author  Alexander Simm

The encryption method defines how the encrypted content can be decrypted.
Values for the field are defined in the following table:

Value	Algorithm
0	no encryption used
1	AES_128_CBC: AES symmetric encryption as defined by NIST. 128 bit keys, Cipher block chaining mode (CBC). For the first block a 128-bit initialisation vector (IV) is used. For DCF files, the IV is included in the OMADRMData as a prefix of the encrypted data. For non-streamable PDCF files, the IV is included in the IV field of the OMAAUHeader and the IVLength field in the OMAAUFormatBox MUST be set to 16. Padding according to RFC 2630
2	AES_128_CTR: AES symmetric encryption as defined by NIST. 128 bit keys, Counter mode (CTR). The counter block has a length of 128 bits. For DCF files, the initial counter value is included in the OMADRMData as a prefix of the encrypted data. For non-streamable PDCF files, the initial counter value is included in the IV field of the OMAAUHeader and the IVLength field in the OMAAUFormatBox MUST be set to 16. For each cipherblock the counter is incremented by 1 (modulo 2128). No padding.

@return the encryption method

The padding scheme defines how the last block of ciphertext is padded.
Values of the padding scheme field are defined in the following table:

Value	Padding scheme
0	No padding (e.g. when using NULL or CTR algorithm)
1	Padding according to RFC 2630

@return the padding scheme