Question: In a SIM-ME interface, how is the ciphering key KcGPRS encoded in terms of its most and least significant bits within its byte structure according to the EFKcGPRS specification?
Option 1: The most significant bit of KcGPRS is the most significant bit of the last byte, and the least significant bit is the least significant bit of the first byte.
Option 2: The most significant bit of KcGPRS is the most significant bit of the first byte, and the least significant bit is the least significant bit of the eighth byte.
Option 3: The encoding does not specify a direct correlation between the bit significance of KcGPRS and specific bytes within its structure.
Option 4: The most significant bit of KcGPRS is in the middle byte, with the least significant bit distributed across all bytes.
Explanation: This correct answer reflects the specified encoding method for the ciphering key KcGPRS, where its most significant bit is located at the beginning (first byte) and its least significant bit at the end (eighth byte). This precise arrangement is crucial for accurate key interpretation in GPRS encryption processes.