private void HandleKey(SubStreamSegment segment, IEnumerable <ExtKeyTagInstance> extKeys, CancellationToken cancellationToken)
{
ExtKeyTagInstance[] extKeyTagInstanceArray = extKeys.ToArray();
if (extKeyTagInstanceArray.Length < 1)
{
return;
}
string url = null;
byte[] iv = null;
foreach (ExtKeyTagInstance extKeyTagInstance in extKeyTagInstanceArray)
{
var b = extKeyTagInstance.AttributeObject(ExtKeySupport.AttrMethod);
if (string.Equals("NONE", b, StringComparison.OrdinalIgnoreCase))
{
url = null;
}
else
{
if (!string.Equals("AES-128", b, StringComparison.OrdinalIgnoreCase))
{
if (string.Equals("SAMPLE-AES", b, StringComparison.OrdinalIgnoreCase))
{
throw new NotImplementedException("Method SAMPLE-AES decryption is not implemented");
}
throw new NotSupportedException("Unknown decryption method type: " + b);
}
string str = extKeyTagInstance.AttributeObject(ExtKeySupport.AttrUri);
if (null != str)
{
url = str;
}
byte[] numArray = extKeyTagInstance.AttributeObject(ExtKeySupport.AttrIv);
if (null != numArray)
{
iv = numArray;
}
}
}
if (null == url)
{
return;
}
if (null == iv)
{
iv = new byte[16];
long num = segment.MediaSequence ?? _segmentIndex - 1;
iv[15] = (byte)((ulong)num & byte.MaxValue);
iv[14] = (byte)((ulong)(num >> 8) & byte.MaxValue);
iv[13] = (byte)((ulong)(num >> 16) & byte.MaxValue);
iv[12] = (byte)((ulong)(num >> 24) & byte.MaxValue);
}
Func <Stream, CancellationToken, Task <Stream> > filter = segment.AsyncStreamFilter;
Uri uri = _parser.ResolveUrl(url);
segment.AsyncStreamFilter = async(stream, ct) =>
{
if (null != filter)
{
stream = await filter(stream, ct).ConfigureAwait(false);
}
byte[] key;
if (!_keyCache.TryGetValue(uri, out key))
{
key = await LoadKeyAsync(uri, cancellationToken).ConfigureAwait(false);
if (16 != key.Length)
{
throw new FormatException("AES-128 key length mismatch: " + key.Length);
}
_keyCache[uri] = key;
}
Debug.WriteLine("Segment AES-128: key {0} iv {1}", BitConverter.ToString(key), BitConverter.ToString(iv));
return(_platformServices.Aes128DecryptionFilter(stream, key, iv));
};
}