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Glossary

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S

Subscription mode

The consumer is granted unlimited access to one or more services subject to conditional access for a fixed time period.

Symmetric algorithm

Algorithm used in symmetric encryption. AES and DES are well known symmetric algorithms.

Symmetric encryption

Type of encryption in which encryption and decryption keys are the same key or can easily be derived from each other. In most cryptographic systems, the decryption key and the encryption keys are identical.

Stream cipher modes

Used for block cipher operation mode that operates the algorithm as a stream cipher.

Subscriber

A household or business that legally receives and pays for cable or Pay TV services for its own use (not for retransmission).

Subscription

The consumer subscribes for some (protected) services and pays for the subscription (e.g. by invoice).

SPTS

Short for Single Program Transport Stream, an MPEG-2 compliant transport stream that contains a single program. Because it contains only one program, an SPTS is referenced to a single time base. The time base is encoded into the SPTS using MPEG-2 PCRs. An SPTS may contain multiple elementary streams. See also MPTS.

STB

Short for set-top box. A device that enables a TV to receive and decode
digital television broadcasts.

Stream cipher

Algorithms that simply produce a keystream to be XORed with the plaintext. The same keystream is reproduced at receiver side for decryption.

SimulCrypt

A mechanism whereby a single transport stream can contain several CA information for several CA systems. This enables different CA decoder populations to receive and correctly descramble the same video and audio streams using the different CA systems.

SMS

(1) Short for Subscriber Management System. Subsystem of the CA system that manages the subscriber's information and requests EMM playout from the SAS.

(2) Short for Short Message System. See GSM/SMS.

SMS-SAS Interface

Interface used by the SMS to authorise its customers by passing requests to the SAS, containing information about what to authorise for and whom to authorise. These requests are then processed by the SAS according to their type.

Security token

A physical device (e.g. a smart card) that together with something that a consumer knows, such as a PIN, will enable authorised access to a computer or network. See also token.

Session key

A key (normally symmetric) used to encrypt each set of data on a transaction basis. A different session key is used for each communication session. The session key is normally transferred to the receiver using a key exchange mechanism or by encrypting the key under the receiver's public key.

SI

Short for Service Information. Service Information data forms a part of the DVB transport stream. It is included for two main reasons: So that an STB can automatically configure itself for the selected service, and so that the consumer can be provided with information to assist in selection of services and/or events within the bit stream. See also PSI.

S-DMB

Short for Satelite-DMB. See DMB.

SECAM

Short for Sequential Couleur Avec Memoire (Sequential Color with Memory). A composite color standard similar to PAL (image format 4:3, 625 lines, 50 Hz and 6 Mhz video bandwidth), but currently used only as a transmission standard in France and a few other countries. Video is produced using the 625/50 PAL standard and is then transcoded to SECAM by the player or transmitter. See also NTSC.

Scrambling

Scrambling is often used as a word for weaker encryption or controlled distortion of an analog signal. The distortion can be removed by possessing and using the descrambling equipment and proper keys.

SCS

Short for Simulcrypt Synchroniser. Logical component that aquires control words and ECMs and synchronizes their playout for all the CA systems connected. See also SimulCrypt.

SCTE

Short for Society of Telecommunications Engineers. See www.scte.org

Satellite uplink / satellite feeder link

The part of a satellite transmission system that transmits programming from the Earth to a communications satellite for subsequent retransmission to the cable head end or individual consumer via a satellite downlink.

Scrambled signal

Signal after scrambling.

SAS

Short for Subscriber Authorisation System. Subsystem of the CA system that translates the subscriber's entitlement information into an EMM. The SAS also ensures that the subscriber's security module (typically a smart card) receives the authorisation needed to view the programs.