Implement AES-CTR for NSS.

Implement AES-128-CTR.

BUG=87152
TEST=None

Review URL: http://codereview.chromium.org/7056026

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@90425 0039d316-1c4b-4281-b951-d872f2087c98

build/build_config.h

@@ -95,14 +95,17 @@
 #define ARCH_CPU_X86_FAMILY 1
 #define ARCH_CPU_X86_64 1
 #define ARCH_CPU_64_BITS 1
+#define ARCH_CPU_LITTLE_ENDIAN 1
 #elif defined(_M_IX86) || defined(__i386__)
 #define ARCH_CPU_X86_FAMILY 1
 #define ARCH_CPU_X86 1
 #define ARCH_CPU_32_BITS 1
+#define ARCH_CPU_LITTLE_ENDIAN 1
 #elif defined(__ARMEL__)
 #define ARCH_CPU_ARM_FAMILY 1
 #define ARCH_CPU_ARMEL 1
 #define ARCH_CPU_32_BITS 1
+#define ARCH_CPU_LITTLE_ENDIAN 1
 #define WCHAR_T_IS_UNSIGNED 1
 #else
 #error Please add support for your architecture in build/build_config.h

crypto/crypto.gyp

@@ -109,6 +109,7 @@
         'crypto_module_blocking_password_delegate.h',
         'cssm_init.cc',
         'cssm_init.h',
+        'encryptor.cc',
         'encryptor.h',
         'encryptor_mac.cc',
         'encryptor_nss.cc',

crypto/encryptor.cc

@@ -0,0 +1,120 @@
+// Copyright (c) 2011 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 "crypto/encryptor.h"
+
+#include "base/logging.h"
+#include "build/build_config.h"
+
+// Include headers to provide bswap for all platforms.
+#if defined(COMPILER_MSVC)
+#include <stdlib.h>
+#define bswap_16(x) _byteswap_ushort(x)
+#define bswap_32(x) _byteswap_ulong(x)
+#define bswap_64(x) _byteswap_uint64(x)
+#elif defined(OS_MACOSX)
+#include <libkern/OSByteOrder.h>
+#define bswap_16(x) OSSwapInt16(x)
+#define bswap_32(x) OSSwapInt32(x)
+#define bswap_64(x) OSSwapInt64(x)
+#else
+#include <byteswap.h>
+#endif
+
+#if defined(ARCH_CPU_LITTLE_ENDIAN)
+#define ntoh_64(x) bswap_64(x)
+#define hton_64(x) bswap_64(x)
+#else
+#define ntoh_64(x) (x)
+#define hton_64(x) (x)
+#endif
+
+namespace crypto {
+
+/////////////////////////////////////////////////////////////////////////////
+// Encyptor::Counter Implementation.
+Encryptor::Counter::Counter(const std::string& counter) {
+  CHECK(sizeof(counter_) == counter.length());
+
+  memcpy(&counter_, counter.data(), sizeof(counter_));
+}
+
+Encryptor::Counter::~Counter() {
+}
+
+bool Encryptor::Counter::Increment() {
+  uint64 low_num = ntoh_64(counter_.components64[1]);
+  uint64 new_low_num = low_num + 1;
+  counter_.components64[1] = hton_64(new_low_num);
+
+  // If overflow occured then increment the most significant component.
+  if (new_low_num < low_num) {
+    counter_.components64[0] =
+        hton_64(ntoh_64(counter_.components64[0]) + 1);
+  }
+
+  // TODO(hclam): Return false if counter value overflows.
+  return true;
+}
+
+void Encryptor::Counter::Write(void* buf) {
+  uint8* buf_ptr = reinterpret_cast<uint8*>(buf);
+  memcpy(buf_ptr, &counter_, sizeof(counter_));
+}
+
+size_t Encryptor::Counter::GetLengthInBytes() const {
+  return sizeof(counter_);
+}
+
+/////////////////////////////////////////////////////////////////////////////
+// Partial Encryptor Implementation.
+
+bool Encryptor::SetCounter(const std::string& counter) {
+  if (mode_ != CTR)
+    return false;
+  if (counter.length() != 16u)
+    return false;
+
+  counter_.reset(new Counter(counter));
+  return true;
+}
+
+bool Encryptor::GenerateCounterMask(size_t plaintext_len,
+                                    uint8* mask,
+                                    size_t* mask_len) {
+  DCHECK_EQ(CTR, mode_);
+  CHECK(mask);
+  CHECK(mask_len);
+
+  const size_t kBlockLength = counter_->GetLengthInBytes();
+  size_t blocks = (plaintext_len + kBlockLength - 1) / kBlockLength;
+  CHECK(blocks);
+
+  *mask_len = blocks * kBlockLength;
+
+  for (size_t i = 0; i < blocks; ++i) {
+    counter_->Write(mask);
+    mask += kBlockLength;
+
+    bool ret = counter_->Increment();
+    if (!ret)
+      return false;
+  }
+  return true;
+}
+
+void Encryptor::MaskMessage(const void* plaintext,
+                            size_t plaintext_len,
+                            const void* mask,
+                            void* ciphertext) const {
+  DCHECK_EQ(CTR, mode_);
+  const uint8* plaintext_ptr = reinterpret_cast<const uint8*>(plaintext);
+  const uint8* mask_ptr = reinterpret_cast<const uint8*>(mask);
+  uint8* ciphertext_ptr = reinterpret_cast<uint8*>(ciphertext);
+
+  for (size_t i = 0; i < plaintext_len; ++i)
+    ciphertext_ptr[i] = plaintext_ptr[i] ^ mask_ptr[i];
+}
+
+}  // namespace crypto

