Cast: Adding helper crypto classes

media/cast/cast_defines.h

Index: media/cast/cast_defines.h
diff --git a/media/cast/cast_defines.h b/media/cast/cast_defines.h
index ec2651e9f506480e7053d687589472ef2a104c88..b8a7d9548d5a7ed9cf194ff9faa745c9e7ef5cb3 100644
--- a/media/cast/cast_defines.h
+++ b/media/cast/cast_defines.h
@@ -55,9 +55,6 @@ const size_t kMinLengthOfRtcp = 8;
 // Basic RTP header + cast header.
 const size_t kMinLengthOfRtp = 12 + 6;
 
-const size_t kAesBlockSize = 16;
-const size_t kAesKeySize = 16;
-
 // Each uint16 represents one packet id within a cast frame.
 typedef std::set<uint16> PacketIdSet;
 // Each uint8 represents one cast frame.
@@ -147,22 +144,6 @@ inline base::TimeTicks ConvertNtpToTimeTicks(uint32 ntp_seconds,
   return base::TimeTicks::UnixEpoch() + elapsed_since_unix_epoch;
 }
 
-inline std::string GetAesNonce(uint32 frame_id, const std::string& iv_mask) {
-  std::string aes_nonce(kAesBlockSize, 0);
-
-  // Serializing frame_id in big-endian order (aes_nonce[8] is the most
-  // significant byte of frame_id).
-  aes_nonce[11] = frame_id & 0xff;
-  aes_nonce[10] = (frame_id >> 8) & 0xff;
-  aes_nonce[9] = (frame_id >> 16) & 0xff;
-  aes_nonce[8] = (frame_id >> 24) & 0xff;
-
-  for (size_t i = 0; i < kAesBlockSize; ++i) {
-    aes_nonce[i] ^= iv_mask[i];
-  }
-  return aes_nonce;
-}
-
 inline uint32 GetVideoRtpTimestamp(const base::TimeTicks& time_ticks) {
   base::TimeTicks zero_time;
   base::TimeDelta recorded_delta = time_ticks - zero_time;