Add ChaCha20Poly1305Encrypter, based on

net/quic/crypto/aead_base_decrypter.h

Index: net/quic/crypto/aead_base_decrypter.h
===================================================================
--- net/quic/crypto/aead_base_decrypter.h	(revision 255481)
+++ net/quic/crypto/aead_base_decrypter.h	(working copy)
@@ -2,43 +2,36 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#ifndef NET_QUIC_CRYPTO_AES_128_GCM_12_DECRYPTER_H_
-#define NET_QUIC_CRYPTO_AES_128_GCM_12_DECRYPTER_H_
+#ifndef NET_QUIC_CRYPTO_AEAD_BASE_DECRYPTER_H_
+#define NET_QUIC_CRYPTO_AEAD_BASE_DECRYPTER_H_
 
-#include <string>
-
 #include "base/compiler_specific.h"
 #include "net/quic/crypto/quic_decrypter.h"
 
 #if defined(USE_OPENSSL)
 #include "net/quic/crypto/scoped_evp_aead_ctx.h"
+#else
+#include <pkcs11t.h>
 #endif
 
 namespace net {
 
-namespace test {
-class Aes128Gcm12DecrypterPeer;
-}  // namespace test
-
-// An Aes128Gcm12Decrypter is a QuicDecrypter that implements the
-// AEAD_AES_128_GCM_12 algorithm specified in RFC 5282. Create an instance by
-// calling QuicDecrypter::Create(kAESG).
-//
-// It uses an authentication tag of 12 bytes (96 bits). The fixed prefix
-// of the nonce is four bytes.
-class NET_EXPORT_PRIVATE Aes128Gcm12Decrypter : public QuicDecrypter {
+// AeadBaseDecrypter is the base class of AEAD QuicDecrypter subclasses.
+class AeadBaseDecrypter : public QuicDecrypter {
  public:
-  enum {
-    // Authentication tags are truncated to 96 bits.
-    kAuthTagSize = 12,
-  };
+#if defined(USE_OPENSSL)
+  AeadBaseDecrypter(const EVP_AEAD* aead_alg,
+                    size_t key_size,
+                    size_t auth_tag_size,
+                    size_t nonce_prefix_size);
+#else
+  AeadBaseDecrypter(CK_MECHANISM_TYPE aead_mechanism,
+                    size_t key_size,
+                    size_t auth_tag_size,
+                    size_t nonce_prefix_size);
+#endif
+  virtual ~AeadBaseDecrypter();
 
-  Aes128Gcm12Decrypter();
-  virtual ~Aes128Gcm12Decrypter();
-
-  // Returns true if the underlying crypto library supports AES GCM.
-  static bool IsSupported();
-
   // QuicDecrypter implementation
   virtual bool SetKey(base::StringPiece key) OVERRIDE;
   virtual bool SetNoncePrefix(base::StringPiece nonce_prefix) OVERRIDE;
@@ -53,11 +46,45 @@
   virtual base::StringPiece GetKey() const OVERRIDE;
   virtual base::StringPiece GetNoncePrefix() const OVERRIDE;
 
+ protected:
+  // Make these constants available to the subclasses so that the subclasses
+  // can assert at compile time their key_size_ and nonce_prefix_size_ do not
+  // exceed the maximum.
+  static const size_t kMaxKeySize = 32;
+  static const size_t kMaxNoncePrefixSize = 4;
+
+#if !defined(USE_OPENSSL)
+  struct AeadParams {
+    unsigned int len;
+    union {
+      CK_GCM_PARAMS gcm_params;
+#if !defined(USE_NSS)
+      // The system NSS <pkcs11n.h> header doesn't define this type yet.
+      CK_NSS_AEAD_PARAMS nss_aead_params;
+#endif
+    } data;
+  };
+
+  virtual void FillAeadParams(base::StringPiece nonce,
+                              base::StringPiece associated_data,
+                              size_t auth_tag_size,
+                              AeadParams* aead_params) const = 0;
+#endif
+
  private:
-  // The 128-bit AES key.
-  unsigned char key_[16];
+#if defined(USE_OPENSSL)
+  const EVP_AEAD* aead_alg_;
+#else
+  CK_MECHANISM_TYPE aead_mechanism_;
+#endif
+  const size_t key_size_;
+  const size_t auth_tag_size_;
+  const size_t nonce_prefix_size_;
+
+  // The key.
+  unsigned char key_[kMaxKeySize];
   // The nonce prefix.
-  unsigned char nonce_prefix_[4];
+  unsigned char nonce_prefix_[kMaxNoncePrefixSize];
 
 #if defined(USE_OPENSSL)
   ScopedEVPAEADCtx ctx_;
@@ -66,4 +93,4 @@
 
 }  // namespace net
 
-#endif  // NET_QUIC_CRYPTO_AES_128_GCM_12_DECRYPTER_H_
+#endif  // NET_QUIC_CRYPTO_AEAD_BASE_DECRYPTER_H_