scope:

Replace Section 1 Scope in its entirety with:

This standard defines a syntax for encrypted Track Files, i.e. MXF files containing a single Essence Track, and specifies a matching reference decryption model. It uses the AES cipher algorithm for essence encryption and, optionally, the HMAC-SHA1 algorithm for essence integrity.

This standard assumes that the cryptographic keys necessary to decrypt and verify the integrity of encrypted Track Files will be available upon demand. More precisely, it does not specify the fashion with which cryptographic keys and usage rights are managed.

In addition, this document does not address, but does not preclude, the use of watermarking, fingerprinting or other security techniques to provide additional protection.