Method and apparatus for encrypted transmission
First Claim
1. A method of encryption of data in a digital television system communicated between a first decoder and a portable security module operatively connected to the first decoder on a receiving side of the digital television system, comprising:
- storing a plurality of precalculated key pairs in a memory of the first decoder, each of said plurality of precalculated key pairs comprising a session key and an encrypted session key prepared using a transport key,selecting and processing at least one session key to generate a definitive session key, wherein the definitive session key is generated by repeatedly encrypting an initial session key value known to both the first decoder and the portable security module in both devices using an ordered sequence of session keys and an encryption algorithm sensitive to an order of encryption; and
communicating the ordered sequence of session keys and an encrypted version of said at least one session key to the portable security module,wherein the portable security module is configured to use the ordered sequence of session keys and the transport key to decrypt the encrypted version of the at least one session key to obtain the definitive session key,wherein the transport key is stored in a memory associated with the portable security module;
wherein data communicated from at least the portable security module to the first decoder may thereafter be encrypted and decrypted by the definitive session key.
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Accused Products
Abstract
A method of encryption of data in a digital television system communicated between a first decoder and a portable security module, wherein a precalculated key pair is stored in a memory of the first decoder, wherein the key pair includes a session key and an encrypted version of the session key prepared using a transport key, the encrypted version of the session key being subsequently communicated to the portable security module which decrypts the encrypted version using an equivalent transport key stored in its memory such that data communicated from at least the portable security module to the first decoder may thereafter be encrypted and decrypted by the session key.
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Citations
17 Claims
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1. A method of encryption of data in a digital television system communicated between a first decoder and a portable security module operatively connected to the first decoder on a receiving side of the digital television system, comprising:
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storing a plurality of precalculated key pairs in a memory of the first decoder, each of said plurality of precalculated key pairs comprising a session key and an encrypted session key prepared using a transport key, selecting and processing at least one session key to generate a definitive session key, wherein the definitive session key is generated by repeatedly encrypting an initial session key value known to both the first decoder and the portable security module in both devices using an ordered sequence of session keys and an encryption algorithm sensitive to an order of encryption; and communicating the ordered sequence of session keys and an encrypted version of said at least one session key to the portable security module, wherein the portable security module is configured to use the ordered sequence of session keys and the transport key to decrypt the encrypted version of the at least one session key to obtain the definitive session key, wherein the transport key is stored in a memory associated with the portable security module; wherein data communicated from at least the portable security module to the first decoder may thereafter be encrypted and decrypted by the definitive session key. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A digital television system for providing secure communication of data, comprising:
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a first decoder comprising; a memory for storing a plurality of precalculated key pairs, wherein each of the plurality of precalculated key pairs comprises a session key and an encrypted session key prepared using a transport key; a means for selecting and processing at least one session key to generate a definitive session key, wherein the definitive session key is generated by repeatedly encrypting an initial session key value known to both the first decoder and a portable security module using an ordered sequence of session keys and an encryption algorithm sensitive to an order of encryption; and communicate the ordered sequence of session keys and an encrypted version of said at least one session key to the portable security module; the portable security module operatively connected to the first decoder on a receiving side of the digital television system comprising; a memory for storing the transport key; means for decrypting the encrypted version of said at least one session key using the transport key and the ordered sequence of session keys to obtain the definitive session key; and means for encrypting data using the definitive session key, wherein the encrypted data is communicated using a communication means to said first decoder. - View Dependent Claims (13, 14, 15, 16, 17)
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Specification