QUIC: support diversified keys with version 33.

net/quic/crypto/quic_decrypter.cc

Index: net/quic/crypto/quic_decrypter.cc
diff --git a/net/quic/crypto/quic_decrypter.cc b/net/quic/crypto/quic_decrypter.cc
index eae1f8fcf6d6f3fcaa5776da6cc01cb19ca869f7..193d1e87eb4a0a44774df4670268d6eb3f47eba4 100644
--- a/net/quic/crypto/quic_decrypter.cc
+++ b/net/quic/crypto/quic_decrypter.cc
@@ -4,11 +4,15 @@
 
 #include "net/quic/crypto/quic_decrypter.h"
 
+#include "crypto/hkdf.h"
 #include "net/quic/crypto/aes_128_gcm_12_decrypter.h"
 #include "net/quic/crypto/chacha20_poly1305_rfc7539_decrypter.h"
 #include "net/quic/crypto/crypto_protocol.h"
 #include "net/quic/crypto/null_decrypter.h"
 
+using base::StringPiece;
+using std::string;
+
 namespace net {
 
 // static
@@ -26,4 +30,20 @@ QuicDecrypter* QuicDecrypter::Create(QuicTag algorithm) {
   }
 }
 
+// static
+void QuicDecrypter::DiversifyPreliminaryKey(StringPiece preliminary_key,
+                                            StringPiece nonce_prefix,
+                                            DiversificationNonce nonce,
+                                            size_t key_size,
+                                            size_t nonce_prefix_size,
+                                            string* out_key,
+                                            string* out_nonce_prefix) {
+  crypto::HKDF hkdf(preliminary_key.as_string() + nonce_prefix.as_string(),
+                    StringPiece(nonce, kDiversificationNonceSize),
+                    "QUIC key diversification", 0, key_size, 0,
+                    nonce_prefix_size, 0);
+  *out_key = hkdf.server_write_key().as_string();
+  *out_nonce_prefix = hkdf.server_write_iv().as_string();
+}
+
 }  // namespace net