because of NSS bug
  69   // https://bugzilla.mozilla.org/show_bug.cgi?id=853285, use CKM_AES_ECB as a
  70   // workaround. Remove this when we require NSS 3.15.
  71   CK_MECHANISM_TYPE key_mechanism = aead_mechanism_;
  72   if (key_mechanism == CKM_AES_GCM) {
  73     key_mechanism = CKM_AES_ECB;
  74   }
  75
  76   // The exact value of the |origin| argument doesn't matter to NSS as long as
  77   // it's not PK11_OriginFortezzaHack, so we pass PK11_OriginUnwrap as a
  78   // placeholder.
  79   crypto::ScopedPK11SymKey aead_key(PK11_ImportSymKey(
  80       slot, key_mechanism, PK11_OriginUnwrap, CKA_ENCRYPT, &key_item, nullptr));
  81   PK11_FreeSlot(slot);
  82   slot = nullptr;
  83   if (!aead_key) {
  84     DVLOG(1) << "PK11_ImportSymKey failed";
  85     return false;
  86   }
  87
  88   AeadParams aead_params = {0};
  89   FillAeadParams(nonce, associated_data, auth_tag_size_, &aead_params);
  90
  91   SECItem param;
  92   param.type = siBuffer;
  93   param.data = reinterpret_cast<unsigned char*>(&aead_params.data);
  94   param.len = aead_params.len;
  95
  96   unsigned int output_len;
  97   if (pk11_encrypt_(aead_key.get(), aead_mechanism_, &param,
  98                     output, &output_len, ciphertext_size,
  99                     reinterpret_cast<const unsigned char*>(plaintext.data()),
 100                     plaintext.size()) != SECSuccess) {
 101     DVLOG(1) << "pk11_encrypt_ failed";
 102     return false;
 103   }
 104
 105   if (output_len != ciphertext_size) {
 106     DVLOG(1) << "Wrong output length";
 107     return false;
 108   }
 109
 110   return true;
 111 }
 112
 113 bool AeadBaseEncrypter::EncryptPacket(QuicPacketSequenceNumber sequence_number,
 114                                       StringPiece associated_data,
 115                                       StringPiece plaintext,
 116                                       char* output,
 117                                       size_t* output_length,
 118                                       size_t max_output_length) {
 119   size_t ciphertext_size = GetCiphertextSize(plaintext.length());
 120   if (max_output_length < ciphertext_size) {
 121     return false;
 122   }
 123   // TODO(ianswett): Introduce a check to ensure that we don't encrypt with the
 124   // same sequence number twice.
 125   const size_t nonce_size = nonce_prefix_size_ + sizeof(sequence_number);
 126   memcpy(output, nonce_prefix_, nonce_prefix_size_);
 127   memcpy(output + nonce_prefix_size_, &sequence_number,
 128          sizeof(sequence_number));
 129   if (!Encrypt(StringPiece(output, nonce_size), associated_data, plaintext,
 130                reinterpret_cast<unsigned char*>(output))) {
 131     return false;
 132   }
 133   *output_length = ciphertext_size;
 134   return true;
 135 }
 136
 137 size_t AeadBaseEncrypter::GetKeySize() const { return key_size_; }
 138
 139 size_t AeadBaseEncrypter::GetNoncePrefixSize() const {
 140   return nonce_prefix_size_;
 141 }
 142
 143 size_t AeadBaseEncrypter::GetMaxPlaintextSize(size_t ciphertext_size) const {
 144   return ciphertext_size - auth_tag_size_;
 145 }
 146
 147 size_t AeadBaseEncrypter::GetCiphertextSize(size_t plaintext_size) const {
 148   return plaintext_size + auth_tag_size_;
 149 }
 150
 151 StringPiece AeadBaseEncrypter::GetKey() const {
 152   return StringPiece(reinterpret_cast<const char*>(key_), key_size_);
 153 }
 154
 155 StringPiece AeadBaseEncrypter::GetNoncePrefix() const {
 156   if (nonce_prefix_size_ == 0) {
 157     return StringPiece();
 158   }
 159   return StringPiece(reinterpret_cast<const char*>(nonce_prefix_),
 160                      nonce_prefix_size_);
 161 }
 162
 163 }  // namespace net