crypto/encryptor.h

@@ -8,6 +8,8 @@
 
 #include <string>
 
+#include "base/basictypes.h"
+#include "base/scoped_ptr.h"
 #include "build/build_config.h"
 #include "crypto/crypto_api.h"
 
@@ -24,13 +26,41 @@ class SymmetricKey;
 class CRYPTO_API Encryptor {
  public:
   enum Mode {
-    CBC
+    CBC,
+    CTR,
   };
+
+  // This class implements a 128-bits counter to be used in AES-CTR encryption.
+  // Only 128-bits counter is supported in this class.
+  class Counter {
+   public:
+    Counter(const std::string& counter);
+    ~Counter();
+
+    // Increment the counter value.
+    bool Increment();
+
+    // Write the content of the counter to |buf|. |buf| should have enough
+    // space for |GetLengthInBytes()|.
+    void Write(void* buf);
+
+    // Return the length of this counter.
+    size_t GetLengthInBytes() const;
+
+   private:
+    union {
+      uint32 components32[4];
+      uint64 components64[2];
+    } counter_;
+  };
+
   Encryptor();
   virtual ~Encryptor();
 
   // Initializes the encryptor using |key| and |iv|. Returns false if either the
   // key or the initialization vector cannot be used.
+  //
+  // When |mode| is CTR then |iv| should be empty.
   bool Init(SymmetricKey* key, Mode mode, const std::string& iv);
 
   // Encrypts |plaintext| into |ciphertext|.
@@ -39,18 +69,54 @@ class CRYPTO_API Encryptor {
   // Decrypts |ciphertext| into |plaintext|.
   bool Decrypt(const std::string& ciphertext, std::string* plaintext);
 
+  // Sets the counter value when in CTR mode. Currently only 128-bits
+  // counter value is supported.
+  //
+  // Returns true only if update was successful.
+  bool SetCounter(const std::string& counter);
+
   // TODO(albertb): Support streaming encryption.
 
  private:
+  // Generates a mask using |counter_| to be used for encryption in CTR mode.
+  // Resulting mask will be written to |mask| with |mask_len| bytes.
+  //
+  // Make sure there's enough space in mask when calling this method.
+  // Reserve at least |plaintext_len| + 16 bytes for |mask|.
+  //
+  // The generated mask will always have at least |plaintext_len| bytes and
+  // will be a multiple of the counter length.
+  //
+  // This method is used only in CTR mode.
+  //
+  // Returns false if this call failed.
+  bool GenerateCounterMask(size_t plaintext_len,
+                           uint8* mask,
+                           size_t* mask_len);
+
+  // Mask the |plaintext| message using |mask|. The output will be written to
+  // |ciphertext|. |ciphertext| must have at least |plaintext_len| bytes.
+  void MaskMessage(const void* plaintext,
+                   size_t plaintext_len,
+                   const void* mask,
+                   void* ciphertext) const;
+
   SymmetricKey* key_;
   Mode mode_;
+  scoped_ptr<Counter> counter_;
 
 #if defined(USE_OPENSSL)
   bool Crypt(bool encrypt,  // Pass true to encrypt, false to decrypt.
              const std::string& input,
              std::string* output);
   std::string iv_;
 #elif defined(USE_NSS)
+  bool Crypt(PK11Context* context,
+             const std::string& input,
+             std::string* output);
+  bool CryptCTR(PK11Context* context,
+                const std::string& input,
+                std::string* output);
   ScopedPK11Slot slot_;
   ScopedSECItem param_;
 #elif defined(OS_MACOSX)