Cryptography – Cellular telephone cryptographic authentication
Reexamination Certificate
1997-11-12
2001-07-24
Peeso, Thomas R. (Department: 2132)
Cryptography
Cellular telephone cryptographic authentication
C235S380000
Reexamination Certificate
active
06266415
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a process for protecting an information item transmitted from a security element such as, for example, a user-card of a conditional-access system, to a decoder.
The invention applies more particularly to conditional-access systems for which the descrambling operation is performed in the security element which is then, for example, a PCMCIA type card complying with the interface standard known by those skilled in the art as “CENELEC/DVB-Common Interface” or a chip card complying with the American NRSS standard (standing for “National Renewable Security System”).
The invention applies to any type of conditional-access system, whether this system be of the on-line type or the standalone type.
In an on-line conditional-access system, the scrambled information item is an information item consisting of a signal distributed simultaneously to various users.
In a standalone conditional-access system, the scrambled information item is contained on standalone information media such as, for example, compact discs or digital video discs.
The information item making up the various programmes originating from the issuing source, such as, for example, a service provider, is transmitted to the security element. The security element descrambles the programme selected by the user (provided that the user's entitlements are present in the security element) and sends this programme, as well as the other programmes which have remained unchanged, to the decoder.
Such a process has the drawback that the programme selected by the user is transmitted unenciphered.
Such a transmission can readily be exploited by a pirate who can use it to distribute the pirated programme illegally.
FIG. 1
represents the schematic of a security element/decoder assembly according to the prior art.
The system of
FIG. 1
comprises an information source I, a decoder
6
and a security element
1
.
The decoder comprises a demodulation device
7
and a demultiplexing and decoding device
8
.
The security element
1
contains a filtering device
2
, a descrambling device
3
, an access control device
4
and a user entitlement storage device
5
.
The information item I issued by the issuing source contains one or more multiplexed programmes, for example, according to the MPEG-
2
transport standard (standing for “Moving Picture Expert Group”).
As is known to those skilled in the art, the programmes output by the issuing source are scrambled programmes. The information item I contains, in messages which will hereafter be denoted ECM, the encrypted control words allowing, after decryption, the descrambling of the scrambled programmes.
After the decoder receives the information item I, the latter is demodulated by the device
7
and then transmitted in full to the security element
1
. The latter filters, with the aid of the device
2
, the ECMs (denoted ECMA in
FIG. 1
) corresponding to the programme selected by the user and transmits them to the device
4
for processing. The non-filtered part of the information item is transmitted without modification to the descrambler
3
. The device
4
carries out the conventional functions for processing the ECMs, and, in particular, decrypts the control words CWi which they contain, provided that the entitlements D necessary for descrambling the selected programme and output by the device
5
are applied to the device
4
.
The control words CWi are subsequently transmitted to the descrambling device
3
which uses them to descramble the programme selected by the user. The information item output by the descrambler
3
is transmitted to the demultiplexing and decoding device
8
so as to generate the usable, i.e., for example, displayable in the case of a film, information item ECG
1
.
SUMMARY OF THE INVENTION
The invention does not have this drawback.
The invention relates to a process making it possible to transfer from a security element to a decoder a stream of data arising from a descrambler included within the security element. The process comprises a first step making it possible to encrypt, in the security element, the information item arising from the descrambler under the action of a first encryption key and a second step making it possible to decrypt, in the decoder, the encrypted information item arising from the first step, under the action of a second encryption key.
The invention also relates to a security element containing a descrambler making it possible to descramble the information item which it receives under the action of control words. The security element comprises a device for encrypting the descrambled information item arising from the descrambler under the action of a first encryption key.
The invention also relates to a decoder making it possible to decode data arising from a security element, the said data representing at least one programme selected by a conditional-access system user. The decoder comprises a decryption device making it possible to decrypt, under the action of a second key, the data arising from the security element, the said data being data which are descrambled and encrypted under the action of a first key.
The invention further relates to an assembly made up of a security element and of a decoder. The security element is a security element according to the invention such as that mentioned above and the decoder is a decoder according to the invention such as that mentioned above.
As has been mentioned earlier, an advantage of the invention consists in protecting the transmission of the programme selected by the user from the security element to the decoder.
Other characteristics and advantages of the invention will emerge on reading embodiments of the invention given with reference to the appended figures in which:
REFERENCES:
patent: 4295039 (1981-10-01), Stuckert
patent: 5703951 (1997-12-01), Dolphin
patent: 5721781 (1998-02-01), Deo et al.
patent: 5870476 (1999-02-01), Fischer
patent: 0471 373 (1992-02-01), None
patent: 96/06504 (1996-02-01), None
J.Giachetti/V.Lenoir/A.Codet/D.Cutts/J.Sager; A Common Conditional Access Interface for Digital Video Broadcasting Decoders; “IEEE Transactions on Consumer Electronics”, vol. 41, No. 3, Aug. 1994, pp. 836-841.
Campinos Arnaldo
Fischer Jean-Bernard
Herrmann E. P.
Jack Todd
Peeso Thomas R.
Shoneman D. T.
Thomson Multimedia S.A.
LandOfFree
Process for protecting an information item transmitted from... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for protecting an information item transmitted from..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for protecting an information item transmitted from... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2465176