rity mechanism that encrypts or signs an Ogg bitstream and thus provides content confidentiality and authenticity. As Ogg encapsulates binary data, it is possible to include executable content in an Ogg bitstream. Implementations SHOULD NOT execute such content without prior validation of its origin by the end-user. Issues may arise on applications that use Ogg for streaming or file transfer in a networking scenario. In such cases, implementations decoding Ogg and its encapsulated bitstreams have to ensure correct handling of manipulated bitstreams, of buffer overflows, and similar issues. It is also possible to author malicious Ogg bitstreams, which attempt to call for an excessively large picture size, high sampling-rate audio, etc. Implementations SHOULD protect themselves against this kind of attack. Ogg has an extensible structure, so that it is theoretically possible that metadata fields or media formats might be defined in the future which might be used to induce particular actions on the part of the recipient, thus presenting additional security risks. However, this type of capability is currently not supported in the referenced specification. Implementations may fail to implement a specific security model or other means to prevent possibly dangerous operations. Such failure might possibly be exploited to gain unauthorized access to a system or sensitive information; such failure constitutes an unknown factor and is thus considered out of the scope of this document. Goncalves, et al. Standards Track [Page 6]