Access control for digital video stream data
View Patent ↗A data encryption apparatus operable to apply encryption to input data having at least a format identifying portion and a payload portion comprises means for discriminating between the format identifying portion of the input data and the payload portion of the input data; and means for selectively applying encryption to the input data in dependence upon an output of the discriminating means so as to encrypt at least a part of the payload portion of the input data but not to encrypt the format identifying portion. A corresponding decryption apparatus is also provided.
1. A data encryption apparatus operable to apply encryption to video stream input data having at least a format identifying portion and a payload portion, said apparatus comprising:
a discriminator to discriminate between said format identifying portion of said input data and said payload portion of said input data; and
an encryptor to selectively apply encryption to said input data in dependence upon an output of said discriminator so as to encrypt at least a part of said payload portion of said input data but not to encrypt said format identifying portion.
2. Apparatus according to claim 1 , in which said format identifying portion occurs repetitively through said input data.
3. Apparatus according to claim 2 , in which said format identifying portion identifies at least picture boundaries.
4. Apparatus according to claim 3 , in which said video data conforms to an MPEG compression standard.
5. Apparatus according to claim 3 , in which said format identifying portion comprises at least MPEG picture headers.
6. Apparatus according to claim 2 , in which encryption is applied to some but not all of said video pictures.
7. Apparatus according to claim 2 , in which, in respect of those pictures which are encrypted, encryption is applied to some but not all of each picture.
8. Apparatus according to claim 2 , in which, in respect of at least some of said pictures, a first encryption scheme is applied to some but not all of each picture, and a second encryption scheme is applied to at least the remainder of each picture.
9. Apparatus according to claim 8 in which said first encryption scheme is visible watermarking and said second encryption scheme is symmetric or asymmetric encryption.
10. Apparatus according to claim 9 , in which said encryptor is operable not to generate said one or more predetermined data patterns within said encrypted payload data.
11. Apparatus according to claim 1 , in which said discriminator is operable to identify one or more predetermined data patterns within said input data.
12. Data encryption/decryption apparatus comprising encryption apparatus according to claim 1 and decryption apparatus operable to apply decryption to video stream input data having at least an unencrypted format identifying portion and an encrypted payload portion, said apparatus comprising:
a discriminator to discriminate between said format identifying portion of said input data and said encrypted payload portion of said input data;
a decryptor to selectively apply decryption to said input data in dependence upon an output of said discriminator so as to decrypt at least a part of said payload portion of said input data but not to decrypt said format identifying portion.
13. Apparatus according to claim 1 , in which said apparatus comprises an audio and/or video capture, processing or output apparatus.
14. A data decryption apparatus operable to apply decryption to video stream input data having at least an unencrypted format identifying portion and an encrypted payload portion, said apparatus comprising:
a discriminator to discriminate between said format identifying portion of said input data and said encrypted payload portion of said input data;
for a decryptor to selectively apply decryption to said input data in dependence upon an output of said discriminator so as to decrypt at least a part of said payload portion of said input data but not to decrypt said format identifying portion.
15. A data encryption method for applying encryption to video stream input data having at least a format identifying portion and a payload portion, said method comprising the steps of:
discriminating between said format identifying portion of said input data and said payload portion of said input data; and
selectively applying encryption to said input data in dependence upon said discrimination so as to encrypt at least a part of said payload portion of said input data but not to encrypt said format identifying portion.
16. A computer readable medium encoded with computer program instructions which cause a data processor to execute the method according to claim 15 .
17. A data decryption method for applying decryption to video stream input data having at least an unencrypted format identifying portion and an encrypted payload portion, said method comprising the steps of:
discriminating between said format identifying portion of said input data and said encrypted payload portion of said input data;
a decryptor to selectively apply decryption to said input data in dependence upon said discrimination so as to decrypt at least a part of said payload portion of said input data but not to decrypt said format identifying portion.