name: DUCK
full_form: Discovery User Confidentility Key
context: The Remote UE does the following: 1. If DUCK available, set DUCK as key K. If DUCK is not available, then choose DUSK as K. If neither DUCK nor DUSK are available, the DCR message is not protected, and Steps 2-4 can be skipped. 2. Form Message = RSC || PRUK ID 3. Calculate Keystream = KDF (K, UTC-based counter, RSC) â see subclause 6.42.2.3. 4. Ciphertext = Message XOR Keystream The UE-to-network relay does the following to retrieve the protected fields of the received DCR message, e.g., RSC and PRUK ID: 1. If DUCK available, set DUCK as key K. If DUCK is not available, then choose DUSK as K. If neither DUCK nor DUSK are available, the DCR message is not protected and Steps 2-5 can be skipped. 2. Form Ciphertext = a part of protected (RSC || PRUK ID) in the received DCR message. 3. Calculate Keystream = KDF (K, UTC-based counter, RSC) â see subclause 6.42.2.3. 4. Obtain (RSC_Received || PRUK ID_Received) = MessageReceived = Ciphertext XOR Keystream 5. If RSC_Received equals RSC in Step
description: DUCK is a key used for protecting the PRUK ID and RSC over the PC5 interface, specifically utilized in the calculation of keystream for encryption and decryption purposes.
explanation: The text describes DUCK as a key used in cryptographic operations to protect specific data elements (PRUK ID and RSC) within a communication context (PC5 interface). This aligns with the definition of a Parameter, which encompasses critical network attributes like keys and identifiers essential for secure communication and message integrity.
section_title: 6.42.2.2	Protection of PRUK ID and RSC over the PC5 interface
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biotag_Description: B-Parameter,O,O,O,O,O,O,O,B-Parameter,B-Parameter,O,B-Parameter,O,O,O,O,O,O,O,O,O,O,O,O,O,O,O,O